tag:theconversation.com,2011:/africa/topics/x-rays-22661/articles
X-rays – The Conversation
2023-07-16T20:00:42Z
tag:theconversation.com,2011:article/209041
2023-07-16T20:00:42Z
2023-07-16T20:00:42Z
Why do I have to take my laptop out of the bag at airport security?
<figure><img src="https://images.theconversation.com/files/537438/original/file-20230714-15-diyhpf.jpeg?ixlib=rb-1.1.0&rect=69%2C688%2C5742%2C2884&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption"></span> </figcaption></figure><p>Anyone who has travelled by air in the past ten years will know how stressful airports can be.</p>
<p>You didn’t leave home as early as you should have. In the mad rush to get to your gate, the security screening seems to slow everything down. And to add insult to injury, you’re met with the finicky request: “laptops out of bags, please”.</p>
<p>But what does your laptop have to do with security?</p>
<h2>The day that changed air travel forever</h2>
<p>Airport security changed dramatically after the terrorist attacks in the US on September 11 2001. Before 9/11, you could pass through security with a carry-on bag full of everything you might need for your holiday, <a href="https://www.npr.org/2021/09/10/1035131619/911-travel-timeline-tsa">including a knife</a> with a four-inch blade. Indeed, that’s how the 9/11 attackers brought their <a href="https://www.npr.org/2021/09/10/1035131619/911-travel-timeline-tsa">weapons on board</a>.</p>
<p>After 9/11, screening processes around the world changed overnight. In the US, private security contractors being paid a minimum wage were swapped out for a federalised program with highly trained security personnel. Anything that could be <a href="https://www.frontiersin.org/articles/10.3389/fnhum.2013.00654/full">considered a weapon</a> was confiscated.</p>
<p>Around the world, travellers were suddenly required to <a href="https://books.google.com.au/books?hl=en&lr=&id=6hBnJ-1hRp0C&oi=fnd&pg=PA86&dq=why+do+I+have+to+take+my+shoes+off+at+airport+security&ots=o6JIFHJzF1&sig=B6azb6xqN2uxM9CP-VZdfyt3Ag0#v=onepage&q=why%20do%20I%20have%20to%20take%20my%20shoes%20off%20at%20airport%20security&f=false">remove their shoes</a>, belts and outerwear, and take out their phones, laptops, liquids and anything else that could be used as part of an improvised explosive device.</p>
<p>This lasted for several years. Eventually, <a href="https://www.sciencedirect.com/science/article/pii/S2212478013000944">more advanced</a> screening methods were developed to effectively identify certain threats. Today, some countries don’t require you to remove your shoes when passing through security.</p>
<p>So why must you still take your laptop out? </p>
<h2>Airport scanners have come a long way</h2>
<p>The machine your bags and devices pass through is an X-ray machine. </p>
<p>The main reason you have to remove your laptop from your bag is because its <a href="https://www.smh.com.au/traveller/reviews-and-advice/why-do-i-have-to-remove-my-laptop-from-my-bag-at-the-airport-xray-machine-20170320-gv1vqs.html">battery</a> and other mechanical components are too dense for X-rays to penetrate effectively – especially if the scanning system is old. The same goes for power cords and other devices such as tablets and cameras.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/537439/original/file-20230714-21-x0ojbc.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/537439/original/file-20230714-21-x0ojbc.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/537439/original/file-20230714-21-x0ojbc.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/537439/original/file-20230714-21-x0ojbc.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/537439/original/file-20230714-21-x0ojbc.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/537439/original/file-20230714-21-x0ojbc.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/537439/original/file-20230714-21-x0ojbc.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/537439/original/file-20230714-21-x0ojbc.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">Due to the size and construction of components in your laptop, X-rays can’t penetrate them as well as other materials.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
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<p>With these items in your bag, security officials can’t use the screened image to determine whether a risk is present. They’ll have to flag the bag for a physical search, which slows everything down. It’s easier if all devices are removed in the first place.</p>
<p>A laptop inside a bag can also shield other items from view that may be dangerous. Scanning it separately reveals its internal components on the screen. In some cases you might be asked to turn it on to prove it’s an actual working computer.</p>
<p>With newer multi-view scanning technology, security officials can view the bag from multiple angles to discern whether something is being covered up, or made to look like something else. For instance, people have tried to <a href="https://www.sciencedirect.com/science/article/pii/S2212478013000944">mix gun parts</a> with other components in an effort to pass checked baggage screening. </p>
<p>Some airports have upgraded <a href="https://www.smh.com.au/traveller/inspiration/no-more-removing-liquids-and-gels-laptops-at-melbourne-airport-as-new-scanners-installed-20191002-h1ijdf.html">3D scanning</a> that allows travellers to pass their bags through security without having to remove their laptops. If you’re not asked to take out your laptop, it’s probably because one of these more expensive systems is being used.</p>
<p>Nonetheless, amping up the technology won’t remove the lag caused by airport screenings. Ultimately, the reason these are a major choke point is because of the speed at which staff scan the imagery (which dictates the <a href="https://www.sciencedirect.com/science/article/pii/S2212478013000944">speed of the conveyor belt</a>).</p>
<p>Unless we find a way to automate the entire process and run it with minimal human supervision, you can expect delays.</p>
<h2>What about body scanners?</h2>
<p>But your bags aren’t the only thing getting scanned at airport security. You are too! </p>
<p>The tall frame you walk through is a <a href="https://science.howstuffworks.com/transport/flight/modern/airport-security3.htm">metal detector</a>. Its purpose is to uncover any weapons or other illegal objects that may be concealed under your clothes. Airport metal detectors use non-ionising radiation, which means they don’t emit X-rays. </p>
<p>The larger body scanners, on the other hand, are a type of X-ray machine. These can be <a href="https://www.sciencedirect.com/science/article/pii/S2212478013000944">active or passive</a>, or a combination of both.</p>
<p>Passive scanners simply detect the natural radiation emitted by your body and any objects that might be concealed. Active scanners emit low-energy radiation to create a scan of your body, which can then be analysed. </p>
<p>The kind of machine you walk through will depend on where in the world you are. For instance, one type of active body scanner that emits X-rays in what’s called “backscatter technology” was once <a href="https://electronics.howstuffworks.com/gadgets/high-tech-gadgets/backscatter-x-ray.htm">used widely</a> in the US, but is no longer used. It’s also banned in <a href="https://www.homeaffairs.gov.au/about-us/what-we-do/travelsecure/passenger-screening">Australia</a> and <a href="https://www.forbes.com/sites/daviddisalvo/2011/11/15/europe-bans-airport-body-scanners-over-health-and-safety-concerns/">the European Union</a>, where only non-ionising technology can be used.</p>
<p>Another type of scanner emits lower-energy <a href="https://science.howstuffworks.com/backscatter-machines-vs-millimeter-wave-scanners.htm">millimetre waves</a>, instead of X-rays, to image the passenger. Millimetre wave frequencies are considered to be non-ionising radiation.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/537440/original/file-20230714-27-gwwiup.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/537440/original/file-20230714-27-gwwiup.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/537440/original/file-20230714-27-gwwiup.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/537440/original/file-20230714-27-gwwiup.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/537440/original/file-20230714-27-gwwiup.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/537440/original/file-20230714-27-gwwiup.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/537440/original/file-20230714-27-gwwiup.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/537440/original/file-20230714-27-gwwiup.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Millimetre wave scanners usually produce a 3D scan of a person.</span>
<span class="attribution"><span class="source">Wikimedia</span></span>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/air-travel-exposes-you-to-radiation-how-much-health-risk-comes-with-it-78790">Air travel exposes you to radiation – how much health risk comes with it?</a>
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</em>
</p>
<hr>
<h2>AI in our airports</h2>
<p>AI seems to be all around us lately, and our airports are no exception. Advancements in AI systems stand to transform the future of airport security.</p>
<p>For now, human reviewers are required to identify potential threats in scanned images. However, what if an advanced <a href="https://thinkspace.csu.edu.au/artiificialintelligenceinsecuritycheck/article/">AI was trained</a> to do this using a database of images? It would do so in a fraction of the time.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/whats-the-safest-seat-on-a-plane-we-asked-an-aviation-expert-198672">What's the safest seat on a plane? We asked an aviation expert</a>
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</em>
</p>
<hr>
<p>Some airports are already using advanced <a href="https://www.in-security.eu/index.php/editorial/the-future-of-airport-security-faster-smarter-safer">computed tomography</a> (CT) <a href="https://www.theguardian.com/australia-news/2022/jun/21/3d-body-scanners-at-australian-airports-what-are-they-and-how-do-they-work">scanners</a> to produce high-definition 3D imagery. In the future, this technology could be further enhanced by AI to detect threats at a much faster rate. </p>
<p>Hypothetically, CT scans could also be used for both humans and their baggage. Could this allow travellers to walk through a body scanner while carrying their bags? Possibly.</p>
<p>Until then, you should probably try your best to leave the house on time.</p>
<hr>
<p><em>Correction: this article previously said X-ray backscatter technology is widely used in US airports, when in fact it is no longer used.</em></p><img src="https://counter.theconversation.com/content/209041/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Doug Drury does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>
Some countries no longer require you to remove your shoes when passing through security – but taking out your laptop is still mostly required.
Doug Drury, Professor/Head of Aviation, CQUniversity Australia
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/209267
2023-07-14T13:04:51Z
2023-07-14T13:04:51Z
Curious Kids: can our brains sense electromagnetic waves?
<figure><img src="https://images.theconversation.com/files/537088/original/file-20230712-24-dkt9zu.jpg?ixlib=rb-1.1.0&rect=0%2C594%2C6016%2C3413&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/boy-listens-retro-radio-dark-candle-2040156215">calzone.photography/Shutterstock</a></span></figcaption></figure><p><strong>Can our brains sense electromagnetic waves? – Taye, aged 10, London</strong></p>
<p><a href="https://www.bbc.co.uk/bitesize/guides/zdx4t39/revision/2">Electromagnetic waves</a> are packets of energy travelling all around us. Some of these waves have lots of energy, and some have less.</p>
<p>We call the lowest energy electromagnetic waves <a href="https://science.nasa.gov/ems/05_radiowaves">radio waves</a>. There’s a good chance radio waves are moving around you right now, shining out of wifi routers, laptops and mobile phones. </p>
<p>The most powerful electromagnetic waves are <a href="https://science.nasa.gov/ems/12_gammarays">gamma rays</a>, though you will never have had these anywhere near you unless you’ve spent time hanging around exploding stars or the inside of a nuclear reactor. </p>
<p>And there are some electromagnetic waves that we can actually see. This is <a href="https://science.nasa.gov/ems/09_visiblelight">visible light</a> – the light we can see all around us. </p>
<figure class="align-center ">
<img alt="Diagram of the electromagnetic spectrum" src="https://images.theconversation.com/files/537071/original/file-20230712-15-pd0rg2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/537071/original/file-20230712-15-pd0rg2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=293&fit=crop&dpr=1 600w, https://images.theconversation.com/files/537071/original/file-20230712-15-pd0rg2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=293&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/537071/original/file-20230712-15-pd0rg2.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=293&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/537071/original/file-20230712-15-pd0rg2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=368&fit=crop&dpr=1 754w, https://images.theconversation.com/files/537071/original/file-20230712-15-pd0rg2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=368&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/537071/original/file-20230712-15-pd0rg2.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=368&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The electromagnetic spectrum, from low energy radio waves to high energy gamma rays.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-vector/electromagnetic-spectrum-diagram-vector-illustration-765933061">VectorMine/Shutterstock</a></span>
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<p>Most electromagnetic waves around you just pass by without you ever noticing them, but some of them are perceived by your brain and form a very important part of your everyday experience of the world.</p>
<h2>Brain – and body</h2>
<p>But your brain can’t detect them on its own. Instead, it has to make sense of information about the electromagnetic waves that has been detected by other parts of your body.</p>
<p>A large part of the human brain is dedicated to making sense of a type of electromagnetic wave that we call “visible light”. This type of electromagnetic wave bounces off objects and into our eyes.</p>
<p>At the back of the <a href="https://www.nei.nih.gov/learn-about-eye-health/healthy-vision/how-eyes-work">human eye</a> there are millions of tiny cells that produce electrical signals when they are hit by an electromagnetic wave with a particular amount of energy. Some of these cells are designed to detect an amount of energy that we call the colour “red”. Others are specialised for another amount of energy that we call the colour “green”, or another that we call “blue”. </p>
<figure class="align-center ">
<img alt="Child looking at butterflies" src="https://images.theconversation.com/files/537084/original/file-20230712-15-9g5770.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/537084/original/file-20230712-15-9g5770.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/537084/original/file-20230712-15-9g5770.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/537084/original/file-20230712-15-9g5770.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/537084/original/file-20230712-15-9g5770.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/537084/original/file-20230712-15-9g5770.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/537084/original/file-20230712-15-9g5770.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Visible light is a kind of electromagnetic wave that cells in our eyes can detect – and is how we see the world around us.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/curly-girl-looking-butterfly-on-wild-774194680">Yuliya Evstratenko/Shutterstock</a></span>
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<p>The eye then sends electrical signals to your brain to describe the type of electromagnetic wave that it has detected – what colour the light was and where it came from. Finally, through a tremendously complicated sequence of electrical signals, a sighted person has the experience of “seeing”. </p>
<p>The fact that human eyes can detect visible light but not other types of electromagnetic wave is just the way that human eyes have evolved. Other animals’ eyes have evolved differently. For example, butterflies can see a <a href="https://doi.org/10.1113%2FJP273917">slightly higher energy</a> electromagnetic wave that our eyes can’t detect, but which we call <a href="https://science.nasa.gov/ems/10_ultravioletwaves">ultraviolet</a>. Some flowers reflect a lot of <a href="https://theconversation.com/the-secret-ultraviolet-colours-of-sunflowers-attract-pollinators-and-preserve-water-175723">ultraviolet waves</a>, which makes it easier for butterflies to find them for food.</p>
<h2>Invisible waves</h2>
<p>Another type of electromagnetic wave that our brain indirectly perceives is called <a href="https://science.nasa.gov/ems/07_infraredwaves">infrared</a>. We can sense this as heat.</p>
<p>When you stand near to a bonfire, your skin detects the fire’s infrared electromagnetic waves. It then sends electrical signals to the brain to tell it that there is something hot nearby. The brain couldn’t detect this wave by itself. </p>
<p>But the human body has no way to <a href="https://illumin.usc.edu/catch-a-wave-radio-waves-and-how-they-work/">detect radio waves</a>, so our brain is completely unaware of them as they pass around us. But we can use technology – like a radio, or wifi – to convert the electrical energy in radio waves into something we can detect, such as the music playing on a radio station. </p>
<p>We also use technology to detect <a href="https://science.nasa.gov/ems/11_xrays">x-rays</a>, another type of electromagnetic wave. X-rays are used in hospitals to look inside bodies – for instance, to see if a bone is broken. If you have an x-ray taken, hospital specialists send the <a href="https://www.nhs.uk/conditions/x-ray/">x-rays through your body</a>, and a machine can pick up how easily the x-rays travelled through different parts of your body. Areas that are more difficult for the x-ray to pass through, such as bone, show up as white. </p>
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<figure class="align-left ">
<img alt="" src="https://images.theconversation.com/files/282267/original/file-20190702-126345-1np1y7m.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/282267/original/file-20190702-126345-1np1y7m.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=293&fit=crop&dpr=1 600w, https://images.theconversation.com/files/282267/original/file-20190702-126345-1np1y7m.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=293&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/282267/original/file-20190702-126345-1np1y7m.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=293&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/282267/original/file-20190702-126345-1np1y7m.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=368&fit=crop&dpr=1 754w, https://images.theconversation.com/files/282267/original/file-20190702-126345-1np1y7m.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=368&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/282267/original/file-20190702-126345-1np1y7m.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=368&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<p><em><a href="https://theconversation.com/au/topics/curious-kids-36782">Curious Kids</a> is a series by <a href="https://theconversation.com/uk">The Conversation</a> that gives children the chance to have their questions about the world answered by experts. If you have a question you’d like an expert to answer, send it to <a href="mailto:curiouskids@theconversation.com">curiouskids@theconversation.com</a> and make sure you include the asker’s first name, age and town or city. We won’t be able to answer every question, but we’ll do our very best.</em></p>
<hr>
<p>Even though your brain is ridiculously clever, it would know nothing without the information that it receives from the rest of your body. You and all your experiences come from your body, your organs, and your senses detecting the world around you, and sending that information to your brain. </p>
<p>An enormously complicated set of tiny electrical signals later and you have a conscious experience of being you, inside your body, and in a world literally full of electromagnetic waves.</p><img src="https://counter.theconversation.com/content/209267/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Damian Cruse does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>
Your brains can perceive some electromagnetic waves – but not without your body’s help.
Damian Cruse, Associate Professor in the School of Psychology, University of Birmingham
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/203786
2023-05-30T11:37:27Z
2023-05-30T11:37:27Z
Ankylosing spondylitis: machine learning could pave the way for early diagnosis of inflammatory arthritis
<figure><img src="https://images.theconversation.com/files/526271/original/file-20230515-21229-5sc62o.jpg?ixlib=rb-1.1.0&rect=0%2C18%2C4140%2C3526&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">An X-ray image comparing a healthy spine and one showing signs of ankylosing spondylitis.</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/ls-spine-xray-image-ap-view-274780355">Suttha Burawonk/Shutterstock</a></span></figcaption></figure><p><a href="https://www.nhs.uk/conditions/ankylosing-spondylitis/">Ankylosing spondylitis</a> (AS) is the second most common type of inflammatory arthritis, often affecting teenagers and young adults. Symptoms of AS can include back pain, stiffness, joint inflammation (arthritis), inflammation where tendons attach to bones (enthesitis), and fatigue. Over time, these symptoms can lead to spinal fusion, which significantly affects quality of life, particularly in young people.</p>
<p>Unfortunately, diagnosing AS can be a lengthy process, taking up to ten years from the onset of symptoms and usually requiring X-rays. The slow progression of the condition, coupled with the lack of a definitive test, contributes to these delays. </p>
<p>However, early detection of the condition can make a tremendous difference, halting the degenerative process and preserving a good quality of life for those affected.</p>
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Read more:
<a href="https://theconversation.com/unexplained-lower-back-pain-it-could-be-ankylosing-spondylitis-56809">Unexplained lower back pain? It could be ankylosing spondylitis</a>
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<p>Our study explored the potential of using routinely collected healthcare data from GPs and hospitals, combined with advanced machine learning techniques, to identify AS at an earlier stage. Machine learning involves using algorithms to analyse sample data, enabling predictions and decisions without explicit programming. </p>
<p>We analysed data separately for men and women, and <a href="https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0279076">our findings</a> could transform the way in which GPs detect and diagnose AS.</p>
<h2>A valuable tool</h2>
<p>To conduct our study, we used anonymous data from a national data repository at Swansea University Medical School. Patients with AS were identified and matched with people with no record of a diagnosis.</p>
<p>Our analysis of this data found that factors such as lower back pain, <a href="https://www.nhs.uk/conditions/uveitis/">uveitis</a> (inflammation of the middle layer of the eye), and use of non-steroidal anti-inflammatory drugs before the age of 20 were factors associated with an increased risk of developing AS in men. </p>
<p>In contrast, our model revealed that women tend to experience AS symptoms at a later age, and often rely on multiple pain relief medications compared with men. This possibly indicates a higher likelihood of misdiagnosis of the condition in women.</p>
<p>Machine learning is a valuable tool for profiling and understanding the characteristics of people who are likely to develop AS. It performs well in test data sets with artificially high prevalence rates. </p>
<p>However, when applied to the general population in GPs and hospitals, where AS is rare, even the best model can only achieve a low positive predictive value of 1.4%. (That’s the probability that following a positive test result, the individual will truly have AS.)</p>
<p>So, using multiple models over time may be necessary to narrow down the population and improve this predictive value, which would result in a faster AS diagnosis.</p>
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<img alt="A person wearing a long sleeved white top faces away from the camera clasping the bottom of their back." src="https://images.theconversation.com/files/526283/original/file-20230515-24356-b8m735.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/526283/original/file-20230515-24356-b8m735.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/526283/original/file-20230515-24356-b8m735.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/526283/original/file-20230515-24356-b8m735.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/526283/original/file-20230515-24356-b8m735.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/526283/original/file-20230515-24356-b8m735.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/526283/original/file-20230515-24356-b8m735.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">Ankylosing spondylitis is the second most common cause of inflammatory arthritis.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/herniated-discspondylosis-scoliosis-asian-woman-she-1481955053">jaojormami/Shutterstock</a></span>
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<h2>Acknowledge the challenges too</h2>
<p>Machine learning techniques have tremendous potential to improve patient care. But it is also crucial to acknowledge the challenges associated with using these techniques effectively. </p>
<p>These models depend on high-quality data that is diverse and comprehensive to produce reliable, accurate results. But healthcare data can be limited due to privacy concerns, data sensitivity and lack of standardisation. These limitations may therefore compromise the accuracy and reliability of the models.</p>
<p>It’s important to acknowledge that machine learning in relation to this topic is still in its infancy. To develop this further, we will need to gather more detailed data to improve prediction rates and clinical usefulness.</p>
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Read more:
<a href="https://theconversation.com/from-a-deranged-provocateur-to-ibms-failed-ai-superproject-the-controversial-story-of-how-data-has-transformed-healthcare-189362">From a 'deranged' provocateur to IBM's failed AI superproject: the controversial story of how data has transformed healthcare</a>
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<p>But our study demonstrates the enormous potential that machine learning has to help identify people with AS and better understand their diagnostic journeys through the health system. </p>
<p>We know that the early detection and diagnosis of AS is crucial to secure the best outcomes for patients. We believe machine learning could help with this. It could also empower GPs, helping them to detect and refer patients more effectively and efficiently.</p><img src="https://counter.theconversation.com/content/203786/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jonathan Kennedy does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>
Our new study demonstrates the enormous potential that machine learning has to help identify people with AS
Jonathan Kennedy, Data Lab Manager, Swansea University
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/198180
2023-04-05T12:12:18Z
2023-04-05T12:12:18Z
The man in the monkey nut coat: how a 1940s scientist made ‘vegan wool’ from peanuts
<p><a href="https://www.britishwool.org.uk/blog-britishwool-history">Woollen clothing</a> has been around for as long as humans have been wearing clothes and sheep have been domesticated. Indeed, our distant ancestors used sheep for three things: food, clothing and shelter – wool makes good insulation and helps to keep in the warmth. </p>
<p>The UK is still one of the <a href="https://theconversation.com/unravelling-british-wool-how-the-local-and-global-are-intertwined-in-the-making-of-everyday-products-99114">largest wool producers</a> in the world and has more than <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8103502/">60 different breeds of sheep</a>.</p>
<p>But with the rise of veganism, many people are now questioning whether it’s <a href="https://theconversation.com/animal-welfare-if-you-want-cheap-knitwear-its-the-sheep-that-may-suffer-102370">ethical to use wool</a> in clothing and fabrics. Vegans don’t wear wool as it is often a <a href="https://www.peta.org/issues/animals-used-for-clothing/wool-industry/">by-product of the meat industry</a>.</p>
<p>This is why the charity Peta (The People for the Ethical Treatment of Animals) has launched a US$1 million (£844,000) <a href="https://www.peta.org.uk/blog/wool-challenge/">vegan wool challenge</a> to find the first individual, group, or company that can create a vegan wool material that is “visually, textually and functionally akin to or better than sheep’s wool.”</p>
<p>But it seems that back in the 1940s, textile physicist <a href="https://www.theguardian.com/science/2015/sep/17/william-astbury-forgotten-hero-of-dnas-discovery">William Astbury</a> was already on the case and making newspaper headlines for wearing what would today be considered a vegan coat. </p>
<p>For Astbury’s jacket was woven not from wool or other conventional textile materials, but from <a href="https://collection.maas.museum/object/242566">Ardil</a>, a fibre made from monkey nut, or peanut proteins.</p>
<h2>The monkey nut coat</h2>
<p>In <a href="https://global.oup.com/academic/product/the-man-in-the-monkeynut-coat-9780198704591?cc=gb&lang=en&">my book</a> The Man in the Monkeynut Coat: William Astbury and How Wool Wove a Forgotten Road to the Double-Helix, I tell the story of Astbury (and that famous coat), who with his colleague <a href="https://theconversation.com/florence-bell-the-housewife-who-played-a-key-part-in-our-understanding-of-dna-175220">Florence Bell</a> laid the foundations for the discovery of the structure of DNA. </p>
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Read more:
<a href="https://theconversation.com/florence-bell-the-housewife-who-played-a-key-part-in-our-understanding-of-dna-175220">Florence Bell: the ‘housewife’ who played a key part in our understanding of DNA</a>
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<p>Scientists <a href="https://www2.mrc-lmb.cam.ac.uk/achievements/lmb-nobel-prizes/1962-francis-crick-james-watson/">James Watson and Francis Crick</a> are famous for having first worked out the structure of DNA. But their success came 15 years after Astbury and Bell had first shown that X-rays could actually reveal DNA’s structure. </p>
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<a href="https://images.theconversation.com/files/507099/original/file-20230130-16-a8rpb4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Newspaper article on Astbury." src="https://images.theconversation.com/files/507099/original/file-20230130-16-a8rpb4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/507099/original/file-20230130-16-a8rpb4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=1168&fit=crop&dpr=1 600w, https://images.theconversation.com/files/507099/original/file-20230130-16-a8rpb4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=1168&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/507099/original/file-20230130-16-a8rpb4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=1168&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/507099/original/file-20230130-16-a8rpb4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1468&fit=crop&dpr=1 754w, https://images.theconversation.com/files/507099/original/file-20230130-16-a8rpb4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1468&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/507099/original/file-20230130-16-a8rpb4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1468&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">A Daily Mail article on the coat made of peanuts, published in 1944.</span>
<span class="attribution"><span class="license">Author provided</span></span>
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<p>And this work had a surprising origin, for Astbury’s aim was not to answer grand questions about the secrets of life, but to study the humble wool fibre while working as a lecturer in textile physics at the University of Leeds. </p>
