Doses of radiation vary markedly by body part scanned: A kidney disease patient undergoing a CT scan in the abdominal area will be exposed to more than 30 mSv, while someone with a suspected brain tumour will be exposed to as little as two mSV of radiation when the head is scanned. By comparison, a mammography test exposes a woman to a radiation dose of less than one mSv.
I wonder how many abdominal CT scans a dialysis patient gets in a year. 30mSv per scan is a lot, according to this chart:
Radiation dosage is measured in Sieverts. This replaces the old unit, the Rem. 1 Sievert = 100 Rem, which is a large unit, so we are usually talking millisieverts (mSv) = 1/1000 of a Sievert.
2 to 3 mSv/year - typical background dose in most countries
2.4 mSv/year - average dose to US nuclear industry employees
up to 5 mSv/year - typical dose for aircrew
20 mSv/year - current limit (average) for nuclear industry employees
100 mSv/year - lowest level at which there is evidence of any increase in cancer rate
350 mSv/lifetime - criterion for relocating people after Chernobyl accident
1 Sv/cumulative - Would probably cause a fatal cancer many years later in 5 out of 100 persons
1 Sv single dose in short time - causes radiation sickness such as nausea and decreased white blood cell count, but not death (ie in short term)
5 Sv single dose - Would kill about 50 percent within a month
10 Sv single dose - fatal within a few weeks
Information from https://www.world-nuclear.org/info/inf05.html