more on BBC: Therapy 'sets off airport alarms'

[David Farber <dave () farber net>]

Begin forwarded message:

From: David Josephson <david () josephson com>
Date: August 5, 2006 12:59:46 PM EDT
To: dave () farber net
Subject: Re: [IP] BBC: Therapy 'sets off airport alarms'

Bob Rosenberg wrote
> I got particular joy from the irony of this paragraph:  "Patients  
> who have received
> treatment involving radioactive particles are already advised to  
> avoid public
> transport for two weeks so that they do not expose nearby  
> passengers to
> radioactivity."
>
> Please, someone, tell me how that patient avoids exposing him/her  
> self to
> radioactivity?!?
>
> Of course, this lunacy is 'protecting' us from ???  Oh yeah, I got  
> it --- rationality.
Sorry, this is not lunacy, but requires a bit more objective thought  
than is usually found in the public on issues of "radiation."

Someone may be cured of cancer for the remainder of their life  
through the administration of a high dose of radiation. The same dose  
spread out over time is enough to significantly increase the risk of  
cancer in a young person, particularly thyroid cancer. So the  
prostate cancer patient with an implant sleeps in a room by himself  
for a few weeks, until the implant has decayed to safe levels.

At a geophysical instrument company where I was an engineer many  
years ago, we all started scurrying around when the background  
radiation levels spiked and then remained elevated at 4x normal one  
morning. Turns out that our purchasing chief had just come back from  
having a radioactive implant installed to treat a cancer in his  
throat (and he had walked through the test area on the way to his  
desk). Relatively short half-life isotopes are used, but for the  
first few hours or days, that person emits a lot of radiation.  
Hospital procedures (see www.ehs.ucsf.edu/Manuals/RP/ 
Rad_Protection.pdf for example) require that a patient not be  
discharged until the radiation has decayed to acceptable levels --  
which are higher if there are no young people (<45 years old) in the  
household. The radiation dose we all received that day was roughly  
equivalent to an x-ray followed by a long airplane flight.

What are the airport monitors protecting us from? Think about small  
"dirty bombs." A terrorist's object is to create hysteria, and we are  
certainly ready to be hysterical. Being knowledgeable about radiation  
safety is probably a more effective defense than any. We understand  
from recent studies that there is no safe exposure to ionizing  
radiation -- any increase is shown to cause a statistically small but  
measurable increase in disease risk. Yet we all are exposed to  
radiation every day. It is hard for people to get the concept of "as  
low as reasonably achievable" until they take the time to think about  
it. If you care, try this homework assignment. What's the single  
largest source of radiation that people are exposed to on a daily  
basis? Hint - some people have this exposure -- by choice -- and  
others have little or no exposure to this radiation source.

--
David Josephson



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