Contaminants in Medical Isotopes?

[goldinem@songs.sce.com]

Can someone point me to published material (Health Physics Journal for
instance) that describes what I have heard in passing:  that medically
administered radioisotopes (sometimes) have contaminants of other isotopes
at small concentrations?   I'm looking specifically for published research
papers on this, not anecdotal experiences.  Please forward any information
to me directly at:

Eric M. Goldin
Southern California Edison
(949) 368-7532
<goldinem@songs.sce.com>

************************************************************************
The RADSAFE Frequently Asked Questions list, archives and subscription
information can be accessed at http://www.ehs.uiuc.edu/~rad/radsafe.html