Body scanning

Last week's attempted airline terror attack by Nigerian Abdul Farouk Abdulmutallab has renewed discussion about controversial airport security measures like full-body or "nude" scanners. Some airports in the US, Amsterdam, Zurich and London have already begun using the scanners, which quickly generate images of anything hidden under a person's clothes - including his or her body.

Security personnel who use the scanners are able to discern many features of scanned individuals' bodies. But security experts and scanner manufacturers have sought to quell related privacy concerns in several ways.

Some scanners blur the head of each scanned individual or obscure the individual's genitals. Also, the scanning procedure can be arranged so that the machine operators do not see the images of the people they scan. In that case, the images produced can be analyzed by staff members in an isolated room elsewhere in the airport, who then notify workers at the terminals if a problem appears.

Germany's Federal Police Force handles security at the nation's airports and has taken another approach to privacy concerns.

"We have been experimenting with the scanners to see how effective it is to generate silhouettes rather than reproducing most features of an individual's body. In that case, security personnel would just be able to see an outline of the body as well as anything hidden on it," Joerg Kunzendorf, a spokesman for the German Federal Police, told Deutsche Welle.

The Federal Police Force in Germany has been working with a type of body scanner known as a millimeter wave scanner.

This operates by emitting millimeter waves, which are situated between radio waves and infrared waves on the spectral scale. Millimeter waves are able to render lightweight layers like clothing transparent while reflecting the human body and concealed explosives, weapons and other objects.

A transceiver collects the reflected signals and forwards them to a computer for processing. There, a 3-D image of the scanned individual is generated, according to a document released by the US Department of Energy.

Another type of body scanner known as a backscatter X-ray has also been developed by American Science and Engineering (AS&E) in the US.

The backscatter scanner works by emitting high energy rays that scatter upon coming into contact with materials rather than penetrating them like in a medical X-ray. The machine detects these scattered X-rays and is able to use them to render images of items that are low in atomic number. Product information on the AS&E website states that these low atomic materials include plastic weapons and explosives.

The backscatter system is also able to detect metal weapons or devices used to detonate bombs. Such materials do not produce a backscatter effect, and the scanner is able to recognize them by noting scanned regions where this effect does not occur.

gsw/AFP/dpa
Editor: Stuart Tiffen