thallium excretion

[stabin@esper.com (Mike Stabin)]

If anyone is interested, here is the kinetic model that we use for Tl-201,
and the details about contaminants.  The question asked in an earlier post
was about excretion, and the one answer was pretty much on target, as I
recall.  The urinary excretion appears to be about 20%, in two components.
The testes residence time was taken from a special study undertaken by the
MIRD Committee (the Thomas et al. citation) - an article by Gupta et al.
suggested that testicular uptake of Tl-201 might be as high as 1.0% (which
was used in ICRP 53).  Other authors had cited from 0.15-0.4%, and the MIRD
Committee study found an average around 0.3%.  

I stand corrected on the amounts of Tl-201 that are typically administered.
My understanding was that around 50 MBq would be typical, but it appears
that upwards of 150 MBq may be used these days.  One percent uptake of that
much activity would keep ya warm at night, yes?

Model based on data gathered in humans by Krahwinkel et al. (J Nucl Med
29(9):1582-1586, 1988) and data on testicular uptake and clearance
gathered in humans by Thomas et al. (personal communication, 1994). 
Assumed distribution and retention:
Brain        1.76%       Tb = infinity
LLI          3.6%        Tb = 191 hr (Activity in wall)
Small Int   14.4%        Tb = 191 hr (Activity in wall)
Stomach      2.8%        Tb = 205 hr (Activity in wall)
ULI          4.7%        Tb = 191 hr (Activity in wall)
Heart Wall   3.4%        Tb = 179 hr 
Kidneys      4.5%        Tb = 260 hr     0.97%    Tb = 27 hr
Liver        4.6%        Tb = 218 hr                   
Spleen       0.74%       Tb = 640 hr     0.28%    Tb = 37 hr
Testes       residence time 0.26 hr
Thyroid      0.29%       Tb = 350 hr     0.24%    Tb = 166 hr
Total Body  31%          Tb = 146 hr    69%       Tb = 502 hr
Urinary Bladder:     6.2%     Tb = 146 hr, 13.8%     Tb = 502 hr, Bladder
voiding interval 4.8 hr.  Contaminants assumed:  Tl-200 (1%), Tl-202
(0.33%), Pb-201(0.33%), Pb-203(0.33%). Includes dose from Tl-201
Auger electrons.

Mike Stabin
Oak Ridge