You do raise an interesting point regarding the actual amount of radiation exposure from the TSA scanners. I agree with you and think that it would be completely irresponsible for our government to condone the use of radiation on innocent folks every day if there was any chance that it could be more harmful than we have been led to believe. That being said, I have read some information from both sides of the issue, and as a physician, I can honestly say that I am not the least bit worried about the radiation received during the scanning process. If we were to suppose that the TSA calculations were off by a factor of 10, the amount of radiation exposure received would still be quite small compared to other sources and in my opinion, no cause for concern. Again, this is just my opinion.
I am definitely not an expert and I am happy to admit that you probably have much more experience than I in dealing with radiation safety (I am completely serious about that). I am merely approaching the topic from the standpoint of radiation exposure that I am familiar with, e.g. a standard chest x-ray. That radiation must penetrate deep enough to shoot completely through the entire body to a plate on the other side. It also shoots partially through more solid structures like bones. This requires a very short pulse of high energy radiation. A CT scan exposes the patient to dozens of times as much radiation as a chest x-ray, and fluoroscopy sometimes even more. Having seen thousands of patients exposed to sometimes dozens of CT scans over a relatively short period of time, I am not too worried about the TSA scanners. CT scanning has been in routine clinical practice for more than 20 years and to my knowledge, there have been no substantial increases in cancer rates as a result.
Again, I did not go through the math and do any specific calculations, I am just using my general understanding of radioactivity that is used in medicine to form a very general opinion. I AM DEFINITELY NOT AN EXPERT!!! It is entirely possible that I am wrong, so please don't anyone file a lawsuit against me.
Just my two cents,