Ion Chamber Instruments

[Karin Gordon <KGordon@exchange.HSC.MB.CA>]

James Bult wrote:
<<I would just as soon take a beating as buy a Victoreen ion chamber.
My misguided predecessor thought they were great, and therefore, I have
inherited a lot of them.  Kudo's for you folks realizing that they need
something else.>>

Ditto for part of my experience with the  Victoreen 450  series.  Back
about 7 years ago, I purchased a Victoreen 450P (pressurized) ion
chamber because it could measure down to lower levels.  It was pretty
jumpy at low dose rates,  which became more apparent  when I compared it
to a more recent version purchased by a colleague. When I phoned
Victoreen to complain about this, they told me I had one of the early
model units, and that the newer units had different electronic
circuitry.  They told me I would have to pay about $900 to upgrade the
unit. At that point I was very unimpressed - they were not amenable to
offering a free upgrade for an obvious defect that they had corrected in
subsequent models.  I didn't have the money, so tolerated the lousy
performance on the low end of the scale.  A year or so later, the
pressurized ion chamber developed a leak, the unit went seriously off
calibration, and I paid about $400 to have Victoreen repair the chamber
and calilbrate the unit.  Within a year, the chamber had leaked again
and was unusable.  At that point we decided that the unit was best used
as an expensive paperwight and it was not worthwhile to send it for any
more expensive repairs. It was obviously a lemon, and Victoreen was not
very responsive to taking ownership of the problem.

Early on in this saga, I advised a number of nuclear medicine
departments and our radiopharmacy to purchase the Victoreen 450  (plain
model, not pressurized).  So far they have been working fine and our
annual calibration data indicate that they are performing consistently.

For my own kit, last year I purchased the ESM-Eberline FH40G-L-10, which
uses a proportional counter detector.  It is very sensitive: down below
100 nSv/hr (0.01 mr/hr) up to 25 mSv/hr  which is just fine for the
hospital environment where I work.. There is another unit designed for
the higher dose rates.  The unit I have is quite slick, lightweight, has
excellent liquid crystal display, alarm points, loads of additional
bells and whistles like computer interface. etc.  It has a shoulder
strap and is small enough to fit into my labcoat pocket, so I wear it
like a personal dosimeter when I'm doing "hot" tasks. I am very
impressed and happy to recommend it to anyone.  The ESM Eberline company
is in Germany , it used to be  "FAG Radiation Measurement" for more than
a decade, before it was purchased by Thermo Instrument Systems Inc.
which also owns Eberline in Santa Fe.  Check out their website at
<www.esm-online.de>.  The unit was pricey, primarily because the
exchange rate between the German mark and the Canadian dollar.  However,
its worth it because I expect to use it for a long time. 

(And no, I don't work for the company or own any shares in it!!)


*****************************************************
Karin Gordon
Radiation Safety Officer
Health Sciences Centre
GC214 - 820 Sherbrook Street,
Winnipeg, Manitoba
CANADA R3A 1R9

phone (204) 787-2903
fax      (204) 787-1313
e-mail  kgordon@hsc.mb.ca    


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