The TSA’s New Scanners Can’t See Your Pancake Shaped Bomb

A report in the Journal of Transportation Security looks the efficacy of the TSA’s new backscatter scanners. Turns out the machines can see your naked body. But they might not be able to see your box cutter—or your gun, depending on how you went about hiding it. And if you decided to tape a pancake-shaped container of the high explosive PETN to your gut, the backscatter machine might make it appear as if the bomb was nothing more than your holiday weight gain:

The penetration not only distributes exposure throughout the body (this affecting the calculation of effective dose, which comprises a sum over all organs), but tends to diffuse the effects caused by contraband materials. Images can be made at low entrance exposures, but of very poor spatial resolution and S/N. The calculated signal excursions at high kilovoltage are so small as to make it doubtful that at any reasonable exposure levels density differences will be noticeable unless the contraband is packed thickly and with hard edges. Although the excursions are larger at low kilovoltage, they are still small and in the noise of the device's operational limits. The eye is a good signal averager at certain spatial frequencies, but it is doubtful that an operator can be trained to detect these differences unless the material is hard-edged, not too large and regular- shaped. Anatomic features and benign objects add structured noise that interferes with signal averaging. Figure 18 shows a widely-distributed backscatter image. On the left is a complete view of her torso, on the right, a section has been blacked out. While the breasts are easily recognized at right, without some prior knowledge of the subject, it would be hard to distinguish the increase of intensity in the superior part of her breasts from the natural gradients of the image.

It is very likely that a large (15-20 cm in diameter), irregularly-shaped, cm-thick pancake with beveled edges, taped to the abdomen, would be invisible to this technology, ironically, because of its large volume, since it is easily confused with normal anatomy. Thus, a third of a kilo of PETN, easily picked up in a competent pat down, would be missed by backscatter "high technology". Forty grams of PETN, a purportedly dangerous amount, would fit in a 1.25 mm-thick pancake of the dimensions simulated here and be virtually invisible. Packed in a compact mode, say, a 1 cm×4 cm×5 cm brick, it would be detected.

The images are very sensitive to the presence of large pieces of high Z material, e. g., iron, but unless the spatial resolution is good, thin wires will be missed because of partial volume effects. It is also easy to see that an object such as a wire or a box- cutter blade, taped to the side of the body, or even a small gun in the same location, will be invisible.

Link via Daily Caller and Boing Boing.

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  • ||

    Just wait 'til some mujahedeen wizard forms a chunk of plastic explosive into an enormous anatomically correct appendage and tapes it to his thigh.

    "Excuse me sir, I'm going to have to examine your penis to see if it's real."

  • Ragin Cajun||

    "Excuse me sir, I'm going to have to examine your penis to see if it's real."

    Chuck Schumer is fine with it as long as he doesn't undergo the same scrutiny.

  • Bucky||

    welcome to IHOP! can i take your order?

  • Tim||

    The machines are there to make us feel safer, not make us safer.

  • Thom||

    The machines are there to make us compliant, not make us safer.

  • Suki||

    The machines are there for columnists to write about.

  • Tim||

    One day the machines will write about us.

  • Quiet Desperation||

    In the past tense.

  • Fist of Etiquette||

    If you're reading this, you are The Resistance.

  • ||

    The machines are there because Congress loves giving defense contractors our money.

  • Neu Mejican||

    And a suicide bomber blowing up in a crowded airport security line would be just as effective as blowing up on the plane...I am not sure I see the point of these kinds of articles.

  • ||

    Then don't read them. And don't bother coming here to share your opinions on them either, ok?

  • Neu Mejican||

    But Tulpa,
    I do see the point in commenting on them. If you don't like my comments, then don't read them and don't bother sharing your opinions on them either...mmmkay?

  • Matrix||

    Unless you intend to use the plane as a missile to hit buildings

  • Old Mexican||

    Re: Neu Mejican,

    I am not sure I see the point of these kinds of articles.

    Well, they certainly are not going to be quoted in the machine's sales brochure...