<p>Ever since the Middle Ages, wool and textiles were the economic lifeblood of this <a href="https://www.jstor.org/stable/141036">Yorkshire city</a> – with mills a major source of employment in the late 19th and early 20th centuries. </p>
<p>In 1928 Astbury came to Leeds and used X-rays to reveal the molecular shape of the proteins in wool fibres. He found that they could be compacted or elongated – rather like a slinky toy. This change in their molecular architecture explained the stretchiness of wool – a property that made it so attractive to the textile industry. </p>
<p>And through it, Astbury left another powerful scientific legacy – thanks to his sporting of that rather unusual “peanut” overcoat.</p>
<h2>A future wool?</h2>
<p>From the mid-1930s onwards, Astbury, along with his collaborators Albert Chibnall and Kenneth Bailey, filed patents on a process that used solvents such as urea to unravel the precise 3D shape of proteins found in seeds – like the peanut. Their method then refolded them by a kind of molecular origami into insoluble fibres, creating a cheap and abundant raw material for the textile industry. </p>
<p>Sharing his optimism, the company <a href="https://www.vam.ac.uk/blog/museum-life/peanuts-in-the-archive-imperial-chemical-industries-tibor-reich-and-the-british-industries-fair">Imperial Chemical Industries</a> bought these patents and built a pilot production plant in Scotland to produce a new textile fibre from peanuts, which they called Ardil and gifted Astbury an overcoat made from it.</p>
<p>During the second world war, wool shortages encouraged investment in Ardil and campaigns were launched to persuade the British public of its benefits. This drive to develop new textile fibres at the time may also have inspired a storyline in the 1951 British comedy film <a href="https://www.imdb.com/title/tt0044876/">The Man in the White Suit</a>. </p>
<p>In the film, an altruistic chemist invents a fabric that resists wear and stain, but (spoiler alert) his dreams come crashing down when management realises the fabric must be suppressed for economic reasons as it threatens their livelihoods.</p>
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<p>Unfortunately, much like the fictional fibre, Ardil did not live up to its promise of saving the British textile industry. But Astbury and his overcoat left an important scientific legacy.</p>
<p>His work remains important because it showcased his lifelong belief that <a href="https://elifesciences.org/articles/56354">understanding living systems</a> requires solving their molecular architecture. While Ardil did not succeed, Astbury’s research laid the foundation for future innovations in molecular biology and materials science.</p>
<p>This approach, known as structural biology, has since allowed us to understand how the <a href="https://pdb101.rcsb.org/motm/41">blood protein haemoglobin</a> can carry oxygen around the body, <a href="https://www.nature.com/scitable/topicpage/the-sliding-filament-theory-of-muscle-contraction-14567666/">how muscles contract</a> and more recently how the spike protein on the surface of <a href="https://www.nature.com/articles/s41579-020-0383-2">SARS-CoV2</a> allows the virus to bind and enter human cells.</p>
<p>When Astbury died in 1961, his friend and colleague, the botanist R.D. Preston, fondly remembered him as “a man of many parts – scientist, scholar, musician, bon viveur, humorist, in some ways, a swashbuckler…boisterous to the end with every morning still a Christmas morning.” Maybe to this list of accolades, we should also add a posthumous nomination for the <a href="https://www.theguardian.com/fashion/2022/nov/17/peta-1m-competition-find-vegan-wool-alternative">$1 million vegan wool prize</a>.</p><img src="https://counter.theconversation.com/content/198180/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Kersten Hall does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>
Vegan wool, peanut coats and the discovery of DNA: the forgotten life of scientist William Astbury
Kersten Hall, Author and Honorary Fellow, School of Philosophy, Religion and History of Science, University of Leeds
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/175220
2022-01-28T12:08:53Z
2022-01-28T12:08:53Z
Florence Bell: the ‘housewife’ who played a key part in our understanding of DNA
<p>When the Yorkshire Evening News reported on an address delivered by 25-year-old physicist Florence Bell at a scientific conference held in Leeds in 1939, it wasn’t her science that made the headlines, but simply the fact that she was a woman doing science.</p>
<p>What neither the writers who came up with the headline “Woman Scientist Explains”, nor their readers could have known was that, in the course of her PhD research, this particular woman scientist had quietly laid the foundations for one of the biggest landmarks in 20th century science: the discovery of the structure of DNA.</p>
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<p>With chapters describing the structure of protein fibres in jellyfish, shark fins and hair, Bell’s PhD thesis might seem an unlikely milestone in biology. But among these, one chapter stands out. This part of Bell’s work describes how X-rays <a href="https://explore.library.leeds.ac.uk/special-collections-explore/650413">could be used</a> to reveal the regular, ordered structure of a biological fibre that at the time was called “thymonucleic acid”. </p>
<p>Today thymonucleic acid is known by the more familiar name of “deoxyribonucleic acid”, or DNA. Bell’s X-ray method was to become a vital tool in eventually revealing the now well-known double helix shape of DNA that allows it to copy genetic information.</p>
<p>Bell, who was born <a href="https://www.whatisbiotechnology.org/index.php/people/summary/Bell">in 1913 in London</a>, was one of a growing number of female students who studied natural sciences at Girton College at the University of Cambridge. </p>
<p>After leaving Cambridge in 1936 Bell first spent a short period in Manchester with <a href="https://www.nobelprize.org/prizes/physics/1915/wl-bragg/biographical/">Lawrence Bragg</a> who, together with his father <a href="https://www.nobelprize.org/prizes/physics/1915/wh-bragg/facts/">William</a>, had received the 1915 Nobel prize in physics. The pair had shown how X-rays could be used to <a href="https://www.leeds.ac.uk/main-index/events/event/44/shaping-the-course-of-modern-science-william-henry-bragg-and-his-legacy-at-the-university-of-leeds">reveal the arrangement</a> of atoms and molecules in simple crystals such as salt. </p>
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Read more:
<a href="https://theconversation.com/rosalind-franklin-still-doesnt-get-the-recognition-she-deserves-for-her-dna-discovery-95536">Rosalind Franklin still doesn't get the recognition she deserves for her DNA discovery</a>
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<p>In 1937, Bell moved to the University of Leeds to take up a post as a research assistant with the physicist <a href="https://www.whatisbiotechnology.org/index.php/people/summary/Astbury">William Astbury</a> who was applying the Braggs’ methods to the study of wool and other biological fibres.</p>
<p>Astbury’s X-ray studies of the proteins in wool fibres revealed that their structure was like a molecular chain, or necklace, formed by joining together smaller chemicals called amino acids. This molecular necklace could be stretched or compacted. </p>
<p>Although this may not seem significant, the fact these proteins could change shape proved to be crucial in understanding how they functioned. Astbury’s studies of wool would transform our understanding of biology at a molecular level. </p>
<p>Emboldened by his success with wool, Astbury began to cast his net wider to study other biological fibres. For this, he needed another pair of hands skilled in this new method of X-ray analysis.</p>
<p>Enter Florence Bell. With her sharp intellect and willingness to challenge his ideas, Astbury called Bell his “devil’s advocate”. He gave her the task of using X-rays <a href="https://www.worldcat.org/title/path-to-the-double-helix-the-discovery-of-dna/oclc/608936643">to study DNA</a>.</p>
<p>Taking an X-ray image was not easy. It required ten-hour exposure times, working in a darkened room in close proximity to high electrical voltages and very hot X-ray tubes. But Bell’s skill and tenacity paid off and in 1938, based on the X-ray images she had taken, she and Astbury proposed <a href="https://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.901.5509&rep=rep1&type=pdf">an early model</a> of the DNA structure. This model later gave <a href="https://www.nobelprize.org/prizes/medicine/1962/watson/biographical/">James Watson</a> and <a href="https://www.nobelprize.org/prizes/medicine/1962/crick/biographical/">Francis Crick</a> a vital foothold when they began <a href="http://sites.bu.edu/manove-ec101/files/2017/09/Watson_The_Double_Helix.pdf">their own work</a> on DNA.</p>
<p>Sadly however, just as it was gathering pace, Bell’s work on DNA was brought to an abrupt halt. In 1941, she was summoned for military service in the Women’s Auxiliary Air Force. According to one of her sons, Chris Sawyer, during her service she did early work on the development of radar (radio detection and ranging).</p>
<p>Astbury, meanwhile, begged the War Office that Bell be allowed to remain in his lab, but his pleas were in vain. The University of Leeds even kept her post open, but Bell never returned.</p>
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<img alt="An artist's impression of the DNA double helix." src="https://images.theconversation.com/files/443135/original/file-20220128-23-bj2iwk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/443135/original/file-20220128-23-bj2iwk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=360&fit=crop&dpr=1 600w, https://images.theconversation.com/files/443135/original/file-20220128-23-bj2iwk.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=360&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/443135/original/file-20220128-23-bj2iwk.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=360&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/443135/original/file-20220128-23-bj2iwk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=453&fit=crop&dpr=1 754w, https://images.theconversation.com/files/443135/original/file-20220128-23-bj2iwk.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=453&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/443135/original/file-20220128-23-bj2iwk.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=453&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">Bell’s research laid important groundwork for other scientists to eventually discover the double helix structure of DNA.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-illustration/long-structure-dna-double-helix-depth-181129397">ktsdesign/Shutterstock</a></span>
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<p>Having married an American serviceman, Bell emigrated to the US where she worked as an industrial chemist, before giving up her career to look after her four children. It is presumably in reflection of these changed circumstances that when she died in 2000, her occupation on her death certificate was recorded as “housewife”.</p>
<p>Sawyer recalled that later in her life his mother liked to claim that one of her greatest achievements was to have been the first woman in the Royal Air Force to wear trousers. But Bell was being modest. </p>
<p>With her X-ray studies of DNA, Bell had not only given Watson and Crick a vital foothold, but had also paved the way for Rosalind Franklin, whose own work in this field was key in helping Watson and Crick to solve the structure of the genetic material. </p>
<p>Franklin now has an award-winning portrayal by <a href="https://www.theguardian.com/stage/2015/nov/22/nicole-kidman-best-actress-award-photograph-51">Nicole Kidman</a> in the West End play Photo 51, a <a href="https://www.bbc.co.uk/news/science-environment-47151778">Mars Rover</a> named in her honour, and <a href="https://www.sourcebooks.com/books-by-marie-benedict.html">a new novel</a> about her – she is thankfully no longer quite the “<a href="https://books.google.co.uk/books/about/Rosalind_Franklin.html?id=leJtDfXvR2kC&redir_esc=y">dark lady of DNA</a>” she once was. Perhaps it is now Florence Bell who truly deserves this title.</p>
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Read more:
<a href="https://theconversation.com/watson-and-crick-took-all-the-glory-but-theres-a-forgotten-hero-of-the-double-helix-28536">Watson and Crick took all the glory, but there’s a forgotten hero of the double helix</a>
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<p><em>The story of Florence Bell is told in the revised edition of Kersten’s book, The Man in the Monkeynut Coat: William Astbury and How Wool Wove a Forgotten Road to the Double Helix, which will be published in paperback by Oxford University Press in March 2022.</em></p><img src="https://counter.theconversation.com/content/175220/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Kersten Hall does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>
Florence Bell’s work producing X-rays of DNA laid the foundations for one of the landmark discoveries of 20th century science.
Kersten Hall, Author and Honorary Fellow, School of Philosophy, Religion and History of Science, University of Leeds
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/169938
2021-12-14T00:04:18Z
2021-12-14T00:04:18Z
Some black holes are anything but black – and we’ve found more than 75,000 of the brightest ones
<figure><img src="https://images.theconversation.com/files/427670/original/file-20211021-15-77a6an.jpeg?ixlib=rb-1.1.0&rect=3%2C51%2C1274%2C1230&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="http://www.eso.org/public/images/eso0903a/">ESO/WFI (Optical); MPIfR/ESO/APEX/A.Weiss et al. (Submillimetre); NASA/CXC/CfA/R.Kraft et al. (X-ray)</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>When the most massive stars die, they collapse to form some of the densest objects known in the Universe: black holes. They are the “darkest” objects in the cosmos, as not even light can escape their incredibly strong gravity. </p>
<p>Because of this, it’s impossible to directly image black holes, making them mysterious and quite perplexing. But our <a href="https://academic.oup.com/mnras/article-abstract/509/4/4940/6458741?redirectedFrom=fulltext">new research</a> has road-tested a way to spot some of the most voracious black holes of all, making it easier to find them buried deep in the hearts of distant galaxies.</p>
<p>Despite the name, not all black holes are black. While black holes come in many different sizes, the biggest ones are at the centres of galaxies, and are still growing in size. </p>
<p>These “supermassive” black holes can have the mass of up to a <a href="https://theconversation.com/overmassive-black-hole-holds-the-mass-of-17-billion-suns-11066">billion Suns</a>. The black hole at the centre of our own Milky Way galaxy – called Sagittarius A*, whose discovery received the <a href="https://www.nobelprize.org/prizes/physics/2020/press-release/">2020 Nobel Prize in Physics</a> – is fairly calm. But that isn’t the case for all supermassive black holes. </p>
<p>If material such as gas, dust or stars gets too close to a black hole, it gets sucked in by the enormous gravitational force. As it falls towards the black hole, it heats up and becomes incredibly bright. </p>
<p>The light produced by these “bright black holes” can span the entire electromagnetic spectrum, from X-rays to radio waves. Another name for the bright black holes at the centre of galaxies is “active galactic nuclei”, or AGN. They can shine trillions of times brighter than the Sun, and can sometimes even outshine all the stars in its galaxy.</p>
<figure class="align-center ">
<img alt="Image of black hole" src="https://images.theconversation.com/files/427657/original/file-20211020-20-6ejhs1.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/427657/original/file-20211020-20-6ejhs1.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/427657/original/file-20211020-20-6ejhs1.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/427657/original/file-20211020-20-6ejhs1.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/427657/original/file-20211020-20-6ejhs1.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/427657/original/file-20211020-20-6ejhs1.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/427657/original/file-20211020-20-6ejhs1.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Matter swirling into the supermassive black hole at the centre of M87.</span>
<span class="attribution"><span class="source">Event Horizon Telescope</span></span>
</figcaption>
</figure>
<h2>The brightest black holes</h2>
<p>Some <a href="https://theconversation.com/radio-galaxies-the-mysterious-secretive-beasts-of-the-universe-64381">AGN violently spew out matter via a jet</a>, which travels millions of kilometres through space and can be seen by radio telescopes. Others produce “winds” at the centre of the galaxy, capable of pushing any gas (the fuel needed for stars to form) out of the galaxy. </p>
<figure class="align-center ">
<img alt="Violent jets spewing from Hercules A" src="https://images.theconversation.com/files/427660/original/file-20211021-27-yh2j20.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/427660/original/file-20211021-27-yh2j20.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=426&fit=crop&dpr=1 600w, https://images.theconversation.com/files/427660/original/file-20211021-27-yh2j20.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=426&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/427660/original/file-20211021-27-yh2j20.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=426&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/427660/original/file-20211021-27-yh2j20.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=536&fit=crop&dpr=1 754w, https://images.theconversation.com/files/427660/original/file-20211021-27-yh2j20.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=536&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/427660/original/file-20211021-27-yh2j20.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=536&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Violent jets spewing from Hercules A.</span>
<span class="attribution"><span class="source">NASA/ESA/NRAO</span></span>
</figcaption>
</figure>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/like-a-spinning-top-wobbling-jets-from-a-black-hole-thats-feeding-on-a-companion-star-116067">Like a spinning top: wobbling jets from a black hole that's 'feeding' on a companion star</a>
</strong>
</em>
</p>
<hr>
<p>With such destructive forces in the middle of a galaxy, astronomers are certain this must have a big impact on the galaxy itself. We know most galaxies are slowly <a href="https://theconversation.com/dont-panic-but-the-universe-is-slowly-dying-45779">turning off their star formation processes</a>, and AGN might be one of the culprits.</p>
<p>AGN can therefore not only help us to better understand elusive black holes, but studying them also teaches us about galaxies themselves. </p>
<h2>Finding bright black holes</h2>
<p>Depending on how much a black hole is “eating”, what galaxy it’s in, and the angle from which we can see it, AGN can look very different to one another. Even when looking at the same galaxy, one astronomer with an X-ray telescope may see it glow and discover an AGN, whereas another astronomer using a radio telescope might see nothing, if the AGN doesn’t happen to produce jets that are visible in the radio spectrum. </p>
<p>Because of this, it was thought they were all different objects, but by looking at the same objects with different telescopes astronomers discovered they had many similarities, and realised the benefits of using more of the electromagnetic spectrum to find them. </p>
<p>The relative brightness of a galaxy across different parts of the electromagnetic spectrum is called its “spectral energy distribution”. This can be used to measure how many stars are in a galaxy, how old they are, what they’re made of, and how much dust is blocking the light. </p>
<figure class="align-center ">
<img alt="Image of galaxy at different wavelengths" src="https://images.theconversation.com/files/427658/original/file-20211021-66011-xlzg8t.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/427658/original/file-20211021-66011-xlzg8t.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=443&fit=crop&dpr=1 600w, https://images.theconversation.com/files/427658/original/file-20211021-66011-xlzg8t.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=443&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/427658/original/file-20211021-66011-xlzg8t.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=443&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/427658/original/file-20211021-66011-xlzg8t.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=556&fit=crop&dpr=1 754w, https://images.theconversation.com/files/427658/original/file-20211021-66011-xlzg8t.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=556&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/427658/original/file-20211021-66011-xlzg8t.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=556&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Composite picture showing how a typical galaxy appears at different wavelengths.</span>
<span class="attribution"><span class="source">ICRAR/GAMA and ESO</span></span>
</figcaption>
</figure>
<p>In our research, <a href="https://academic.oup.com/mnras/article-abstract/509/4/4940/6458741?redirectedFrom=fulltext">published today</a> in Monthly Notices of the Royal Astronomical Society, we show that this technique can also be used to spot AGN. This means we can now measure not just the properties and histories of the stars in the galaxy, but also the brightness of its central black hole. </p>
<p>It’s not a simple thing to do. The difference between starlight and the light from an AGN is incredibly subtle, so it’s possible to confuse young stars for a bright black hole, and vice versa. </p>
<p>Here in Australia, astronomers have been <a href="https://theconversation.com/explainer-seeing-the-universe-through-spectroscopic-eyes-37759">using Australian telescopes</a> to make 3D maps of galaxies in specific patches of the sky. These maps let us scour hundreds of thousands of galaxies, spanning 11 billion years of history, for possible AGN. </p>
<p>By applying our new method to 700,000 galaxies we identified and quantified more than 75,000 AGN to begin understanding how their number has evolved over time and how they have impacted their host galaxies. Astronomers think the number of AGN in the Universe is linked to the amount of star formation, which we know was almost ten times higher roughly 10 billion years ago. But until we can be certain we’ve identified all the AGN across cosmic time in our galaxy samples, we won’t know for sure.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/the-heaviest-stellar-black-hole-in-our-galaxy-is-even-more-massive-than-we-thought-155484">The heaviest stellar black hole in our galaxy is even more massive than we thought</a>
</strong>
</em>
</p>
<hr>
<p>Right now, the astronomical community is still passionately debating the nature of active black holes. While we haven’t yet answered the questions needed to soothe the debate, we’re now one step closer to reliably being able to spot these fascinating objects within galaxies. And that’s an important step towards shedding more light on the mystery of black holes.</p><img src="https://counter.theconversation.com/content/169938/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jessica Thorne is supported by the Australian Government Research Traning Program (RTP) Scholarship. </span></em></p><p class="fine-print"><em><span>Sabine Bellstedt receives funding from the Australian Research Council. </span></em></p>
Despite the name, some black holes effectively “shine” as they suck up nearby material with such force that it begins to glow. New research reveals a new method for detecting these active black holes.
Jessica Thorne, Astrophysics PhD Candidate, The University of Western Australia
Sabine Bellstedt, Research Associate in Astronomy, The University of Western Australia
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/124367
2019-11-08T10:02:26Z
2019-11-08T10:02:26Z
Helena Gleichen: pioneer radiographer, suffragist and forgotten hero of World War I
<figure><img src="https://images.theconversation.com/files/298927/original/file-20191028-114005-mjekz5.jpg?ixlib=rb-1.1.0&rect=51%2C8%2C5725%2C3797&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Gleichen sacrificed her own well-being to help save the lives of injured soldiers on the Italian Front. </span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/mature-man-xray-showing-right-pulmonary-1504168982?src=1mKvAmvXoKR80N5doKk9Hw-1-24">Douglas Olivares/ Shutterstock</a></span></figcaption></figure><p>“Women, your country needs you,” Millicent Fawcett, the campaigner for women’s suffrage, proclaimed when war was declared in August 1914. One enthusiastic respondent to the call was Helena Gleichen, a rich aristocrat and a cousin of George V who had dined with Queen Victoria, danced at debutante balls and spent much of her life riding or painting animals. But when the war started, she renounced her Germanic family titles and committed herself to war work. More than 100 years after the armistice was signed, Gleichen has become a forgotten hero of the World War I – despite her brave contributions having saved thousand of lives on the Italian Front.</p>
<p>Although the British Army scornfully refused offers from women willing to travel overseas, that failed to stop many brave volunteers from getting involved. Although now forgotten, Gleichen was Britain’s war-time Marie Curie – the Polish scientist who invented mobile X-ray units that she took to the French front. While Curie was saving French lives, this English landscape artist was rescuing Italian soldiers. </p>
<figure class="align-left ">
<img alt="" src="https://images.theconversation.com/files/299242/original/file-20191029-183136-eyc7aq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/299242/original/file-20191029-183136-eyc7aq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=873&fit=crop&dpr=1 600w, https://images.theconversation.com/files/299242/original/file-20191029-183136-eyc7aq.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=873&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/299242/original/file-20191029-183136-eyc7aq.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=873&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/299242/original/file-20191029-183136-eyc7aq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1097&fit=crop&dpr=1 754w, https://images.theconversation.com/files/299242/original/file-20191029-183136-eyc7aq.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1097&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/299242/original/file-20191029-183136-eyc7aq.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1097&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Lady Helena Gleichen.</span>
<span class="attribution"><a class="source" href="https://www.iwm.org.uk/collections/item/object/205380422">© IWM</a></span>
</figcaption>
</figure>
<p>Medical radiography was still in its infancy. The German physicist Wilhelm Conrad Röntgen had <a href="https://www.bl.uk/learning/cult/bodies/xray/roentgen.html">discovered X-rays in 1895</a>, and the following year created the first X-ray photograph, memorably revealing the bones of his wife’s hand. Two decades later, suitable machines were available in major hospitals, but they were located too far away to help soldiers injured on the battle field.</p>
<p>Curie <a href="https://www.nobelprize.org/prizes/physics/1903/marie-curie/biographical/">won two Nobel Prizes</a> for her pioneering research into radioactivity, but during the war she abandoned her laboratory to support her adopted country. Her Curie cars brought radiography equipment – including miniature dark rooms for developing prints – right to the scene of battle, so that <a href="https://theconversation.com/marie-curie-and-her-x-ray-vehicles-contribution-to-world-war-i-battlefield-medicine-83941">soldiers could be examined and treated immediately</a>.</p>
<p>In 1915, Gleichen and her friend Nina Hollings converted a French chateau into a military hospital before travelling to Paris and training with X-rays. But the War Office informed them with unassailable illogic that because no women were radiographers it was impossible to employ them. Undeterred, they came back to London and organised their own relief operation.</p>
<p>To get advice, Gleichen contacted the distinguished Scottish pioneer of <a href="https://specialcollectionslearning.wordpress.com/2017/10/17/sir-james-mackenzie-davidson-a-founding-father-of-british-radiology/">medical radiography, James Mackenzie Davidson</a>. She raised enough money from her wealthy family to buy one of the new portable machines he was developing, as well as a specially adapted Austin car to drive it in.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/298930/original/file-20191028-114005-ph3z7t.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/298930/original/file-20191028-114005-ph3z7t.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=391&fit=crop&dpr=1 600w, https://images.theconversation.com/files/298930/original/file-20191028-114005-ph3z7t.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=391&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/298930/original/file-20191028-114005-ph3z7t.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=391&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/298930/original/file-20191028-114005-ph3z7t.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=492&fit=crop&dpr=1 754w, https://images.theconversation.com/files/298930/original/file-20191028-114005-ph3z7t.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=492&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/298930/original/file-20191028-114005-ph3z7t.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=492&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Gleichen would have used a mobile X-ray unit similar to this one that Marie Curie designed.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Marie_Curie_-_Mobile_X-Ray-Unit.jpg">Eve Curie/Wikimedia Commons</a></span>
</figcaption>
</figure>
<p>Gleichen and Hollings set off for Italy, where they settled just behind the frontline in a country villa near the border town of Gorizia. Their home became a busy X-ray department, its machinery powered by a cable snaking along the hallway from the car parked outside. Alone in the middle of a battle zone, the pair learnt how to service their electrical equipment and fix their car. On one occasion, Gleichen enterprisingly melted two large altar candles to replace some cracked insulation.</p>
<p>Although photos show two demure women in heavy uniform, hats firmly in place even when working inside, Gleichen recounts adventures as hair-raising as those of any frontline soldier. Often at risk from enemy bullets, they took many thousands of X-rays, eventually damaging their hands and their eyes. </p>
<p>In a letter to Davidson, Gleichen explained that they needed to work quickly. With more and more wounded soldiers arriving daily, many of them already close to death, there was often no time for the luxury of standard procedures. Weighing down their un-anaesthetised patients with sandbags, they explored precisely yet rapidly to locate bullets lodged in a soldier’s body by a rough-and-ready technique of aiming along two perpendicular lines to see where they intersected.</p>
<p>Gleichen was particularly jubilant about managing to pinpoint a bullet deep inside a soldier’s skull. She sent Davidson a small sketch, telling him that she was “cocka hoopy”. Despite this experimental success, she faced up to wartime realities: “Anyway it has been deeply interesting + I expect they will kill him by operating + equally kill him by leaving it. I am sorry as he was such a nice boy in tremendous spirits + health.”</p>
<p>Gleichen was forced to leave rapidly when Gorizia fell in 1916, but after the war she was awarded medals by both Britain and Italy for her distinguished contributions. <a href="https://archive.org/details/in.ernet.dli.2015.211199/page/n7">In her memoir</a>, she wrote: “And after the War? What then? As with many other people, we were incapable of sitting still, or of resuming a normal existence.”</p>
<p>Gleichen was one of the women who were able to experience the freedom and independence which are normally deserved for men. Although she later returned to her apparently contented rural life as an artist, she had – <a href="https://global.oup.com/academic/product/a-lab-of-ones-own-9780198794998?q=A%20Lab%20of%20One%27s%20Own&lang=en&cc=gb">like so many other women</a> – become a different person.</p><img src="https://counter.theconversation.com/content/124367/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Patricia Fara does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>
The landscape artist bravely left her aristocratic life behind to help save lives on the Italian front.
