FW: U-235 In Vivo Lung Counting Comparisons

["Olsen, Peter C" <peter.olsen@pnl.gov>]

-----Original Message-----
From:	Olsen, Peter C 
Sent:	Friday, November 13, 1998 3:03 PM
To:	'DOSE-Net@orau.gov'; 'radsafe@romulus.ehs.uiuc.edu'
Subject:	U-235 In Vivo Lung Counting Comparisons

Dear In Vivo Bioassay Colleagues:

The Phantom Library at Pacific Northwest National Laboratory is offering a
DOELAP LLNL torso lung set containing 99% U-235 for interested labs to measure
for a special intercomparison.  The calibration phantom lung set will be
independently analyzed by complete radiochemistry by the US Transuranium and
Uranium Registry (USTUR) at Pullman WA after the phantom measurements are
finished.  This special intercomparison is being offered for free to in vivo
laboratories, in an attempt to clear-up some evaluation uncertainties in the
measurement of U-235 using LLNL lung phantoms.  Calibration biases from the use
of some curve-fitting equations are being seen, and are quite large at the 185.7
keV energy for LEGe detectors.  This particular lung set (RSD #574) was
previously in a DOELAP pilot test, and has some NBS-traceable pedigree.

Simply put, the lung set will be sent to interested US in vivo labs, the results
will be returned to the Library, and then a total analysis of the lung set by
the USTUR will be completed.  Results of the intercomparison and true
U-235/U-238 content will be made available.  The plan is to keep it "short and
simple" (ie under 1 year).  Four labs have already completed measurements.  Labs
who want their results to remain anonymous will be respected.  If interested or
for more detailed information contact:

Peter C. Olsen  CHP 
PNNL/DOE Phantom Library Manager
Dosimetry Research and Technology Group
Battelle PNNL
(509) 372-6021
E-mail: peter.olsen@pnl.gov


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