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I am a little freaked out because when I was traveling over Christmas I noticed that a carry-on baggage scanner had a really long shielding tunnel. The shielding is metal plates that are placed along the conveyor and looks like this:

enter image description here

I never really thought about it before, but different machines have different amounts of shield. Some of none, some have a foot or so, and the machines I just saw had like 3 feet of shielding. One thing to note is that the shields usually have holes and the x-rays will go right through those holes.

Since in many cases you have to stand right next to the machine to make sure your bag is getting fed into the machine right, it is concern, especially since your nuts are right at beam height.

According to the FAA slash "Department of Health and Human Services" there is nothing to be concerned about:

Q5: Is it safe to stand or walk near a cabinet x-ray system while it is producing x-rays?

A5: Yes. Manufacturers are required to certify that their products meet the Federal radiation safety performance standard for cabinet x-ray systems. Specifically, the standard requires that the radiation emitted from a cabinet x-ray system not exceed an exposure of 0.5 milliroentgens in one hour at any point five centimeters from the external surface. Most cabinet x-ray systems emit less than this limit. In addition, the standard also requires safety features that include warning lights, warning labels, and interlocks.

For comparison, the average person in the United States receives a dose of about 360 millirem of radiation per year from background radiation. (Note: 1 milliroentgen of exposure to x-rays will result in approximately 1 millirem of dose. These terms are defined later in this document.) Background radiation is radiation that is always present in the environment. Eighty percent of that exposure comes from natural sources: radon gas, the human body, outer space, rocks, and soil. The remaining 20 percent comes from man-made radiation sources, primarily medical x rays.

Hmm, ok, so if this is true, why are they putting 3-freakin-feet of shielding at the entrances of the machine???

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  • 6
    I think those are more to keep passengers from prematurely fetching their belongings from the ramp rather than as shielding. When I passed through security at Boston Logan earlier this month, they were clear plastic so you could observe your belongings exiting the machine and (potentially) being routed for extra screening.
    – Roddy of the Frozen Peas
    Commented Dec 29, 2016 at 22:28
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    Why the inverted commas around "Department of Health and Human Services"? Do you not believe that this is the true name of the Department?
    – David Richerby
    Commented Dec 30, 2016 at 0:08
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    They are probably also there to make it harder for people to stick their hands inside the machine (where they really shouldn't go) to rearrange things on the tray, add whatever they left in their pocket, grab their stuff, grab someone else's stuff, etc.
    – djr
    Commented Dec 30, 2016 at 0:12
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    There are people who work next to the machine regularly. Think of them as a canary in the coalmine: if there was anything for an occasional traveller to worry about from a correctly functioning machine, the staff death rate would be through the roof.
    – djr
    Commented Dec 30, 2016 at 0:17
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    @LemuelGulliver The DHHS also has no vested interest in zapping your nads. Can't you just reform your tin-foil hat into a jock strap?
    – David Richerby
    Commented Dec 30, 2016 at 0:36

1 Answer 1

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The ones at the start of the machine are there as guides, to make sure bags are on the conveyor belt and not rubbing against the surfaces inside. The ones at the exit are to keep impatient travelers from reaching into the machine to grab their bags (because then they would get slight exposure to radiation).

The machines themselves emit very little radiation, as that could be a occupation health issue otherwise since there are TSA agents stationed right by the mouth and exit of the machine.

Source of info: just asked a buddy who works at the local airport.

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  • I've always figured the other purpose of the cage at the end is so that if anything suspicious is detected, the agents can take it out for further inspection (through an opening in the side) long before the traveler can grab it themselves.
    – Nate Eldredge
    Commented Dec 30, 2016 at 6:16
  • @pnuts: I don't understand.
    – Nate Eldredge
    Commented Jan 1, 2017 at 18:58
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    @pnuts: Suppose a criminal who is unfamiliar with the capabilities of X-ray scanners, or has a piece of contraband that they are not sure whether or not will be detected. If they do put it in the machine, and the machine does detect it, surely the agents want the opportunity to confiscate it before the criminal (who has just passed through the body scanner) can grab it and run away into the airside area.
    – Nate Eldredge
    Commented Jan 1, 2017 at 19:08

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