Radiation Detection Questions

["Eric A. Goldman" <ea.goldman@baylordallas.edu>]

Hi all!!

I've got a question/problem that I hope some of you can answer/solve.

Concerning I-131 therapy patients. The initial exposure measurement is
done at 1 meter w/ an Ion Chamber.  Assume the reading is around 30 mR/h
~ 1hr post administration of 150mCi I-131 oral solution.  Is it OK to
make the same 1 meter measurement 2 days later, when the patient is
really an extended source of radiation, in order to discharge the
patient if the reading is less than 5 mR/h? 
What would be the difference if a pancake GM detector were to be used
instead of an Ion Chamber for both the initial and final measurements?
Lets also assume that the patient has had a total thyroidectomy.

Some other questions.  

When should a GM be used as opposed to an Ion Chamber and vise-versa in
I-131 cases?  What would be the efficiency difference between a sliding
side-window GM and a thin-window Pancake for I-131 contamination
detection?
-- 
Eric A. Goldman, B.S.,CNMT	


"Gotta run, the cat's caught in the printer."