Re: No Subject

[Ccja@aol.com]

I've addressed the question of the usefulness of the package inserts in
another email, as has, I now see, Mike Stabin. Let me simply reiterate that
they frequently, if not usually, contain out-of-date and/or misleading
information.
If the FDA publications to which you're referring are those in the series
that includes the "Handbook of Selected Tissue Doses for Projections Common
in Diagnostic Radiology" (published 12/88, superseding the one published in
5/76), the problem with the older ones is that they don't give enough tissue
doses to complete the ICRP weighting protocol in a straightforward way. The
newer ones, (e.g., the Handbook of Selected Tissue Doses for Fluoroscopic and
Cineangiographic Examination of the Coronary Arteries) it's true, do.
Clearly one of the most important tasks of a nuclear physician is to evaluate
the ways in which a specific patient's pathology may affect the biokinetics
of radiopharmaceuticals; without the ability to do that, I'm not sure that
someone should be prescribing radioactive drugs, or trying to interpret the
studies. ICRP Publication 53 "Radiation Dose to Patients from
Radiopharmaceuticals" is very useful to health physicists, in this regard.
Any method we use to estimate patient doses, especially with an eye to
explaining them  to the patients, is going to have drawbacks or pitfalls. I
still prefer the ICRP methodology, and, anyway, it's a regulatory requirement
(10CFR35.2) for nuclear medicine. I've had good experiences (i.e., apparent
patient satisfaction with explanation) by giving them comparisons between the
EDE from their procedure and that from natural background sources. For
instance, if I can tell patient that their exposure from a 200 uCi
administration of Cr51-labelled platelets is about 180 mrem and that this is
about the same as the average annual natural EDE in Seattle, but that the
national average is twice that, and in some places it's much more (NE
Washington > 1600 mrem), this seems to help them put it in perspective.
Typical doses from airline travel I've also found useful.
Also, I said that there is no other way of doing this. That's not really
true. In Europe, particularly the UK, they use the concept of total imparted
dose, primarily I think with "xrays", i.e. external beam diagnostics. It's
very attractive intellectually, because of it's simplicity, but as far as I
know, it's not in use in the USA. Certainly the FDA doesn't endorse it.