Answer to Question #2149 Submitted to "Ask the Experts"

Q

I-131 bioassay for room cleanup—I know that the regulations state that anyone involved in the preparation or administration of the dose must get bioassays, but what about the technicians who clean the room after the patient has been discharged? Is there any need for them to get thyroid burden tests?

A

It should first be noted that the revision to Title 10, Code of Federal Regulation, Part 35, "Medical Uses of Byproduct Material" (10 CFR 35) no longer requires that persons who prepare or administer a dosage of ¹³¹I have bioassays. However, licensees need to ensure that occupational worker doses, listed in 10 CFR 20.1201, are controlled. This applies to those involved with the preparation and administration of ¹³¹I dosages and with the decontamination of the patient's room.

U.S. NRC Regulatory Guide 8.20, "Applications of Bioassay for I-125 and I-131," Rev 1, 1979, provides monitoring criteria acceptable to the NRC for programs using radionuclides of iodine. A copy should be obtainable by sending an email to distribution@nrc.gov requesting this document. Alternately, a copy can be downloaded from the Internet.

It should be kept in mind that the decontamination of patient rooms usually involves very small quantities of radioactive iodine. Also, the radioactive material is essentially bound to the contaminated surfaces and does not become airborne unless the radioactive iodine is attached to a dust particle. At our facility, technicians involved with the decontamination of the patient's room are on a quarterly thyroid scan schedule based on the negative bioassay results we have routinely obtained.

John P. Jacobus, MS
Certified Health Physicist