February 2010

Straight Talk about Body Scanners
By John McNicol
Director of Business Development and Marketing
MMIC Solutions

Since the incident on Flight 253 on Christmas Day, much has been said about “Body Scanners.” A lot of what’s been said has been inaccurate and has led to much confusion.

“Body Scanner” actually covers three different technologies being deployed against bombers. Amid controversy over privacy, and concerns over radiation, the question is raised: Can body scanners do the job?

Most of the TV footage and published pictures show a technique in which the passenger is irradiated by X-rays which penetrate their clothes. The radiation that scatters back is processed, revealing objects carried on the body. This approach produces high quality images, but opens the door to public concern about privacy for travelers, especially children.

Despite the low levels of X-ray used, public concern about the safety of X-ray persists. This approach has operational disadvantages, too; scanning is too slow to screen every passenger and the high resolution images make automated detection hard – so effective detection still relies on operator vigilance.

Microwaves are non-ionizing radiation and so are arguably a “safer” solution. In another body scanner, microwaves are transmitted at the passenger, and the radar reflections are collected by an array of receivers scanned mechanically around the traveler. This makes scanning slow, like X-ray. Detection is by the strong reflections from edges rather than the objects themselves, which again makes automation difficult and also reveals anatomical detail. So privacy concerns remain.

Naturally occurring millimetre waves emitted by and reflected from the body also penetrate many fabrics, and can reveal objects without transmitting any radiation at all. The whole body can be imaged in real time, which is much more like walking through a metal detector archway. Lower quality images due to fewer and less sensitive detectors are the disadvantage of these passive systems. Ironically however, detecting the shape of the object by the difference in the material actually makes automatic threat detection easier. This has been operating reliably for years, eliminating mistakes due to fatigue and cutting operating costs dramatically.

Until recently, transportation authorities have been reluctant to invest heavily in body scanners to screen every airport passenger, partly due to the high costs of the equipment ($200,000 per unit) and the trained operators to perform manual screening. Also, the low passenger throughput of some systems is not viable in the front-line.
In a crescendo of criticism in the press, the right question to ask is not ‘would body scanners have caught the “underwear bomber?”’ However good they are, there will always be some way to defeat the scanners.

As the dust settles in Detroit, the right question the authorities are asking is, “is the price both in operator costs and inconvenience to passengers worth the level of safety the body scanners bring?”

MMIC SOLUTIONS
Email this article to a friend!