(Risks described are approximations for a 45-year-old person; risks are halved for 70- year-olds, doubled for 20-year-olds, and quadrupled for young children)
“Mr. Smith. The best way I can diagnose your pain is a CT scan. This means having radiation exposure. I will explain how much radiation. You are always exposed to ‘background’ radiation from the ground, stars, air, and food. To use money as an example, it is 2 cents per hour. For comparison, a chest x-ray is $2 and the abdominal CT scan is $1,000 of radiation. Risk of cancer during your lifetime increases by about 1 in 1,000 for every $1,000 of radiation exposure. Of 1,000 people, about 420 will have cancer in their lifetimes. Therefore, every $1,000 of radiation increases the cancer risk from 420 to 421 of 1,000. About half the cancers are fatal.
You can see that the risk of cancer from the CT scan is low. For every 1,000 patients getting your scan, only 1 will probably get cancer because of it. I recommend the scan for you because I believe the benefit of diagnosis outweighs the risk. If you disagree, we can discuss other options that avoid radiation exposure, but these may be less helpful in diagnosing your pain. A delay in diagnosis also carries a risk of complications or death.”
Veysman, Acad Emerg Med 2009 16:1 p95
also, from Michelle Lin:
also, from Safety of Radiographic Imaging During Pregnancy: Am Fam Physician. 1999 Apr 1;59(7):