I didn't remember that a lot of the exchanges on this subject have been on 
the Pathology listserver rather than on Histonet.

Here's an exchange we had on the Pathology Listserver just a month ago.
http://www.ualberta.ca/htbin/lwgate/PATHO-L/archives/patho-l.archive.2002-01/A

uthor/article-231.html
That really contains some useful information with references, and addresses 
the CAP issue.

And an earlier one:
http://www.ualberta.ca/htbin/lwgate/PATHO-L/archives/patho-l.archive.2000-10/d

ate/article-6.html

I posted this one on Histonet
http://histosearch.com/histonet/Sep99/Re.RadioactivetissuesC.html

Not the least of problems in searching this topic is that the incorrect 
spelling "sentinal" is about as common as the correct one.

Bob Richmond
Samurai Pathologist
Knoxville TN