http://en.wikipedia.org/wiki/Backscatter_X-ray http://en.wikipedia.org/wiki/Backscatter_X-ray Well, it does use x-rays, they are called "x-ray backscatter scan

http://en.wikipedia.org/wiki/Backscatter_X-ray http://en.wikipedia.org/wiki/Backscatter_X-ray Well, it does use x-rays, they are called "x-ray backscatter scanners". Serious scientists have expressed concern. The concern is with the fact that inadequate testing has been performed, and comparisons made with other radiation sources are flawed because they take the absorbed dose and average over the entire volume of a person. Anyone in radiation safety understands the important number is the dose absorbed in specific portions of the body. In this case, the x-ray radiation is absorbed in the skin (minus the very small scattered fraction), not your entire body volume, resulting in a much higher local dose than you would expect if you modeled the exposure as uniform through the volume. Since the x-ray source strength is quite low (assuming the machine isn't multifunctioning), the health risks to occasional travelers are assumed to be low. Maybe frequent travelers or airline employees should have greater concern, or those at risk of cataracts.