RE: NDT of diagnostic x-ray rooms

["Tonry, Louie L MAJ EAMC" <Louie.Tonry@se.amedd.army.mil>]

We use our Co-57 flood source for the check of walls.  It is often hard to
find the source when it is collimated to a small spot.  

As far as using Am-241 - remember it is hard to get rid of once obtained.

Further, the energy spectrum for x-ray is considerably different than that
of a rad source.  So if you use your readings/measurements to calculate the
wall attenuation and then determine if this meets your requirements as
determined for the x-ray system, great.  If however, you mistakenly think
the source's attenuation characturistics mimic the x-ray, think again.

Louie Tonry, CHP
U.S. Army
C, HEalth Physics
louie.tonry@se.amedd.army.mil

-----Original Message-----
From: Gary Isenhower [mailto:garyi@bcm.tmc.edu]
Sent: Tuesday, March 14, 2000 5:42 PM
To: Multiple recipients of list
Subject: Re: NDT of diagnostic x-ray rooms


We also use Tc-99m, but we use a scint for the measurements because that
allows us to use only 7 or 8 mCi and still get a good reading inside and
outside the room. The exposure is not high, but your collimator method is a
good idea for the inside measurements - I should adopt it.  I have a simple
spreadsheet that corrects for background and attempts to guess the lbs/ft2
in the wall - let me know at garyi@bcm.tmc.edu if you would like a copy.

Gary Isenhower
Baylor College of Medicine
713-798-8353

-----Original Message-----
From: Dave Derenzo <dave@uic.edu>
To: Multiple recipients of list <radsafe@romulus.ehs.uiuc.edu>
Date: Tuesday, March 14, 2000 9:09 AM
Subject: Re: NDT of diagnostic x-ray rooms


>Dear David,
>
>You can use a Tc-99m source, which should be readily available from your
>nuclear medicine department.  Use the lead pig as a shield and collimator
>and point the open top at the wall of interest.  In the past I have used  a
>Co-57 dose calibrator source too.  Transmission through lead for Tc-99m is
>approximately:
>
>0.1 mm lead - 65.5%
>1 mm lead - 8.1%
>2 mm lead - 0.8%
>
>You can use a geiger counter to make the measurements.  Have fun.
>
>Dave Derenzo
>
>At 04:54 PM 03/13/2000 -0600, you wrote:
>>dear all
>>
>>we have a need to perform NDT of diagnostic x-ray rooms (perhaps up to 2.5
>>mm lead) in remote locations i.e. need a procedure which is simple,
>>versatile and very transportable.  we are thinking of using a sealed
>>source of Am-241 in a suitable container & a sensitive survey meter-type
>>detector.
>>
>>i have 2 questions:
>>
>>1.  is this the optimum method?  what do others do?
>>
>>2. where can we obtain a >= 500 mCi Am-241 source?
>>
>>many thanks!
>>  ===================================
>>  David Thiele PhD
>>  Manager, Statewide Medical Physics
>>  Biomedical Engineering & Health Technology Services (7D)
>>  Royal Brisbane Hospital
>>  Herston  Qld  4029
>>  Australia
>>   ----------------------------------------------------
>>  Phone: +61 7 3636 7896
>>  Fax: +61 7 3636 3518
>>  Email: thieled@health.qld.gov.au
>>  ===================================
>>
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>
>
>Dave Derenzo, RSO (dave@uic.edu)
>UIC Radiation Safety Section, M/C 932
>Phones: Voice (312) 996-1177  Fax: (312) 996-8776
>
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>The RADSAFE Frequently Asked Questions list, archives and subscription
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