re: puzzler

[NUCPHARM@aol.com]

The most commonly supplied "simulated" Tc99m source back in the 1970's from
New England Nuclear was Co-57.  It was used in a crude assay of activity for
Tc99m which was eluted from the Mo99/Tc99m generator but for which there
existed no "requirement" to possess or use a dose calibrator.  Therefore
these simulated sources were counted in a well counter and with appropriate
correction factors ( approximately .915 I believe for C057:Tc99m) the
activity of the Tc99m was calculated. Incidentally these sources were
typically red in color but no guarantees here. You do not state if there is
any measurable radioactivity from this particular source.  If not, then this
is the most likely candidate. 

I'll dig a little deeper for the SIM In-113m tomorrow.

Hope this helps some.

I'll