BIOASSAY for Iodine of those without Thyroids

[VERNIG.PETER@FORUM.VA.GOV]

I am not an apologist for the NRC nor do the following comments reflect
any opinion other than my own.  Certainly not those of any agency of the
U.S. Government. 
 
1.|TAB|Part 20 I believe does not specify thyroid measurment.  The require-
ment is to have less than an ALI.  Prior to the "NEW part 20" it was
either to keep dose less than 50 rem to the thyroid or keep below the
MPC.  Anyway the ALI [let's talk current regs] is designed to prevent
or be equivolent to the smaller of a 50 rem dose to the target organ
[lenses of eyes have lower limit] AND a whole body EDE of 5 rem.
 
2.|TAB|Reg Guide 8.20 on bioassay of I-125 & I-131 defines bioassay as 
either direct in vivo measurement or in vitro analysis of material
excreted or removed from the body.
 
3.|TAB|A person without a thyroid doesn'tneed the protection of a 50 rem
limit on organ dose but s/he still needs the 5 rem whole body EDE.
 
4.|TAB|So I would say that if the NRC person said measure the thyroid
anyway s/he was wrong. 
 
5.|TAB|The argument I would have submitted would have been I will do 
urine or blood analysis to show the researcher is under the ALI.
Now you could argue that the ALI based on a 50 rem thyroid dose is
more restrictive than necessary and you'd probably be right.  But to
get an adjustment you'd have to provide a lot of evidence as to jsut
just what the whole body dose would be assuming no thyroid uptake/binding
and probably have to consider the bladder as a new target organ.
Easier to just accept the ALI a a consevative number.
 
Now can anybody tell me how to approach 35.315(a)(8) which requires
measurement of thyroid burden after >30 millicurie therapies for
a Nuc Med Tech without a thyroid? 
 
As I said earlier this does not represent the position or opinion of 
this Medical Center, the Dept  of Veterans Affairs, or any government
agency, or the U.S. Government.
 
Peter G. Vernig, VA Medical Center, Denver, vernig.peter@forum.va.gov