Patricia Fara, Fellow of Clare College, Cambridge, University of Cambridge
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/122504
2019-09-04T11:53:52Z
2019-09-04T11:53:52Z
Artificial intelligence in medicine raises legal and ethical concerns
<figure><img src="https://images.theconversation.com/files/290371/original/file-20190830-166001-r7wwij.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Scientists are working with artificial intelligence in hopes of being able to better detect cancer.</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/download/success?u=http%3A%2F%2Fdownload.shutterstock.com%2Fgatekeeper%2FW3siZSI6MTU2NzIyODI2MCwiYyI6Il9waG90b19zZXNzaW9uX2lkIiwiZGMiOiJpZGxfMTE4MTg1MTMwOSIsImsiOiJwaG90by8xMTgxODUxMzA5L2h1Z2UuanBnIiwibSI6MSwiZCI6InNodXR0ZXJzdG9jay1tZWRpYSJ9LCI0ZDcxNjNDWGlJMWg3M21rQ1pQaitGTGhzNWciXQ%2Fshutterstock_1181851309.jpg&pi=33421636&m=1181851309&src=-1-70">www.shutterstock.com</a></span></figcaption></figure><p>The use of artificial intelligence in medicine is generating great excitement and hope for treatment advances.</p>
<p>AI generally <a href="https://www.merriam-webster.com/dictionary/artificial%20intelligence">refers to</a> computers’ ability to mimic human intelligence and to learn. For example, by using machine learning, <a href="https://www.sciencedaily.com/releases/2019/04/190424153444.htm">scientists</a> are working to develop <a href="https://www.pewresearch.org/fact-tank/2019/02/13/7-things-weve-learned-about-computer-algorithms/">algorithms</a> that will help them make decisions about cancer treatment. They hope that computers will be able to analyze radiological images and discern which cancerous tumors will respond well to chemotherapy and which <a href="https://www.ncbi.nlm.nih.gov/pubmed/30358693">will not</a>.</p>
<p>But AI in medicine also raises significant legal and ethical challenges. Several of these are concerns about privacy, discrimination, psychological harm and the physician-patient relationship. In a <a href="https://papers.ssrn.com/sol3/papers.cfm?abstract_id=3363856">forthcoming</a> article, I argue that policymakers should establish a number of safeguards around AI, much as they did when genetic testing became commonplace.</p>
<h2>Potential for discrimination</h2>
<p>AI involves <a href="https://www.healthcatalyst.com/wp-content/uploads/2014/06/What-is-data-mining-in-healthcare.pdf">the analysis</a> of very large amounts of data to discern patterns, which are then used to predict the likelihood of future occurrences. In medicine, the data sets can come from electronic health records and health insurance claims but also from several surprising sources. AI can draw upon <a href="https://www.charlotteobserver.com/living/health-family/article9135980.html">purchasing records</a>, <a href="https://www.charlotteobserver.com/living/health-family/article9135980.html">income</a> data, <a href="https://www.politico.com/story/2018/10/30/the-doctor-will-see-through-you-now-893437">criminal records</a> and even <a href="https://www.npr.org/2018/11/17/668408122/facebook-increasingly-reliant-on-a-i-to-predict-suicide-risk">social media</a> for information about an individual’s health. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/290351/original/file-20190830-166001-1mzagz8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/290351/original/file-20190830-166001-1mzagz8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=395&fit=crop&dpr=1 600w, https://images.theconversation.com/files/290351/original/file-20190830-166001-1mzagz8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=395&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/290351/original/file-20190830-166001-1mzagz8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=395&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/290351/original/file-20190830-166001-1mzagz8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=497&fit=crop&dpr=1 754w, https://images.theconversation.com/files/290351/original/file-20190830-166001-1mzagz8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=497&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/290351/original/file-20190830-166001-1mzagz8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=497&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The hope is that AI will be able to read radiological images more efficiently than a human.</span>
<span class="attribution"><a class="source" href="http://www.apimages.com/metadata/Index/Flu-Season/cdec4f4ed814454180cf81eec7c3036c/10/0">AP Photo/David Goldman</a></span>
</figcaption>
</figure>
<p>Researchers are already using AI to predict a multitude of medical conditions. These include <a href="https://www.theverge.com/2018/2/19/17027902/google-verily-ai-algorithm-eye-scan-heart-disease-cardiovascular-risk">heart disease</a>, <a href="https://www.itnonline.com/content/fda-clears-first-ai-powered-clinical-decision-support-software-stroke">stroke</a>, <a href="https://www.politico.com/story/2014/07/data-mining-health-care-109153https:/www.politico.com/story/2014/07/data-mining-health-care-109153">diabetes</a>, <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5880633/">cognitive decline</a>, future <a href="https://www.politico.com/story/2019/02/03/health-risk-scores-opioid-abuse-1139978">opioid abuse</a> and even <a href="https://www.npr.org/2018/11/17/668408122/facebook-increasingly-reliant-on-a-i-to-predict-suicide-risk">suicide</a>. As one example, Facebook employs an algorithm that <a href="https://www.washingtonpost.com/outlook/suicide-prediction-technology-is-revolutionary-it-badly-needs-oversight/2018/12/20/214d2532-fd6b-11e8-ad40-cdfd0e0dd65a_story.html?noredirect=on&utm_term=.6e4e7a5dae38">makes suicide predictions</a> based on posts with phrases such as “Are you okay?” paired with “Goodbye” and “Please don’t do this.”</p>
<p>This predictive capability of AI raises significant ethical concerns in health care. If AI generates predictions about your health, I believe that information could one day be included in your electronic health records.</p>
<p>Anyone with access to your health records could then see predictions about cognitive decline or opioid abuse. Patients’ medical records are seen by <a href="http://bok.ahima.org/doc?oid=60048#.XS33iehKg2x">dozens or even hundreds</a> of clinicians and administrators in the course of medical treatment. Additionally, patients themselves often authorize others to access their records: for example, when they apply for employment or life insurance.</p>
<p>Data broker industry giants such as <a href="https://www.politico.com/story/2018/10/30/the-doctor-will-see-through-you-now-893437">LexisNexis and Acxiom</a> are also mining personal data and engaging in AI activities. They could then sell medical predictions to any interested third parties, including marketers, employers, lenders, life insurers and others. Because these businesses are not health care providers or insurers, the <a href="https://www.hhs.gov/hipaa/for-individuals/faq/187/what-does-the-hipaa-privacy-rule-do/index.html">HIPAA Privacy Rule</a> does not apply to them. Therefore, they do not have to ask patients for permission to obtain their information and can freely disclose it. </p>
<p>Such disclosures can lead to discrimination. Employers, for instance, are interested in workers who will be healthy and productive, with few absences and low medical costs. If they believe certain applicants will develop diseases in the future, they will likely reject them. Lenders, landlords, life insurers and others might likewise make adverse decisions about individuals based on AI predictions. </p>
<h2>Lack of protections</h2>
<p>The <a href="https://adata.org/learn-about-ada">Americans with Disabilities Act</a> does not prohibit discrimination based on future medical problems. It applies only to current and past ailments. In response to genetic testing, Congress enacted the <a href="https://www.genome.gov/about-genomics/policy-issues/Genetic-Discrimination">Genetic Information Nondiscrimination Act</a>. This law prohibits employers and health insurers from considering genetic information and making decisions based on related assumptions about people’s future health conditions. No law imposes a similar prohibition with respect to nongenetic predictive data.</p>
<p>AI health prediction can also lead to psychological harm. For example, many people could be traumatized if they learn that they will likely suffer cognitive decline later in life. It is even possible that individuals will obtain health forecasts directly from commercial entities that bought their data. Imagine obtaining the news that you are at risk of dementia through an electronic advertisement urging you to buy memory-enhancing products.</p>
<p>When it comes to genetic testing, patients are advised to seek genetic counseling so that they can thoughtfully decide whether to be tested and better understand test results. By contrast, we do not have AI counselors who provide similar services to patients.</p>
<p>Yet another concern relates to the doctor-patient relationship. Will AI diminish the role of doctors? Will computers be the ones to make predictions, diagnoses and treatment suggestions, so that doctors simply implement the computers’ instructions? How will patients feel about their doctors if computers have a greater say in making medical determinations?</p>
<p>These concerns are exacerbated by the fact that AI predictions are far from infallible. Many factors can contribute to errors. If the data used to <a href="https://onlinelibrary.wiley.com/doi/epdf/10.1111/imj.14172">develop</a> an algorithm are flawed – for instance, if they use medical records that contain errors – the algorithm’s output will be incorrect. Therefore, patients may suffer discrimination or psychological harm when in fact they are not at risk of the predicted ailments.</p>
<h2>A call for caution</h2>
<p>What can be done to protect the American public? I have argued in past <a href="https://papers.ssrn.com/sol3/papers.cfm?abstract_id=931069">work</a> for the expansion of the HIPAA Privacy Rule so that it covers anyone who handles health information for business purposes. Privacy protections should apply not only to health care providers and insurers, but also to commercial enterprises. I have also <a href="https://papers.ssrn.com/sol3/papers.cfm?abstract_id=2841431">argued</a> that Congress should amend the Americans with Disabilities Act to prohibit discrimination based on forecasts of future diseases.</p>
<p>Physicians who provide patients with AI predictions should ensure that they are thoroughly educated about the pros and cons of such forecasts. Experts should counsel patients about AI just as trained professionals do about genetic testing. </p>
<p>The prospect of AI can over-awe people. Yet, to ensure that AI truly promotes patient welfare, physicians, researchers and policymakers must recognize its risks and proceed with caution.</p>
<p>[ <em>Like what you’ve read? Want more?</em> <a href="https://theconversation.com/us/newsletters?utm_source=TCUS&utm_medium=inline-link&utm_campaign=newsletter-text&utm_content=likethis">Sign up for The Conversation’s daily newsletter</a>. ]</p><img src="https://counter.theconversation.com/content/122504/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Sharona Hoffman received funding from Case Western Reserve University School of Law to write "What Genetic Testing Teaches about Predictive Health Analytics Regulation," forthcoming in the North Carolina Law Review. </span></em></p>
Artificial intelligence holds great promise for medicine, but safeguards are needed to ensure it does not harm patients.
Sharona Hoffman, Professor of Health Law and Bioethics, Case Western Reserve University
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/108875
2019-09-02T11:17:04Z
2019-09-02T11:17:04Z
The test that could save the life of a long-time smoker you know
<figure><img src="https://images.theconversation.com/files/290285/original/file-20190830-165972-5332l6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Smoking is the biggest cause of preventable death in the U.S. A test for long-time smokers might be able to detect lung cancer earlier, thereby saving lives. </span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-illustration/smoking-death-danger-concept-cigarette-burning-458145142?src=-1-59">Lightspring/Shutterstock.com</a></span></figcaption></figure><p>A test called CT lung cancer screening could save the lives of <a href="https://www.cancer.gov/types/lung/research/nlst">tens of thousands</a> of American smokers and former smokers every year, but only <a href="https://www.cdc.gov/cancer/dcpc/research/articles/lung-cancer-screening.htm">only 4%</a> of those eligible are getting it. </p>
<p>One such patient, a 58-year-old woman I’ll call Marie, battled cigarette smoking for over three decades before finally quitting on her 50th birthday. A few years later, Marie had the test, and the radiologist found an 8 millimeter nodule in her right lung, which proved to be a small cancer. She had the tumor removed, and now she is five years out from surgery, with no signs of cancer. In two months, she will welcome her first grandchild.</p>
<p>Marie’s story is not unusual. While <a href="https://theconversation.com/smoking-rates-in-us-have-fallen-to-all-time-low-but-how-did-they-ever-get-so-high-107185">U.S. smoking rates</a> have fallen to a historic low, 38 million Americans still smoke. Men who currently smoke have a <a href="https://www.lung.org/lung-health-and-diseases/lung-disease-lookup/lung-cancer/resource-library/lung-cancer-fact-sheet.html">risk of lung cancer</a> about 23 times that of nonsmokers, while the risk for women is about 13 times higher. Naturally, the best thing smokers can do to lower their risk of lung cancer is to quit, but the increased risk of cancer does not disappear immediately. It gradually declines over decades. </p>
<p>Battling lung cancer matters, because it is the <a href="https://www.cancer.org/content/dam/cancer-org/research/cancer-facts-and-statistics/annual-cancer-facts-and-figures/2018/cancer-facts-and-figures-2018.pdf">number one cancer killer</a> in the U.S., causing an estimated 154,000 deaths a year – more than all colon, breast and prostate cancer deaths combined. The American Lung Association estimates that 234,000 Americans will be diagnosed with lung cancer this year, 85% of whom will have been cigarette smokers.<br>
<a href="https://www.lung.org/lung-health-and-diseases/lung-disease-lookup/lung-cancer/resource-library/lung-cancer-fact-sheet.html">Five-year survival rates</a> are about 19%, which is relatively poor compared to most other cancers, such as breast and prostate. Until recently, this has meant that the only highly effective means of combating mortality is smoking avoidance. But now there is a new tool for reducing death rates even among smokers. </p>
<h2>CT screening</h2>
<p>As a radiologist, I am familiar with CT lung cancer screening. CT stands for computed tomography, a sophisticated type of X-ray imaging. When lung cancer is diagnosed at an early stage, <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5627048/">long-term survival</a> is 70%, compared to only 5% when it has spread to other parts of the body. Its value was established in the <a href="https://www.cancer.gov/types/lung/research/nlst">National Lung Screening Trial</a>, a US$300 million National Cancer Institute study launched in 2002 that followed 53,000 current or former smokers for five years. Investigators found a 20% mortality reduction among those screened by CT. A more recent <a href="https://academic.oup.com/jjco/advance-article/doi/10.1093/jjco/hyy185/5239841?searchresult=1">Japanese study</a> showed a 51% reduction in mortality.</p>
<p>CT scanning is not new. It was invented in the 1960s by a British engineer, <a href="https://www.nobelprize.org/prizes/medicine/1979/hounsfield/biographical/">Godfrey Hounsfield</a>, who shared the 1979 Nobel Prize in Physiology or Medicine for it. Unlike standard X-ray imaging, which sends X-rays through the patient in only one direction, CT transmits and detects X-rays in many different directions, dramatically improving imaging of the body’s interior.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/290287/original/file-20190830-165977-1r0bom6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/290287/original/file-20190830-165977-1r0bom6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/290287/original/file-20190830-165977-1r0bom6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/290287/original/file-20190830-165977-1r0bom6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/290287/original/file-20190830-165977-1r0bom6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/290287/original/file-20190830-165977-1r0bom6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/290287/original/file-20190830-165977-1r0bom6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A type of lung cancer cell reflective of adenocarcinoma, one of many types of lung cancer cells.</span>
<span class="attribution"><span class="source">David Litman/Shutterstock.com</span></span>
</figcaption>
</figure>
<p>Like any cancer, <a href="https://www.cancer.org/cancer/lung-cancer.html">lung cancer</a> consists of abnormal cells that proliferate in an uncontrolled fashion, do not obey normal signals to die and cannot repair their DNA. Normal lung cells become cancerous through exposure to tobacco smoke, radon gas, asbestos or airborne pollutants. </p>
<p>In recent years, low-dose CT has begun to be used to screen for lung cancer. Regular chest X-rays detect lung cancers only when they measure centimeters in diameter – the size of a penny or bigger – but CT can find them much earlier, when they are only millimeters wide. As with any cancer, early detection is key to improved survival. Unfortunately, once lung cancer causes symptoms – such as persistent cough, coughing up blood, and weight loss – it has already reached an advanced stage. These newer CT scans also use a lower dosage of X-rays, lowering the risk of causing other health problems. </p>
<h2>Saving lives</h2>
<p>The U.S. Preventive Services Task Force <a href="https://www.uspreventiveservicestaskforce.org/Page/Document/RecommendationStatementFinal/lung-cancer-screening">recommends</a> annual low-dose CT screening in adults between the ages of 55 and 80 who have a 30 pack-year smoking history – meaning that they have smoked the equivalent of one pack a day for 30 years, two packs per day for 15 years, and so on. This includes current smokers and those who have quit within the past 15 years.</p>
<p>The benefits of CT lung cancer screening depend on the <a href="https://www.radiologyinfo.org/en/info.cfm?pg=screening-lung">population in question</a>. There appears to be no benefit to screening people who do not have an increased lung cancer risk, such as nonsmokers. On the other hand, the benefits of screening appear to be highest in those at highest risk for lung cancer – in other words, those who have smoked the most cigarettes. With more research, it is possible that these screening guidelines will be modified.</p>
<p>So why are only 4% of patients being screened? One barrier is cost: Some patients lack insurance, and others may face high deductibles and copayments. Depending on location, costs can range <a href="https://www.americanhealthimaging.com/how-much-does-a-ct-scan-cost/">from hundreds of dollars to a few thousand dollars</a>. Another factor is the anxiety associated with a positive result. Yet another is education – many patients and even some physicians simply don’t know about the test, and even patients who do may decline to undergo it. </p>
<p>By spreading the word about CT lung cancer screening, my colleagues and I hope to save many more lives like Marie’s. By and large, lung cancer is only curable when detected early. Current and former smokers wondering if this test is right for them should talk with their doctor. </p>
<p>[ <em>You’re smart and curious about the world. So are The Conversation’s authors and editors.</em> <a href="https://theconversation.com/us/newsletters?utm_source=TCUS&utm_medium=inline-link&utm_campaign=newsletter-text&utm_content=youresmart">You can read us daily by subscribing to our newsletter</a>. ]</p><img src="https://counter.theconversation.com/content/108875/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Richard Gunderman does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>
Low-dose CT scans can detect lung cancer in smokers and former smokers at an early and sometimes treatable stage. Why are so few smokers and former smokers getting them?
Richard Gunderman, Chancellor's Professor of Medicine, Liberal Arts, and Philanthropy, Indiana University
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/108945
2018-12-19T10:00:21Z
2018-12-19T10:00:21Z
Radium revealed: 120 years since Curies found the most radioactive substance on the planet
<figure><img src="https://images.theconversation.com/files/251278/original/file-20181218-27752-1h19iwp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Curies and curiouser. </span> <span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Pierre_and_Marie_Curie.jpg#/media/File:Pierre_and_Marie_Curie.jpg">Wikimedia</a></span></figcaption></figure><p>Scientific discovery can be achingly slow, but it was moving swiftly in the 1890s. X-rays <a href="https://www.nde-ed.org/EducationResources/CommunityCollege/Radiography/Introduction/history.htm">had been</a> discovered in Germany just a few days before Christmas in 1895. Several months later, while researching these new X-rays, the French physicist Henri Becquerel accidentally discovered another new mysterious type of ray when he <a href="https://www2.lbl.gov/abc/wallchart/chapters/03/4.html">detected</a> radiation emitting from uranium. </p>
<p>Many scientists, doctors and inventors – including Thomas Edison – were fascinated by X-rays and their ability to make the invisible observable. But Marie Curie, a young Polish-born doctoral student at the University of Paris, suspected there was much more to be discovered from Becquerel’s “uranic rays”. </p>
<p>She reached this conclusion on the back of a curious observation. In testing countless rocks and minerals for radiation emissions, using measuring equipment invented by her husband Pierre and his brother Jacques, she noticed that uranium ores gave off greater emissions than pure samples of uranium. Soon Pierre, a professor of physics at the university, set aside his own research to help her explain why. </p>
<p>In July of 1898, they <a href="https://www.iupac.org/publications/ci/2011/3301/5_adloff.html">showed that</a> the ore contained a new element that was giving off similar radiation. They named it <a href="https://www.livescience.com/39452-polonium.html">polonium</a> after Marie’s home country, coining the term “radioactivity” in the process. Yet it became apparent to the Curies that there was another substance in the ores that was considerably more radioactive than either uranium or polonium. The challenge now was to find out what. </p>
<h2>Enter radium</h2>
<p>The discovery of radium was hard work. Corrosive acids, strong alkalis and hard labour were required as the Curies performed many separations to tease away the tiny quantities of radium from the 30 or so other elements present. They were working with an ore called pitchblende which they had sourced from a mine in the <a href="https://www.britannica.com/place/Ore-Mountains">Ore Mountains</a> that separate Germany from the Czech Republic, in what was still part of the Austrian empire. </p>
<p>The university had only given them a shed next to the departments of chemistry and physics for their work. This was the cold and damp environment in which they had to grind, crush, dissolve, precipitate, filter, wash and painstakingly measure what they found. By December 21 of that year, they had made the discovery. On Boxing Day, it was published in a paper read to the French Academy of Sciences: </p>
<blockquote>
<p>The new radioactive substance certainly includes a very large portion of barium; in spite of that, the radioactivity is considerable. The radioactivity of radium then must be enormous. </p>
</blockquote>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/251281/original/file-20181218-27770-1rd5g2n.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/251281/original/file-20181218-27770-1rd5g2n.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/251281/original/file-20181218-27770-1rd5g2n.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=480&fit=crop&dpr=1 600w, https://images.theconversation.com/files/251281/original/file-20181218-27770-1rd5g2n.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=480&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/251281/original/file-20181218-27770-1rd5g2n.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=480&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/251281/original/file-20181218-27770-1rd5g2n.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=603&fit=crop&dpr=1 754w, https://images.theconversation.com/files/251281/original/file-20181218-27770-1rd5g2n.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=603&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/251281/original/file-20181218-27770-1rd5g2n.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=603&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">What it looks like.</span>
<span class="attribution"><a class="source" href="https://en.wikipedia.org/wiki/Radium#/media/File:Radium226.jpg">Wikimedia</a></span>
</figcaption>
</figure>
<p>This substance is the most radioactive natural element, a million times <a href="http://www.radioactivity.eu.com/site/pages/Radium.htm">more so</a> than uranium. It is so radioactive that it gives off a pale blue glow. Yet it would still take the Curies another three years to produce a pure radium salt. Having originally worked with 100g of the ore, equivalent to a tenth of a bag of sugar, they would need a tonne of ore to isolate just a tenth of a gram of radium dichloride. They <a href="https://www.nobelprize.org/prizes/physics/1903/summary/">received</a> the Nobel Prize in Physics in 1903 for this work, sharing it with Becquerel. </p>
<p>Pierre was tragically killed in a coach accident in 1906 (he was also deeply unwell from the effects of his work with radiation). Marie Curie took his professorship and continued with their research, later isolating pure radium metal and <a href="https://www.nobelprize.org/prizes/chemistry/1911/summary/">receiving</a> the Nobel Prize in Chemistry in 1911.</p>
<h2>Radium with everything</h2>
<p>The boom and bust of radium over the first three decades of the 20th century remains one of the great cautionary tales of our times. Among a slew of papers that the Curies published in the years after its discovery, one <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3093546/">showed that</a> radium could treat cancer by killing cancer cells more quickly than healthy cells. It became used as one of the first radiation treatments for cancer and other skin diseases. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/251280/original/file-20181218-27752-1q4m8q.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/251280/original/file-20181218-27752-1q4m8q.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/251280/original/file-20181218-27752-1q4m8q.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=860&fit=crop&dpr=1 600w, https://images.theconversation.com/files/251280/original/file-20181218-27752-1q4m8q.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=860&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/251280/original/file-20181218-27752-1q4m8q.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=860&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/251280/original/file-20181218-27752-1q4m8q.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1081&fit=crop&dpr=1 754w, https://images.theconversation.com/files/251280/original/file-20181218-27752-1q4m8q.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1081&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/251280/original/file-20181218-27752-1q4m8q.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1081&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Radium-infused soap.</span>
</figcaption>
</figure>
<p>Yet the metal’s strange blue glow <a href="https://www.reuters.com/article/us-france-radium-decontamination/frances-20th-century-radium-craze-still-haunts-paris-idUSBRE86I0AH20120719">convinced some</a> that it had other benefits. It became widely used in quack treatments and elixirs, from therapeutic waters to soap to chocolate bars, where the buyer was only safe if the mixtures contained no radium at all. </p>
<p>Among other uses, entrepreneurs used radium to create “glow-in-the-dark” paint. This led to <a href="https://www.spectator.co.uk/2016/06/the-radium-girls-still-glowing-in-their-coffins/">the tragedy</a> of the radium dial painters in New Jersey – an all too familiar story of the promise of profit over safety, and denial of the facts. Factory workers, mostly young girls seeking an independent income, ingested the metal while applying the paint to watch faces. The radium bound to their bones like its chemical cousin, calcium, injuring, disfiguring and killing many of the two thousand workers estimated to have been employed at peak. </p>
<p>The radium industry dramatically declined after health concerns began <a href="https://www.theatlantic.com/health/archive/2013/03/how-we-realized-putting-radium-in-everything-was-not-the-answer/273780/">emerging</a> in the mid-1920s. It still has a lingering presence in the contaminated soils and land around the old extraction and industry buildings in Denver, Pittsburgh and New Jersey. The UK is still dealing with the legacy of radium-painted dials used in World War II, with Dalgety Bay in Fife just one area affected by radium displaced from old waste dumps. When once the challenge was to extract this buried treasure, now the focus is on safely treating it as buried waste.</p>
<p>Marie Curie made it her lifelong goal to work out what radioactivity was, what produced it and what it could mean for the nature of matter. This almost certainly contributed to <a href="https://cosmosmagazine.com/physics/this-week-in-science-history-marie-curie-dies">her death</a> from leukaemia at the age of 66, though she
remains the only scientist to have received Nobel Prizes in both physics and chemistry. She became a landmark figure for women in science, and the element curium was later named in her honour. </p>
<p>Today radium is barely used in medicine, apart from treating some specific bone cancers. It was too expensive and rare to be a widespread feedstock for radiation therapy, and was replaced by alternatives like radon gas and later an isotope of cobalt. Yet radiation therapy and the knowledge about radioactivity that came with discovering radium remain hugely important. The story of radium mirrors that of radiation itself – a double-edged sword, with great benefits that always need to be balanced against the potential for massive harm.</p><img src="https://counter.theconversation.com/content/108945/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Stephen Mansell does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>
With its strange bluish glow and cancer-killing qualities, meet the wundermetal that became one of the great cautionary tales of modern times.
