Secondary personnel monitoring, I-125 & P-32

["Sandy Perle" <sandyfl@earthlink.net>]

I have been asked to provide assistance regarding secondary 
monitoring for I-125 and P-32, to be used as an estimate of the 
DDE, LDE and SDE, when the primary dosimeter can not be read, 
or the dose used, due to a contaminated dosimeter. The individual 
currently performs a dose reconstruction, which often is a very 
conservative estimate of the dose. I  would like any 
recommendations Radsafer's may have regarding what may be a 
viable secondary monitoring capability.

(1) I have informed the individual that I am not aware of a secondary 
device that will monitor the spectrum of interest, i.e., I-125 and P-
32 effectively.

(2) A typical PIC will not measure the low energy x-ray from the I-
125. I mentioned that it is even difficult to perform an extremely 
accurate assessment of I-125 using a film or TLD, even though 
each dosimeter is NVLAP accredited in NIST Beam Code M30, 
which is an average 20 keV x-ray. The PIC will not effectively 
measure the P-32 beta either. While there may be some 
measurement of the Deep Dose component, there is no way to 
measure the Shallow Dose component.

(3) An Electronic Dosimeter is also not an effective dosimeter as 
well,, for some of the same reasons above. The dosimeter can 
measure the low energy x-ray, if appropriately calibrated, but can 
not effectively measure the Shallow Dose component. I was 
fortunate to be able to discuss this with 3 manufacturers of 
electronic dosimeters, while at the International AL:ARA 
Symposium last week. Each of the 3 told me that they could 
measure portions of what I asked about, but not effectively to meet 
all fo the requirements as stated.

(4) I told the individual that the key element was to minimize the 
contamination that is the Root Cause, which will allow all of the 
TLDs to be processed and used for dose of record.

(5) In the event there is still contamination, and dosimeters can not 
be read, that a more realistic dose reconstruction process be 
implemented. If the method is viable, and accurate, the need for a 
secondary dosimeter is reduced.

(6) Cost effectiveness is another issue. The facility badges 
hundreds of individuals, and I stated that it would not be prudent to 
provide costly secondary dosimeters if they are unable to provide 
accurate DDE. LDE and SDE determinations.

In summary, based on the above synopsis of the issues, I would be 
appreciative of any suggestions that I can pass on to this 
individual. Perhaps there is something else they can implement 
and meet their monitoring requirements.

Thanks to all for any assistance...

Sandy Perle
E-Mail: sandyfl@earthlink.net 
Personal Website: http://www.geocities.com/capecanaveral/1205

"The object of opening the mind, as of opening 
the mouth, is to close it again on something solid"
              - G. K. Chesterton -
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