Re: Deviations of Nuclear Medicine

The decay of radioactive material will follow such a curve if that is the 
only process involved in the removal of the radioactive atoms.  However, 
once you administer such a material the body also eliminates it through is 
normal pathways like urine, feces, sweat, etc...

So it is not a true exponential removal (or decay).  The body also will 
retain some of this iodine in specific tissues/organs like the thyroid.

So simple measurements of a persons thyroid after an uptake is a very 
dynamic process with several removal pathways and some retention and 
even a 
small amount of recycling within the body.

What you plotted is the TOTAL removal rate and not just the 
radiological decay.

Regards,