Stephen Mansell, Assistant Professor, Chemistry, Heriot-Watt University
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/103843
2018-09-26T20:12:36Z
2018-09-26T20:12:36Z
Unexpected find from a neutron star forces a rethink on radio jets
<figure><img src="https://images.theconversation.com/files/237878/original/file-20180925-149967-125y575.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">An artist’s impression of the strong magnetic field neutron star in Swift J0243.6+6124 launching a jet.</span> <span class="attribution"><span class="source">ICRAR/University of Amsterdam</span>, <span class="license">Author provided</span></span></figcaption></figure><p>Just a little to the left of the leftmost part of the “W” in the constellation <a href="https://www.iau.org/public/themes/constellations/#cas">Cassiopeia</a> lies a binary system of a neutron star in a 27-day orbit with a more massive, rapidly rotating star.</p>
<p>It’s from here we’ve detected <a href="https://www.britannica.com/science/radio-jet">radio jets</a> – material travelling close to the speed of light and emitting radio waves – with details <a href="http://dx.doi.org/10.1038/s41586-018-0524-1">published today in Nature</a>.</p>
<p>But the find was something not predicted by current theory. This particular neutron star has a very strong magnetic field, yet jets from neutron stars had only previously been observed in systems with magnetic fields about 1,000 times weaker.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/explainer-what-is-a-neutron-star-29341">Explainer: what is a neutron star?</a>
</strong>
</em>
</p>
<hr>
<p><a href="http://astronomy.swin.edu.au/cosmos/N/Neutron+Star">Neutron stars</a> are dense stellar corpses, with about one and a half times the mass of the Sun squeezed into a sphere just ten kilometres across.</p>
<p>With enormous densities (similar to that of an atomic nucleus), they are the densest objects that can support themselves against their own gravity. If they were any denser they would collapse to form a <a href="http://astronomy.swin.edu.au/cosmos/B/Black+Hole">black hole</a>.</p>
<h2>A Swift discovery</h2>
<p>This particular binary system, known as Swift J0243.6+6124, was first discovered on October 3, 2017, by NASA’s <a href="https://swift.gsfc.nasa.gov/">Neil Gehrels Swift Observatory</a>. This satellite, known as Swift, continuously scans the sky looking for new, bright sources of X-ray emission. </p>
<p>After a bright new burst of X-rays was detected from the location of this binary system, astronomers from across the world trained their telescopes on the source to try to determine what was producing them.</p>
<p>It turned out that the strong gravity of the neutron star in this system was capturing material thrown off by the rapid rotation of the other star. For many years this gas had been piling up in a disk of matter swirling around the neutron star.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/237879/original/file-20180925-149982-732e1l.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/237879/original/file-20180925-149982-732e1l.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/237879/original/file-20180925-149982-732e1l.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=424&fit=crop&dpr=1 600w, https://images.theconversation.com/files/237879/original/file-20180925-149982-732e1l.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=424&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/237879/original/file-20180925-149982-732e1l.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=424&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/237879/original/file-20180925-149982-732e1l.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=533&fit=crop&dpr=1 754w, https://images.theconversation.com/files/237879/original/file-20180925-149982-732e1l.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=533&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/237879/original/file-20180925-149982-732e1l.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=533&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">An artist’s impression of the binary system Swift J0243.6+6124 with a neutron star in a 27-day orbit and a more massive, rapidly-rotating donor star.</span>
<span class="attribution"><span class="source">ICRAR/University of Amsterdam</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>When enough matter had accumulated, it all started to move inwards at once. We’re all familiar with a weight thrown from the top of a hill picking up speed as it falls. The physics behind this everyday phenomenon is the release of gravitational energy, which is converted into the energy of motion.</p>
<p>In exactly the same way, the gravitational energy of the mass was released as it fell in towards the neutron star. That energy was initially converted into motion, and eventually into X-ray radiation, which was what the Swift satellite detected.</p>
<h2>Closer inspection</h2>
<p>Our team, led by PhD student Jakob van den Eijnden from the University of Amsterdam, also detected radio waves from the source, using the Karl G Jansky <a href="https://public.nrao.edu/telescopes/vla/">Very Large Array</a> observatory, in New Mexico.</p>
<p>The brightness of the radio emission tracked the brightness of the X-rays from the source as the burst rose and then faded away over a period of a few months. The behaviour of the radio emission led us to conclude that it was coming from jets.</p>
<p><a href="http://astronomy.swin.edu.au/cosmos/J/Jets">Jets</a> are narrowly-focused beams of matter and energy that travel outwards at close to the speed of light. They carry away some of the gravitational energy released when matter falls in towards a central object, such as a black hole or neutron star.</p>
<p>The jets deposit this energy into the surroundings, often at very large distances from the launch point.</p>
<p>In neutron stars and black holes that are only a few times more massive than the Sun, this energy can be transported many light years away. For supermassive black holes that lie at the centres of galaxies, the jets can carry away energy to hundreds of thousands of light years from the galaxy centre.</p>
<p>The first jet was discovered 100 years ago by the <a href="https://apod.nasa.gov/debate/1920/curtis_obit.html">astronomer Heber Curtis</a>, who noticed a “curious straight ray” associated with the nearby galaxy M87. Since the dawn of radio and X-ray astronomy in the middle of last century, jets have been studied extensively.</p>
<p>They are produced whenever matter falls onto a dense central object, from newly-forming stars to white dwarfs, neutron stars and black holes. The one exception had been neutron stars with strong magnetic fields - around a trillion times stronger than that of the Sun.</p>
<h2>Against the theory</h2>
<p>Despite decades of observations, jets had not been detected in these systems. This had led to the suggestion that strong magnetic fields prevented jets from being launched.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/kMGUxmZJLQw?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Astronomers need a new theory to explain these jets.</span></figcaption>
</figure>
<p>Our detection of jets from a neutron star <em>with</em> a strong magnetic field disproved the idea that had held for the past several decades. But it requires a re-examination of our theories for how jets are produced.</p>
<p>There are two main theories explaining how jets are launched. If a magnetic field threads the <a href="http://astronomy.swin.edu.au/cosmos/E/Event+Horizon">event horizon</a> of a spinning black hole, the rotational energy of the hole can be extracted to power the jets.</p>
<p>But as neutron stars have no event horizon, their jets are instead thought to be launched from rotating magnetic fields in the inner part of the disk of gas surrounding it. Particles can be flung out along magnetic field lines in much the same way as a bead will move outward on a wire that you whirl around above your head.</p>
<p>If a neutron star’s magnetic field is sufficiently strong, it should prevent the disk of matter from getting close enough to the neutron star for this second mechanism to work. We therefore need another explanation.</p>
<p>Recent theoretical work has suggested that under certain circumstances it might be possible to launch jets from the extraction of the neutron star’s rotational energy.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/once-upon-a-time-sleeping-beauties-and-the-importance-of-storytelling-in-science-102497">Once upon a time ... 'sleeping beauties' and the importance of storytelling in science</a>
</strong>
</em>
</p>
<hr>
<p>In our case, this could have been enabled by the high rate at which matter was falling inwards. It would also explain why the jets that we saw were about 100 times weaker than seen in other neutron stars with weaker magnetic fields.</p>
<p>Whatever the explanation, our result is a great example of how science works, with theories being developed, tested against observations and revised in light of new experimental results. </p>
<p>It also provides us with a new class of sources to test how magnetic fields affect the launching of jets, helping us to understand this key feedback mechanism in the universe.</p><img src="https://counter.theconversation.com/content/103843/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>James Miller-Jones receives funding from the Australian Research Council, and serves on the Editorial Board of the journal New Astronomy Reviews.</span></em></p>
Astronomers found something not predicted by current theory when they took a closer look at the emissions from a neutron star with a very strong magnetic field.
James Miller-Jones, Associate Professor, Curtin University
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/101373
2018-08-16T21:54:19Z
2018-08-16T21:54:19Z
How Canadian technology could protect Space Force troops
<figure><img src="https://images.theconversation.com/files/232178/original/file-20180815-2915-15fjjis.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">U.S. Vice-President Mike Pence speaks about the creation of a United States Space Force on Aug. 9, 2018 at the Pentagon.</span> <span class="attribution"><span class="source">(AP Photo/Evan Vucci)</span></span></figcaption></figure><p>U.S. Vice-President Mike Pence <a href="https://www.defense.gov/News/Article/Article/1598071/space-force-to-become-sixth-branch-of-armed-forces/">has announced</a> that the United States plans to establish a “Space Force.” President Donald Trump endorsed the announcement in a follow-up tweet.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1027586174448218113"}"></div></p>
<p>The response was mixed: Some <a href="https://www.bloomberg.com/news/articles/2018-08-13/nasa-administrator-supports-trump-space-force-proposal">support</a>, some <a href="https://www.snopes.com/fact-check/mark-kelly-space-force/">pushback</a>. The topic also became fodder for late-night <a href="https://www.cnn.com/videos/cnnmoney/2018/08/10/late-night-pence-trump-space-force-orig-gs.cnn">TV shows</a>. </p>
<p>The U.S. says it’s establishing Space Force as a response to perceived threats to American space hardware from <a href="https://globalnews.ca/news/4379395/space-force-china-russia-anti-satellite-weapons/">Russia and China</a>. Both countries have been developing high-powered lasers to knock out communications equipment on satellites. The U.S. government is taking <a href="https://www.defensenews.com/space/2018/08/09/think-space-force-is-a-joke-here-are-four-major-space-threats-to-take-seriously/">a number</a> of space threats seriously; hence the desire for space military capability.</p>
<p>It was not clear from Pence’s announcement whether troops would actually be sent to space, but <a href="http://fortune.com/2018/08/09/trump-pac-asking-supporters-vote-space-force-logo-campaign-gear/">fundraising emails</a> from the Trump campaign included the logo “Mars awaits.”</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1027651993341448192"}"></div></p>
<p>This suggests support for plans to send humans to our neighbouring planet. But the journey to Mars will be perilous. </p>
<h2>Protecting astronauts from radiation</h2>
<p>I am a professor of radiation physics and a co-investigator on a team that is launching a <a href="http://mcmasterneudose.ca/">new satellite</a> to look into radiation doses in space. I know that one of the big space exploration challenges is how to protect astronauts and troops from high radiation fields in space. </p>
<figure class="align-right ">
<img alt="" src="https://images.theconversation.com/files/232184/original/file-20180815-2909-okdm45.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/232184/original/file-20180815-2909-okdm45.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=860&fit=crop&dpr=1 600w, https://images.theconversation.com/files/232184/original/file-20180815-2909-okdm45.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=860&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/232184/original/file-20180815-2909-okdm45.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=860&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/232184/original/file-20180815-2909-okdm45.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1080&fit=crop&dpr=1 754w, https://images.theconversation.com/files/232184/original/file-20180815-2909-okdm45.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1080&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/232184/original/file-20180815-2909-okdm45.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1080&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">NASA astronaut Scott Kelly says his DNA profile no longer matches his twin’s after space travel.</span>
<span class="attribution"><span class="source">(AP Photo/Pat Sullivan)</span></span>
</figcaption>
</figure>
<p>Past astronauts were found to have a higher risk of <a href="https://www.ncbi.nlm.nih.gov/pubmed/19580503">cataracts</a>, for example. Last year, Scott Kelly found that his <a href="http://time.com/5201064/scott-kelly-mark-nasa-dna-study/">DNA profile</a> was no longer the same as his twin after a year in space. </p>
<p>A trip to Mars (and back) would take years, and astronauts and troops would be subjected to substantial radiation doses. We don’t yet fully understand all of the radiation risks from space travel.</p>
<p>On Earth, we are bombarded with <a href="https://home.cern/about/physics/cosmic-rays-particles-outer-space">radiation from space</a>, but we have the Earth’s magnetic field and our atmosphere to protect us. </p>
<p>Fly or travel up a mountain, and you’ll be exposed to <a href="https://www3.epa.gov/radtown/cosmic-radiation.html">more radiation</a>, because there is less atmosphere between you and space. Once outside the atmosphere, space travellers will be exposed both to higher levels of radiation and to different types of radiation than at sea level. </p>
<p>Space Force fighters would be exposed to higher fields of <a href="https://imagine.gsfc.nasa.gov/science/toolbox/cosmic_rays1.html">neutrons, protons and heavy ions</a>, including the ionized atoms of helium and even iron. Some of the radiation comes from supernovae outside of our solar system and some comes from occasional high bursts of <a href="https://ccmc.gsfc.nasa.gov/RoR_WWW/SWREDI/2014/SEP_YZheng_20140602.pdf">energetic solar particles</a> from our sun. </p>
<p>A portion of the radiation exposure will be a result of interactions of particles with the space craft materials. The radiation field changes over time, and also varies with location in space.</p>
<h2>Cancer, cataracts</h2>
<p>Radiation can result in biological and health effects because it can <a href="https://www.nrc.gov/reading-rm/basic-ref/students/for-educators/09.pdf">directly damage DNA</a> or cause build-up of toxic molecules, like hydrogen peroxide, inside cells. Studies of the survivors of the atomic bombs in Hiroshima and Nagasaki found increased levels of <a href="https://www.rerf.or.jp/en/programs/roadmap_e/health_effects-en/late-en/cancrisk/">cancer</a> and a higher incidence of <a href="https://www.ncbi.nlm.nih.gov/pubmed/15223766">cataracts</a> in people exposed to high levels of radiation. </p>
<p>Troops sent to Mars could <a href="https://www.newscientist.com/article/dn23619-return-trips-to-mars-pose-unacceptable-radiation-risk/">receive doses</a> comparable to some atom bomb survivors, although at a slower rate over a longer period of time. However, some could be exposed to heavy charged particles that are more densely ionizing than X-rays. Heavy charged particles have a <a href="https://journals.lww.com/health-physics/Abstract/2012/11000/DNA_and_Cellular_Effects_of_Charged_Particles.8.aspx">more significant biological impact</a> relative to X-rays because they deposit more energy, in shorter tracks, as they pass through human cells.</p>
<figure class="align-left ">
<img alt="" src="https://images.theconversation.com/files/232099/original/file-20180815-2894-1pji467.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/232099/original/file-20180815-2894-1pji467.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=900&fit=crop&dpr=1 600w, https://images.theconversation.com/files/232099/original/file-20180815-2894-1pji467.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=900&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/232099/original/file-20180815-2894-1pji467.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=900&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/232099/original/file-20180815-2894-1pji467.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1131&fit=crop&dpr=1 754w, https://images.theconversation.com/files/232099/original/file-20180815-2894-1pji467.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1131&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/232099/original/file-20180815-2894-1pji467.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1131&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">NEUDOSE team member Dr. Ishwar Singh holds the CubeSat.</span>
<span class="attribution"><span class="source">J.D. Howell, McMaster University</span></span>
</figcaption>
</figure>
<p>It will be important for Space Force to monitor radiation fields in real time, so that troops can don suits with radiation shielding or move to shielded areas of spacecraft for protection during high radiation episodes. </p>
<p>This is where Canadian technology may play a future role. I am one of the co-investigators in the NEUDOSE satellite team. We are a multidisciplinary student team from the Faculties of Engineering and Science at McMaster University who are designing and building a <a href="http://www.rrjournal.org/doi/abs/10.1667/RR14491.1?code=rrs-site">novel radiation detector</a> that we plan to test in space. </p>
<p>The detector will be mounted in a small satellite — about the size of a loaf of bread — known as a CubeSat. </p>
<p>If we meet our <a href="http://www.asc-csa.gc.ca/eng/satellites/cubesat/selected-teams.asp">mission goals</a>, our satellite will be launched from the International Space Station by the Canadian Space Agency in 2021. We have already completed one successful <a href="https://www.nasa.gov/Wallops/2017/image-feature/student-payloads-take-to-the-skies-on-nasa-scientific-balloon">balloon mission</a> using NASA’s High Altitude Student Platform (HASP). </p>
<h2>Detector launched into space</h2>
<p>In 2017, the detector was launched 34 kilometres above the Earth on a zero pressure, 11-million-cubic-foot, helium-filled balloon from Fort Sumner, New Mexico.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/231975/original/file-20180814-2891-pfmbwg.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/231975/original/file-20180814-2891-pfmbwg.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/231975/original/file-20180814-2891-pfmbwg.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/231975/original/file-20180814-2891-pfmbwg.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/231975/original/file-20180814-2891-pfmbwg.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/231975/original/file-20180814-2891-pfmbwg.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/231975/original/file-20180814-2891-pfmbwg.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A photograph taken during the 2017 HASP launch. The Neudose detector is the white dome on the left of the image. The balloon was so high that the Earth can be seen to curve below.</span>
<span class="attribution"><span class="source">Image provided by Renert School HASP Team</span></span>
</figcaption>
</figure>
<p>This September, the detector will be tested inside the CubeSat on a second NASA HASP launch. Our team plans to test our ground receiving station by mounting it on a truck and driving over the New Mexico countryside, chasing the balloon test. We hope to confirm that we can receive test signals from our satellite back on the ground.</p>
<p>The novelty of our radiation detector is that it will, through an ingenious design first proposed by Andrei Hanu, a senior scientist at Bruce Power, simultaneously measure in real time both charged and neutral particles and distinguish them. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/Lxkgm3x6AJI?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Time lapse video from the HASP 2017 launch.</span></figcaption>
</figure>
<p>The detector is based on designs that are being developed at McMaster by Prof. Soo Hyun Byun for radiation protection in the nuclear industry, adapted for space radiation. </p>
<p>Launching the detector on a CubeSat allows us to test the detector performance in space, and will also provide several months of data of the space radiation fields in near-Earth orbits after launch. </p>
<p>The satellite will orbit for nine to 12 months. Every time it passes over McMaster, it will beam back radiation data to a ground station. That data should allow improvements to be made to current radiation modelling tools that will help the planning for future missions into deep space, including Mars.</p>
<h2>A new era of space exploration</h2>
<p>The NEUDOSE team members, myself included, truly believe that humanity is entering a new era of exploration. Human beings may soon fly on missions back to the moon and out to Mars. </p>
<p>Our hope is that our radiation instrument could ultimately replace current equipment on the International Space Station and be used on future space craft to identify high-dose areas in space and incoming solar storms. </p>
<p>And who knows? Maybe our detectors will be installed on the first Space Force deep space mission vehicles.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/3-8g2arjnA4?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">McMaster goes to space!</span></figcaption>
</figure><img src="https://counter.theconversation.com/content/101373/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Fiona E. McNeill receives research funding from the Natural Sciences and Engineering Research Council of Canada and is a co-applicant on funding from the Canadian Space Agency. Funding for NEUDOSE has also been provided by Bruce Power, the Candu Owner's Group and the Canadian Nuclear Safety Commission.</span></em></p>
Could Canadian technology play a part in the newly announced U.S. Space Force? A team at McMaster University has developed an instrument that could keep Space Force troops safe from radiation.
Fiona E. McNeill, Professor of Radiation Sciences, McMaster University
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/101344
2018-08-16T11:26:15Z
2018-08-16T11:26:15Z
Why X-rays could be about to get a lot more personal
<figure><img src="https://images.theconversation.com/files/231873/original/file-20180814-2894-5gdxj7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Finger mounted flexible detector</span> </figcaption></figure><p>X-rays could be about to change. Since its discovery at the end of the 19th century, the radiation has provided a window into the inner workings of the body, and later gave us the power to “see” inside everything from buildings to suitcases. But the technology has remained in principle the same: the rays are fired through whatever object is being inspected onto a fixed, rigid and usually small detector that can produce the desired image.</p>
<p>But X-rays could be much more flexible in future. New technology means that X-ray detectors could one day effectively be printed onto any suitable surface. So they could be made curved to wrap around the part of the patient’s body being scanned to produce a much more accurate image. They could be large enough to scan an entire truck in one go. And they could be portable enough to quickly carry through a crowd to inspect a suspicious package. And this future is now a step closer thanks to a recent advance that my colleagues and I have made.</p>
<p>Today, many X-ray images are created by firing the rays onto a <a href="http://iopscience.iop.org/article/10.1088/0031-9155/42/1/001/pdf">digital detector</a> rather than photographic film. These detectors convert the X-rays into electrical charges and a computer converts these into a digital image. Many industries have benefitted from this massive leap from X-ray film because it has enabled the creation of more detailed images that can be viewed in real time. But the solid detectors are also rigid and flat and so limited.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/13J16FqWeXg?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
</figure>
<p>By contrast, the human body naturally consists of curved surfaces. And firing X-rays through a curved object onto a flat detector can cause <a href="https://www.holstcentre.com/news---press/2017/curvedxray/">errors</a>. This can lead to a cancer misdiagnosis or a patient being given the wrong dose of radiotherapy. Overexposing someone to X-rays can also cause tissue damage and even the growth of <a href="http://stopcancerfund.org/pz-environmental-exposures/everything-you-ever-wanted-to-know-about-radiation-and-cancer-but-were-afraid-to-ask-2/">secondary tumours</a>.</p>
<p>Because current X-ray detectors are mostly made from thick slabs of inorganic material, they are expensive to make in large sizes for scanning large objects such as vehicles. Some detectors also require very high voltages to operate and so would’t be suitable for <a href="https://www.or-technology.com/en/products/mobile/leonardo-dr-mini.html">portable applications</a>.</p>
<p>For inspecting manufactured parts and products for defects (known as non-destrutive testing), traditional X-ray films are still commonly used to capture images because they are cheaper than digital detectors. But these films need to be processed in a special lab so they can’t provide the real-time images that digital detectors can.</p>
<h2>Flexible detectors</h2>
<p>All these applications would benefit from the creation of more flexible digital X-ray detectors. And it looks as if there might finally be a solution. In 2017, researchers demonstrated the <a href="http://www.osadirect.com/news/article/2053/holst-centre-imec-and-philips-demo-worlds-first-curved-plastic-photodetector/">world’s first</a> curved plastic X-ray imager. And now, my colleagues and I have developed a way to create detectors using a <a href="https://www.nature.com/articles/s41467-018-05301-6">special ink</a> that can be deposited on a surface to create an X-ray sensitive film.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/eeVovEfLFe8?wmode=transparent&start=1" frameborder="0" allowfullscreen=""></iframe>
</figure>
<p>The ink contains nanoparticles that can stop the incoming X-rays and generate an electrical charge, and organic material that carries the charge to a set of electrodes. It can be coated or printed onto any suitable surface of any size and only needs to be several micrometers thick, less than a sheet of paper.</p>
<p>As a result, it is now possible to create large, flexible X-ray detectors powered using only a couple of coin cell batteries. Alternatively, we could create portable X-ray detectors that, coupled with portable X-ray sources, could fit into ambulances and be used to make diagnoses on the road and not just in hospitals. And improving the resolution of the images could allow the technology to be used for detecting cancer.</p>
<p>Researchers are also <a href="https://healthcare-in-europe.com/en/news/high-resolution-detectors-to-create-safer-x-ray-diagnosis.html">working</a> to create detectors that can work with lower X-ray doses, to minimise the amount of radiation that patients and operators are exposed to. This will require identifying materials that are more sensitive to X-rays so that a better response can be achieved with a lower dose. This technology has such exciting potential to revolutionise current imaging techniques and where this would take us is only limited by our imagination.</p><img src="https://counter.theconversation.com/content/101344/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Hashini Thirimanne receives funding from the Leverhulme Trust. </span></em></p>
An X-ray sensitive ink means future detectors could be printable, portable and flexible.
