Re: Film badge/TLD results

["Cummings, Frederick" <CUMMINFM@inel.gov>]

     As the performance evaluation program administrator for DOELAP, I feel
     an overwhelming need to respond to Sandy's comments regarding the use
     of proficiency test results and assessments to assess commercial
     processors.  I believe that those two items only provide a starting
     point in the evaluation of a commercial processor.

     (first some preaching) Your goal is to provide the best dosimetry
     service you can to your customers, the people who work at your
     facility.  The commercial processor only processes dosimeters; they do
     not estimate dose of record for you.  As such, passing DOELAP or NVLAP
     testing weeds out the acceptable performers from the unacceptable, but
     not necessarily the good from the bad (gosh, that's hard to believe,
     but it's true.)  Therefore, for each processor you evaluate, you have
     to look at other things like: the completness of information you
     receive, the timeliness of reports and the controls put on special
     processing.

     After you select a processor, your job becomes even bigger.  In the
     DOE, for those laboratories using commercial processors, we require
     three things: (1) that the laboratory can demonstrate the accuracy of
     the results received from the processor; (2) that the laboratory can
     identify and correct anomalous dosimetry results at every point of the
     dose evaluation and (3) that the dose records for individuals contain
     sufficient information to track doses back to dosimeter reports that
     include processing information.  For #1, we recommend a combination of
     a blind audit program and a close relationship with the processor so
     the user can obtain QA information (such as QC processing information,
     calibration factors, ongoing test data and assessment reports.)  For
     #2, the DOE labs are using a 2-tier approach: (1) to identify
     anomalous doses and (2) to request that the processor provide
     information regarding anomalous chip response data as it occurs.  #3
     is pretty self-explanatory, i.e., you, as the supplier, need to
     provide the documentation linking dose histories to processing
     information.

     Okay, after this lengthy diatribe, I acknowledge that sometimes, we
     are all stuck with balancing accuracy, service and costs.  So even
     though, I believe that the major portion of our effort should be
     placed in obtaining the best accuracy and service, the question
     remains: How much do you want to spend to assure that doses below 100
     mrem/year are accurate?  Finally, with a nod to Sandy, you may want to
     contact him regarding how to track and trend dosimeter results to
     improve the performance of your program and identify ways to conduct
     cost/benefit analyses.

     Happy dosimetry.

     Rick Cummings      cumminfm@inel.gov

     Usual disclaimer regarding my opinions and employer's.

     "Shun advice at any price.  Now, that's what I call good advice."
                        Piet Hein


______________________________ Reply Separator _________________________________
Subject: Film badge/TLD results
Author:  RADSAFE (INELMAIL.RADSAFE) at _EMS
Date:    6/27/95 2:55 PM


Yesterday, Sandy Perle wrote:


    > Anyone who is concerned with the accuracy and precision of the
    > dosimetry processor they use, or are considering using, need only to
    > ask them for their NVLAP Proficiency test results ANSI N13.11 (1983 or
    > 1993 version). In addition I recommend that you ask them for the
    > on-site assessment report that is left with the lab.

    > These two items will provide enough information regarding the
    > processor to make a valid assessment of their overall program.


While true in principle, one should apply a reasonable dose of salt to the
proposal "if they did well on NVLAP (or DOELAP) then your processor will give
you good results".   I'm not taking issue with the validity of the NVLAP
process or with the idea of checking your processor's results, it should just
be kept in mind that a periodic controlled test does not guarantee "good"
dosimetry results.

A couple of things that come to  mind in this vein:


        A processor may pass NVLAP but fail DOELAP (or vice versa)...
        Or they may not be able to pass in a certain category...
        There is nothing forcing you to qualify in a given category, even
                though you may have exposure in that category...
        A processor may even use a special algorithm for reading TLDs for the
                NVLAP test that's not routinely used for personnel badges...

Other problems may creep in, such as a systematic error that is introduced by a
calibration foul-up that doesn't get corrected until months after introduction.
Or their QA may simply not be good enough to give consistent results in the
"real world".

I have heard of a number of horror stories regarding dosimetry snafu's and seen
some interesting results from limited blind spikes I have performed myself.