The I-131 Bioassay Issue -Reply

[James Dwyer <JPD1@nrc.gov>]

RADSAFERS:

Sorry to weigh in on this so late but I have been away from my desk for several
days.  

Medical RSOs should be aware that while the revision of 10 CFR 35.75 has
removed, in my opinion, the legal basis for a 10 CFR 35.315(a)(8) violation if a
patient is released in accordance with the revised 35.75, many licensees have
committed (during the licensing process) to establishing and implementing the
"Model Procedure for Radiation Safety During Iodine Therapy Over 30 Millicuries"
published in Appendix P of Regulatory Guide 10.8, Revision 2.  Item 10 of this
Model Procedure states the following: 

"For patients treated with liquid or gelatin-capsuled I-131, 1 day after the dosage
administration, measure the thyroid burden of all personnel who were present for
the administration.  Also consider a thyroid burden assay for patient care personnel
2 days after the administration.  Make a record of the worker's name, amount of
I-131 activity in a thyroid phantom in microcuries and associated counts per minute,
the counts per minute from the worker's thyroid, the calculated thyroid burden, and
date."

If you have committed to establishing and implementing this Model Procedure, this
procedure becomes a requirement and you can still be cited for failure to perform a
thyroid bioassay on individuals who were present for the administration if the I-131
dosage exceeded 30 millicuries, regardless of whether the patient was released or
not.

Check the documents that are referenced in the last condition of your NRC license.

Clearly my own opinion.

Jim Dwyer
Senior Health Physicist, Medical Branch
NRC Region I
JPD1@NRC.GOV
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