Hashini Thirimanne, PhD Candidate in Electronic Engineering, University of Surrey
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/96771
2018-05-31T10:45:00Z
2018-05-31T10:45:00Z
Immigration agents X-raying migrants to determine age isn’t just illegal, it’s a misuse of science
<figure><img src="https://images.theconversation.com/files/221038/original/file-20180530-120518-d8e1xv.jpg?ixlib=rb-1.1.0&rect=3%2C2%2C772%2C542&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Teeth and bones can tell something about age – but not someone's birthday.</span> <span class="attribution"><a class="source" href="https://openi.nlm.nih.gov/detailedresult.php?img=PMC3190433_JFDS-3-14-g005&query=&req=4&npos=-1">Journal of Forensic Dental Sciences</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-sa/4.0/">CC BY-NC-SA</a></span></figcaption></figure><p>A teenager’s father is murdered in Somalia, and the boy travels to the United States seeking asylum. Another teen’s father and brother are murdered by extremist groups in Afghanistan and he too makes his way to the U.S. to seek asylum. Since both are minors, <a href="https://www.gpo.gov/fdsys/pkg/PLAW-107publ296/html/PLAW-107publ296.htm">federal law decrees</a> that they must be held separately from adults under the oversight of the Office of Refugee Resettlement (<a href="https://www.acf.hhs.gov/orr">ORR</a>).</p>
<p>However, <a href="https://www.revealnews.org/blog/heres-how-ice-sent-children-seeking-asylum-to-adult-detention-centers/">in these two cases</a>, and an unknown number of others, these minors were taken in handcuffs by Immigration and Customs Enforcement and held in adult detention facilities. The reason? In the absence of other information that could corroborate the teens’ self-reported ages, analysis of their dental X-rays revealed that both could be adults.</p>
<p>Lawyers for these two teens <a href="https://www.nwirp.org/wp-content/uploads/2016/05/050516-Pechman-Order.pdf">sued on</a> <a href="https://www.documentcloud.org/documents/4451390-H-S-order.html">the grounds</a> that sole reliance on X-rays for age determination is illegal, and several federal judges agreed.</p>
<p>As a forensic anthropologist, I support these judicial decisions. My work can include estimating the ages of deceased persons using X-rays of bones and teeth, and I’m intimately familiar with the limitations of how specific these techniques can be. In my field, we generate an age range alongside several caveats; it’s irresponsible for ICE to rely solely on X-rays to provide a definitive answer in determining if a person is a minor or an adult.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/220866/original/file-20180529-80637-1e77wee.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/220866/original/file-20180529-80637-1e77wee.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/220866/original/file-20180529-80637-1e77wee.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=266&fit=crop&dpr=1 600w, https://images.theconversation.com/files/220866/original/file-20180529-80637-1e77wee.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=266&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/220866/original/file-20180529-80637-1e77wee.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=266&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/220866/original/file-20180529-80637-1e77wee.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=334&fit=crop&dpr=1 754w, https://images.theconversation.com/files/220866/original/file-20180529-80637-1e77wee.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=334&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/220866/original/file-20180529-80637-1e77wee.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=334&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">X-ray of a mouth with wisdom teeth emerging on the outside.</span>
<span class="attribution"><a class="source" href="https://doi.org/10.4103/0975-1475.137068">Journal of Forensic Dental Sciences</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-sa/4.0/">CC BY-NC-SA</a></span>
</figcaption>
</figure>
<h2>What can bones and teeth tell us?</h2>
<p><a href="https://www.crcpress.com/Forensic-Anthropology-An-Introduction/Langley-Tersigni-Tarrant/p/book/9781439898253">Forensic anthropologists study</a> the hard tissues of the human body, which includes bones and teeth. I’m typically charged with <a href="https://www.elsevier.com/books/research-methods-in-human-skeletal-biology/digangi/978-0-12-385189-5">estimating biological characteristics</a> of deceased persons, including how old a person was when they died.</p>
<p>For children and teenagers, such an analysis can be carried out by examining X-rays. Growth and development are predictable processes, and milestones occur in a particular order. This is the reason that a tooth such as the first adult molar is also known as the “six-year molar,” because it generally erupts in everyone around age 6, give or take.</p>
<p>The analysis proceeds the same way whether we’re examining the X-rays of a living or deceased person. Essentially, we compare the stage of growth shown in the X-ray to <a href="https://www.atlas.dentistry.qmul.ac.uk">existing growth charts</a> from children and teenagers of known ages.</p>
<p>The crucial point is that it’s not possible to make a definitive, single age determination from X-rays or examination of bones or teeth. A variety of factors affect how well chronological age corresponds with biological age; that is, the amount of time since birth doesn’t necessarily correlate to the exact same stage of growth in every child or teenager. </p>
<p><a href="http://admin.cambridge.org/academic/subjects/life-sciences/biological-anthropology-and-primatology/paleodemography-age-distributions-skeletal-samples#jmjs2GKsG24UOjZ3.97">Lots of things</a> can influence how well <a href="https://global.oup.com/academic/product/biological-anthropology-and-aging-9780195068290?lang=en&cc=be">biological and chronological age line up</a>, including nutrition, environmental exposure to disease-causing germs and viruses (and their level of virulence), whether the person has been vaccinated against preventable diseases, body weight, hormones and genetics, among many others.</p>
<p>While these factors differ between individuals, they also differ broadly between populations of people – for instance, as a group, Americans likely develop at a different rate than sub-Saharan Africans. </p>
<p>Many of the studies relied upon to make age estimations are based on populations not representative of the individuals to whom they’re being applied. Therefore, a <a href="https://www.wiley.com/en-us/A+Companion+to+Forensic+Anthropology-p-9781118959794">certain amount of error</a> can be expected in the final age estimation. What’s more, this error is immeasureable. Without scientific studies on growth that are specific to each population, we don’t know if on average, Population A ages six months, one year or two years faster or slower than Population B. And while many methods are bolstered by a statistical likelihood, this is not the same thing as being certain. We can never be 100 percent sure.</p>
<h2>Estimation ranges versus exact ages</h2>
<p>Of course, the amount of time since birth is the legally important age. But because a disparity exists, forensic anthropologists refer to the results of the scientific methods we use as “age estimation.” The estimation will never be a pinpointed exact age, because of the variation that exists between individuals and between populations of people.</p>
<p>Therefore, forensic anthropologists report age estimations as a range. For example, rather than saying someone is 17 years and 8 months old, our estimation may be that she is between 17 and 20 years old.</p>
<p><iframe id="dqTSx" class="tc-infographic-datawrapper" src="https://datawrapper.dwcdn.net/dqTSx/4/" height="400px" width="100%" style="border: none" frameborder="0"></iframe></p>
<p>Sometimes, the estimated age range might include ages below and above 18. Take the development of the wisdom tooth, something we often look at when estimating age of older teenagers and young adults. But the development of this tooth is extremely variable, ranging from never developing at all to erupting anywhere from the mid-teens to early 20s. In such cases, how would a final decision of adult or minor status be made?</p>
<p><a href="https://www.state.gov/j/tip/laws/113178.htm">Federal law</a> dictates that X-rays in cases where adult age is not obvious be used only in concert with other methods, such as verification of documentation and interviews. This makes sense because X-rays only provide orienting information rather than a definitive answer. </p>
<p>The recent court cases demonstrate that ICE has broken the law by exclusively relying on X-rays for age determination, ruling that the teens be released back into ORR’s custody as minors. Are these cases isolated or illustrative of a bigger problem? <a href="https://www.documentcloud.org/documents/4450510-DHS-OIG-Report-on-ICE.html">A 2008 report</a> by the Office of Homeland Security found that it was not only unclear how often ICE needed to resort to X-rays to assist with age determination, but unknown how common it was for them to rely solely on X-ray results. Without accurate numbers, there is no way to know how widespread the practice is or how to improve the process.</p>
<p>The stakes are high. Children – especially unaccompanied ones – are especially vulnerable. For this reason, the <a href="https://www.aclu.org/sites/default/files/assets/flores_settlement_final_plus_extension_of_settlement011797.pdf">1997 Flores Settlement Agreement</a>, which ICE is bound by, stipulates that migrant minors be kept separate from unrelated adults. </p>
<p>Given recent news that ORR doesn’t know the <a href="https://www.nytimes.com/2018/04/26/us/politics/migrant-children-missing.html">whereabouts of almost 1,500 children</a> it placed, many people have lost confidence in these agencies to do the right or moral thing regarding migrants. If ORR can’t keep track of children under its care, can ICE be trusted to lawfully treat people whose ages are uncertain?</p>
<p>In this situation, the law is consistent with the science. And as a scientist, I am obligated to ensure my interpretations are not used irresponsibly in a way that could cause harm. Citizens, scientists and government officials alike should ensure that refugees and migrants are treated fairly, with the dignity and respect they deserve, and in a way consistent with how we would expect to be treated. Making age determinations based on X-rays alone is not in line with that goal and can have serious punitive consequences for young migrants.</p><img src="https://counter.theconversation.com/content/96771/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Elizabeth A. DiGangi is affiliated with the ACLU. </span></em></p>
If an undocumented migrant is a minor or an adult can have far-reaching implications. A forensic anthropologist explains why relying solely on dental X-rays to determine age doesn’t work.
Elizabeth A. DiGangi, Assistant Professor of Anthropology, Binghamton University, State University of New York
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/95852
2018-05-02T10:40:23Z
2018-05-02T10:40:23Z
Rossi X-ray Timing Explorer ends mission after ‘listening’ to the universe
<figure><img src="https://images.theconversation.com/files/217084/original/file-20180501-135830-15i0u6p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Top-down artist depiction of a tiny black hole and a pileup of gas and matter swirling toward the center.</span> <span class="attribution"><a class="source" href="https://www.nasa.gov/centers/goddard/news/topstory/2008/smallest_blackhole.html">NASA</a></span></figcaption></figure><p>On May 1, NASA’s Rossi X-ray Timing Explorer spacecraft reentered and burned up in Earth’s atmosphere. Although not as well-known to the public as Hubble and Chandra, RXTE ranks among NASA’s most successful astrophysics missions. For the past 16 years RXTE continuously <a href="http://www.xraypulsars.space/pulsar-sounds">“listened”</a> to the streams of X-ray radiation coming from black holes, neutron stars and pulsars.</p>
<p>Pulsars probe the physics of matter under the most extreme conditions, answering questions not accessible in earthbound laboratories. Along with black holes, neutron stars are responsible for injecting the majority of ionizing radiation – X-rays and gamma rays – into the the interstellar medium, and their birth and death events produce the majority of the elements heavier than iron. The surprising conclusion is that they sculpt the conditions needed for life to arise in the cosmos. </p>
<p>Whereas some telescopes look at the visible wavelengths that stars emit, RXTE honed in specifically on X-rays. Compared to the relatively unchanging night sky we see with our eyes, the X-ray universe is dynamic and filled with bursts, pulsations and flares. This radiation comes from matter being heated to millions of degrees as it is swallowed up by “<a href="https://astrobiology.nasa.gov/news/of-white-dwarfs-zombie-stars-and-supernovae-explosions/">zombie stars</a>.” </p>
<p>Far from being super-rare, our own galaxy probably contains millions of these degenerate stellar relics, left behind after massive stars exploded during a supernova. Most such zombie stars are invisible, but RXTE could hear the “sound” of them munching on nearby stars! </p>
<p>You may know the familiar clicking sound of a Geiger counter from TV and movie depictions of scientists working with radioactive materials. Similarly, RXTE was like a giant Geiger counter, the size of an SUV, filled with Xenon gas and a grid of high voltage electrodes. Each individual X-ray photon that passed through the gas generated a tiny voltage pulse that registered on sensitive electronics and recorded its precise arrival.</p>
<p>Using computer codes based on the same math used by the spectrum analyzer in a music recording studio, astrophysicists like me and my students at UMass Lowell scan the stream of incoming photons for patterns. Then we use physics to interpret the patterns much as a cardiologist interprets an EKG trace. We can reveal what is going on as matter falls in into black holes, or as it swirls around a neutron star – the densest and most magnetic objects in the universe. </p>
<p>RXTE detected many <a href="https://www.nasa.gov/subject/8731/pulsars/">pulsars</a> – neutron stars that produce X-rays in a similar way to the auroras on Earth, but at vastly higher energies. The pulsar’s magnetic field (a trillion times stronger than the Earth’s field) captures the stellar wind, a flow of energetic particles from a neighboring star, just like the solar wind is captured by the Earth. The pulsar’s magnetic field then accelerates these particles toward its poles, where they crash down and release their energy, lighting up the polar regions like auroras. </p>
<p>RXTE is dead, but astrophysicists are exploring the fundamental physics of neutron stars and black holes through its huge archive of data. We analyze pulsars’ signals, and the noise emitted by black holes, using a combination of math that includes Einstein’s General Relativity, and Electromagnetism. We then build computer models that try to physically map their X-ray “northern lights.”</p>
<p>When I was a student back in the late 1990s, we pointed RXTE at a nearby galaxy, the Small Magellanic Cloud, hoping to discover how many pulsars existed outside our own galaxy. We were amazed to find three pulsing at the same time. Our record became seven simultaneously active pulsars, eventually reaching a total of more than 50 in that tiny galaxy. </p>
<p>Today other spacecraft, including Chandra, Swift and XMM-Newton, image the X-ray sky, but they cannot provide those all-sky X-ray “ears.” We’re hard at work on a new mission called STROBE-X for launch in the 2020s that will once again let us hear the music.</p><img src="https://counter.theconversation.com/content/95852/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Silas Laycock receives funding from NASA. He is affiliated with the American Astronomical Society, High Energy Astrophysics Division. </span></em></p>
The little-known Rossi X-ray Timing Explorer spacecraft was like a Geiger counter for the universe, listening to black holes and zombie stars.
Silas Laycock, Professor of Astronomy, UMass Lowell
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/94423
2018-04-04T17:03:33Z
2018-04-04T17:03:33Z
Astronomers may have just discovered a dozen black holes in the centre of our galaxy
<figure><img src="https://images.theconversation.com/files/213157/original/file-20180404-189807-11balvx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The Milky Way seen in infrared.</span> <span class="attribution"><span class="source">NASA/JPL-Caltech/S. Stolovy (SSC/Caltech)</span></span></figcaption></figure><p>Astronomers first noticed an enigmatic object, <a href="https://www.nasa.gov/mission_pages/chandra/multimedia/black-hole-SagittariusA.html">dubbed “Sagittarius A*”</a>, at the very heart of our Milky Way galaxy in the 1960s – the earliest days of radio and infrared astronomy. But just how extraordinary this source was only became clear three decades later, when it was identified as a supermassive black hole with the mass of whopping four million suns. </p>
<p>Theory predicts that such supermassive black holes, which reside at the centre of most large galaxies, should be surrounded by a cluster of smaller black holes and other objects. But decades of searches have revealed nothing – until now. In a new paper, <a href="http://nature.com/articles/doi:10.1038/nature25029">published in Nature</a>, a team of researchers report the discovery of what seems to be about 13 black holes close to Sagittarius A*.</p>
<p>The discovery of Sagittarius A* was only possible thanks to the first generation of <a href="http://www2.keck.hawaii.edu/inst/nirc2/">infrared imagers</a> on the best ground-based observing sites in Hawaii and Chile. These could follow the motion of stars very close to the unseen object as they orbited around it. After a decade of observing, complete orbits of stars were <a href="http://iopscience.iop.org/article/10.1086/592738/meta">mapped out in detail</a> – allowing scientists to calculate the mass of Sagittarius A* with high accuracy. </p>
<p>This work had to be done by looking at infrared light. That’s because, at visual wavelengths, huge clouds of dust and gas obstruct our vision – we can only see about 10% of the distance to the galactic centre in this way (Sagittarius A* is approximately 26,000 light years away). Some infrared light, radio waves and X-rays, however, can penetrate the obstacles in the galaxy to reach our detectors on Earth. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/213159/original/file-20180404-189804-16eg2jh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/213159/original/file-20180404-189804-16eg2jh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/213159/original/file-20180404-189804-16eg2jh.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/213159/original/file-20180404-189804-16eg2jh.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/213159/original/file-20180404-189804-16eg2jh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/213159/original/file-20180404-189804-16eg2jh.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/213159/original/file-20180404-189804-16eg2jh.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Sagittarius A* seen by Chandra.</span>
<span class="attribution"><span class="source">X-ray: NASA/UMass/D.Wang et al., IR: NASA/STScI</span></span>
</figcaption>
</figure>
<p>How supermassive black holes grow so large is <a href="https://www.space.com/32973-supermassive-black-holes-born-big.html">still controversial</a>. Sagittarius A* is actually fairly small – distant objects of a billion solar masses have been found. One possible explanation is that they are created as galaxies merge or interact – trapping their central supermassive black holes into orbits about each other and eventually merging into an even bigger supermassive black hole. </p>
<p>We know that active star formation <a href="https://arxiv.org/abs/1712.01453">is going on</a> in the region of our galactic centre. This will naturally produce copious neutron stars (very dense stars) and black holes, which can form close “binary systems” in which a normal star and a neutron star or a black hole orbit each other. As the normal star evolves, its matter can get sucked up by the black hole or fall onto the neutron star – reaching extremely high temperatures. This makes the system emit X-rays, which we can detect.</p>
<p>It is not surprising then that the unique and very high resolution of the space-based <a href="http://chandra.harvard.edu/">Chandra X-ray Observatory</a> has detected hundreds of X-ray sources in and around our galactic centre. You can view some superb images of these objects <a href="http://chandra.harvard.edu/photo/2018/gcenter360/">here</a>.</p>
<h2>X-ray puzzle</h2>
<p>The new study has used Chandra data to investigate X-ray sources close to Sagittarius A*. Over the last 12 years, Chandra has observed Sagittarius A* many times – adding up to a huge total of two weeks of exposure time. By combining all these data, and concentrating on the area close to the centre, the team discovered diffuse X-ray emission and about 100 distinct X-ray sources within 13 light years of Sagittarius A*, 26 of which are contained within just three light years of it. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/213149/original/file-20180404-189801-r22zyu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/213149/original/file-20180404-189801-r22zyu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=480&fit=crop&dpr=1 600w, https://images.theconversation.com/files/213149/original/file-20180404-189801-r22zyu.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=480&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/213149/original/file-20180404-189801-r22zyu.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=480&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/213149/original/file-20180404-189801-r22zyu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=603&fit=crop&dpr=1 754w, https://images.theconversation.com/files/213149/original/file-20180404-189801-r22zyu.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=603&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/213149/original/file-20180404-189801-r22zyu.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=603&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Artist’s impression of an X-ray binary.</span>
<span class="attribution"><span class="source">wikipedia</span></span>
</figcaption>
</figure>
<p>So what are these mysterious sources? It’s been known for some time that thousands of unresolved binary systems involving a normal star and a magnetised <a href="https://imagine.gsfc.nasa.gov/science/objects/dwarfs1.html">white dwarf</a> (a star that has exhausted its fuel, just like our sun will do in a few billion years) can create diffuse X-ray emission. Unlike the X-rays from binary systems involving neutron stars, these are relatively weak. However, there are millions of white dwarfs in the galaxy. </p>
<p>The team also looked at the ratio of hard to soft X-rays (basically just the higher energy light compared to the lower energy rays) to show that the central X-ray sources closest to Sagittarius A* are likely either from binary systems (involving neutron stars or black holes), or from “millisecond pulsars”, which are highly magnetised rotating neutron stars that emit a beam of electromagnetic radiation. </p>
<p>Both types (binary systems and pulsars) undergo occasional X-ray outbursts, but their properties differ. The neutron stars outburst regularly, but Chandra’s observations show that none of the sources near Sagittarius A* have done so – meaning we can rule these out. Pulsars, however, could account for about half of the sources – they are very steady and quiet. But that means that the remaining half at least must be binary systems involving black holes – a class that have much rarer outbursts (usually many decades between them) and properties generally similar to those seen in the study. The team suggests there could be hundreds of such black hole binaries at the centre of our galaxy and thousands of black holes without a companion star. </p>
<p>Future observations are needed to confirm this finding. It can be particularly tricky to distinguish between binary systems involving quiescent (minimally accreting) black holes and millisecond pulsars. But the better the technology gets, the more accurately will we be able to do this.</p>
<p>If these really are black holes, it is extremely exciting – showing that we are on the right track in understanding how supermassive black holes impact the behaviour of stars around them. It might even be important for future observations using <a href="https://theconversation.com/explainer-what-are-gravitational-waves-53239">gravitational waves</a> (ripples in the fabric of space itself). If one of these new sources merge into Sagittarius A*, this should give rise to gravitational waves that we can detect. </p>
<p>Clearly, we still have a lot to learn about our own galaxy. In a way that’s very exciting – there may be many more black holes in the region left to discover.</p><img src="https://counter.theconversation.com/content/94423/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Phil Charles receives funding from the Leverhulme Trust.</span></em></p>
There could be thousands of black holes at the heart of the Milky Way.
Phil Charles, Professor of Astrophysics, University of Southampton
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/90393
2018-02-25T21:11:05Z
2018-02-25T21:11:05Z
Curious Kids: Is x-ray vision possible?
