More on: X-Ray Vision Is Here

["Robert M. Loesch" <loesch@spok.eh.doe.gov>]

At 03:21 PM 4/8/97 -0500, you wrote:
>I find this somewhat amazing (incredible?).
>3 microrem at 40 keV (a guess) represents about 3 E+4 photons per sq.cm.
>Assuming the body is 20 cm thick this given an attenuation of E-3,
>resulting in 30 photons/sq.cm to image with (assuming the weapon removes
>the rest). At 100 keV one would have 1000 photons/cm2, but with less
>differential contrast and a poorer detection efficiency.
>And this has to be put on top of a background of some sort in an active
>detector. And a real xray spectrum would add dose without adding image
>photons.
>
>Is the imaging technology that good?
>I know the light-stimulated luminescent phosphor film (Fuiji plates, etc)
>are, but that is a rather large system.
>
>It will be interesting to see just how exaggerated the dose claims are. -- 
>the above are the personal musing of the author,
>and do not represent any past, current, or future
>position of NIST, the U.S. Government, or anyone else
>who might think that they are in a position of authority.
>NBSR Health Physics
>NIST
>Gaithersburg, MD 20899
>301 975-5810
>-----------------------------------------------------------
>Lester.Slaback@nist.gov
>-----------------------------------------------------------
>
>

According to the manufacturer's home page, the Secure 1000 uses:

"A narrow, low energy x-ray beam ... scanned over the body surface.
The reflection or backscatter of the beam is detected, digitized
and computer stored. The data is then enhanced, using state-of-the-art
imaging techniques to create a display of the person and any concealed
objects."

It appears that the unit uses a different approach to x-ray imaging
than most of us are accustomed to.  I haven't run across this method
before so I can't really comment other than - interesting .......


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      _/_/        _/_/      _/_/_/_/   Robert M. Loesch
     _/  _/    _/   _/     _/         US Department of Energy
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   _/	  _/ _/       _/  _/_/_/_/   19901 Germantown Road	
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_/_/_/       _/_/     _/_/_/_/   loesch@spok.eh.doe.gov
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 "The definition of a public health disaster is a catastrophe so large
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