Re: Shopping for portable gamma spec system

[bgb3@mhg.edu]

John
I'm posting this reply on the net in the offchance that others may be interested
in one evaluation of a protable gamma ray detector/analyzer.  We purchased a
MiniSpec from Exploranium about two years ago to monitor and identify
radioactive waste coming from the hospital wards (including nuclear medicine).
We were very happy with the unit with two exceptions.  The GR30 had a very wide
energy range ( 0 - 1500 Kev) and the resolution for low energy radionuclides
such as Tc-99m, Tl-201, etc. was limited.  We could still use the unit to
identify the low energy stuff but it was limited.  The other exception was the
built-in library of identifiable radionuclides.  There were none of medical
interest.  Most were for nuclear power plant environments.  The newer model
which we have had a few months is much better.  A pretty comprehensive library
is now available and a wider energy range at the low end is available.

We had an opportunity to test the durability of the device.  One of our
technicians was hanging off the side of a truck laden with medical waste being
readied for transport to a disposal site using one hand to hang on and the other
holding the mini-spec to locate a radioactive box.  He lost his grip and had to
drop the mini-spec to use his other hand to grab a support.  The instrument fell
about 10 feet onto a concrete surface.  Needless to say the instrument stopped
working.  We sent it back to the manufacturer for a repair evaluation expecting
several thousand dollars in repairs.  It turns out that the only damage was a
dent in the case and a slight dent in the handle.  The processor board was
disconnected at a cable junction which was the reason for the operational
cessation.   The crystal was undamaged.    Overall the cost was minimal since we
had to send the unit back for calibration anyway so we had it upgraded to
include the newer library and improved energy resolution at lower energies.

Our experience with the unit has been very good.   You can measure exposure
rate, dose, obtain pulse height spectrum, get identification of all peaks (
resolution is excellent, especially for Tc99m and Tl-201), it is rugged (as you
might guess) and it is easy to operate.  We were able to train rather unskilled
individuals to use it.  Unfortunately, they couldn't interpret the data without
detailed instructions.  But overall we have been happy with the device.  You can
also download the data into a larger computer for more sophisticated analysis.

If you have any detailed questions about our experience with the device feel
free to contact me personally.

Bill

Billy Bass, PhD
Radiation Safety Office
Washington Hospital Center
Washington, DC
Telephone (202) 877-8025
e-mail  bgb3@mhg.edu



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