Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!samsung!caen!sol.ctr.columbia.edu!lll-winken!hpuplca!jeff
From: jeff@hpuplca.nsr.hp.com (   Jeff Gruszynski  )
Newsgroups: sci.electronics
Subject: Re: How to measure/detect X-ray (cheap)?
Message-ID: <12780004@hpuplca.nsr.hp.com>
Date: 7 May 91 21:26:06 GMT
References: <1991Apr23.172122.13076@Informatik.TU-Muenchen.DE>
Organization: Hewlett-Packard Pleasanton Ca. Sales
Lines: 60

>
> In article <1991May3.194713.15676@rand.org> edhall@rand.org writes:
>   [description of testing a dosimeter by x-raying it, but not being informed
>   of an exposure deleted]
>
>>Could well be that the badge showed a high exposure, then a human was
>>called into the loop who took one look at it and said "Looks like some
>>joker put this one in the beam; no problem."  I'm sure that your wife's
>>co-worker wasn't the first one to "test" the system in this way.
>
In a past life I worked in lab that used KCs of Co-60.  As a "prank"
someone's film badge was put on the lead shielding (outside cell).
(I heard about it after the badge was found.) It read a several times 
higher than normal (still just mRem) when it was read a the end of the 
month.  Radiation Safety brought the 'victim' in and intensely quized him 
on whether he'd walked by the source more often than usual, whether he 
was leaning closer to it, etc.  Their diligence seemed impressive.  Even 
so, when the source can deliver a instantly lethal dose of gamma to 
10 people every second, you can relax only so much... 

(i.e. 10KRad/sec.  Yes, yes, it's not physically possible to shuffle
10 people into the source path, let alone bring the sources up with
the door open, and 1KRad is not instantaneous either, but it's a way 
to get a feeling for 'how big' the dose rate is.)

>I hope that wasn't the case.  Consider this:  person positioning patient
>when the x-ray machine machine either goes off spontaneously, or some
>fool walks up and hits a button.  I'd sure want to know if this happened.
>
>Is this really rare enough to be not a concern?
>
>Aside:  My wife was informed that her badge was too hot one month.  She 
>was told it was probably a fluke, and it never happened again.  They said
>she may have left it too close to a TV or something.  She doesn't work
>near x-ray anymore, and probably won't again.  (That incident wasn't the
>decider, but why even risk it if you don't have to?)
>
>
>-- 
Another more amusing story.  One of the people in the lab went into
the hospital for some medical diagnostics.  He came back to work in the
afternoon.  As I was returning from lunch the radiation alarms went off
as I was walking into the building lobby.  I immediately got a sinking
feeling as I thought of the aforemention gamma source *and* the people
who had skipped lunch to finish up some work.  The building was
evacuated.  Radiation Safety came in with detectors.  It wasn't the
source though.  But there were some diffuse readings that kept moving around
as they searched the room.  "Hey, wait a second!  It's you!"  The guy had 
had a tracer diagnostic and was hot!  If we'd had something that hot from
the lab, we would have had to put it in lead, used DOT and state permits
to move it, etc.  (of course, our source couldn't have made it hot,
gammas don't activate, but someone else's reactor could.) I was shocked by 
how much they must have used, but apparently it was "normal" therapeutic 
levels.  Go figure.

Jeff Gruszynski
T&M STE SE
Santa Clara Sales
Hewlett Packard
---