(Originally Posted January 2010) - Amid concerns regarding terrorists targeting airliners using weapons less detectable by traditional means, the Transportation Security Administration (TSA) is ramping up deployment of whole body scanners at security checkpoints in U.S. airports. These systems produce anatomically accurate images of the body and can detect objects and substances concealed by clothing.

To date, TSA has deployed two types of scanning systems:

Millimeter wave technology uses low-level radio waves in the millimeter wave spectrum. Two rotating antennae cover the passenger from head to toe with low-level RF energy.

Backscatter technology uses extremely weak X-rays delivering less than 10 microRem of radiation per scan ─ the radiation equivalent one receives inside an aircraft flying for two minutes at 30,000 feet.

An airline passenger flying cross-country is exposed to more radiation from the flight than from screening by one of these devices. The National Council on Radiation Protection and Measurement (NCRP) has reported that a traveler would need to experience 100 backscatter scans per year to reach what they classify as a Negligible Individual Dose. The American College of Radiology (ACR) agrees with this conclusion. By these measurements, a traveler would require more than 1,000 such scans in a year to reach the effective dose equal to 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 ACR encourages those interested in learning more regarding radiation associated with imaging and radiation oncology procedures as well as radiation naturally occurring in the Earth’s atmosphere to visit www.radiologyinfo.org.