[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: NDT of diagnostic x-ray rooms
Please note that the Am241 *gamma* is at 60 keV. The Tc99m gamma is at 141
keV. There are also some diddley xrays of ~ 18-21 keV.
chris a.
At 10:43 AM 3/15/00 -0600, you wrote:
>David,
>
>I have used both Am-241 and Tc-99m. For diagnostic x-ray energies, I find
>Tc-99m will give superior results, plus it is cheap. One can use a
>relatively light-weight vial shield and make a handy "gamma camera" that
>give a collimated but conveniently broad beam. the main concern is that it
>is liquid and can be broken. In tests, I have found it to provide an
>almost exact lead thickness result. For testing unknown walls, the source
>to detector distance must be well controlled and consistent. I use a 1
>meter distance unshielded reading, comparing to the 1 meter readings
>through a barrier (I prefer to use an ion chamber, but any detector is
>fine). "Walkie-Talkie" radios are great to coordinate between the person
>maneuvering the source and the person taking the measurements.
>
>My tests indicate that it will require about a Ci of Am-241 to be generally
>useful, and the Am x-ray is a much higher energy than diagnostic x-ray.
>For sheet lead, this means that the thickness resolution is not so good.
>
>There are some really good Australian papers on using Am, however.
>
>Bob
>
>At 04:55 PM 3/13/00 -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
>> ===================================
>>
>>************************************************************************
>>The RADSAFE Frequently Asked Questions list, archives and subscription
>>information can be accessed at http://www.ehs.uiuc.edu/~rad/radsafe.html
>
>Bob Wilson, Director
>Radiation Safety Office
>University of Kentucky
>102 Animal Pathology
>Lexington, KY 40546-0076
>W: 606-323-6308
>FAX: 606-323-4752
>bmwils2@pop.uky.edu
>http://www.uky.edu/FiscalAffairs/Environmental/radiation/
>************************************************************************
>The RADSAFE Frequently Asked Questions list, archives and subscription
>information can be accessed at http://www.ehs.uiuc.edu/~rad/radsafe.html
>
************************************************************************
The RADSAFE Frequently Asked Questions list, archives and subscription
information can be accessed at http://www.ehs.uiuc.edu/~rad/radsafe.html