Dose Calibrator Setting for I-123

[VERNIG.PETER@forum.va.gov]

We at Forum (.va.gov) have been incommunicado for some time and
being only semi computer literate, I'm not sure why except it
seems to have to do with traffic volume and our system limitations.
I want to get this post in while the posting is good.
 
We recently got a new CRC-15 and also recently bought some I-123 from
Syncor rather than our normal supplyer Mallinkrodt.  It was assayed
on our old CRC-12 and read ~25% low.  Turns out the CRC-12 had had 
it's gain setting adjusted to 380 instead of the "recommended" 277
on advice from Mallinkrodt.  When I talked to them they said the 
I-123 from the p-2n reaction was the reason.  That the old 277 setting
accounted for the higher level of impurities in the I-123 from the
p-5n reaction.  The Syncor supplied I-123 is produced by Golden
Pharmaceuticals [formerly North American Chemical formerly Benedict
Nuclear Pharmaceuticals] and assay using the 277 gain setting gave a 
reading
consistent with Syncor's assay as did assaying it on the new CRC15.
This implies that Capintec has not changed their recommended gain
setting from 277.  Syncor/Golden's I-123 is also p-2n from Nordian
International [same supplier as Mallinkrodt's]
 
Anybody out their know anything about what gain setting should be used?
I'm going to call Syncor and Golden but wanted to post this quick befor
the gateway clogs.  Thanks in advance to anybody who can shed some
light on this.
Peter G. Vernig RSO, VA Med Center, Denver, vernig.peter@forum.va.gov
(303)399-8020 ex 2447