Answer to Question #5645 Submitted to "Ask the Experts"

Q

I had an Agreement State inspector give my facility a violation for not doing a geometry test on a 10 ml vial which was being used to assay iodine-123 capsules. Is it possible for a geometry test to be performed in this situation?

A

You raise an interesting question. In my experience of consulting for a number of nuclear medicine departments in different Nuclear Regulatory Commission (NRC) and Agreement States, there has been a definite trend in recent years to have each facility perform a geometry test for each configuration that is measured in the dose calibrator (that is, syringes and vials). I have not, however, heard of a request to do geometry for the vial that iodine-123 capsules are shipped in.

National Council on Radiation Protection and Measurements (NCRP) Report No. 99, Quality Assurance for Diagnostic Imaging, contains a section on dose calibrator geometry and provides a couple of areas of interest, but makes no mention of iodine-123 capsule measurements. There is also no mention in NRC licensing guides. You should verify that the regulations and licensing guide for your Agreement State do not address this situation.

Since you are technically measuring a 10 cc vial, I recommend that you perform a geometry test starting with approximately 2 mCi of technetium-99m in 1 cc of saline and make measurements up to 10 cc. Even though this does not give you an exact geometry situation for iodine-123, it will give you a measurement with the same container in volumes that will approximate the geometric size and area of the capsules in the vial.

Ken "Duke" Lovins, CHP