Subject: Deviations of Nuclear Medicine

I am doing a project on radioactive decay with a focus on medical 
applications.  My chemistry teacher was just diagnosed with hyperthyroidism 
and doctors used Iodine-131 to monitor his thyroid activity.  He happened to 
use a Geiger counter himself to record the decay of the Iodine in his thyroid 
area over a period of 22 days.  I graphed his data and the expected 
exponential decay curve. They don't match at all! His data is in a curve 
that "bows" outward.  I was wondering if there was an explanation for this; is 
their another process by which the body gets rid of the radioactive Iodine or 
adds to it?

Re: Deviations of Nuclear Medicine