    "As mentioned on Journal of Transportation Security!"

    Other than that, these reports do point out the utter futility of government-run programs. I find THAT useful.

  • ||

    I am not sure I see the point of these kinds of articles.

    It could have something to do with the pointless expenditure of vast sums of money on utterly ineffective "terror interdiction" technologies.

  • Inquiring Minds||

    Not to mention the creeping loss of ability to travel, the diminishing right to bodily privacy, and the increasing arrogance of the powerseekers, both 'left' and 'right' who keep saying 'if you have nothing to hide, what are you worried about?'

  • Tim||

    What's to stop a terrorist from walking into the airport with an AK-47 and opening fire on all those unarmed TSA agents and civillians?

  • Matrix||

    AK-47s are illegal to own by most people unless they have a Class III license. Because of that, no one without a Class III license owns them or any other automatic rifles.

  • T||

    Wait, I thought we were selling all those AKs to the Mexican drug cartels.

  • Almanian||

    Fortunately for the cartels, they possess a Class III license.

    Blast....

  • Fatty Bolger||

    Also, many airports are gun free zones, so they are obviously in the clear.

  • Agent Pervy||

    While the breasts are easily recognized at right, without some prior knowledge of the subject, it would be hard to distinguish the increase of intensity in the superior part of her breasts from the natural gradients of the image.

    Only one way to solve that problem... (*slurp*)

  • Inquiring Minds||

    Posted again with correct contact info--just in case anyone cares... :-)

  • Suki||

    If you decide to take the train, don't forget to unload before you "climb aboard." AMTRAK has new rules for riding with guns.

  • Tim||

    These X-rays are low voltage but it appears one can dial it up to get a better image. I predict attractive women are going to get dosed heavily so that TSA can get a good look at those "superior breast surfaces"...

  • Brett L||

    Surely the "Save the ta-tas" campaign has filed a complaint.

  • Thom||

    In a couple of decades when doctors are asking questions to assess your risk of cancer, they're going to need to see a headshot.

  • ||

    It's getting harder and harder to believe that the government is fighting terrorists; easier and easier to believe that the government is employing them.

    After all, every incident--however ludicrous and piddly--results in increased government power. I mean, what's the excuse for the porno-scanners and the groping? One fucking guy, who sets his own balls on fire. One fucking guy who by the way had been delivered to the government on a silver platter which they studiously ignored.

    Cui bono?

  • CatoTheElder||

    With every passing year I become more cynical about the USG, and look back with some amazement at my earlier naivete. Still, I am relucant to believe that the USG employs terrorists for the purpose of terrorizing Americans. But I'm getting there ... maybe next year.

  • cynical||

    Don't they openly admit to it? I mean, they "catch terrorists", by fabricating terrorist plots and luring impressionable Muslim dumbshits into participating. But the end result is essentially the same, plus they don't have to pay their terrorists anything or actually get anyone killed.

  • IceTrey||

    And 40 grams of PETN shoved up your ass would be undetectable by this high technology or pat down

  • John Pistole||

    We know.

  • jasno||

    Can they detect it via gait-recognition? Just look for the people who walk like they have stick shoved up their ass? Is that why congress gets a free pass through security?

  • ||

    "And if you decided to tape a pancake-shaped container of the high explosive PETN to your gut, the backscatter machine might make it appear as if the bomb was nothing more than your holiday weight gain"

    Obviously, the whole sham is a ruse by the pancake smuggling cartel to get people so worried about terrorists bombs that they completely lose site of the cheap foreign pancakes being smuggled between fat women's buttocks into this country.

  • Almanian||

    I suddenly have the urge to never eat pancakes again.

  • jasno||

    such as a wire or a box- cutter blade

    box-cutter blade? WTF? Is this article from December 2001?

  • IceTrey||

    Not to mention the 9/11 hijackers used bomb threats not box cutters to take over the planes.

  • Mr Lizard||

    Man I suck at making pancakes, otherwise I'm a breakfast God.

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