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RE: NDT of diagnostic x-ray rooms
If any company that is licensed to handle 20 curies of Am-241 is interested
in manufacturing Am-241 NDT x-ray room sources, we have a 20 curie source
which contains 20 1-curie sealed sources. This source was sold by Picker in
the 60's for thyroid imaging and is currently in storage. I envision that it
may be possible to remove the 20 sources and position each in a separate pig
and meet the requirements for a special form (sealed source) for
transporting the devices. As Louie Tonry said, these sources are very
difficult to dispose of and if someone can use it for another purpose please
let me know.
CPT Arthur Morton
Chief, Health Physics Operations
Walter Reed Army Medical Center
Washington, DC
(202) 356-0058
-----Original Message-----
From: Dave Derenzo [mailto:dave@uic.edu]
Sent: Wednesday, March 15, 2000 9:18 AM
To: Multiple recipients of list
Subject: RE: NDT of diagnostic x-ray rooms
Dear Louie,
When I said collimated, I used the term loosely. What I meant was, shield
the back end of the source so that the radiation is only pointed toward the
wall being checked. This will reduce the exposure of anyone (including the
surveyors) that need to be in the x-ray room while the test procedure is
being conducted (ALARA consideration). Use of a flood source is a good
idea, but it is less readily transported (the original question referred to
remote locations).
Dave Derenzo
At 07:25 AM 03/15/2000 -0600, you wrote:
>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
> >> ===================================
> >>
> >
> >Dave Derenzo, RSO (dave@uic.edu)
> >UIC Radiation Safety Section, M/C 932
> >Phones: Voice (312) 996-1177 Fax: (312) 996-8776
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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