[ RadSafe ] Fwd: Effective half life question

Thu Oct 25 11:59:22 CDT 2012

Folks

Yes.  I should have said originally that the concept also applies to
the occupational arena, wherein one has to consider whether a nuclide
of interest has Annual Limits on Intakes (ALI's) of the various
Classes D, W, and Y (Days, Weeks, and Years).  Separately, we might
also note the synonymous, or equivalent, use of term "residence time"
instead of "effective half-life", in the literature.

Beware, too, of multiple effective half-lives.  So, in the case of
ingested NaI in the euthyroid individual, one first sees a very rapid
uptake, with a correspondingly rapid wash-out, of large fractions of
the intake, followed by a second, relatively long, effective
half-life.

Cheers
cja
---------- Forwarded message ----------
From: Brennan, Mike  (DOH) <Mike.Brennan at doh.wa.gov>
Date: Thu, Oct 25, 2012 at 12:23 PM
Subject: Re: [ RadSafe ] Fwd:  Effective half life question
To: "The International Radiation Protection (Health Physics)
MailingList" <radsafe at health.phys.iit.edu>

H-3 is even a clearer example.  Assuming the tritium enters the body as
water (usually valid), the biological half life is about 13 days,
compared to the radiological half life of over 12 years.  The biological
half life can be even less with the consumption of large quantities of
beer (OK, other liquids will work, also, but why wouldn't you use beer?)

-----Original Message-----
From: radsafe-bounces at health.phys.iit.edu
[mailto:radsafe-bounces at health.phys.iit.edu] On Behalf Of
edmond0033 at comcast.net
Sent: Wednesday, October 24, 2012 3:44 PM
To: The International Radiation Protection (Health Physics) Mailing List
Subject: Re: [ RadSafe ] Fwd: Effective half life question

The radionuclide that I have run into is Iodine-131.  It's biological
half-life is less than its physical half-life

Ed Baratta

edmond0033 at comcast.net

-----Original Message-----
From: radbloom at comcast.net
Sent: Wednesday, October 24, 2012 5:27 PM
To: The International Radiation Protection (Health Physics) Mailing List
Subject: Re: [ RadSafe ] Fwd: Effective half life question

Jeffrey,

If you are talking about prepared pharmaceuticals, these would have
package
inserts that would include information on the effective half-life for
the
particular radiopharmaceutical .

Cindy

----- Original Message -----

From: "Chris Alston" <achris1999@ gmail .com>
To: "The International Radiation Protection (Health Physics) Mailing
List" <
radsafe @health.phys. iit . edu >
Sent: Wednesday, October 24, 2012 4:16:54 PM
Subject: [ RadSafe ] Fwd:  Effective half life question

Jeffrey

There are a multitude of these, depending on exactly what you mean.
The MIRD Committee publishes reports, and there are ICRP Publications
53, 80, and 106.  There is also the RADAR website, doseinfo-radar.com.

But you might want to start with NUREG /CR-6345, Radiation Dose
Estimates for Radiopharmaceuticals , of April 1996.

Happy hunting
cja

---------- Forwarded message ----------
From: Kulp , Jeffrey  ( DOH ) <Jeffrey. Kulp @ doh . wa .gov>
Date: Wed, Oct 24, 2012 at 2:59 PM
Subject: [ RadSafe ] Effective half life question
To: radsafe @health.phys. iit . edu

Hello Radsafers ,

I have a question that is related to radiopharmaceuticals . I have been
told by a colleague that the effective half-life of a radioactive
isotope can differ based on the chemical preparation the isotope is in.
Essentially the biological half life will change due to the varying
clearance rates for different chemicals, thereby changing the effective
half-life. Is there a database that addresses the different biological
half-lives for various radiopharmaceuticals ?

Thanks,

Jeffrey Kulp , RRPT

Radiation Health Physicist

DOH - Office of Radiation Protection

P.O. Box 47827

Olympia, Washington  98504-7827

(360) 236-3237

"Public Health - Always Working for a Safer and Healthier Washington"

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