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Re : Dose estimates when dosimetry is lost/damaged
Fellow Radsafers,
As a former nuclear power plant health physicist, and
now a regulator involved in the approval of
dosimetry services operating in Canada, I can assure you
that I would expect Dosimetry Services and Users of
Dosimetry Services to operate in a manner similar
to what Sandy has outlined.
I applaud Sandy for correcting a situation which I would
call unacceptable.
Jim Presley
Health Physicist
Atomic Energy Control Board
presley.j@atomcon.gc.ca
Date: Wed, 18 Dec 1996 08:02:06 -0800
From: "Sandy Perle" <sandyfl@ix.netcom.com>
Subject: Dose estimates when dosimetry is lost/damaged
The practice of dose estimates when dosimetry was either lost or
damaged, during my 22 years as a power reactor health physicist, was
to conduct a dose investigation based on survey data, secondary
dosimetry, dosimetry results from others who worked with the
individual in question and most importantly, an interview with the
individual. This investigation led to a dose estimate which was first
discussed with the individual, a signature obtained from the
individual signifying that the investigation was conducted, what the
resultant dose was and that the individual concurred with the dose
estimate. What I am finding in the world of commercial dosimetry and
what the customers want is well beyond this, and a practice I find
disturbing at a minimum.
I have learned that many of the current dosimetry processors, as well
as the former Siemens Dosimetry service, routinely provided their own
estimate to the customer when a dosimeter was lost or damaged. They
would base this estimate on the previous two or more dosimeters. This
estimate is based on the assumption that the previous work history
and doses assigned are indicative and correlated well to the current
time period. I find this practice to be disturbing, for many reasons
I will elaborate on. Let me also state that it is my policy that my
operation will not provide an estimate for any lost or damaged
dosimeter. The methodology is simple as to how this is accomplished,
who initiates the estimate and how it is documented.
In my opinion, when a processor provides an automatic dose estimate,
the following problems are evident:
1. Isn't it the responsibility of the individual who is monitored to
be cognizant of their radiation exposure?
2. Isn't the RSO or whoever is accountable for the dosimetry program
accountable as the caretaker of the individual's doses, to ensure
that they are as accurate as possible, and if there is a question
regarding an individual's dose, that they become an integral part of
the investigation which results in a dose estimate to be assigned?
3. IF a processor automatically assigns an estimate, automatically
without any intervention from the customer, isn't this a liability
issue, and could within all probablility, end up in litigation some
time later?
4. How is the individual notified that their dosimetry was damaged
during processing, and that an estimate has been assigned? How are
they informed of the methodology used to arrive at the dose estimate?
5. How do the regulators look at a dose assigned without any
intervention from the customer, especially without any documented
investigation?
6. The processor takes on a serious liability without a detailed
audit trail which shows the chain of command of the dose assignment
process ... if, there is this automatic dose estimation without any
intervention from the customer, who I believe should be legally bound
to defend the dose assigned, with the assistance of the processor.
The policy I have implemented is as follows. While it is one that is
much different than what our customers have been used to, it is one
they agree with after the policy and reasons for it are discussed
with them. As in all things, effective communication is required.
1. If after a dosimeter is processed, and the flag and intervention
reports are run, and it is determined that the dosimeter either is
damaged, had an erroneous processing or some other anomaly is
identified, the customer is notified and a discussion ensues to
assist the customer in providing us with a written estimate of what
the most likely dose is, and when it is entered in our database, it
is identified as a "customer provided dose estimate".
2. If a customer calls and requests that a dosimeter be reevaluated,
and that evaluation determines that the resultant dose is accurate,
the customer must request in writing that a different dose be
assigned and their reason for the request. The dose is changed in the
radiation history file, the original dose is maintained as one that
was the result of the processing, and the file is noted that the
estimate was provided by the customer. This is necessary to protect
both the customer as well as my operation from liability issues.
3. If a dosimeter is lost or not returned, it is again the
responsibility of the customer to provide us with a written estimate
for the dose to be assigned.
If one thinks about this logically, it is NOT very difficult for an
individual, who is aware that a high dose was received, or that a
procedural violation has occurred, to simply "lose" the dosimeter or
"damage" it in some was to cause an estimate to be assigned. In this
event, to assume that the current dose is equivalent to previous
exposures without an investigation in my opinion is reckless and
brings into question the entire dosimetry processing program. It is
critical that when a dose is assigned to any worker, that the utmost
in care be assured to arrive at a reasonable representation of an
individual's dose. In a "litigation happy society" it is essential
that we, the health physics community" ensure that doses are treated
with respect, accuracy and a thorough understanding and practice
based on sound methods.
Comments from the group will be appreciated.
Sandy Perle
Director, Technical Operations
ICN Dosimetry Division
Office: (800) 548-5100 Ext. 2306
Fax: (714) 668-3149