By the time the X-ray beam goes through the plastic wall between the source and the person being scanned, the X-rays with energies low enough to have significant photo-electric interactions with the primary elements of skin, namely H, C, N & O will have been attenuated. That leaves Rayleigh or Compton scattering for the primary interaction. Keep in mind that the cross-section for 180 degree Compton scattering is fairly constant to close to 50 keV, requiring Z's to be in the mid-20's for significant photo-electric absorption (and this is something that I found out from an astrophysics text book - most physicists, radiologists or oncologists don't seem to care about differential cross-section for Compton scattering).
There have been anecdotes about breasts reconstructed after a mastectomy showing up on backscatter as the silicone fluid attenuates the back scattered photons more than normal tissue.
You apparently don't know the difference between radiation flux and radiation dose. Dose, by definition, takes into account the interaction (or lack thereof) with matter, where a lower interaction rate for a given flux will result in a lower dose. In addition, the dose units "REM" and "Sieverts" also take into account the different biological effects of different radiation - a given energy deposition in tissue from neutrons will have a higher dose than a given energy deposition from gamma rays.
You're also a bit off base about the depth of interaction from the X-rays used in backscatter - after going through a couple of mm of plastic on the backscatter system and through clothing, all of the really low energy X-rays are already attenuated before they reach the skin. The "interaction depth" is not so much from a lack of penetration from the incident X-rays as it is the higher attenuation of the backscattered photons.
Finally, a significant portion of the dose while flying is delivered by muons induced by cosmic rays. While they do have a very long range in matter, they do interact with matter.
I saw the Lost in Space pilot a month ago and all of the news photographers covering the launch at Alpha Control were using Speed Graphics (this was supposed to be October 1997). Then again, the President didn't look at all like Bill Clinton.
I've also had quite a bit of experience shooting with a Polaroid model 360, which was a bit like using a scaled down Speed Graphic.
I have a 4 by 5 Calumet stashed in my collection - been a long time since it has been used. It might be fun getting a digital back for the beast.
A long time friend had a C220 for a while along with a collection of lenses. My only experience with a TLR was my parents Argus.
I was visiting a computer store owned by a friend. A man walked in who looked homeless. He wore clothes that everyone else I knew would have thrown away. This was in California before Reagan, before there were a lot of homeless people.
Reagan was the Governor from early 1967 to early 1975, and I doubt that Electric Pencil even came out before 1975. My guess the scene you described happened in Jerry "Moonbeam" Brown's first year of office.
Jerry Pournelle's first though when seeing Electric Pencil for the first time was that he would never have to retype another page again. The breakthrough with Electric Pencil was that it would run on "low cost" hardware, the magnetic tape typewriter provided similar functionality in the 1960's for about 10k$, or about the same as the base price for a Cessna 172.
I agree on including SPICE in this mix, in adition to giving us a powerful circuit simulator it also gave us the Berkeley license.
It would have been nice for Aatish to go a bit into what Purcell and Pound did in their 1951 experiment, namely "inverting" the orientation of the fluorine nuclei in the presence of an applied magnetic field by application of a radio frequency magnetic pulse, where the frequency is the Larmor frequency of fluorine and the pulse amplitude and length was sufficient to cause a 180 degree nutation. The result is that the nuclei have the same order (entropy) as the rest state, but have higher energy. In NMR, this is referred to as applying a 180 degree or pi pulse.
Aatish's comment about reality being liberal is unconvincing.