Discovering X-rays

How did the technologies that we now routinely use to look inside the body first come about?
26 January 2021

Interview with 

Katie Dabin, Science Museum


radiograph of the chest


Anatomists and doctors have been looking at and illustrating the body since ancient times. But having the tech to image the inside of the body while a person is still alive arguably comes about with the discovery of X-rays, which happened in the late 1890s. Katie Dabin, is curator of medicine at the Science Museum in London. She took Katie Haylor on a virtual tour of some of the museum’s relevant relics...

Katie D - When we think of x-rays, maybe when we've broken a bone, we go to hospital, it's all very high-tech medical equipment. But what you're looking at here is essentially a mahogany wooden table with a very strange looking coil on top, and then a wooden tripod with an oversized looking light bulb attached to it, and at the back the equivalent of a car battery. And this was the kind of equipment you could quite easily get hold of in the 1890s and produce x-rays with. And this was built just a few months after Wilhelm Röntgen, the German physicist who discovered x-rays in 1895, surprised the whole world with this amazing discovery. People began to experiment and build their own kit. You can imagine the scary levels of radiation people were sort of getting exposed to at that point.

Katie - So what's going on with this kit? How do you make an x-ray image?

Katie D - All the other kit essentially starts creating the right kind of current and voltage that you need to produce that electrical charge. And then when you come to the oversized light bulb, this glass vacuum tube, electrons get emitted from one end, the cathode, and they go across the vacuum and hit the positive end, the anode. And when those electrons start hitting that anode that's when they start emitting these higher energy radiation x-rays. Röntgen the German physicist didn't know what these were when he first started observing them. So that's why he termed them X for unknown.

Katie - So how do you get an image of something? Say a part of the body?

Katie D - The high energy x-rays, they act like lights. Sometimes light gets reflected, or sometimes it gets absorbed by different materials. X-rays are able to pass through a lot of our soft body tissues, and that's when we see the sort of shadowy dark areas on a body x-ray, but they get absorbed by our bones. So that's when the bones show up as the kind of lighter areas on an x-ray.

Katie - And so what was the German physicist that you just mentioned, Röntgen, what was he up to then?

Katie D - Like a lot of other physicists at the time, Wilhelm Röntgen was really interested in exploring electrical properties of these vacuum tubes, these oversized light bulbs. And he was doing all sorts of experiments, especially these ones called Crookes tubes. He started observing, even though he'd covered up all the light-emitting properties of the tube, he had some sort of photochemical materials on cardboard nearby, and then he started noticing this weird fluorescing glow in his lab. He started observing and then began to carry out experiments to understand what was causing this weird fluorescence. And then he realized that the tubes themselves, even though he was covering them up so they couldn't emit any light that we would see, that there must be some rays coming from these tubes that was causing that material to fluoresce, and gradually started experimenting. And then, by accident I think, put his hands in front of the rays and ended up capturing an image. And when he first showed an image of his wife's hands, I mean, she saw the sort of skeletal image and looked aghast and was like "Oh, I've seen my death!"

Katie - I can imagine if the only skeletal images you've seen are of dead people, that sounds like it could be quite disconcerting!

Katie D - Absolutely. I mean x-rays are transformative in the ways people were seeing things at the time. This is the Victorian period, generally they were seen more as a new form of entertainment. It became very fashionable to get your own sort of x-ray image of your own hand or foot. But increasingly and gradually, we became aware of the real harmful health consequences of the radiation that x-rays emitted. It became much more medicalised and industrialised and very much out of the hands of your regular everyday person. And pretty quickly within the Boer war, which was around about 1896 as well, and then into the first world war in particular where the technology had improved so bit more reliable, x-rays were carried onto the frontline and they really proved themselves to be useful in identifying bullet wounds or different fractures or wounds. And gradually it became such an important part of medical practice from there on in.

Katie - So how do you get from x-rays to something a bit more sophisticated, like a CT scan?

Katie D - That's a technology that still makes use of x-rays. So rather than more like a photographic image, what's really clever about scanning technologies like CT is that you can make these 3D slices all the way through the body in all sorts of different ways - up, down, through sideways, horizontal, and reconstruct a whole 3D image through the use of computers.

Katie - Science has come an enormously long way from the late 1800s to now in 2021 with the medical imaging that is possible. Can you summarise the sort of public perception journey through that time?

Katie D - From its birth with x-rays - technology that could be used for entertainment - it wasn't conceived as just a medical or an industrial tool. You would even find x-ray machines within shoe shops and people could go in and try shoes on under these fluoroscopes called Pedoscopes and see their toes wriggling around in real time. Equally, along with that sort of shifting and increasingly medicalised sense of medical imaging, what really partly drove that was the risk attached with the radiation of x-rays. So increasingly we became really aware of the health risks. And so increasingly as the regulations got tightened and also the kind of practical applications really became much more seen within either medicine or industry in different ways, we've come to understand these technologies predominantly within a hospital setting and definitely not one for the home.


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