Re: NDT of diagnostic x-ray rooms

[Bob Wilson <bmwils2@pop.uky.edu>]

Chris,

That Tc-99m spectrum sure seems to make the difference, though.

Bob 

At 11:07 AM 3/15/00 -0600, you wrote:
>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

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