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:
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???