The studies are based on extrapolating the incidence of cancer from acute high radiation doses to low radiation dose using the linear- no threshold model. Using this model, any radiation dose, increases the risk of cancer. This is generally thought to be a simplistic and conservative assumption. Some ballpark numbers (based on my recollection) to consider: CT dose 750 mrem per scan, chest x-ray 30 mrem, annual background exposure in US 300mrem, transcontinental flight 10mrem, regulatory limit for radiation worker annual exposure 5000mrem. So, the CT dose is not insignificant but the medical benefit from the diagnostic test will likely far exceed the cancer risk. I would be hesitant to have children receive many CT scans but for middle age persons, I wouldn’t worry. Even in the highly unlikely event the radiation exposure did result in cancer, the cancer probably would probably not present itself for 20-25 years.
I’ve had 4 MRIs and 3 CT scans this year. If Goseminoles quits posting, someone call my mom (and a good lawyer).
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People really, really need to be wary of CT scans and only get them if really necessary. I have read that ONE CT scan can have as much radiation as 25 regular X-rays! My twin boys both had plagiocephaly (head-flattening — usually a cosmetic condition, long since cured now with my boys) and the idiot “expert” Kaiser sent us to wanted them both to have CT scans BEFORE she would even see them! I read up on CT scans and put my foot down on that. There are at least two studies (maybe more now) that implicated CT scans to the head in infants with brain cancer later on. We found a real expert who dealt with plagiocephaly all the time and he not only did not want CT scans, but he was dumbfounded that the other doc did.
Bottom line: Be SURE you need that CT scan before you get it!
As I asked on an earlier, related post, What is the dose / exposure that is being discussed? Without that number, all this is meaningless drivel.