Arizona State University physics professor Peter Rez calculated the amount of radiation exposure a human is likely to receive in one of those newfangled Rapiscan porno-scanners the TSA is so fond of, and determined that exposure to be roughly one-fiftieth to one-hundredth the amount of a standard chest X-ray.
http://boingboing.net/2010/11/19/odds-of-cancer-from.html?x=1
