On my ski patrol there is a professor at Univ. of Las Vegas, Nevada who teaches medical imageing.
He told me that the "backscatter" radiation used in airport security scanning is actually a bit MORE radiation than a chest X-ray!! There are scientific papers on this that the Feds would rather you don't read.
My wife and I have never submitted to a "backscatter" x-ray scan, always choosing the more time-consuming pat down. I did this before my patroller friend informed me of the danger B/C I don't want any additional radiation exposure. I prefer mine naturally, at high altitudes, if I'm going to get any at all.