In case you were wondering whether pornoscanners are harder on the vast majority of innocent, non-terrorist fliers, or the minuscule minority of terrorists, wonder no more. From Leon Kaufman and Joseph W. Carlson’s “An evaluation of airport x-ray backscatter units based on image characteristics,” published in the Journal of Transportation Security:
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.
High explosives and wires, along with razor blades can be hidden if they are thin enough and have thin edges against the skin. I would be willing to bet that Hollywood makeup artisans who create all sorts of facial and body appliances made to look real would have the knowledge to accomplish fairly easy demonstrations. Perhaps a Mythbusters episode, since both of the hosts have some experience with these sorts of artistic deceptions.
I’d love it if Mythbusters showed that these machines did absolutely nothing to make us safer.