Letter to Dr. John P. Holden, Assistant to the President (Sci/Tech) about backscatter machines.

[KansDem]

--excerpt--

The Red Flags

The physics of these X-rays is very telling: the X-rays are Compton-Scattering off outer
molecule bonding electrons and thus inelastic (likely breaking bonds).

Unlike other scanners, these new devices operate at relatively low beam energies
(28keV). The majority of their energy is delivered to the skin and the underlying
tissue. Thus, while the dose would be safe if it were distributed throughout the volume
of the entire body, the dose to the skin may be dangerously high.

The X-ray dose from these devices has often been compared in the media to the cosmic
ray exposure inherent to airplane travel or that of a chest X-ray. However, this
comparison is very misleading: both the air travel cosmic ray exposure and chest Xrays
have much higher X-ray energies and the health consequences are appropriately
understood in terms of the whole body volume dose. In contrast, these new airport
scanners are largely depositing their energy into the skin and immediately adjacent
tissue, and since this is such a small fraction of body weight/vol, possibly by one to two
orders of magnitude, the real dose to the skin is now high.

In addition, it appears that real independent safety data do not exist. A search,
ultimately finding top FDA radiation physics staff, suggests that the relevant radiation
quantity, the Flux
has not been characterized. Instead an indirect test (Air Kerma) was made that
emphasized the whole body exposure value, and thus it appears that the danger is low
when compared to cosmic rays during airplane travel and a chest X-ray dose.

In summary, if the key data (flux-integrated photons per unit values) were available, it
would be straightforward to accurately model the dose being deposited in the skin and
adjacent tissues using available computer codes, which would resolve the potential
concerns over radiation damage.

--more--
NPR

Also, this paragraph:
After review of the available data we have already obtained, we suggest that additional
critical information be obtained, with the goal to minimize the potential health risks of
total body scanning. One can study the relevant X-ray dose effects with modern
molecular tools. Once a small team of appropriate experts is assembled, an
experimental plan can be designed and implemented with the objective of obtaining
information relevant to our concerns expressed above, with attention paid to completing
the information gathering and formulating recommendations in a timely fashion.

Was this team assembled, and what was the outcome?

[mahina]

1. He was my prof

but he wouldn't know me if I bit him, which I can't see doing anyway.

Not that it's relevant.

[damntexdem]

2. Another reason to fly as little as possible.

Or not at all, if possible.

[nc4bo]

3. I'm curious as to the added risk to people who are suspectible to skin cancer

or are being treated for skin cancer.

[KansDem]

4. Good question...

...since it appears that the skin receives high exposure...

[Delphinus]

5. Hope this

gets more exposure.