Security procedures are being stepped up with the deployment of whole body scanners at the country's airports by the Transportation Security Administration (TSA) in the US. This is following the foiled attempt by a Nigerian to blow up an airline on Christmas Day.
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 2,500 backscatter scans per year to reach what they classify as a Negligible Individual Dose. The American College of Radiology (ACR) agrees with this conclusion.
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.