For the next two to three months, passengers randomly selected for additional screening at Phoenix's Sky Harbor International Airport will have the option of a typical pat down by security personnel or a one-minute, full body scan from a new type of x-ray machine that allows screeners to see through clothes. The federal government is testing so-called backscatter x-ray machines there, which can detect potentially threatening objects under a person's clothes by picking up x-rays scattered by materials. (Traditional x-ray machines pick up signals that pass through or are absorbed.)

"It's using edge detection to detect anomalies," says Joe Reiss, vice president of marketing at American Science and Engineering (AS&E), the Boston-based manufacturer of the SmartCheck machine. "If you are a suicide bomber and have a vest on, that would appear as clear as day in an image."

But critics charge the system is an invasion of privacy. "You should not have to go naked to board an aircraft," says Barry Steinhardt of the American Civil Liberties Union. If full backscatter images were used, screeners would see every detail of each individual scanned. AS&E, however, has built an algorithim into its machine that matches individuals to a general outline of the male or female form. "It looks like the chalk outline of a body rather than the x-ray image of a body," says Amy Kudwa, a spokesperson for the federal Transportation Security Administration (TSA), which is conducting the trial. "It is a nonintrusive technology; it does not require a pat down."

The downside is that by removing some of the potentially salacious detail, the developers may have diminished the device's effectiveness in detecting threats, according to Steinhardt. "The more explicit the image, the better the technology is for actually detecting weapons," he says. "The more obscured the image, the less realistic the image, the less likelihood it is going to detect contraband." In other words, he says: "You can have what amounts to a virtual strip search that may have some minor security benefit. Or you can have the illusion of security which will not detect the contraband."

The machine, however, has passed all tests set for it thus far, Reiss says. "The exact threats are classified. It has been evaluated for detecting certain threats by our engineers and TSA's and it has performed well."

Full-detail backscatter systems are already in use in the U.K., where objections focus less on nude images and more on background checks, which is a common practice in the U.S. for registered traveler programs. Michael Jenkins, a senior advisor at the RAND Corporation and a former member of the White House Commission on Aviation Safety and Security argues that security can be improved by randomly applying better detection measures. "One of the factors you have to look at is ease of circumvention," he says. "You have to look for a net security benefit."

Areas where such net security benefits could be easily gained, he says, include better screening of cargo, baggage and personal items (where backscatter is already employed to enhance regular x-ray screening at locations like the White House); securing airport perimeters; and broadening antiterrorism measures to other forms of transportation. But, he adds: "If we can keep terrorist saboteurs off commercial aviation, that is a net security benefit."

Other competing technologies include millimeter wave scanning that uses wavelengths of the electromagnetic spectrum between infrared and x-rays. By bouncing such waves off human beings, similar images can be created without as much detail as backscatter x-ray images and much more quickly. QinetiQ, L3 Communications and GE Security are all working on such systems, some of which are already being used at London Heathrow Airport and elsewhere to scan large crowds without the need for exclusive screening.

"The challenge is finding that balance between increased probability of finding that threat, increased efficiency for TSA and those operating airports, and privacy and ease of use of the passenger," says Joe Krisciunas, business program manager of security technologies at GE Global Research. "We are working on technologies with the goal of getting passengers through the checkpoint in 20 seconds."

7 Comments

1. 1. christy21 08:33 PM 4/18/08

   They should at least have only women screen women, and males screen other men. If they don't, then men will be screening way more women then men. I'm not comfortable with that. I don't want some creep male airlines employee looking at essentially my naked body. Bad enough they leer when we have to take off our shoes and sweaters already. Plus, I'm not happy about being irridated.

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2. 2. Prudence 04:15 PM 10/19/09

   Perhaps a cheaper option for the budget airlines could be to get everyone to strip off and walk through naked. In fact all the staff could be naked too, avoiding embarrassment to passengers. We could then be made to use the toilet publicly to prove we're not concealing anything inside us and to be doubly sure, some of us could get x-rayed! (for this you'd pay extra!) Ok, so this is a bit ridiculous and I agree security is important, but so is my personal privacy and space. I reserve the right to choose who sees me naked and any x-rays I require will be for medical purposes only.

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3. 3. hotblack 02:57 AM 12/1/09

   Maybe some of us will just take the friggin train and skip the nude search. I swear if I have to go through one of these, I'm going to think about whatever I have to to get a rippin erection and grin like a maniac at the operator. If someone's gonna be uncomfortable, it sure isn't going to be me.
   
   Christy, don't assume just because you're a woman everybody wants you. Most of us don't like most women, and many of us don't like women at all. Contrary to what women are told since birth, not everyone finds you sexually appealing.

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4. 4. jack.123 09:46 PM 12/31/09

   Who are going to get to scan 300 LB fat people without getting sick?

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5. 5. jack.123 09:52 PM 12/31/09

   Who are we going to get to look at 300 LB fat people without getting sick?Maybe the producers of biggest losers.

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6. 6. ennui 11:07 PM 11/22/10

   We can add a device that gives a short neutron pulse.
   If any explosives are incorporated in clothing, they will blow up, taking the would-be terrorist to his reward.
   Of course it would entail a bomb-proof passage to save the inspectors.

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7. 7. rockyflatsgear 03:15 AM 2/21/11

   The AS&E system uses 125KV x-rays like that of a medical CT-scanner, VERY penetrating. A small % bounce off your skin about 90% is absorbed by your body. The Rapiscan backscatter system uses 60KV x-rays most are absorbed by the skin and will increase your chance for skin cancer. Young children, expecting mothers and people with certain genetic conditions should avoid un-medically necessary x-rays. Jeff Rocky Flats Gear USA mfg of radiation protective undergarments.
   
   Breast Cancer Gene
   http://ghr.nlm.nih.gov/gene/BRCA1
   To read up on how the system works here is a patent link:
   www.freepatentsonline.com/5313511.html
   

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