Ionising Radiation



X-rays are carried out by radiographers, who are healthcare professionals trained to use imaging technology, including X-ray machines and ultra-sound scanners

During an X-ray, you'll be asked to lie on a table or stand against a flat surface so that the part of your body being examined is positioned between the X-ray machine and a photographic plate.

The X-ray will last for a fraction of a second. As the X-rays hit the photographic plate, the plate will capture a snapshot of the image.

The image will then be transferred to a computer so that it can be studied on a screen and, if necessary, printed out.


Exposure to high levels of radiation can be very harmful. However, the X-rays used for medical purposes are safe because the dose of radiation is very small.

The strength of radiation in relation to long-term risk is measured using units called millisieverts (mSv). Some examples of typical exposures are:

  • chest X-ray – 0.02 mSv
  • a year's worth of medical tests – 0.4 mSv
  • average annual exposure to natural radiation – 2.2 mSv

In the UK, 20 mSv is the maximum that someone who works with radiation is allowed to be exposed to in any given year. Most workers receive considerably less than this.