wrote:
On Jul 24, 12:04 pm, H. Wabnig .... .-- .- -... -. .. --.
@ .- --- -. DOT .- - wrote:
On Tue, 24 Jul 2007 09:37:25 -0700, "




I need of a Geiger counter to do radiation measurements of x-ray
equipment, cabinets, etc. Since these are numbers going into FDA
reports the counter has to be calibrated and meet all requirements for
the US. Something like a Bicron Surveyor would work quite well. I
would like to get a digital unit that could be used for long term
measurement (downloadable to a computer), though. So the requirements
a
1) Constant real-time measurement, i.e. not just one measurement for
one button click plus quick response time.
2) Beeper that beeps quicker and/or louder depending on the mR/h
measured.
3) Digital read-out for long term measurement.
There are two units I have seen:
1)http://www.gammascout.com/
2)http://www.imagesco.com/geiger/digit...r-counter.html
Any input is highly appreciated.
Geigers are not used for medical X-rays.
The energy spectrum of geiger tubes forbids that.

You may use either a ionisation chamber, or even better
a modern cadmium-zink-telluride sensor.

There are very stringent rules how to monitor medical equipment
and you better contact the manufacturers of your machines.

w.- Hide quoted text -

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w.

Thanks for the input. This is actually not for a medical device. FDA
does not just regulate medical devices but also for instance x-ray
cabinet systems. They have certain requirements that need to be met
for these kind of devices. One stipulation is that you cannot exceed
0.5mR/h 5cm from the cabinet. So I need a device that can verify this
reliably. If any of the cheap ($500) digital devices I mentioned can
do this then that's fine. Do they?

I'm still puzzled why there are such huge differences between
different devices ($500 vs $3000).

Since we use tube voltages similar to medical I am intersted in your
statement that a GM tube can't be used. Why is that?



I am going to take your word for it and assume you know what you are
doing. You ask why prices differ so much. I can think of may reasons,
boiled down to words such as MILSPEC, Marine and Medical. Those words
can make a world of difference in prices, usually up.

Of those, I think that Milspec is legitimate in this case. A counter of
that type must meet a pretty good shock.