Now that there are nearly 200 body scanning machines in about 50 domestic airports, with 800 more on the way, passengers are facing real-life decisions about what to do.
The more controversial "backscatter" devices project an X-ray beam onto the body, creating an image displayed on a monitor viewed by a T.S.A. employee in another room. The "millimeter wave" machines, which are considered less risky because they do not use X-rays, bounce electromagnetic waves off the body to produce a similar image.
The main concerns are how much radiation the scanners give off (the manufacturers say the amount is very low), whether the scanners might malfunction and emit more radiation than they are supposed to, and what the health effects may be for travelers.
Full story from the New York Times