corrections for Radionuclide Impurities in Nuclear Medicine

[Schoenhofer <schoenho@via.at>]

I have been away for a time and before I left I hastely wrote some reply to
the question of impurities of radiopharmaceuticals. One should never do
this, because I made some errors, which I apologize for. Another fault was
that I gathered very quickly information from a friend, who is not a chemist
and did not check it for plausibility. I apologize again.

May I correct my contribution:

1) I referred to radiopharmaceuticals generally rather than to the ones used
in therapy. So I am aware that an in vitro study cannot give a dose to the
patient, but impurities may influence measurement results, which might not
be favourable for the patient.

2) I referred wrongly to Tc-99 breakthrough, but it should have been
molybdenum. I should have thought so far, that the Tc-99 cannot arise in
significant quantities, because I know about the half-life. I should have
thought of this especially since I have made once a calculation of how much
Tc-99 could be expected in the Danube river coming from Germany to Austria
and it was clear, that all Tc-99 created from all technetium generators in
Germany would not be detectable if all was emitted into the Danube river.
Sorry. 

3) The question of impurities from accelerator production has been well
mentioned by Mallinckrodt in a mail. 

4) The radionuclide mentioned is of course Ga-67 and not 57 (even if it
existed it might be a little too shortlived...). Ga-67 is still used, but in
Austria it is used much less now than some years before.

Franz
Schoenhofer
Habichergasse 31/7
A-1160 WIEN
AUSTRIA/EUROPE
Tel./Fax:	+43-1-4955308
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e-mail:		schoenho@via.at