[ RadSafe ] NBC News story on airport scanner (25 mrem dose)

[Hansen, Richard]

Sandy,

I agree. The news article should have used a reasonable example. They
could have used an example similar to the ones the airports with
scanners would be required to post. The ANSI/HPS N43.17-2002 standard
requires: [Quote] An example shall be provided to compare the dose to a
commonly known source of radiation, such as "The radiation from one scan
is equivalent to approximately 20 minutes of exposure to naturally
occurring background radiation" [end quote].

When talking about very small doses, I like to compare the dose to the
time on an airline flight that gives an equivalent dose. Especially if
you are talking about a dose received as part of an airline trip. If you
compare the maximum dose a passenger would get from a security scan
(0.10 microsievert, 10 microrem) to the length of time it would take for
that passenger to receive the same dose on the airline flight. Using the
FAA Civil Aeromedical Institute Federal Aviation Administration CARI
program (http://jag.cami.jccbi.gov./cariprofile.asp), I made a rough
estimate earlier this month for a flight from Los Angeles to New York
City. Each passenger would receive a dose of about 18.60 microsieverts
(1860 microrem), with a dose rate of about 3.8 microsievert per hour
(380 microrem/h) at a cruising altitude of 30,000 feet. This means the
dose from the x-ray scanner is equivalent to the dose a passenger would
receive in less than 2 minutes at cruising altitude. Or another way to
look at it is that getting the x-ray scan increases the passenger's dose
for the airline trip by less than 0.6% (not counting the dose from
natural background during the 2+ hours the passenger was on the ground
at the airport before boarding and after exiting the aircraft).

We often use comparisons to explain low doses of radiation for the
emergency responders we train using radioactive material. We limit the
students to radiation fields less than 4 millirem/hour (so that they do
not enter a Radiation Area during training). The students perform in
exercises at a training facility built around the ground zero location
of four above ground nuclear detonations. The ground is still emits low
levels of radiation. The students learn that they typically receive a
larger dose of radiation during their airline flights to and from Las
Vegas to attend the training than they receive during the four days of
training.

Of course, our goal is to put risks in proper perspective, not to scare
people.

Best regards,
Rick Hansen
Senior Scientist
Counter Terrorism Operations Support Program
National Security Technologies, LLC
hansenrg at nv.doe.gov
www.ctosnnsa.org


-----Original Message-----
From: Perle, Sandy [mailto:SPerle at mirion.com] 
Sent: Thursday, March 18, 2010 10:24 AM
To: Hansen, Richard; 'radsafe at health.phys.iit.edu'
Subject: RE: [ RadSafe ] NBC News story on airport scanner (25 mrem
dose)

Thanks Rick,

I really appreciate everyone's feedback. I've learned a lot. I just wish
that a different value were used for the news piece, one with a higher
dose value, to demonstrate that the estimated dose 0 0.005 mrem is not
only insignificant, and it extremely small compared to what a declared
pregnant female is allowed to receive. That demonstrates if the female
can be exposed to 500 mrem (and the fetus), then 0.005 mrem is
ridiculously low.

Regards,

Sandy

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