Re: Finger Dosimetry

[sandy_perle@email.fpl.com]

     >>(1) The frequency of readings<<
     
     This depends on hour routine monitoring period, and the administrative 
     limits you establish for processing a ring prior to the end of the 
     routine monitoring period. Most process their dosimeters on a 
     quarterly basis, but some process monthly, as we do. However, we do 
     process on demand whenever an administrative limit is reached, or, 
     there is a questionable estimated dose or event involving the 
     dosimeter.
     
     
     >>(2) The proper location of the TLD ring. 
         
         (a)underneath gloves or on top of gloves?
     
     Depends on what you are attempting to measure. In our environment we 
     have engineered away the beta exposure and therefore are only 
     interested in the gamma exposure. Our spectra is such that the beta is 
     attenuated with ~ 70 mg/cm^2, or, two rubber gloves. Again, this issue 
     is dependent on what you are trying to measure. I suspect that in your 
     environment you are interested in the shallow dose equivalent, and I 
     would recommend that you wear them on the outside of the gloves.
     
         (b)facing the palm or opposite the palm?
     
     Again, depends on the type of dosimeter. We wear Panasonic 807 TLDs, 
     and wear them on the bottom of the finger, facing the source we are 
     interested in. The key is locate the dosimeter based on the geometry 
     of the source.
     
     
     (3) Precautions to prevent contamination.
     
     Ensure that whatever finger ring material you use,. that they are 
     sealed properly. Since the LiBO phosphors are susceptible to moisture, 
     we do a heat seal of the element in a plastic bubble that is part of 
     the ring material. We also desiccate all rings for a minimum of 24 
     hours, or longer is moisture is visible. Every ring must me visually 
     checked prior to processing.
     
     
     >>(4) Is there any standard protocol or guideline?<<
     
     I recommend that you obtain a copy of the NVLAP Handbook 150-4 and 
     associated checklists which shows some of the minimum requirements for 
     extremity monitoring. 
     
     For some specifics, ensure uniform geometry for the ring whenever it 
     is processed, using a mark of some kind, ensuring that it is always in 
     the same configuration as to when the element correction factor was 
     developed, annealed and then processed... This is very important, be 
     it a chip or a phosphor.
     
     Hopefully this will initiate some information for you, and food for 
     thought.
     
     
     Sandy Perle
     Supervisor Health Physics
     Florida Power and Light Company
     Nuclear Division
     
     (407) 694-4219 Office
     (407) 694-3706 Fax
     
     sandy_perle@email.fpl.com
     
     HomePage: http://www.lookup.com/homepages/54398/home.html
     


______________________________ Reply Separator _________________________________
Subject: Finger Dosimetry
Author:  radsafe@romulus.ehs.uiuc.edu at Internet-Mail
Date:    1/18/96 1:22 AM


Dear Radsafer,

We are going to establish our own finger dosimetry at the Hong Kong
University of Science and Technology. Your experience and advices are most
appreciated on:


Regards

Paul

Paul M W Chan, PhD
University Radiation Protection Officer
Hong Kong University of Science and Technology
IN%"eomwchan@usthk.ust.hk"