<figure><img src="https://images.theconversation.com/files/203702/original/file-20180129-100902-1us2up.png?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">X-ray vision is not only possible, it already exists -- but using computers, not eyes.</span> <span class="attribution"><span class="source">Marcella Cheng/The Conversation</span>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span></figcaption></figure><p><em>This is an article from <a href="https://theconversation.com/au/topics/curious-kids-36782">Curious Kids</a>, a series for children. The Conversation is asking kids to send in questions they’d like an expert to answer. All questions are welcome – serious, weird or wacky!</em> </p>
<blockquote>
<p><strong>Dear CSIRO, My name is Finn and I’m eight. I would like to know please if making x-ray vision is possible? Thank you so much for your help. – Finn, age 8, Brisbane.</strong> </p>
</blockquote>
<p>Hi Finn. Thanks for your question. X-ray vision is not only possible, it already exists! The science is called radiography. </p>
<p>As you know, human eyes don’t have x-ray vision. But we can use radiography machines to allow our eyes to see inside things the human eye cannot.</p>
<p>Radiography machines use different types of radiation (such as x-rays, visible light, or microwaves) to look inside objects. Some machines make a photograph of the object, called a radiograph, while others let you watch the object move and change in real time. </p>
<p>To make a simple radiograph using x-rays, for example, you need to shine your x-rays on the object you would like to see through. The x-rays pass right through the air and lighter stuff inside the object but are stopped by heavy or thick stuff (like bones). On the other side of the object you need a few fancy cameras, called “detectors”. The detectors produce the x-ray image by collecting the x-rays that make it through the object.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/203369/original/file-20180125-107937-1ifr4kb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/203369/original/file-20180125-107937-1ifr4kb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=437&fit=crop&dpr=1 600w, https://images.theconversation.com/files/203369/original/file-20180125-107937-1ifr4kb.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=437&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/203369/original/file-20180125-107937-1ifr4kb.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=437&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/203369/original/file-20180125-107937-1ifr4kb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=550&fit=crop&dpr=1 754w, https://images.theconversation.com/files/203369/original/file-20180125-107937-1ifr4kb.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=550&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/203369/original/file-20180125-107937-1ifr4kb.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=550&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A radiograph of a person’s arm, showing the x-ray source (the generator), the object (the man’s arm) and the detectors.</span>
<span class="attribution"><span class="source">Wikimedia</span></span>
</figcaption>
</figure>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/curious-kids-how-do-x-rays-see-inside-you-85895">Curious Kids: How do x-rays see inside you?</a>
</strong>
</em>
</p>
<hr>
<p>There are several radiography machines that you may have used before – such as a medical or dental x-ray machine. If you hurt your hand playing sport, a doctor may use x-rays to make a radiograph of your hand to see if you’ve broken a bone. The x-rays pass straight through the soft parts of your hand but are stopped by the thick and strong bones. The doctor uses the radiograph to see if the bones of your hand and fingers are broken. </p>
<p>At some point in your life, you will probably visit an airport. You might have been to one already. In the security line at the airport, you put your bag on the conveyor belt and it passes through an x-ray radiography machine. The operator can look right through your suitcase – without even touching it – to see what’s inside and make sure there’s nothing dangerous in there. You can then pick up your bag after it comes out of the machine without ever having to open it.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/203366/original/file-20180125-107940-1hgcore.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/203366/original/file-20180125-107940-1hgcore.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=465&fit=crop&dpr=1 600w, https://images.theconversation.com/files/203366/original/file-20180125-107940-1hgcore.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=465&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/203366/original/file-20180125-107940-1hgcore.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=465&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/203366/original/file-20180125-107940-1hgcore.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=584&fit=crop&dpr=1 754w, https://images.theconversation.com/files/203366/original/file-20180125-107940-1hgcore.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=584&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/203366/original/file-20180125-107940-1hgcore.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=584&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Baggage x-ray of a backpack. Can you identify some of the items inside?</span>
<span class="attribution"><span class="source">www.farlabs.edu.au</span></span>
</figcaption>
</figure>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/curious-kids-how-does-pain-medicine-work-in-the-body-82495">Curious Kids: How does pain medicine work in the body?</a>
</strong>
</em>
</p>
<hr>
<p>What else can you see using radiography? Scientists and engineers have designed powerful radiography machines that can see through objects much more interesting than a suitcase. </p>
<p>You can use these machines to see right through cars and trucks to check what they are carrying. You can see the flow of water or oil through big metal pipes. You can shine x-rays through walls, aeroplane wings, and even nuclear reactors to look for cracks or other problems that the human eye cannot see. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/203370/original/file-20180125-107971-1pufal1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/203370/original/file-20180125-107971-1pufal1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=306&fit=crop&dpr=1 600w, https://images.theconversation.com/files/203370/original/file-20180125-107971-1pufal1.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=306&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/203370/original/file-20180125-107971-1pufal1.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=306&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/203370/original/file-20180125-107971-1pufal1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=385&fit=crop&dpr=1 754w, https://images.theconversation.com/files/203370/original/file-20180125-107971-1pufal1.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=385&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/203370/original/file-20180125-107971-1pufal1.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=385&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Neutrons, another type of radiation, work differently than x-rays. Neutrons can shine straight through heavy objects like metals but are stopped by lighter objects. This picture is a neutron radiograph showing a soft flower inside a thick and heavy lead box.</span>
<span class="attribution"><span class="source">darpa.mil</span></span>
</figcaption>
</figure>
<p>Scientists and engineers also use radiography to help museums look inside very old objects that are too delicate to touch. This way, they can learn more about the object without breaking it. This has been used to see a 2000 year old mummy still inside a coffin, to see inside statues and paintings and to check whether objects in the museum are real or fake. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/203368/original/file-20180125-107967-mau8n1.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/203368/original/file-20180125-107967-mau8n1.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=376&fit=crop&dpr=1 600w, https://images.theconversation.com/files/203368/original/file-20180125-107967-mau8n1.PNG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=376&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/203368/original/file-20180125-107967-mau8n1.PNG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=376&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/203368/original/file-20180125-107967-mau8n1.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=473&fit=crop&dpr=1 754w, https://images.theconversation.com/files/203368/original/file-20180125-107967-mau8n1.PNG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=473&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/203368/original/file-20180125-107967-mau8n1.PNG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=473&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A computed tomography (CT) scan of an ancient Egyptian mummy.</span>
<span class="attribution"><span class="source">British Museum</span></span>
</figcaption>
</figure>
<p>The catch is – these machines use computers to make x-ray vision, not human eyes. If you believe the world needs Superman-style x-ray vision, become a scientist or engineer and make it happen!</p>
<p><em>Hello, curious kids! Have you got a question you’d like an expert to answer? Ask an adult to send your question to us. You can:</em></p>
<p><em>* Email your question to curiouskids@theconversation.edu.au
<br>
* Tell us on <a href="https://twitter.com/ConversationEDU">Twitter</a> by tagging <a href="https://twitter.com/ConversationEDU">@ConversationEDU</a> with the hashtag #curiouskids, or
<br>
* Tell us on <a href="http://www.facebook.com/conversationEDU">Facebook</a></em></p>
<figure class="align-left ">
<img alt="" src="https://images.theconversation.com/files/168011/original/file-20170505-21620-huq4lj.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/168011/original/file-20170505-21620-huq4lj.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=376&fit=crop&dpr=1 600w, https://images.theconversation.com/files/168011/original/file-20170505-21620-huq4lj.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=376&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/168011/original/file-20170505-21620-huq4lj.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=376&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/168011/original/file-20170505-21620-huq4lj.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=472&fit=crop&dpr=1 754w, https://images.theconversation.com/files/168011/original/file-20170505-21620-huq4lj.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=472&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/168011/original/file-20170505-21620-huq4lj.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=472&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption"></span>
<span class="attribution"><a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p><em>Please tell us your name, age and which city you live in. You can send an audio recording of your question too, if you want. Send as many questions as you like! We won’t be able to answer every question but we will do our best.</em></p><img src="https://counter.theconversation.com/content/90393/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Chanel Tissot is a member of the Australian Nuclear Association and Women in Nuclear Australia. </span></em></p>
Human eyes don’t have x-ray vision. But we can use radiography machines to allow our eyes to see inside things the human eye cannot.
Chanel Tissot, Postdoctoral Fellow, Nuclear Engineer, CSIRO
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/85895
2017-11-28T19:08:19Z
2017-11-28T19:08:19Z
Curious Kids: How do x-rays see inside you?
<figure><img src="https://images.theconversation.com/files/195384/original/file-20171120-18547-m75uqh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">X-rays are like light rays, but they can pass through more stuff.</span> <span class="attribution"><span class="source">Marcella Cheng/The Conversation</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span></figcaption></figure><p><em>This is an article from <a href="https://theconversation.com/au/topics/curious-kids-36782">Curious Kids</a>, a series for children. The Conversation is asking kids to send in questions they’d like an expert to answer. All questions are welcome – serious, weird or wacky!</em> </p>
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<p><strong>How do x-rays see inside you? – Eva, age 9 from Marrickville</strong></p>
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<p>Have you ever played shadow puppets to make shadow pictures on the wall? When you do, your hand is stopping the light rays from the lamp reaching the wall. X-ray images are a little like that.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/196021/original/file-20171123-6061-jf3gq5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/196021/original/file-20171123-6061-jf3gq5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/196021/original/file-20171123-6061-jf3gq5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=578&fit=crop&dpr=1 600w, https://images.theconversation.com/files/196021/original/file-20171123-6061-jf3gq5.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=578&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/196021/original/file-20171123-6061-jf3gq5.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=578&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/196021/original/file-20171123-6061-jf3gq5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=727&fit=crop&dpr=1 754w, https://images.theconversation.com/files/196021/original/file-20171123-6061-jf3gq5.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=727&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/196021/original/file-20171123-6061-jf3gq5.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=727&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Try putting your hand over a torch.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/psychobabble/190779618/in/photolist-hRN8L-5S8q79-6o8ode-9HySxf-76jBmH-8fBmPG-6iDjNX-GigUzJ-cnwiAq-7q31kj-pGexoJ-oswaWP-6bojKi-4Qo3GN-bhe1-SwR1BA-muTXSA-KuziB-dJacWW-5GztX3-gNvEoK-6sLEBt-4UAtBA-aVX2xD-YrZ5xG-6SSNqL-731xqS-pqKpmg-pJJBNd-shUgi-bEPm7E-6uYudg-evKWZ-jv83H-jHk13T-8Roxb-6So2Tr-rsfV4z-e8d7B5-5Qg5Mx-4kPzcw-6bsv7d-9Cigw8-qQCsrV-bL2UDP-4bF9WJ-7Akoph-9GBrV7-9qTeg8-7LAXfS">Flickr/Amy</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
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<p>Try putting a torch up against your hand and seeing how some light passes through the skin of your fingers. </p>
<p>Some light doesn’t shine through. That’s because some of the energy has been removed from the beam and some has managed to make its way through your skin and you can see it. </p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/curious-kids-why-are-fern-leaves-shaped-the-way-they-are-and-are-all-ferns-identical-83976">Curious Kids: Why are fern leaves shaped the way they are, and are all ferns identical?</a>
</strong>
</em>
</p>
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<p>X-rays are like light rays, but the difference is that they can pass through more stuff. Skin and fat don’t block much of the energy in the x-ray beam. Muscle blocks more, but even more energy is blocked by bone, which is why you can see bones so clearly on x-rays.</p>
<p>An x-ray image shows shades of grey, which is just how much of the x-ray beam manages to get through your body. If the part is very dense (like bone) it will come up white, if it is less dense (like your lungs) it will come up as a darker shade of grey.</p>
<figure class="align-left zoomable">
<a href="https://images.theconversation.com/files/196023/original/file-20171123-6072-1f8jwdu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/196023/original/file-20171123-6072-1f8jwdu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/196023/original/file-20171123-6072-1f8jwdu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=655&fit=crop&dpr=1 600w, https://images.theconversation.com/files/196023/original/file-20171123-6072-1f8jwdu.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=655&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/196023/original/file-20171123-6072-1f8jwdu.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=655&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/196023/original/file-20171123-6072-1f8jwdu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=823&fit=crop&dpr=1 754w, https://images.theconversation.com/files/196023/original/file-20171123-6072-1f8jwdu.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=823&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/196023/original/file-20171123-6072-1f8jwdu.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=823&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">X-rays help doctors see inside our bodies.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/pulmonary_pathology/6316268468/in/photolist-aC9wyu-3qVzxb-3qVzq5-fZSuN2-bZYxhd-efC231-cLcn5Q-pYambd-f1QXog-a54Byu-s6ta6E-a54BxW-87Gr6X-dkGDbC-7WJVj3-a54Bz7-5Brq7y-dEWSvb-7iSnfn-drqUtF-fKcZFw-9fsDUU-DkUgwL-7sPcJ-7KcwoT-fCiALt-4p9HJk-sniJCx-aw4zHu-aZjPsa-fhmAJd-5oeG1Y-akpX3w-RMtoAC-p1NXQ-e8A4Xe-9kocs4-7vopgx-F7WFo-f5wTd-nu2UV-kCj1K-eDZDUg-huxuj-3rutGt-5EbHGa-6QP3P5-cnXnD7-6QzjHo-3c7cn4">Flickr/Yale Rosen</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
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<p>Radiographers (the people who work the x-ray machines) can control the amount and strength of the x-ray beam (just like you can make light dimmer or brighter) so that the body parts they want to see come up on the images. </p>
<p>X-rays are used in hospitals to help diagnose and treat many injuries and illnesses. Radiographers use x-ray images in the operating theatre to help guide the surgeons. There’s also a special type of scan called a CT scan. CT scans use lots of x-ray pictures to create fantastic 3D images of the body. </p>
<p>Having too many x-ray scans can be dangerous. They can damage the cells in your body (which is why the radiographer leaves the room while you get your x-ray done). The amount of x-rays used for each picture is tiny though, so if your doctor thinks you need an x-ray picture, don’t worry.</p>
<p>Sometimes the damage to cells is a good thing; a treatment called radiotherapy uses x-rays to kill bad cells (like cancer cells). </p>
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<iframe width="440" height="260" src="https://www.youtube.com/embed/hTz_rGP4v9Y?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">YouTube video explaining x-rays.</span></figcaption>
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<h2>Did you know?</h2>
<p>X-rays were discovered in November 1895 by German physicist Wilhelm Roentgen – by accident! He was doing an experiment and was surprised when a screen on the other side of the lab glowed. </p>
<p>Wilhelm worked out that some invisible rays were causing it but had no idea what they were. That is why they’re called x-rays, with “x” meaning “I don’t know”! </p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/curious-kids-what-started-the-big-bang-79845">Curious Kids: what started the Big Bang?</a>
</strong>
</em>
</p>
<hr>
<p><em>Hello, curious kids! Have you got a question you’d like an expert to answer? Ask an adult to send your question to us. You can:</em></p>
<p><em>* Email your question to curiouskids@theconversation.edu.au
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* Tell us on <a href="https://twitter.com/ConversationEDU">Twitter</a> by tagging <a href="https://twitter.com/ConversationEDU">@ConversationEDU</a> with the hashtag #curiouskids, or
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<img alt="" src="https://images.theconversation.com/files/168011/original/file-20170505-21620-huq4lj.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/168011/original/file-20170505-21620-huq4lj.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=376&fit=crop&dpr=1 600w, https://images.theconversation.com/files/168011/original/file-20170505-21620-huq4lj.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=376&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/168011/original/file-20170505-21620-huq4lj.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=376&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/168011/original/file-20170505-21620-huq4lj.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=472&fit=crop&dpr=1 754w, https://images.theconversation.com/files/168011/original/file-20170505-21620-huq4lj.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=472&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/168011/original/file-20170505-21620-huq4lj.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=472&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="attribution"><a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
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<p><em>Please tell us your name, age and which city you live in. You can send an audio recording of your question too, if you want. Send as many questions as you like! We won’t be able to answer every question but we will do our best.</em></p><img src="https://counter.theconversation.com/content/85895/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Karen Finlay does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>
X-rays are like light rays, but they can pass through more stuff. Some of the x-ray’s energy is blocked by bone, which is why you can see bones so clearly on x-ray scans.
Karen Finlay, Senior Lecturer Medical Imaging , CQUniversity Australia
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/60061
2017-05-10T03:50:19Z
2017-05-10T03:50:19Z
Explainer: what is cancer radiotherapy and why do we need proton beam therapy?
<figure><img src="https://images.theconversation.com/files/140413/original/image-20161005-20235-zqbkxz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Radiotherapy treats cancer by directing beams of high energy x-rays at the tumour. </span> <span class="attribution"><span class="source">from shutterstock.com</span></span></figcaption></figure><p>In last night’s federal budget, the <a href="http://budget.gov.au/2017-18/content/bp3/download/bp3_03_part_2b.pdf">government dedicated up to A$68 million</a> to help set up Australia’s first proton beam therapy facility in South Australia. The <a href="http://www.health.gov.au/internet/ministers/publishing.nsf/Content/health-mediarel-yr2017-hunt45.htm">government says</a> this will help Australian researchers develop the next generation of cancer treatments, including for complex children’s cancers. </p>
<p>Proton beam therapy is radiation therapy that uses heavier particles (protons) instead of the X-rays used in conventional radiotherapy. These particles can more accurately target tumours closer to vital organs, which can be especially beneficial to patients suffering from brain cancer and children whose organs are still developing and are more vulnerable to damage.</p>
<p>So, the facility will also be an alternative to conventional radiotherapy for treating certain cancer. But what is traditional radiotherapy, and how will access to proton beam therapy improve how we manage cancer?</p>
<h2>What is radiotherapy?</h2>
<p>Radiotherapy, together with surgery, chemotherapy and palliative care, are the cornerstones of cancer treatment. Radiotherapy is recommended for <a href="https://www.ncbi.nlm.nih.gov/pubmed/24833561">half of cancer patients</a>. </p>
<p>It is mostly used when the cancer is localised to one or more areas. Depending on the cancer site and stage, radiotherapy can be used alone or in combination with surgery and chemotherapy. It can be used before or after other treatments to make them more effective by, for example, shrinking the tumour before chemotherapy or treating cancer that remains after surgery.</p>
<figure class="align-right ">
<img alt="" src="https://images.theconversation.com/files/150859/original/image-20161220-26710-1ayj6h4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/150859/original/image-20161220-26710-1ayj6h4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=556&fit=crop&dpr=1 600w, https://images.theconversation.com/files/150859/original/image-20161220-26710-1ayj6h4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=556&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/150859/original/image-20161220-26710-1ayj6h4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=556&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/150859/original/image-20161220-26710-1ayj6h4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=699&fit=crop&dpr=1 754w, https://images.theconversation.com/files/150859/original/image-20161220-26710-1ayj6h4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=699&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/150859/original/image-20161220-26710-1ayj6h4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=699&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A drawing of the X-ray machine used by Wilhelm Röntgen to produce images of the hand.</span>
<span class="attribution"><span class="source">Golan Levin/Flickr</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>Most <a href="http://www.cancervic.org.au/about-cancer/types-treatments-trials/radiotherapy">radiotherapy treats cancer</a> by directing beams of high energy X-rays at the tumour (although other radiation beams, such as gamma rays, electron beams or proton/heavy particle beams can also be used). </p>
<p>The X-rays interact with tumour cells, damaging their DNA and restricting their ability to reproduce. But because X-rays don’t differentiate between cancerous and healthy cells, normal tissues can be damaged. Damaged healthy tissue can lead to minor symptoms such as fatigue, or, in rare cases, more serious outcomes such as hospitalisation and death. </p>
<p>Getting the right amount of radiation is a fine balance between therapy and harm. A common way to improve the benefit-to-cure ratio is to fire multiple beams at the tumour from different directions. If they overlap, they can maximise the damage to the tumour while minimising damage to healthy tissue.</p>
<h2>How it works</h2>
<p>Wilhelm Röntgen <a href="http://www.bl.uk/learning/cult/bodies/xray/roentgen.html">discovered X-rays</a> in 1895 and within a year, the link between exposure to too much radiation and skin burns led scientists and doctors to pursue radiation in cancer treatment.</p>
<p>There are three key stages in the radiotherapy process. The patient is first imaged – using such machines as computer tomography (CT) or magnetic resonance imaging (MRI). This estimates the extent of the tumour and helps to understand where it is with respect to healthy tissues and other critical structures. </p>
<p>In the second stage, the doctor and treatment team will use these images and the patient’s case history to plan where the radiation beams should be placed – to maximise the damage to the tumour while minimising it to healthy tissues. Complex computer simulations model the interactions of the radiation beams with the patient to give a best estimate of what will happen during treatment.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/150862/original/image-20161220-26759-1as1d7n.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/150862/original/image-20161220-26759-1as1d7n.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/150862/original/image-20161220-26759-1as1d7n.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/150862/original/image-20161220-26759-1as1d7n.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/150862/original/image-20161220-26759-1as1d7n.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=502&fit=crop&dpr=1 754w, https://images.theconversation.com/files/150862/original/image-20161220-26759-1as1d7n.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=502&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/150862/original/image-20161220-26759-1as1d7n.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=502&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A single radiotherapy treatment takes 15 to 30 minutes.</span>
<span class="attribution"><span class="source">IAEA Imagebank/Flickr</span>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
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<p>During the third, treatment-delivery stage, the patient lies still while the treatment beam rotates, delivering radiation from multiple angles.</p>
<p>Each treatment generally takes 15 to 30 minutes. Depending on the cancer and stage, there are between one and 40 individual treatments, typically one treatment a day. The patient cannot feel the radiation being delivered.</p>
<h2>Benefits and side effects</h2>
<p>Radiotherapy’s targeting technology has made a significant difference to many cancers, in particular early-stage lung and prostate cancers. It is now possible to have effective, low toxicity treatments for these with one to five radiotherapy sessions.</p>
<p>For early-stage lung cancer <a href="https://www.ncbi.nlm.nih.gov/pubmed/25981812">studies estimate</a> with radiotherapy, survival three years after diagnosis is at 95%. For prostate cancer, one study <a href="https://www.ncbi.nlm.nih.gov/pubmed/24060175">estimates survival</a> at the five year mark is about 93%. </p>
<p>Side effects for radiotherapy vary markedly between treatment sites, cancer stages and individual patients. They are typically moderate but can be severe. A general side effect of radiotherapy is fatigue. </p>
<figure class="align-right ">
<img alt="" src="https://images.theconversation.com/files/150843/original/image-20161219-24303-13q1xsj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/150843/original/image-20161219-24303-13q1xsj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/150843/original/image-20161219-24303-13q1xsj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/150843/original/image-20161219-24303-13q1xsj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/150843/original/image-20161219-24303-13q1xsj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/150843/original/image-20161219-24303-13q1xsj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/150843/original/image-20161219-24303-13q1xsj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Radiotherapy is often used to treat brain tumours.</span>
<span class="attribution"><span class="source">Eric Lewis/Flickr</span>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>Other side effects include diarrhoea, appetite loss, dry mouth and difficulty swallowing for head and neck cancer radiotherapy, as well as incontinence and reduction in sexual function for pelvic radiotherapy. </p>
<p>Long-term effects of radiotherapy are a concern, particularly for children. For instance, radiation to treat childhood brain tumours can have <a href="https://theconversation.com/many-survivors-of-childhood-brain-cancer-have-cognitive-difficulties-but-these-can-be-treated-57566">long-lasting cognitive effects</a> that can affect relationships and academic achievement. </p>
<p>Again doctors will need to weigh up the risks and benefits of treatment for individual patients. Proton beam therapy is arguably most beneficial in these cases.</p>
<h2>Other radiotherapy challenges</h2>
<p>There are several challenges to current radiotherapy. It is often difficult to differentiate the tumour from healthy tissue, and even experts do not always agree on where exactly the tumour is.</p>
<p>Radiotherapy can’t easily adapt to the <a href="http://www.sciencedirect.com/science/article/pii/S0360301611036042">complex changes in patients’ anatomy</a> when a patient moves – for instance, when they breathe, swallow, their heart beats or as they digest food. As a result, radiation beams can be off-target, missing the tumour and striking healthy tissue.</p>
<p>Also, we currently treat all parts of the tumour equally, despite knowing <a href="http://link.springer.com/article/10.1007/s10555-007-9056-0">some of the tumour’s regions</a> are more aggressive, resistant to radiation and likely to spread to other parts of the body.</p>
<p>The tumour itself also changes in response to the treatment, further confounding the problem. An ideal radiotherapy solution would image and adapt the treatment continuously based on these changes.</p>
<p>Improvements in technology, including in imaging systems that can better find the tumour, can help overcome these challenges.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/MS590Xtq9M4?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Proton therapy requires large accelerators to give protons enough energy to penetrate deep into patients.</span></figcaption>
</figure>
<h2>Proton beam therapy and other innovations</h2>
<p>Proton beam therapy will help maximise benefits for many patients, including those with cancers near the spinal cord and pelvis. It requires large accelerators to give protons enough energy to penetrate deep into patients. The energetic protons are transported into the treatment room using complex steering magnets and directed to the tumour inside the patient.</p>
<p>Protons slow down and lose energy inside the patient, with most of the energy loss planned to occur in the tumour. This reduces energy loss in healthy tissues and reduces side effects. </p>
<p>The problems of changing patient anatomy and physiology in other forms of radiotherapy are also challenges for proton beam therapy. </p>
<p>Australia has a <a href="http://sydney.edu.au/medicine/radiation-physics/research-projects/nano-x.php">number of research teams</a> tackling such challenges, including developing <a href="http://sydney.edu.au/medicine/radiation-physics/research-projects/MRI-linac-program.php">new radiation treatment devices</a>, breathing aids for cancer patients, radiation measurement devices, shorter and more convenient treatment schedules and the optimal combination of radiotherapy with other treatments, such as chemotherapy and immunotherapy.</p><img src="https://counter.theconversation.com/content/60061/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Paul Keall is an NHMRC Professorial Research Fellow at the University of Sydney. He is a director and shareholder of three start-up companies. He receives research funding from government and industry sources. </span></em></p>
Getting the right amount of radiation is a fine balance between therapy and harm. A common way to improve the benefit-to-cure ratio is to fire multiple beams at the tumour from different directions.
