Radionuclide Impurities in Nuclear Medicine

["Moroney, Roger W" <WRMoroe@MKG.com>]

Jocelyn Towson's reply pretty much sums up the reason why isotopic 
impurities are undesirable. Here at Mallinckrodt, our Quality Control 
Department performs gamma spect on  the raw cyclotron product and at 
various stages in the production process looking for contaminants. The 
levels allowed are specified in either the NDA or by the FDA. Using Ga-67 
as an example, the activity ratio of Ga-66 to Ga-67 is < 0.001. Ga-66 also 
has some undesirable radiation emitted in the form of a 2.75 MeV gamma and 
a 4 MeV positron. It creates problems here when the sample is pulled before 
most of the Ga-66 has decayed away.

Some of our employees have received Tl stress tests. We use them (with 
their permission of course :) to test our bioassay and internal dosimetry 
models. I do occasionally see Tl-202, at extremely low levels, in the urine 
(counted on an HPGe detector).

 Roger Moroney
Radiation Specialist
Mallinckrodt - Nuclear Medicine
wrmoroe@mkg.com
314.770.7457 	voice
314.770.7458 	fax