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Thanks for working with me here.

Regarding my analogies: OK, no analogy is perfect, so please let me try again to explain the analogies. The analogy with the ants was intentionally written about a group of ants, rather than one ant, to make visualization easier. So, let me add some details, so that the visualization is even more clear. The group of ants are in fixed positions, carapace-to-carapace, over, say, a 10 cm diameter circle. Some steady-handed grad student has carefully glued them in place one by one. The group of ants is then put in the sun for, say, 15 minutes. The total amount of sunlight falling on the ants is spread out over all the ants. The ants are radiated by the sun. The ants live.

A 10 cm diameter magnifying glass is then put over the 10 cm circle on which the ants have been placed. The total amount of sunlight falling on the entire group of ants is the same. Now, however, the light falling on the ants is not simply radiating them, but arranged in a scanning apparatus. The ant at the focal point of the magnifying glass is burned to death. The whole apparatus is adjusted to scan the next ant, and the next, and the next, for the next 15 minutes.

At the end of that 15 minutes, exactly the same amount of light hit the whole group of ants when the magnifying glass was in place, as during the 15 minutes the glass was not in place. The difference is that, during the 15 minutes the glass was in place, the ants all died. There is NO INCREASE in the total amount of energy delivered to the entire group of ants, just in the intermittent intensity of that energy. That change in intermittent intensity, however, was enough to make a significant difference to those ants. That, I hope, illustrates the potential differences between “normal” irradiation and scanning.

As for your statement “The scanner, were it as intense in delivering gamma radiation as a standard radiographic exam, would show the dense material in the body, ie the bony skeleton on the image collector” : I don’t think that’s so.

As background, please let me state that I think that your meaning of the word “intense” in your post suggests that the Rapiscan X-rays are the same wavelength as medical diagnostic X-rays, just using a smaller number of photons.

In contrast, the general assessment about the Rapiscan devices is that they do, instead, use lower-frequency, longer wavelength, X-rays, closer to the range of “soft” X-rays than to the “hard” X-rays used in medical imaging. That would explain why the X-rays are detected via scattering rather than via transmittance. The actual characteristics of the Rapiscan device are not public, so people are just guessing about the X-ray wavelengths being used. That said, many people believe that the X-rays from the Rapiscan device would NOT generate transmittance images if only it delivered as many photons as a standard medical X-Ray device. It’s not just the number of photons that is different than a medical X-ray device, but also (many believe) that there is a different set of wavelengths used.

I regret having to use the words “many believe” and “general assessment.” Someone knows exactly what are the wavelength characteristics of the Rapiscan devices ... but that information has not been made public.

Characterizing scanned, “soft” X-rays based on their air kerma, then trying to predict medical effects of those X-rays by using observations of the effects of non-scanned, “hard” X-rays with the same air kerma, is simply not valid with the current state of knowledge at this time. I have a feeling that, over the next few years, we may see an explosion of new knowledge regarding the effects of these scanned soft X-rays on human subjects, but that knowledge does not exist just yet.