This had some good information that I either didn't know or hadn't taken on board my aging brain, especially the information about service calls.

"John Sedat, emeritus professor of biochemistry and biophysics at the University of California, San Francisco, believes that the effective dose could be 45 times as high as the T.S.A. has estimated, equivalent to about 10 percent of a single chest X-ray."

"The machines, though, have had mechanical problems. A recent T.S.A. report said that between May 2010 and May 2011, there were 3,778 service calls concerning mechanical problems in backscatter X-ray machines. Radiation safety surveys were conducted after only 2 percent of the calls."

http://well.blogs.nytimes.com/2012/0...ering-worries/