Re: Beta Emitters and Dose Calibrators

["John R. Laferriere 671-8316" <John.R.Laferriere@dupontpharma.com>]

Carol Marcus wrote:

"Dear Radsafers:

Yes, the error in the measurement can be significant, but that is a physics
issue.  From the point of view of the accuracy that is needed in medicine,
the error is of no significance.  So, why should we worry about it?"

Carol- Your assertion that the error is of no significance may be true, but
there is a need for more facts before you can convince me of it.  How much
variability is there in dose calibrator response from one calibration geometry
to another?  Do the people doing the assay realize the greater sensitivity
to container material/geometry that beta emitters have compared to gamma 
emitters?  Given that beta emitters are going to be used for therapy rather
than just diagnostic imaging, I would think that delivering an accurate dose
would be significantly more critical than for a diagnostic application.  What
is a safe +/- range for therapy doses of Sr-89, P-32, Y-90 etc before you 
start to cause serious injury to critical organs?  Is this range
smaller or larger than the +/- range of the assay?


John Laferriere, CHP
DuPont Pharmaceuticals Co.
Medical Imaging Division
john.r.laferriere@dupontpharma.com
Standard disclaimers.

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