Paul Keall, Professor and NHMRC Australian Fellow, Medicine, University of Sydney
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/72801
2017-03-13T02:33:13Z
2017-03-13T02:33:13Z
Why we’re wasting money on medical tests and how behavioural insights can help
<figure><img src="https://images.theconversation.com/files/159708/original/image-20170307-20739-1wayi0i.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Doctors know most scans for low back pain are useless, but they have trouble convincing patients. </span> <span class="attribution"><span class="source">from www.shutterstock.com</span></span></figcaption></figure><p>In 2013 and 2014, more than 314,000 <a href="https://www.radiologyinfo.org/en/info.cfm?pg=bodyct">CT scans</a> of the lower back were ordered in Australia, <a href="https://www.safetyandquality.gov.au/atlas/">most of which showed no abnormalities</a>. In routine cases of low back pain, X-rays and CT scans provide no meaningful information to guide treatment, exposing patients to unnecessary radiation. </p>
<p>A number of factors have contributed to this, including increased consumer expectations, an ageing population, financial incentives (where doctors have a stake in imaging services) and “defensive medicine”, which is doctors protecting themselves against possible litigation arising from missing a diagnosis. </p>
<p>This is one of numerous areas of wasted health-care expenditure around the world. Studies in the US have reported that 20 to 25% of all healthcare delivered <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2690270/">is either not needed, or harmful</a>. The situation in Australia appears much the same. A conservative estimate of avoidable costs in Australia’s public hospital system is <a href="https://grattan.edu.au/wp-content/uploads/2014/03/806-costly-care.pdf">A$928 million</a>. </p>
<p>We can reduce some of this waste by looking at why doctors continue to order these tests and use behavioural techniques to change the situation.</p>
<h2>Why so much waste?</h2>
<p>One of the drivers of this waste is increasing consumer demand for medical tests. New technologies and increased public awareness have led to <a href="https://www.betterhealth.vic.gov.au/health/conditionsandtreatments/cancer-screening">increases in mass screening</a> for breast, bowel and cervical cancer. </p>
<p>Popular media further fuels demand; <a href="http://edition.cnn.com/2013/05/14/showbiz/angelina-jolie-double-mastectomy/">publicity of Angelina Jolie’s preventative mastectomy</a> in 2013 led to the “Angelina Jolie effect” – a <a href="http://breast-cancer-research.biomedcentral.com/articles/10.1186/s13058-015-0650-8">two-fold increase in consultations</a> for breast cancer genetic testing and risk-reduction surgery. While there is evidence to support screening in these cases, it has empowered consumers to request tests for a variety of other ailments, including X-rays and CT scans for routine low back pain. </p>
<p>Reducing healthcare waste relating to unnecessary tests has been a major priority for researchers, governments and health services for decades. Ironically, much of this effort has itself been wasted. Historical approaches to improving healthcare quality have revolved around the assumption that providing knowledge will solve the problem; if doctors are told X-rays and CT scans are not recommended in routine cases of low back pain, they will stop ordering them. </p>
<p>But the idea that knowledge leads to action is a flawed assumption. We know we should eat more vegetables and exercise more, but it doesn’t mean we do. In medicine, as in everyday life, there is a gap between what we know and what we do.</p>
<h2>How to use behavioural insights to help change doctors’ behaviour</h2>
<p>If it’s not just knowledge that drives human behaviour, how can we find out what does? The answer is deceptively simple: ask people why they do what they do.</p>
<p><a href="https://implementationscience.biomedcentral.com/articles/10.1186/1748-5908-7-37">Behavioural researchers</a> have identified 14 domains that influence our behaviour. In addition to knowledge, some of these influences include social influences, the environmental context, our professional identity and our beliefs about our capabilities.</p>
<p>When a team of researchers applied this psychological framework to the problem of overuse of X-rays in routine low back pain, they uncovered new insights into this behaviour. Some GPs reported they <a href="https://implementationscience.biomedcentral.com/articles/10.1186/1748-5908-7-38">lacked skills in communicating</a> to patients these investigations are of little or no value.</p>
<p>This was addressed through role play: using a prepared script to simulate a patient demanding an X-ray and giving doctors a response script suggesting alternative approaches, such as advice about appropriate activities and pain management strategies. </p>
<p>An example of such a script is: </p>
<blockquote>
<p>X-rays don’t really provide useful information that would change how we manage routine cases of back pain. They also expose you to radiation. Right now the best thing I can give you is some advice on how to manage your back pain. We can revisit the need for an X-ray or CT scan if more serious symptoms develop.</p>
</blockquote>
<p><a href="https://www.ncbi.nlm.nih.gov/pubmed/15805455">Studies have demonstrated</a> positive impacts of such techniques in changing low back pain health-care practices. But behaviour change should not stop at doctors. It’s also important to create more widespread public awareness that some tests are unnecessary and potentially harmful. <a href="http://www.choosingwisely.org.au/resources/consumers/5-questions-to-ask-your-doctor">NPS MedicineWise</a>, an independent, federal government-funded health organisation, developed a consumer resource outlining five questions to ask your doctor about tests. </p>
<h2>Studying the ‘why’</h2>
<p>The X-ray example shows that rather than continually producing and passively disseminating guidelines telling doctors what to do, it’s more worthwhile analysing why they do what they do. </p>
<p>Surprisingly, linking psychological theory to health-care improvement only began in earnest at the turn of the century. Alarmingly, over 15 years later, less than 10% of published quality-improvement studies explicitly report the use of such theory. </p>
<p>But this approach has demonstrated potential. For example, <a href="http://www.cochrane.org/news/support-health-professionals-reduces-unnecessary-use-antibiotics-hospitals">a recent review</a> of 29 studies aiming to reduce overuse of antibiotics found education alone was not as effective as interventions that employed additional behavioural techniques such as “enablement” (making it easier to do the right thing) and “restriction” (using rules such as restricting prescriptions to prevent doing the wrong thing). </p>
<p>However, much more research is needed in this area. An <a href="http://journals.plos.org/plosmedicine/article?id=10.1371/journal.pmed.1000326">estimated 75 trials</a> testing new cures for diseases and injuries are published per day, equating to 319,000 since the year 2000. In comparison, roughly 7,000 studies have evaluated the effectiveness of the use of behavioural insights to make sure these cures are put into practice. </p>
<p>In other words, for every 45 trials designed to discover new cures, there is only one trial designed to test the use of behaviour change techniques to ensure these cures are applied to patients. </p>
<p>Without re-balancing this equation, there’s a risk of compounding the problem of waste in health care. Knowledge of what to do isn’t enough. We need to explore why doctors, patients and health-care professionals behave the way they do, and how we can influence their behaviour for the better. Only this can harness the full potential of medical research breakthroughs.</p><img src="https://counter.theconversation.com/content/72801/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Peter Bragge receives funding from a variety of government and research granting organisations to conduct healthcare quality improvement research, all of which is paid to his employer, Monash University. He played no role in any of the research outlined in this article. </span></em></p>
Reducing health-care waste relating to unnecessary tests has been a major priority for researchers, governments and health services for decades. But how do we change the behaviour of doctors?
Peter Bragge, Associate Professor, Healthcare Quality Improvement (QI) at Behaviour Works, Monash University
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/70636
2016-12-20T20:15:26Z
2016-12-20T20:15:26Z
Why you can’t fry eggs (or testicles) with a cellphone
<figure><img src="https://images.theconversation.com/files/151083/original/image-20161220-26741-nmhzbw.jpg?ixlib=rb-1.1.0&rect=721%2C0%2C3197%2C1982&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Pocket your phone without worry.</span> <span class="attribution"><a class="source" href="http://www.shutterstock.com/pic.mhtml?id=533966416">Phone image via www.shutterstock.com.</a></span></figcaption></figure><p>A minor craze in men’s underwear fashions these days seems to be <a href="http://www.nbcnews.com/news/world/boxer-shorts-claim-protect-testicles-cellphone-radiation-n538576">briefs that shield the genitals</a> from cellphone radiation. The sales claim is that these products protect the testicles from the harmful effects of the radio waves emitted by cellphones, and therefore help maintain a robust sperm count and high fertility. These undergarments may shield the testicles from radiation, but do <a href="http://www.newsweek.com/boxer-rebellion-pocketed-cellphone-may-be-behind-your-infertility-287075">male cellphone users really risk infertility</a>?</p>
<p>The notion that electromagnetic radiation in the radio frequency range can cause male sterility, either temporary or permanent, has been around for a long time. As I describe in my book <a href="http://press.princeton.edu/titles/10691.html">“Strange Glow: The Story of Radiation</a>,” during World War II some enlisted men would consistently and inexplicably volunteer for radar duty just prior to their scheduled leave days. It turned out that a rumor had been circulating that exposure to radio waves from the radar equipment produced temporary sterility, which the soldiers saw as an employment benefit.</p>
<p>The military wanted to know whether there was any substance to the sterility rumor. So they asked <a href="https://www.nobelprize.org/nobel_prizes/medicine/laureates/1946/muller-bio.html">Hermann Muller</a> – a geneticist who <a href="https://www.nobelprize.org/nobel_prizes/medicine/laureates/1946/muller-lecture.html">won the Nobel Prize</a> for showing that x-rays could cause sterility and genetic mutations – to evaluate the effects of radio waves in the same fruit fly experimental model he had used to show that x-rays impaired reproduction. </p>
<p>Muller could find no dose of radio waves that produced either sterility or genetic mutations, and concluded that radio waves did not present the same threat to fertility that x-rays did. Radio waves were different. But why? Aren’t both x-rays and radio waves <a href="http://www.livescience.com/38169-electromagnetism.html">electromagnetic radiation</a>?</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/151022/original/image-20161220-26741-1sutwex.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/151022/original/image-20161220-26741-1sutwex.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/151022/original/image-20161220-26741-1sutwex.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=326&fit=crop&dpr=1 600w, https://images.theconversation.com/files/151022/original/image-20161220-26741-1sutwex.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=326&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/151022/original/image-20161220-26741-1sutwex.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=326&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/151022/original/image-20161220-26741-1sutwex.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=410&fit=crop&dpr=1 754w, https://images.theconversation.com/files/151022/original/image-20161220-26741-1sutwex.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=410&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/151022/original/image-20161220-26741-1sutwex.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=410&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The electromagnetic spectrum, tiny wavelengths on the left, longer wavelengths on the right.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:EM_Spectrum_Properties_reflected.svg">Inductiveload</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>Yes, they are – but they differ in one key factor: They have very different wavelengths. All electromagnetic radiation travels through space as invisible waves of energy. And it’s the specific wavelength of the radiation that determines all of its effects, both physical and biological. The shorter wavelengths carry higher amounts of energy than the longer wavelengths.</p>
<p>X-rays are able to damage cells and tissues precisely because their wavelengths are extremely short – one-millionth the width of a human hair – and thus are highly energetic and very harmful to cells. Radio waves, in contrast, carry little energy because their wavelengths are very long – about the length of a football field. Such long-wavelength radiations have really low energies – too low to damage cells. And it’s this big difference between the wavelengths of x-rays and radio waves that the infertility theorists fail to recognize.</p>
<p>X-rays, and other high-energy waves, produce sterility by killing off the testicular cells that make sperm – the “<a href="https://www.repropedia.org/spermatogonium">spermatogonia</a>.” And x-ray doses must be extremely high to kill enough cells to produce sterility. Still, even when the doses are high, the sterility effect is usually temporary because the surviving spermatogonia are able to <a href="http://doi.org/10.1002/aja.1001180211">spawn replacements</a> for their dead comrades, and sperm counts typically return to their normal levels within a few months.</p>
<p>So, if high doses of highly energetic x-rays are needed to kill enough cells to produce sterility, how can low doses of radio waves with energies too low to kill cells do it? Good question.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/axUBeF-W7II?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Don’t fall for the phone-cooking-egg hoax.</span></figcaption>
</figure>
<p>At this point you may be thinking that you’ve seen videos of <a href="https://www.youtube.com/watch?v=axUBeF-W7II">cellphones cooking eggs</a>. And you’ve even experienced your cellphone getting pretty warm when it’s used heavily. But this doesn’t show that cellphones put out a lot of radiation energy. The cooked egg video is a prank, and the phone gets hot because of the heat generated by the chemical reactions going on within the battery, not from radio waves.</p>
<p>Still you protest: What about those sporadic reports claiming that cellphones suppress sperm counts? For the moment, that’s all they are – sporadic reports, unconfirmed by other investigators. You can find all kinds of random assertions about the effects of radiation on health, both <a href="http://www.orau.org/ptp/collection/quackcures/quackcures.htm">good</a> and <a href="https://www.scribd.com/document/59721111/TOP10-Myths-About-Radiation">bad</a>, most of which imply that there is some type of validated scientific evidence to support the claim. Why not believe all of them?</p>
<p>If we’ve learned anything over the years about scientific evidence, it’s that isolated findings from individual labs, reporting limited experimental data, do not a strong case make. Most of the very limited “scientific” reports of infertility caused by cellphones, often <a href="http://www.ewg.org/cell-phone-radiation-damages-sperm-studies-find">cited by anti-cellphone activists</a>, come from outside the radiation biology community, and are published in lower-tier journals of questionable quality. Few, if any, of these reports make any attempt at actually measuring the radiation doses received from the cellphones (probably because they lack either the expertise or the equipment required to do it).</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/151040/original/image-20161220-26748-1ive95i.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/151040/original/image-20161220-26748-1ive95i.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/151040/original/image-20161220-26748-1ive95i.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=384&fit=crop&dpr=1 600w, https://images.theconversation.com/files/151040/original/image-20161220-26748-1ive95i.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=384&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/151040/original/image-20161220-26748-1ive95i.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=384&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/151040/original/image-20161220-26748-1ive95i.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=483&fit=crop&dpr=1 754w, https://images.theconversation.com/files/151040/original/image-20161220-26748-1ive95i.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=483&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/151040/original/image-20161220-26748-1ive95i.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=483&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Human sperm, unconcerned by what’s in your pocket.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Sperm_(265_33)_human.jpg">Doc. RNDr. Josef Reischig, CSc.</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>And none actually measure fertility rates – the health endpoint of concern – but rather measure sperm counts and other sperm quality parameters and then infer that there will be an impact on fertility. In fact, sperm counts can vary widely between normally fertile individuals and even within the same individual from day to day. For example, men who frequently ejaculate have lower sperm counts, as you might expect, because they are regularly jettisoning sperm. (Men who ejaculate daily can have <a href="http://doi.org/10.1186/s12958-015-0045-9">sperm counts 50 percent lower</a> than men who don’t.) Perhaps the allegedly lower sperm counts of cellphone users just means that they are having more sex!</p>
<p>But seriously, the point is this: There are so many things that can affect sperm counts in big ways that minor fluctuations in sperm counts have no practical impact on whether a man will produce babies, even if it were true that cellphones can modestly suppress sperm counts.</p>
<p>It is clear that these infertility claims are not the consensus of the mainstream scientific community – a community that demands more rigorous evidence. There are many excellent laboratories around the world that study radiation effects, and it isn’t difficult to study infertility in fruit flies, mice and even people. (It’s fairly easy to find men willing to <a href="https://verdict.justia.com/2012/01/24/men-who-give-it-away">donate sperm samples</a>.) If the sterility story were true, there would be a chorus of well-respected laboratories from around the world singing the cellphone infertility song, not just a few.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/151036/original/image-20161220-26748-eadyou.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/151036/original/image-20161220-26748-eadyou.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/151036/original/image-20161220-26748-eadyou.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=666&fit=crop&dpr=1 600w, https://images.theconversation.com/files/151036/original/image-20161220-26748-eadyou.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=666&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/151036/original/image-20161220-26748-eadyou.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=666&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/151036/original/image-20161220-26748-eadyou.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=837&fit=crop&dpr=1 754w, https://images.theconversation.com/files/151036/original/image-20161220-26748-eadyou.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=837&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/151036/original/image-20161220-26748-eadyou.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=837&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Guglielmo Marconi, inventor of the radio.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/smithsonian/2551824648">Smithsonian Institution</a></span>
</figcaption>
</figure>
<p>The fact is, the current data suggesting that cellphones cause infertility are too weak to challenge the dogma of over 100 years of commercial experience with radio waves. Radio waves are not unique to cellphones. They have been used for telecommunication ever since <a href="http://www.history.com/this-day-in-history/marconi-sends-first-atlantic-wireless-transmission">Marconi first demonstrated in 1901</a> that they could carry messages across the entire Atlantic Ocean. Early radio workers received massive doses of radio waves, yet there is no indication they had any problems with their fertility. If they didn’t experience fertility problems with their high doses, how can the relatively low doses from cellphones have such an effect? Hard to understand.</p>
<p>Nevertheless, people can spend their money as they please and wear any underwear they want. But if you are still concerned about radio waves affecting your fertility, why not just carry your cellphone in your shirt pocket rather than your pants, and let your testicles be?</p><img src="https://counter.theconversation.com/content/70636/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Timothy J. Jorgensen does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>
Did your holiday gift list include radiation-shielding undies to protect your privates from cellphone radio waves? A radiation expert explains they’re unnecessary – your phone won’t affect your fertility.
Timothy J. Jorgensen, Director of the Health Physics and Radiation Protection Graduate Program and Associate Professor of Radiation Medicine, Georgetown University
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/63430
2016-09-12T15:40:08Z
2016-09-12T15:40:08Z
Fossil evidence reveals that cancer in humans goes back 1.7 million years
<figure><img src="https://images.theconversation.com/files/137218/original/image-20160909-13375-q954u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The earliest hominin cancer.</span> <span class="attribution"><span class="source">Patrick Randolph-Quinney (University of Central Lancashire/University of the Witwatersrand)</span></span></figcaption></figure><p>Cancer is often viewed as a fundamentally modern and monolithic disease. Many people think its rise and spread has been driven almost exclusively by the developed world’s toxins and poisons; by our bad eating habits, lifestyles, and the very air we breathe.</p>
<p>Actually, cancer is not a single disease. It is also far from modern. New fossil evidence suggests that its origins lie deep in prehistory.</p>
<p>We recently published two papers in the South African Journal of Science that describe the discovery and diagnosis of the <a href="http://sajs.co.za/osteogenic-tumour-australopithecus-sediba-earliest-hominin-evidence-neoplastic-disease/patrick-s-randolph-quinney-scott-williams-maryna-steyn-marc-r-meyer-jacqueline-s-smilg-steven-e">earliest benign tumour</a> and <a href="http://sajs.co.za/earliest-hominin-cancer-1-7-million-year-old-osteosarcoma-swartkrans-cave-south-africa/edward-j-odes-patrick-s-randolph-quinney-maryna-steyn-zach-throckmorton-jacqueline-s-smilg-bernhard">earliest malignant cancer</a> to affect the human family.</p>
<p>Tumours and cancers are collectively known as <a href="http://www.cancerantiquity.org/neoplastic-disease">neoplastic diseases</a>. Until now, the oldest evidence of neoplasia in the hominin fossil record dated back <a href="http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0064539">120,000 years</a>. This was found in a rib fragment of a Neanderthal from Krapina in Croatia. </p>
<p>But our <a href="http://sajs.co.za/earliest-hominin-cancer-1-7-million-year-old-osteosarcoma-swartkrans-cave-south-africa/edward-j-odes-patrick-s-randolph-quinney-maryna-steyn-zach-throckmorton-jacqueline-s-smilg-bernhard">discovery</a>, in two South African cave sites, offers definitive evidence of cancer in hominins – human ancestors – as far back as 1.7 million years ago.</p>
<h2>Finding the earliest cancer</h2>
<p>Our research involved two overlapping teams of multi-disciplinary scientists. Some specialised in human evolutionary anatomy, others in ancient and modern diseases. Others are experts in the latest medical and research-based non-invasive imaging techniques. </p>
<p>The aim was to marry the work of scientists who focus extensively on the morphology of dry or fossil bone – including bone diseases – with medical specialists who are practised in diagnosing disease in living humans.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/65TjgYFB9uw?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Wits University video of the discovery of the earliest hominin cancer.</span></figcaption>
</figure>
<p>These discoveries were made possible by state-of-the-art 3D imaging techniques. We used <a href="https://www.wits.ac.za/microct/">Micro-Focus X-ray Computed Tomography</a>, or Micro-CT imaging. This is similar to the more familiar medical CAT scans, but allows a much greater degree of resolution.</p>
<p>Another technique, <a href="http://www.esrf.eu/files/live/sites/www/files/events/Seminars/2015,01,19%20ESRF%20palaeontology%20lecture-compressed.pdf">Phase Contrast X-ray Synchrotron Microtomography</a>, was also used. It is widely accepted globally as the global standard for 3D imaging of fossils without causing them any damage.</p>
<h2>Fossil evidence</h2>
<p>Finding any cancer or neoplastic disease in the archaeological record has always been a contentious issue. </p>
<p>In 2010 two scientists published <a href="http://www.manchester.ac.uk/discover/news/scientists-suggest-that-cancer-is-man-made">a study</a> based on their analysis of Egyptian mummies. They found extremely low incidences of benign tumours and an almost complete absence of malignancy. They concluded: </p>
<blockquote>
<p>There is nothing in the natural environment that can cause cancer. So it has to be a man-made disease, down to pollution and changes to our diet and lifestyle. </p>
</blockquote>
<p>Our findings prove that they are wrong. We made two relevant fossil discoveries which falsify their claims. One was an example of a benign tumour and the other a malignant cancer.</p>
<p>The benign tumour comes from the site of Malapa, and is dated to 1.98 million years ago. This is a case of <a href="http://orthoinfo.aaos.org/topic.cfm?topic=A00507">osteoid osteoma</a>, a benign bone tumour. It was found in a vertebra of the <a href="http://www.timeslive.co.za/local/2010/06/01/fossil-named-karabo">well-known</a> <em>Australopithecus sediba</em> child <a href="http://www.timeslive.co.za/local/2010/06/01/fossil-named-karabo">Karabo</a>. </p>
<figure class="align-left ">
<img alt="" src="https://images.theconversation.com/files/136308/original/image-20160901-1015-nund08.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/136308/original/image-20160901-1015-nund08.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=947&fit=crop&dpr=1 600w, https://images.theconversation.com/files/136308/original/image-20160901-1015-nund08.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=947&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/136308/original/image-20160901-1015-nund08.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=947&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/136308/original/image-20160901-1015-nund08.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1191&fit=crop&dpr=1 754w, https://images.theconversation.com/files/136308/original/image-20160901-1015-nund08.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1191&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/136308/original/image-20160901-1015-nund08.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1191&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Vertebra U.W. 88-37. Sixth thoracic vertebra of juvenile <em>Australopithecus sediba</em>. The tumour’s segmented boundaries are rendered solid pink.</span>
<span class="attribution"><span class="source">Paul Tafforeau (ESRF)</span></span>
</figcaption>
</figure>
<p>The tumour would probably have caused pain and discomfort, but would not have been directly responsible for Karabo’s death. However, the disease may have limited his ability to climb and move, and may have been implicated in the manner of his death. Results <a href="http://www.nature.com/articles/srep15120">published in 2015</a> suggest Karabo was the victim of a fall from a height into a natural death trap. </p>
<p>The second fossil find is perhaps the more important. A foot bone from Swartkrans cave provides the <a href="http://sajs.co.za/earliest-hominin-cancer-1-7-million-year-old-osteosarcoma-swartkrans-cave-south-africa/edward-j-odes-patrick-s-randolph-quinney-maryna-steyn-zach-throckmorton-jacqueline-s-smilg-bernhard">earliest evidence</a> for a malignant human cancer, and is dated to roughly 1.7 million years ago. </p>
<figure class="align-right ">
<img alt="" src="https://images.theconversation.com/files/132800/original/image-20160802-17185-1nrw745.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/132800/original/image-20160802-17185-1nrw745.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=379&fit=crop&dpr=1 600w, https://images.theconversation.com/files/132800/original/image-20160802-17185-1nrw745.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=379&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/132800/original/image-20160802-17185-1nrw745.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=379&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/132800/original/image-20160802-17185-1nrw745.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=476&fit=crop&dpr=1 754w, https://images.theconversation.com/files/132800/original/image-20160802-17185-1nrw745.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=476&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/132800/original/image-20160802-17185-1nrw745.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=476&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The earliest hominin cancer. Volume rendered Micro-CT image of the external morphology, showing the extent of expansion of osteosarcoma beyond the surface of the bone.</span>
<span class="attribution"><span class="source">Patrick Randolph-Quinney (University of Central Lancashire/University of the Witwatersrand)</span></span>
</figcaption>
</figure>
<p>This was seen as a large mass of bone growing on the surface of a fifth metatarsal, which is found in the body of the foot, behind the little toe. The external bone mass might have suggested a benign tumour. But when we looked inside the bone, using advanced Micro-CT imaging, we saw that the medullary cavity – the hollow part of a normal tubular bone – was completely obliterated by new bone growth. </p>
<p>This indicated an aggressive bone-forming condition: a cancer. </p>
<p>We used advanced imaging techniques that helped us to visualize the pathological lesion better. We were able to identify new bone growth inside the medullary cavity, which expanded through to the surface. We then compared the mass and the cross-section with modern clinical cases and concluded it was an osteosarcoma, a primary bone malignancy. </p>
<p>This means that the cancer actually started deep in the bone tissue itself, before spreading to the surface. Such cancers are invariably life-threatening if untreated and would lead to death if allowed to divide and spread. The cancer’s presence might also have affected the hominin’s ability to walk and would have been painful when in contact with the ground.</p>
<h2>Understanding palaeo-oncology</h2>
<p>So, is our discovery the earliest evidence for neoplastic disease? In the human lineage, yes. However, much older tumours and cancers have been observed in the fossil record of non-hominins. Cancer is not simply a disease affecting humans. And it is ancient.</p>
<p>The earliest unequivocal case of benign neoplasia is an <a href="http://www.pathologyoutlines.com/topic/boneosteoma.html">osteoma</a> from 300 million years ago. It was found in a <a href="http://onlinelibrary.wiley.com/doi/10.1002/ijc.20610/pdf">fossil fish</a> from North America. Later cases include benign tumours in Jurassic dinosaurs, Cretaceous hadrosaurs, and later European mammoths. The earliest true cancer comes from a <a href="https://books.google.co.za/books?id=y9o_SgXM2U4C&pg=PA20&lpg=PA20&dq=theropod+dinosaur+from+the+late+Jurassic+of+Utah+cancer&source=bl&ots=DXGKRcy-s6&sig=2ZQi25XOxa1bPQitec-Bpee2-r8&hl=en&sa=X&ved=0ahUKEwjKiPGHoILPAhVoD8AKHWgoDMYQ6AEIGjAA#v=onepage&q=theropod%20dinosaur%20from%20the%20late%20Jurassic%20of%20Utah%20cancer&f=false">theropod dinosaur</a> from the late Jurassic of Utah in the US. </p>
<p>Today various cancers and tumours are prevalent in animals. A parasitic cancer called Devil Facial Tumour Disease has been implicated in the collapse of wild Tasmanian Devil populations. Tasmanian Devils are carnivorous marsupials.</p>
<p>In the human world, it is true that rates of tumours and cancers are <a href="http://www.healthdata.org/news-release/new-cancer-cases-rise-globally-death-rates-are-declining-many-countries">accelerating</a> because environmental toxins and other tumour forming factors in the modern (particularly Western) lifestyle. But such diseases were present in the past, even without the influence of modern lifestyles. </p>
<p>However, by any modern standard these primary bone tumours are very rare. Finding them in two of our fossil ancestors is highly unusual. The next step is to ask what mechanisms may be behind the presence of tumours and cancers deep in prehistory and how that may have an impact on the evolution of cancer in the modern world.</p><img src="https://counter.theconversation.com/content/63430/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Edward John Odes receives funding from the NRF of South Africa, The DST/NRF South African Centre of Excellence in Palaeosciences, and the University of the Witwatersrand </span></em></p><p class="fine-print"><em><span>Patrick Randolph-Quinney does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>
Cancer is not the modern disease many believe it to be. New fossil evidence from two South African caves suggests that its origins lie deep in prehistory.
