Jan. 8, 2010 -- Air travelers going through whole-body scanners don't need to worry about radiation from the devices, according to the American College of Radiology.

Two kinds of devices are being deployed:

• Millimeter wave technology uses low-level radio waves. Two radio antennas rotate around the body at high speed and generate a 3-D image on a remote monitor. The image looks like a fuzzy photo negative.
• Backscatter technology uses extremely weak X-rays used to create a two-sided image. The image looks like a chalk drawing.

The radiology group says a traveler would have to undergo more than a thousand scans in a year to equal one standard chest X-ray.

"The ACR is not aware of any evidence that either of the scanning technologies that the TSA is considering would present significant biological effects for passengers screened," the group says in a statement provided to WebMD.

The Transportation Safety Administration says that millimeter wave technology exposes a passenger to 10,000 times less radiation energy than a cell phone does.

The TSA says a backscatter X-ray scan gives a person as much radiation as he or she would get from two minutes of flying in an airplane at 30,000 feet.