[ RadSafe ] airport scanners at Heathrow

[McMahan, Kimberly L.]

Amen to your second paragraph.

Here is a link to the product literature for the system in question. The manufacturer claims the dose to the scanned individual is about 3 microrem (30 nSv). They say it is a backscatter device that detects Compton scatters. No incident or representative backscattered spectrum is given that I could find.
http://www.rapiscansystems.com/sec1000faqs.html

[An aside: Because of the very low x-ray energies involved, an individual needs to be scanned twice - front and back - in order to be completely screened. However, in the spirit of Rainer's second paragraph I submit that the dose to the person is not doubled with the second screening. This might be a good side thread for discussion.]

Page 29 of the following link discusses the backscatter technique but still does not give a spectrum.
http://www.ncjrs.gov/pdffiles1/nij/183260.pdf

The Mirror article could be taken as saying the dose to the passenger from a single screening is 1000 times the annual occupational dose of a security guard, since Terminal 4 handles international ("long haul") passengers. But in reading the "fact sheet" on the device where they highlight the in-flight dose to a passenger, I think you probably have the right comparison. 


Kim McMAHAN    ORNL External Dosimetry    865.576.1566

-----Original Message-----
From: radsafe-bounces at radlab.nl [mailto:radsafe-bounces at radlab.nl] On Behalf Of Rainer.Facius at dlr.de
Sent: Thursday, May 11, 2006 10:00 AM
To: trentino at iol.it; radsafe at radlab.nl
Subject: AW: [ RadSafe ] airport scanners at Heathrow

The Mirror article reproduces a statement of the Heathrow authorities to the effect that guards working 2000 hours (which is about the annual time at work) receive 1/1000 the radiation dose of long-haul passengers. Since passengers in contrast to flight crew are mentioned, this can be construed as representing the dose per individual long-haul flight. Such exposures rarely exceed 100 microSv. Taking this number at face value, the guards would receive an added annual occupational radiation dose of 100 nanoSv, the equivalent of residing about 7 minutes in Cornwall at 8 mSv/a. 

Of course, the comparison of the guards' exposure with that of long-haul passengers is radiobiological nonsense - to begin with. Atmospheric ionising radiation comprises a mixture of thoroughly penetrating radiation of all radiation qualities Q between 1 and 20 whereas the guards are exposed to very soft X-rays penetrating about a cm only. The dose to the foetus therefore is zero anyway. Thus it is even obsolete to speculate about a potentially huge relative biological effectiveness of such low energy photons (there is some reason to assume an enhanced RBE for photons used in mammography). Only if unheard of huge RBEs were combining with an enormous 'bystander-effect' an influence on the foetus is conceivable.

Rainer

Is anyone able to provide an energy spectrum typical for such a device?


Dr. Rainer Facius
German Aerospace Center
Institute of Aerospace Medicine
Linder Hoehe
51147 Koeln
GERMANY
Voice: +49 2203 601 3147 or 3150
FAX:   +49 2203 61970

-----Ursprüngliche Nachricht-----
Von: radsafe-bounces at radlab.nl [mailto:radsafe-bounces at radlab.nl] Im Auftrag von Mauro Campoleoni
Gesendet: Donnerstag, 11. Mai 2006 10:06
An: radsafe at radlab.nl
Betreff: [ RadSafe ] airport scanners at Heathrow

Dear colleagues,
I'd be curious to know whether anybody of you, expecially if working in Britain, is involved in the case of the suspected "baby losses" due to X-rays at Heathrow....
as I read in the Mirror:  
http://www.mirror.co.uk/news/tm_objectid=16984613&method=full&siteid=94762&headline=five-x-ray-scanner-guards-lose-babies--name_page.html

I'd like to exchange some info.

Thanks.

Mauro Campoleoni
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Unità Operativa di Fisica Sanitaria
Fondazione "Ospedale Maggiore Policlinico Mangiagalli e Regina Elena"
Via Pace, 9 20122 - Milano - ITALY
tel. 02-5503.3007
fax 02-5503.5100
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