RE: EPDs for personnel monitoring and surveys

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

> f course, Sandy's there!!  Can you miss him?

Mike is very astute... and yes, I've been sitting back regarding this 
thread. Mike and I are in full agreement with respect to the useful 
purpose of an "electronic dosimeter". We both believe that it is a 
great ALARA and radiological control device, but is not currently 
viable for primary "dose of record". I'm not going to go into the 
various reasons why, since they are well documented by Mike in 
his PEP lectures (HPS Meetings) and in his RPM article published 
a couple of years ago. I will just state that the "electronic 
dosimeter" can only be considered viable for "dose of record" if the 
working environment is stable, the spectra in which the worker is 
exposed does not change, and that the calibration factors don't 
change, based on all of the above. Experience has demonstrated 
that this is not often the case. The fact that the primary spectra 
happens to be high energy photons, with whatever beta spectra 
you have within your facility, does not mean that when there is a 
"radiological incidence" that the spectra doesn't change. It does 
and it will. The calibration of the device drives the final dose 
determination, as well as the dose rate. When there is a change, 
the values obtained are no longer valid, and can result in  severe 
under-response, often leading to a dose that could exceed 
regulatory limits, exceed administrative guidelines, etc. In essence, 
while the manufacturers swear that the "electronic dosimeter" is 
not a processing dosimeter, such as found with dose determination 
from a film or TLD, it is just that. There are built in algorithms and 
parameters set and those that are hidden, within the device, and if 
those factors changes, so does the final dose reported.



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 -
************************************************************************
The RADSAFE Frequently Asked Questions list, archives and subscription
information can be accessed at http://www.ehs.uiuc.edu/~rad/radsafe.html