Yes, that would make a lot of sense ... for a standard X ray device. Thing is, the TSA scanners are, well, scanners. They may not deliver a large total X ray dose (something that could be measured by a dosimetry badge), but the dose that they do deliver at any instant and spot is relatively intense and focused. The scanner is NOT the same as a standard Roentgen-type X-ray machine, so calculating radiation flux (which we do not know for these scanners) cannot be done just by knowing the air kerma (which we do know for these scanners) or by knowing the dosimetry badge readings (which we could get for the scanners in the manner you describe).
As a visual aid to the importance of radiation flux, you might want to look at this article (It describes the action of a laser rather than an X ray scanner, but the concept is the same):
http://nextbigfuture.com/2008/02/femtosecond-laser-can-change-any-metal.html
If you look at the pic of different colors of aluminum, note that years worth of normal light absorption does not make aluminum change color. Consider an aluminum beer can. The can may sit out in the sun for years, being hit with tens of watts worth of energy at a time, (depending on how bright the sun is), at wavelegnths from infrared to X-ray, and the aluminum generally will not undergo significant surface alterations (chemical alterations due to atmospheric interaction aside). That’s because, while the photonic energy delivered may be tens of watts, the intensity of that radiation is low (actually, in this case, it’s the same tens of watts).
The pics on the linked page, however, show the results of tens of MILIwatts (I think) of delivered light, delivered over the course of 1/2 hour. Total energy delivered by the laser is relatively small. The key is not the total amount of energy delivered; the key is the intensity with which those photons are delivered.
At most times and places during the femtosecond laser treatment described in the article, there is no laser light impinging on the aluminum disk. Approx 100,000 times per second, for a femtosecond at a time, however, a very intense (terrawat range) laser light impinges on the disk. The overall delivered power (the sort of thing that might be measured by a dosimeter) is low, but the point intensity (photon flux) is so high, when the laser is on, that the affected surface of the disk becomes a plasma, then re-cools (when the laser is off again) into a pitted, twisted set of shapes that, at the macro level, makes the surface of the disk appear to have changed color. Again: total energy delivered is low. Intensity is high. Result: visible changes in the physical properties of the aluminum disk being treated.
Intensity matters. Simple dosimeters can’t detect intensity. The TSA refuses to release figures relating to the intensity of the X-rays they deliver, and refuses to let anyone else measure that intensity.
This really is a simple concept, but I’m not so sure that I explained it well. If you don’t understand, please let me know, and I would be happy to try again.