[ RadSafe ] It happened again

[Jim Hardeman]

Stewart --
 
I wouldn't immediately rule out Tc-99m in this scenario. My experience has been that Tc-99m would be the radionuclide of choice for cardiac stress tests and similar procedures except in instances where a higher body mass ratio would result in poor imaging, at which point Tl-201 would be the radionuclide of choice. I wouldn't think an active firefighter would fall into the high BMR category. I personally have detected Tc-99m activity in a patient many hours after the procedure (the article states, from memory, that the procedure was done earlier that day).
 
Unless the trooper had a gamma spectrometer (some do) it would be tough to tell the difference, unless you detained the subject long enough (compared to the half-life) to monitor the decay -- something that just isn't going to happen in practice.
 
Jim Hardeman

>>> "Dawry, Frank" <FDawry at med.miami.edu> 5/14/2012 16:15 >>>
According to the package insert, Tl-201 provides the greatest dose to the testes; from augers I believe.

-Frank


Frank P. Dawry
Medical Physicist
University of Miami - Radiation Control Center
1600 NW 10 Avenue
Rosenstiel Medical Science Building (B050B)
Miami, Florida 33136
(305) 243-6360
fdawry at med.miami.edu 


It's All About The Care !



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Message: 1
Date: Fri, 11 May 2012 13:45:25 -0400
From: Stewart Farber <SAFarber at optonline.net>
Subject: Re: [ RadSafe ] It happened again
To: "'The International Radiation Protection (Health Physics) Mailing
List'"<radsafe at health.phys.iit.edu>
Message-ID: <002701cd2f9d$d9197e70$8b4c7b50$@net>
Content-Type: text/plain; charset=us-ascii

Hi all,
Regarding the news article Joel posted about the Firefighter in Milford, CT
setting off a State Trooper's rad monitor as the two cars were in proximity,
the "small" amount of radioactivity [ 201Tl most likely vs Tc-99m]
mentioned in the article is discussed in some detail in the excellent full
paper about cardiac testing at the following reference:

http://circ.ahajournals.org/content/118/16/1668.full 

>From the above for 201-Tl:
"Whole-body radiation exposure after a typical dose (2 to 4 mCi) is
approximately 0.68 rad, and the kidneys are the organ exposed to the most
radiation. The relatively long half-life (T1/2=73 hours) and low energy of
201Tl are important considerations during imaging. The long T1/2 contributes
to its significant inpatient residence time and requires lower doses to
minimize risk of radiation exposure."

This kind of event happens regularly. Many years ago, a visitor on a tour of
the White House [when the public was taken on tours]  set off rad monitors
there because he had had a nuclear stress test.

The article at the link Joel supplied below also states:

"In the test, a small amount of a radioactive material is injected into the
veins and used to help track blood flow to the heart.

Though the amount of radioactive material used in the test is relatively low
-- equal to a few X-rays or a diagnostic CT scan -- it was enough to set off
a radioactivity detector in the state police car. "

As we know a "small amount" of radioactivity or dose is relative. Had a
release [ aka "spewing" as invariably used by the press in writing about any
release] from a nuclear plant like Millstone nuclear station in CT [ which
supplies power to over 1 million people in CT] resulted in a fraction of the
exposure and dose rate cited, even to one person, many professional
anti-nuclear scaremongers would be calling for shutting down every nuclear
plant in the region and be wearing out the word "Fukushima". "Ain't it
awful" :-)

Stewart Farber
farber at farber.info 

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