Answer to Question #13510 Submitted to "Ask the Experts"
The following question was answered by an expert in the appropriate field:
I am a 34 year-old-male. I had an abdomen and pelvis CT scan because of an abnormality detected in my urine. I was told my radiation exposure from the scan was 12 mSv. Was I unnecessarily exposed to radiation? Having had the exam, I am worried that the radiation exposure will increase my chances of developing a serious disease, affect my fertility, or cause damage or genetic illness for my future offspring? Is there anything I can do to counter the negative effect of the radiation exposure?
For the average American, background radiation exposure is about 3 mSv y-1. Whole-body effects of radiation exposure less than 100 mSv above background are not measurable, if there are any substantial effects at all. Neither cancer risk nor any other radiation-induced diseases would be expected from the scan. A more thorough breakdown of these numbers can be found in the Health Physics Society's "Radiation Risk in Perspective" position statement.
The necessity of medical scans is determined by your medical provider. Part of that decision is whether the potential to learn new information warrants radiation exposure. If nothing shows up in the CT scan, that can be important information in diagnosing conditions. Even a series of full-body scans, having much higher doses, is unlikely to ever cause negative effects, whereas the images could immediately help identify and treat pressing issues.
You do not need to worry about any reproductive problems from your imaging. Doses of at least 150 mSv are required to cause temporary sterility effects in males. There is also no evidence to date of reproductive mutations being passed on to offspring, even with very large exposures. It is due to these reasons that you might notice shielding not being used for future imaging. The American Association of Physicists in Medicine has an FAQ sheet on patient gonadal shielding that may be of interest to you, as it covers many of these concerns.
Lastly, you cannot counter the kind of radiation exposure you receive from a CT machine in the same way you cannot undo a tan from the sun once it is there. The main concern with radiation is cancer risk which can be reduced in a myriad of ways from diet, to exercise, to avoiding other carcinogens.
Peter James Seel, MS