What every dosimetry processor should be asked

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

John Laferriere broached an issue that has always amazed me 
when  when addressing a facilities dosimetry needs. While I will 
never address any dosimeter specifically, be it ours or another 
processors, I will address what I believe all facilities should ask 
their current processor, or another when considering providing 
dosimetry processing requirements.

What I find most often is that a facility seems to be primarily 
concerned with cost (expending most of their questions on that 
topic) and very little in the area of technical basis or performance. 
Often the only specification listed is that the processor must be 
NVLAP accredited, or must meet some other accreditation 
standard, besides ANSI N13.11-1993 (some still refer to the 1983 
version, that has been updated quite a few years ago). What they 
don't consider is that NVLAP means that a processor only meets 
the minimum standards to be accredited. What a facility should be 
asking are the same type of questions I as a NVLAP on-site 
assessor asks when I assess a facility, or any other NVLAP 
assessor may ask (there is always subjectivity in any 
assessment). I would love to see the following performance 
questions asked when I have to review a bid proposal. These are 
the types of areas all facilities should be asking, be it of me, or any 
other processor, whether they are internal or external processors:

(1) First and foremost ask for the NVLAP Proficiency Test results 
for several years. While the NVLAP test is more controlled, if a 
processor's results are excessive, consider that if this is the case 
in a controlled test, under sterile conditions, be really concerned as 
to how the processor will handle field type exposures, where there 
are significant environmental and external factors affecting the dose 
assessment. This is part of the quantitative assessment by the 
facility, to ensure that the processor has tested, and performed 
adequately in the various NIST Beam Code tests.

(2) Did the processor test in all of the appropriate categories 
correlated to the facility radiation environment. Low-Energy X-ray 
Category III is a specific test. However, did the facility only test in 
the 70 to 122 keV ranges, or did they test the 15 to 122 keV range. 
Depending on the Category III test determines the Category VI 
mixture test (Low-Energy X-Ray + Cs-137 test).

(3) Dis they test Category V beta only high energy, or did they test 
the low and high energy beta mixture. This affects the Category VII 
mixture test (beta + Cs-137).

(4) NVLAP doesn't test (currently) beta + Low-Energy X-Ray, or 
neutron and beta mixtures yet. This is tested within the DOELAP 
standard, and will be coming to NVLAP to some degree during the 
next revision (under consideration now).

(5) Ask for the past on-site assessment reports and any responses 
sent back to NVLAP (if there were any). This is the qualitative 
NVLAP assessment, differed from the proficiency qunatitative 
assessment.

(6) Ask the processor for their technical basis for their program.

(7) Ask for LLD calculations for the dosimeters to be used.

(8) Ask for the overall system measurement uncertainty for the 
dosimeters to be used.

(9) Ask for the calibration standards used.

(10) Ask for what external factors that might affect the dosimeter 
response (chemical, heat, moisture, neutron environment - 
especially if not monitoring for neutron). 

(11) Is dosimeter fading incorporated in the dose assessment 
process.

(12) How are anomalies determined that mitigates an erroneous or 
questionable dose being reported to the customer. Being proactive 
is a key technical ingredient.

(13) How are background subtracted when no control is returned.

(14) How are chemical processes monitored to identify systematic 
changes, predominantly film and CR39.

(15) What is the confirmatory measurements program in place.

(16) How are on-line QCs used, read and are they used to 
normalize doses.

(17) What are the process and outcome indicators tracked and 
assessed to determine systematic issues and areas for 
improvement.

(18) How is the maintenance program managed. 

These are just simple types of factors that all processors should be 
asked, based on how much information the user is concerned with. 
As I stated at the outset, cost and being NVLAP accredited are 
important, but read between the lines. You'll be more confident in 
the results you receive from whomever does your processing.

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


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