When performing an x-ray (in the UK specifically) does a radiologist use different settings based on which body part they are x-raying? Or do they have the machine on one setting for everyone? I'm curious because I would like to think that they adjust the x-ray dosage for each individual (and each body part) in order to minimise the amount of radiation the patient receives.

1 Answer 1


According to this Harvard Medical article, in order to x-ray an arm or leg the average dose is 0.001mSv with a range reported in literature of 0.0002—0.1mSv.

A lumbar spine x-ray would require an average of 1.5mSv with a range reported in literature of 0.5—1.8mSv.

Therefore, it would be safe to say that dosages are adjusted according to the part of the body needing an x-ray image.

  • Thanks Chris. The information you provided would definitely indicate that the radiation levels of most x-rays are indeed adjusted based on the body part being x-rayed — this is good to know. However it would be nice to hear first hand from a radiologist if this is strict practice for every x-ray, or just done every now and then. For example, does the x-ray machine explicitly require the body part to be specified before each new x-ray is performed, or is there room for human error if the radiologist simply forgets to adjust it from the previous patient?
    – Ben Clarke
    Commented Aug 18, 2021 at 13:16
  • 2
    @BenClarke - No radiologist here is going to answer a question that has already been answered correctly. The dose isn't dictated by the radiologist; it's dictated by protocol, which the technician follows for every Xray, or the image would be sub-par. Little people get less; larger than normal people may need more. See epa.gov/radiation/…; "Using only as much radiation dose as is required to achieve adequate image quality should be the goal." Commented Aug 18, 2021 at 15:39
  • Thank you @anongoodnurse - your comment helped to further clarify the previous answer. It would still be good to hear from an actual radiologist though, just to get some finer detail about how the protocol is followed in terms of the user interface on the machine.
    – Ben Clarke
    Commented Aug 19, 2021 at 13:37
  • @BenClarke - Not gonna happen. Your expectations are way too high. The tech presses buttons, enters info, et voila! Ask a radiology tech you might know. Commented Aug 19, 2021 at 17:15

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