The "underpants bomber" has renewed calls for new and more invasive security measures. Already, there's a push to install scanners that show travelers' naked bodies through clothing, using either millimeter wave or backscatter X-ray imaging. But even those scanners might not have caught the terrorist who nearly brought down Northwest flight 253.

That's why one company is trumpeting a sensor that can supposedly "detect substances such as explosive materials ... hidden inside or outside of the human body." First step: Actually build a human-sized machine.

There has already been one report of a suicide bomber carrying explosives internally. Many sources, including the BBC, carried an early report suggesting that Abdullah Hassan Al Aseeri adopted the new tactic of "carrying explosives in his anal cavity" for an attack in September. The target, a Saudi prince, survived, but Aseeri was reportedly blown in half by the blast. Later reports suggest the explosives were actually sewn into his underwear, but security experts believe there is a real danger of "internally carried" bombs, a technique used for years by drug smugglers.

Nesch, a company based in Crown Point, Indiana, may have a solution. It's called diffraction-enhanced X-ray imaging or DEXI, which employs proprietary diffraction enhanced imaging and multiple image radiography (.pdf).

Rather than simply shining X-rays through the subject and looking at the amount that passes through (like a conventional X-ray machine), DEXI analyzes the X-rays that are scattered or refracted by soft tissue or other low-density material. Conventional X-rays show little more than the skeleton, but the new technique can reveal far more, which makes it useful for both medical and security applications.

"Our patented technology can detect substances such as explosive materials, narcotics, and low-density plastics hidden inside or outside of the human body," company CEO Ivan Nesch claims. DEXI allows explosives to create contrast, he adds, so it would be able to detect both the underpants bomber and the shoe bomber before they boarded.

The image above shows how a conventional radiograph does not detect two packets of "illegal materials" concealed in soft tissue, while they are plainly visible in when DEXI technology is used.

The process of taking the images, analyzing them, and then recognizing substances of interest – such as explosives – can be automated. Alerts issued can be computer-generated. Security staff would simply have to get passengers in and out of the imaging unit.

"The initial expected throughput is approximately one to two passengers a minute," according to Nesch. "Once installed and tested in real applications, the throughput will be increased."

Nesch has already demonstrated the technology with a unit originally designed for imaging small animals. The next stage is a human-sized unit, which is being "finalized for extensive testing." Nesch plans to start taking orders for the new unitin March this year.

Of course, X-ray scanners always bring up a concern over the level of radiation involved. One of Nesch's corporate slogans is "Less radiation, more information," as DEXI uses significantly less radiation than other approaches.

"It is far less than what a passenger would receive simply by flying on an airplane across the United States," says Nesch. "Passengers who are imaged using DEXI security will be exposed to approximately 50 times less radiation than that of a conventional radiograph. "

There is likely to be a ready market for the new technology. Although an X-ray might be seen as more intrusive than an image of the outside of your body, it may be less controversial. In Britain, plans for "naked body" scanners may run into trouble because they break British child pornography laws: Creating "indecent" images of children is illegal. Those scans may also offend the modesty of some Muslims.

DEXI may be able to see into your body cavities, but it may be less obnoxious than some of the alternatives.

Photo: Nesch LLC

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