Hi Mark,
The answer to your question is dependant on the isotope being used.  We
receive breast specimens which have had a radioactive label used.  These are
labelled with technecium 99 which has a half-life of 2 or 3 hours so by the
time we receive the specimen there is virtually no activity and therefore we
do not have to worry about contaminated reagents.  I suggest you speak to
the Nuclear Medicine people involved.  They can fill you in with all the
details about the isotope and its risks etc.

Penny Marr