[ RadSafe ] Airport Body Scanners

[Cheng Kit-man]

While the effective dose is "almost" negligible (<0.1microsievert per scan)
from backscattered x-ray scanner and probably "nil" from T-ray scanners,
scanning should be performed on suspected subjects only as an alternative to
"strip search" and be based on reasonable assessment of the possibility of
averting an offence to the law.  If scanning is required, reasonable efforts
should be taken to protect the rights and dignity of the subjects.  Scanning
must NOT be adopted as a standard security procedure on each and every
passenger going through the airport security or on arbitrarily selected
subjects.

Clement Cheng
Radiation Health Unit
Hong Kong SAR, China

-----Original Message-----
From: radsafe-bounces at agni.phys.iit.edu
[mailto:radsafe-bounces at agni.phys.iit.edu] On Behalf Of Doug Huffman
Sent: Monday, March 08, 2010 2:58 AM
To: radsafe at agni.phys.iit.edu
Subject: Re: [ RadSafe ] Airport Body Scanners


That is correct, millimeter wavelength, also known as "terahertz 
radiation" and "T-rays", and backscatter X-ray are used.

The dose from a backscatter X-ray airport body scan is estimated by the 
Health Physics Society at 0.005 milliREM (0.05 microSievert) and 0.009 
milliREM (0.09 microSievert) by the manufacturer of one such device, 
American Science and Engineering.  1 milliREM is considered a negligible 
dose equal to two hundred such Health Physics Society scans.

Millimeter waves are reflected off clothing according to some sources. 
In any case, the energy of such a photon is insufficient to break a 
chemical bond or ionize an atom.

Unfortunately this is received knowledge from public sources and no more 
believable to the doubter than the empirical knowledge from which it is 
derived.

On 3/7/2010 10:36, Ed Hiserodt wrote:
>> "Regarding the virtual strip-search machines that will be appearing 
>> at
> airports across the country, how much radiation do they actually 
> release and how does this compare to the radiation we are normally 
> exposed to anyway? How dangerous are these machines, if at all, for 
> someone who does a lot of flying?  I understand that there are two 
> technologies the TSA uses to peer through clothing:
>
> "One uses millimeter waves - does this involve any radiation; is it 
> completely safe?  > "The other is the backscatter X-ray."
>
> For information on how to subscribe or unsubscribe and other settings 
> visit: http://health.phys.iit.edu
>

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