Patrick Randolph-Quinney, Senior Lecturer in Biological and Forensic Anthropology, University of Central Lancashire
Edward John Odes, PhD Candidate in Anatomical Sciences, University of the Witwatersrand
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/60822
2016-06-24T12:40:18Z
2016-06-24T12:40:18Z
Do CT scans really cause cancer?
<figure><img src="https://images.theconversation.com/files/127361/original/image-20160620-8885-1t1b6em.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="http://www.shutterstock.com/cat.mhtml?lang=en&language=en&ref_site=photo&search_source=search_form&version=llv1&anyorall=all&safesearch=1&use_local_boost=1&autocomplete_id=&searchterm=CT%20scan&show_color_wheel=1&orient=&commercial_ok=&media_type=images&search_cat=&searchtermx=&photographer_name=&people_gender=&people_age=&people_ethnicity=&people_number=&color=&page=1&inline=149926556">bikeriderlondon/Shutterstock.com</a></span></figcaption></figure><p>Computerised tomography (CT) scans are being increasingly used for medical diagnoses. In the UK, about <a href="http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.584.8974">3m CT scans</a> are carried out each year, and the rate per person is around <a href="http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.584.8974">five times higher</a> in the US. However, concerns have been raised about the increased risk of cancer in people who have undergone these scans.</p>
<p>A CT scan (or “CAT scan”) provides doctors with a much clearer picture of what is happening inside the body than conventional X-rays. But they also deliver a much higher dose of <a href="http://www.who.int/ionizing_radiation/about/what_is_ir/en/">ionising radiation</a>. Ionising radiation causes tissue damage and can increase the risk of cancer. The increase in risk is proportional to the amount of radiation received. </p>
<p>Risk accumulates with repeated exposure, and children are more susceptible than adults. Because CT scans require many images to be taken in the same body area, they deliver more radiation than a conventional X-ray. For example, 50 times more radiation in the abdominal area has <a href="http://bit.ly/28MHOSK">been detected</a>. But a 50-fold increase in a very small number is still a small number. </p>
<p>It has been estimated that an abdominal scan delivers about six times as much ionising radiation as a person would receive from the environment in a year. </p>
<h2>Finding a link</h2>
<p>Authors of a large UK study found that children exposed to higher radiation doses from CT scans faced threefold increases in their risks of developing leukaemia and brain tumours compared with those who received <a href="http://bit.ly/28NC7p2">lower doses</a>. The higher the amount of radiation the children received, the greater their chances of developing these cancers were. </p>
<p>The number of children diagnosed with either cancer over a 17-year period was about 200 out of 180,000 who were scanned. About 170 of these 200 children would, according to the researchers, have developed cancer as a result of having had higher radiation exposure from CT scans. (They were chosen because the authors considered them to be most affected by radiation exposure.) The overall estimated risk was therefore 170 in 180,000, or about one in a thousand. </p>
<p>But there are methodological problems with this and similar research. Some 30,000 children could not be included in the data analysis, mainly because their medical records were incomplete, and their omission might have affected the findings. And, although the researchers attempted to do so, we cannot rule out “reverse causation”, that is, some children having had more CT scans because they had underlying health problems, rather than vice versa. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/127774/original/image-20160622-7196-1tclfpv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/127774/original/image-20160622-7196-1tclfpv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=413&fit=crop&dpr=1 600w, https://images.theconversation.com/files/127774/original/image-20160622-7196-1tclfpv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=413&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/127774/original/image-20160622-7196-1tclfpv.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=413&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/127774/original/image-20160622-7196-1tclfpv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=519&fit=crop&dpr=1 754w, https://images.theconversation.com/files/127774/original/image-20160622-7196-1tclfpv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=519&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/127774/original/image-20160622-7196-1tclfpv.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=519&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Brain cancer cells.</span>
<span class="attribution"><a class="source" href="http://www.shutterstock.com/cat.mhtml?lang=en&language=en&ref_site=photo&search_source=search_form&version=llv1&anyorall=all&safesearch=1&use_local_boost=1&autocomplete_id=&search_tracking_id=trFVqyNMqmhDf4EvaLF6sw&searchterm=brain%20cancer&show_color_wheel=1&orient=&commercial_ok=&media_type=images&search_cat=&searchtermx=&photographer_name=&people_gender=&people_age=&people_ethnicity=&people_number=&color=&page=1&inline=389772325">royaltystockphoto.com/Shutterstock.com</a></span>
</figcaption>
</figure>
<p>The researchers excluded children who were given CT scans because cancer was suspected.</p>
<p>As the authors acknowledge, this approach has limitations. Children who receive CT scans may differ from those who do not in unknown ways which also make the former more likely to develop cancer. The only way to definitively exclude reverse causation would be to do a randomised controlled trial. This would involve randomising children into higher and lower exposure groups and following them up over a long period to see how many in each group developed cancer. This would, of course, be totally unethical.</p>
<p>Also, the findings don’t exclude the possibility that children who have CT scans become at greater risk of experiencing other diseases, or over longer time periods than were considered in the study. Reverse causation might result in the risk from scans being overstated because the children who had more scans might have been more likely to develop cancers even if they had not been exposed to extra radiation. On the other hand, exclusion of other conditions and longer time periods might lead to the risk from scans being understated. Overall, there is considerable uncertainty about the risk estimates generated by the study.</p>
<h2>US study</h2>
<p>Using UK data similar to that outlined above, <a href="http://archinte.jamanetwork.com/article.aspx?articleid=415368">researchers in the US</a> concluded that about 2% of US cancers would be caused by radiation from CT scans. This conclusion is subject to the same cautions as detailed above. Also, the absence in the US of centralised databases of health records adds further complications to risk estimates. </p>
<p>If the estimate is approximately right, and current UK usage of CT scans in the UK is about a fifth of the US level, then about 0.4% of UK cancers would be caused by exposure to CT scans. Although readers may view this risk as acceptably low, it would mean that about 1,400 of the 350,000 annual <a href="http://www.cancerresearchuk.org/health-professional/cancer-statistics/incidence#heading-Zero">new cancer cases</a> estimated to occur in the UK would result from CT scans. Given the trend towards increasing medical usage, this rate can be expected to increase in the future. </p>
<h2>Comparing apples with oranges</h2>
<p><a href="http://pubs.rsna.org/doi/full/10.1148/radiol.12121248">Most experts believe</a> that the risks associated with CT scans are greatly outweighed by their benefits. This conclusion might seem worryingly tentative. However, most decisions about risks entail value judgements because like is not being compared with like, in this case the clinical benefits of having CT scans to the additional cancer risk faced by those who undergo them, including otherwise healthy people. </p>
<p>Patients and parents offered a CT scan should ask their doctor to explain why it’s needed, and whether alternatives not involving exposure to radiation could be used.</p><img src="https://counter.theconversation.com/content/60822/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Bob Heyman does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>
CT scans deliver a hefty dose of ionising radiation. But the benefits outweigh the risks – most of the time.
Bob Heyman, Chair professor, University of Huddersfield
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/57406
2016-05-31T01:04:47Z
2016-05-31T01:04:47Z
How computing power can help us look deep within our bodies, and even the Earth
<figure><img src="https://images.theconversation.com/files/122911/original/image-20160517-9476-w78fh8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The computer does more of the work than you might think.</span> <span class="attribution"><a class="source" href="http://www.shutterstock.com/pic-401715220/stock-photo-thessaloniki-greece-february-official-opening-of-the-first-ct-imaging-pet-ct-scanner.html?src=wcSemSkkJRQbjbDYm9SbKA-2-59">CT computer and scan room image via shutterstock.com</a></span></figcaption></figure><p>CAT scans, MRI, ultrasound. We are all pretty used to having machines – and doctors – peering into our bodies for a whole range of reasons. This equipment can help diagnose diseases, pinpoint injuries, or give expectant parents the first glimpse of their child.</p>
<p>As computational power has exploded in the past half-century, it has enabled a parallel expansion in the capabilities of these computer-aided imaging systems. What used to be pictures of two-dimensional “slices” have been assembled into high-resolution three-dimensional reconstructions. Stationary pictures of yesteryear are today’s real-time video of a beating heart. The advances have been truly revolutionary.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/EN5qgpVxrcU?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">A cardiac MRI scan shows a heart beating.</span></figcaption>
</figure>
<p>Though different in their details, X-ray computed tomography, ultrasound and even MRI have a lot in common. The images produced by each of these systems derive from an elegant interplay of sensors, physics and computation. They do not operate like a digital camera, where the data captured by the sensor are basically identical to the image produced. Rather, a lot of processing must be applied to the the raw data collected by a CAT scanner, MRI machine or ultrasound system to produce before it the images needed for a doctor to make a diagnosis. Sophisticated algorithms based on the underlying physics of the sensing process are required to put Humpty Dumpty back together again.</p>
<h2>Early scanning methods</h2>
<figure class="align-left ">
<img alt="" src="https://images.theconversation.com/files/122907/original/image-20160517-9491-18otosr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/122907/original/image-20160517-9491-18otosr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=360&fit=crop&dpr=1 600w, https://images.theconversation.com/files/122907/original/image-20160517-9491-18otosr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=360&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/122907/original/image-20160517-9491-18otosr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=360&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/122907/original/image-20160517-9491-18otosr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=453&fit=crop&dpr=1 754w, https://images.theconversation.com/files/122907/original/image-20160517-9491-18otosr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=453&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/122907/original/image-20160517-9491-18otosr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=453&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">One of the first published X-rays (at right, with normal view of the hand at left), from 1896.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File%3AX-ray_1896_nouvelle_iconographie_de_salpetriere.jpg">Albert Londe</a></span>
</figcaption>
</figure>
<figure class="align-left ">
<img alt="" src="https://images.theconversation.com/files/122908/original/image-20160517-9464-1m98rqs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/122908/original/image-20160517-9464-1m98rqs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=367&fit=crop&dpr=1 600w, https://images.theconversation.com/files/122908/original/image-20160517-9464-1m98rqs.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=367&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/122908/original/image-20160517-9464-1m98rqs.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=367&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/122908/original/image-20160517-9464-1m98rqs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=461&fit=crop&dpr=1 754w, https://images.theconversation.com/files/122908/original/image-20160517-9464-1m98rqs.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=461&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/122908/original/image-20160517-9464-1m98rqs.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=461&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A modern hand X-ray.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/golanlevin/19300737031/">golanlevin/flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>Though we use X-rays in some cutting-edge imaging techniques, X-ray imaging actually <a href="https://www.nde-ed.org/EducationResources/CommunityCollege/Radiography/Introduction/history.htm">dates back to the late 1800s</a>. The shadowlike contrast in X-ray images, or projections, shows the density of the material between the X-ray source and the data sensor. (In the past this was a piece of X-ray film, but today is usually a digital detector.) Dense objects, such as bones, absorb and scatter many more X-ray photons than skin, muscle or other soft tissue, which appear darker in the projections.</p>
<p>But then in the early 1970s, X-ray CAT (which stands for Computerized Axial Tomography) scans were developed. Rather than taking just a single X-ray image from one angle, a CAT system rotates the X-ray sources and detectors to collect many images from different angles – a process known as tomography. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/yTDgFW2UZFI?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Computerized tomography imagery of a hand.</span></figcaption>
</figure>
<p>The difficulty is how to take all the data, from all those X-rays from so many different angles, and get a computer to properly assemble them into 3D images of, say, a person’s hand, as in the video above. That problem had a mathematical solution that had been studied by the <a href="https://thatsmaths.com/2013/03/07/ct-scans-and-the-radon-transform/">Austrian mathematician Johann Radon</a> in 1917 and rediscovered by the American physicist (and Tufts professor) <a href="http://www.nytimes.com/1998/05/09/us/allan-cormack-74-nobelist-who-helped-invent-cat-scan.html">Allan Cormack</a> in the 1960s. Using Cormack’s work, <a href="http://dx.doi.org/10.1148/radiol.2343042584">Godfrey Hounsfield</a>, an English electrical engineer, was the first to demonstrate a working CAT scanner in 1971. For their work on CAT, Cormack and Hounsfield received the <a href="http://www.nobelprize.org/nobel_prizes/medicine/laureates/1979/">1979 Nobel Prize in Medicine</a>. </p>
<h2>Extending the role of computers</h2>
<p>Until quite recently, these processing methods had more or less been constant since the 1970s and 1980s. Today, additional medical needs – and more powerful computers – are driving big changes. There is increased interest in CT systems that <a href="http://www.fda.gov/Radiation-EmittingProducts/RadiationEmittingProductsandProcedures/MedicalImaging/MedicalX-Rays/ucm115329.htm">minimize X-ray exposure</a>, yielding high-quality images from fewer images. In addition, certain uses, such as breast imaging, encounter physical constraints on how much access the imager can have to the body part. This requires scanning from only a very limited set of angles around the subject. These situations have led to research into <a href="http://www.massgeneral.org/imaging/services/3D_mammography_tomosynthesis.aspx">what are called “tomosynthesis” systems</a> – in which limited data are interpreted by computers to form fuller images. </p>
<p>Similar problems arise, for example, in the context of imaging the ground to see what objects – such as pollutants, land mines or oil deposits – are hidden beneath our feet. In many cases, all we can do is <a href="http://physicsworld.com/cws/article/news/2016/feb/16/ground-penetrating-radar-boosts-asparagus-production">send signals from the surface</a>, or drill a few holes to take sampling measurements. <a href="https://www.ncjrs.gov/school/ch3c_5.html">Security scanning in airports</a> is constrained by cost and time, so those X-ray systems can take only a few images.</p>
<p>In these and a host of other fields, we are faced with less overall data, which means the Cormack-Hounsfield mathematics can’t work properly to form images. The effort to solve these problems has led to the rise of a new area of research, “computational sensing,” in which sensors, physics and computers are being brought together in new ways. </p>
<p>Sometimes this involves applying more computer processing power to the same data. In other cases, hardware engineers designing the equipment <a href="https://www.ecse.rpi.edu/homepages/saulnier/eit/eit.html">work closely with the mathematicians</a> figuring out how best to analyze the data provided. Together these systems can provide new capabilities that hold the promise of major changes in many research areas.</p>
<h2>New scanning capabilities</h2>
<p>One example of this potential is in bio-optics, the use of light to look deep within the human body. While visible light does not penetrate far into tissue, anyone who has shone a red laser pointer into their finger knows that red light does in fact make it through at least a couple of centimeters. Infrared light penetrates even farther into human tissue. This capability opens up entirely new ways to image the body than X-ray, MRI or ultrasound.</p>
<p>Again, it takes computing power to move from those images into a unified 3D portrayal of the body part being scanned. But the calculations are much more difficult because the way in which light interacts with tissue is far more complex than X-rays.</p>
<p>As a result we need to use a different method from that pioneered by Cormack in which X-ray data are, more or less, directly turned into images of the body’s density. Now we construct an algorithm that follows a process over and over, feeding the result from one iteration back as input of the next. </p>
<p>The process starts by having the computer guess an image of the optical properties of the body area being scanned. Then it uses a computer model to calculate what data from the scanner would yield that image. Perhaps unsurprisingly, the initial guess is generally not so good: the calculated data don’t match the actual scans. </p>
<p>When that happens, the computer goes back and refines its guess of the image, recalculates the data associated with this guess and again compares with the actual scan results. While the algorithm guarantees that the match will be better, it is still likely that there will be room for improvement. So the process continues, and the computer generates a new and more improved guess. </p>
<p>Over time, its guesses get better and better: it creates output that looks more and more like the data collected by the actual scanner. Once this match is close enough, the algorithm provides the final image as a result for examination by the doctor or other professional.</p>
<p>The new frontiers of this type of research are still being explored. In the last 15 years or so, researchers – including my Tufts colleague <a href="https://ase.tufts.edu/biomedical/research/Fantini/">Professor Sergio Fantini</a> – have explored many potential uses of infrared light, such as <a href="http://dx.doi.org/10.1007/s10549-013-2802-9">detecting breast cancer</a>, functional brain imaging and <a href="http://dx.doi.org/10.1016/j.bbapap.2013.01.025">drug discovery</a>. Combining “big data” and “big physics” requires a close collaboration among electrical and biomedical engineers as well as mathematicians and doctors. As we’re able to develop these techniques – both mathematical and technological – we’re hoping to make major advances in the coming years, improving how we all live.</p><img src="https://counter.theconversation.com/content/57406/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Eric Miller receives funding from NSF, NIH, DHS. </span></em></p>
Pairing more powerful computers with increasingly sensitive scanners can yield many benefits in medicine and other fields.
Eric Miller, Professor and Chair of Electrical and Computer Engineering, Adjunct Professor of Computer Science, Adjunct Professor of Biomedical Engineering, Tufts University
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/59504
2016-05-24T09:49:25Z
2016-05-24T09:49:25Z
The flower breeders who sold X-ray lilies and atomic marigolds
<p>The <a href="https://www.rhs.org.uk/shows-events/rhs-chelsea-flower-show">Chelsea Flower Show</a>, one of the biggest and best known horticultural shows in the world, is now open. In the coming days, some <a href="http://www.standard.co.uk/goingout/attractions/chelsea-flower-show-2016-tickets-times-highlights-and-travel-info-a3252546.html">150,000</a> visitors will make their way to the Royal Hospital Chelsea, expecting to be wowed by innovative garden designs and especially by gorgeous flowers. Among other things, show-goers will have a chance to learn the winner of the Royal Horticultural Society’s <a href="https://www.rhs.org.uk/shows-events/rhs-chelsea-flower-show/2015/articles/Plant-of-the-Year">Plant of the Year</a> award. This annual prize goes to the “most inspiring new plant” on display at the show – a high honour indeed given the number and range of varieties introduced each year.</p>
<p>The relentless pursuit of showy flowers for garden display extends back significantly further than the 104 years of the Chelsea show. One need only recall the <a href="https://www.rijksmuseum.nl/en/explore-the-collection/timeline-dutch-history/1637-tulipmania">infamous Dutch tulip craze</a> of the 17th century to be reminded that fascination with floral novelties has a long and storied history. </p>
<p>Over the centuries, entrepreneurial cultivators have endeavoured to create unique plant varieties, either by bringing together the genetic material from established lines through <a href="http://www.biologyreference.com/Ho-La/Hybridization-Plant.html">hybridisation</a> or through the discovery of new genetic variation such as a chance mutation in a field. Today, flower breeding is pursued with a far better understanding of plant biology than ever before, in some cases with the aid of technologies such as tissue culture and genetic transformation. Yet the goal remains the same: the creation of tantalising tulips, ravishing roses, show-stopping snapdragons and myriad other plants that will ideally prove irresistible to gardeners and turn a handsome profit.</p>
<p>The quest to produce profitable new varieties – and to do so as fast as possible – at times led to breeders to embrace <a href="http://press.uchicago.edu/ucp/books/book/chicago/E/bo24313051.html">methods that today seem strange</a>. There is no better illustration of this than the mid-century output of one of America’s largest flower-and-vegetable-seed companies, <a href="http://www.burpee.com/">W Atlee Burpee & Co</a>. </p>
<h2>Gardening with X-rays</h2>
<p>In 1941, Burpee Seed introduced a pair of calendula flowers called the “X-Ray Twins”. The company president, <a href="https://flic.kr/p/gaYqK">David Burpee</a>, claimed that these had their origins in a batch of seeds exposed to X-rays in 1933 and that the radiation had generated mutant types, from which the “X-Ray Twins” were eventually developed.</p>
<p>At the time, Burpee was not alone in exploring whether X-rays might facilitate flower breeding. Geneticists had only recently come to agree that radiation could lead to genetic mutation: the possibilities for creating variation “on demand” now seemed boundless. Some breeders even hoped that X-ray technologies would help them press beyond existing biological limits. </p>
<p>The Czech-born horticulturist Frank Reinelt thought that subjecting bulbs to radiation might help him produce an elusive red delphinium. Unfortunately, the experiment did not produce the hoped-for hue. Greater success was achieved by two engineers at the General Electric Research Laboratory, who produced – <a href="https://patents.google.com/patent/USPP165P">and patented</a> – a new variety of lily as a result of their experiments in X-ray breeding.</p>
<p>Though Reinelt’s and other breeders’ tangles with X-ray technology resulted in woefully few marketable plant varieties, David Burpee remained keen on testing new techniques as they appeared on the horizon. He was especially excited about methods that, like X-ray irradiation, promised to generate manifold genetic mutations. He thought these would transform plant breeding by making new inheritable traits – the essential foundation of a novel flower variety – available on demand. He estimated that “in his father’s time” a breeder chanced on a mutation “once in every 900,000 plants”. He and his breeders, by comparison, equipped with X-rays, UV-radiation, chemicals, and other mutation-inducing methods, could “turn them out once in every 900 plants. Or oftener”.</p>
<h2>Scientific sales pitches</h2>
<figure class="align-right ">
<img alt="" src="https://images.theconversation.com/files/123630/original/image-20160523-11025-1sr1nq4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/123630/original/image-20160523-11025-1sr1nq4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=930&fit=crop&dpr=1 600w, https://images.theconversation.com/files/123630/original/image-20160523-11025-1sr1nq4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=930&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/123630/original/image-20160523-11025-1sr1nq4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=930&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/123630/original/image-20160523-11025-1sr1nq4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1169&fit=crop&dpr=1 754w, https://images.theconversation.com/files/123630/original/image-20160523-11025-1sr1nq4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1169&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/123630/original/image-20160523-11025-1sr1nq4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1169&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A 1973 Burpee cover.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/burpee/167768850/in/album-72157594166703655/">Burpee</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<p>Burpee’s numbers were hot air, but in a few cases plant varieties produced through such methods did prove hot sellers. In the late 1930s Burpee breeders began experimentation with a plant alkaloid called <a href="https://archive.org/details/useofcolchicinei3424derm">colchicine</a>, a compound that sometimes has the effect of doubling the number of chromosomes in a plant’s cells. They exploited the technique to create new varieties of popular garden flowers such as marigold, phlox, zinnia, and snapdragons. </p>
<p>All were advertised as larger and hardier as a result of their chromosome reconfiguration – and celebrated by the company as the products of “chemically accelerated evolution”. The technique proved particularly successful with snapdragons, giving rise to a line of “Tetra Snaps” that were by the mid-1950s the best-selling varieties of that flower in the United States.</p>
<p>Burpee’s fascination with (in his words) “<a href="https://books.google.co.uk/books?id=IEEEAAAAMBAJ&pg=PA15">shocking mother nature</a>” to create novel flowers for American gardeners eventually led him to explore still more potent techniques for generating inheritable variation. He even had some of the company’s flower beds seeded with radioactive phosphorus in the 1950s. These efforts do not appear to have led to any new varieties – Burpee Seed never hawked an “atomic-bred” flower – but the firm’s experimentation with radiation did result in a new Burpee product. Beginning in 1962, they offered for sale packages of “atomic-treated” marigold seeds, from which home growers might expect to grow a rare white marigold among other oddities.</p>
<p>Burpee was, above all, a consummate showman and a master salesman. His enthusiasm for the use of X-rays, chemicals, and radioisotopes in flower breeding emerged as much from his knowledge that these methods could be effectively incorporated into sales pitches as from his interest in more efficient and effective breeding. Many of his mid-century consumers wanted to see the latest science and technology <a href="http://dx.doi.org/10.1017/S0007087412001057">at work in their gardens</a>, whether in the form of plant hormones, chemical treatments, or varieties produced through startling new techniques. </p>
<p>Times have changed, 60-odd years later. Chemicals and radiation are as more often cast as threatening than benign, and it is likely that many of today’s visitors to the Chelsea Flower Show hold a different view about the kinds of breeding methods they’d like to see employed on their garden flowers. But as the continued popularity of the show attests, their celebration of flower innovations and the human ingenuity behind these continues, unabated.</p><img src="https://counter.theconversation.com/content/59504/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Helen Anne Curry does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>
The relentless pursuit of showy flowers for garden display – as seen at Chelsea Flower Show – has seen some odd uses of radiation and chemicals .
Helen Anne Curry, Peter Lipton Lecturer in History of Modern Science and Technology, University of Cambridge
Licensed as Creative Commons – attribution, no derivatives.