• Question: How does an x-ray work?

    Asked by to Simon, Becky, Thomas, Daniel, Clara on 13 Mar 2014. This question was also asked by .
    • Photo: Thomas Elias Cocolios

      Thomas Elias Cocolios answered on 13 Mar 2014:

      An x-ray is a high-energy photon emitted by an atom after an electron has been kicked out from its shell following the absorption of a gamma ray from the decay of the nucleus.

      What you probably enquire about is how an x-ray machine works. Well, the idea is that those high-energy photons will penetrate through soft tissues, or thin surfaces, but will be absorbed by dense material, such as bones. In some cases, you may also have resonances, that is the x-ray energy is exactly such that it is absorbed by an element.

      I either case, what you get is that the photons do not go through. So it is like playing with shadows: you shine light on one side (the x-rays) and record it on the other (like a photographic plate at the hospital) and you look at where the light go to or did not.

    • Photo: Simon Albright

      Simon Albright answered on 13 Mar 2014:

      An X-Ray is a type of light with lots of energy. Red light has less energy than blue light and X-rays have a lot more than blue (but still less than gamma).

      When you get an X-Ray at the dentist or the hospital they use the very high energy light to look inside you. Because X-Rays are so high energy they’re very hard to stop, skin and muscle don’t really do anything to them but bones are able to stop them so you get a picture of just the bones.

    • Photo: Clara Nellist

      Clara Nellist answered on 16 Mar 2014:

      To add to the answers given by Thomas and Simon:

      You can also get an x-ray from the inside, out. By this I mean, instead of shining x-rays onto a patient, a doctor can give the patient something that will give off x-rays from inside the body. They then can use a screen that detects these x-rays to see what is happening as it happens, like a movie. This is called Fluoroscopy and is very useful to look at how digestion is working for example. But, the danger with this method that instead of a quick photo with an x-ray machine, making an ‘x-ray movie’ requires the patient to be exposed to x-rays for a lot longer, and this can increase the cancer risk for them.

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