[ RadSafe ] Cs-137 beam calibrator output

[JPreisig at aol.com]

Radsafe,
 
    Some of us theoretical/computational health physicists  use MCNP, other 
computer codes, and dose versus distance curves. also.  See  articles by 
Hunt (England), Eisenhauer and Schwartz (USA) and more recent  articles.
 
     Joe Preisig
 
 
 
 
In a message dated 9/22/2014 10:51:43 P.M. Eastern Daylight Time,  
doctorbill34 at gmail.com writes:

You  can't rely on theoretical calcs; there are too many  complicating
factors.  You have to develop dose versus distance curves  using NIST
traceable ion chambers or similar instruments.  Maybe TLD's  as part of a
NVLAP certified system would work.

Bill Lipton
It's  not about dose, it's about trust.


On Mon, Sep 22, 2014 at 7:00 PM,  clayton bradt <dutchbradt at gmail.com> 
wrote:

> My apologies if  this duplicates an earlier post. Having received no 
bounce
> notice for  the previous one, I am re-sending from a different email
>  account.
>
> ********
>
> Original  post:
>
>
> I’ve been reviewing data for a beam calibrator  containing a Cs-137 source
> with nominal activity 600 mCi on  1/18/2005.  The measured output at 1 
meter
> along the beam center  line was 0.2443 R/h on the same date.  Comparing 
that
> with the  calculated exposure rate at 1meter from a 600 mCi point source I
> get  0.193 R/h, assuming a Gamma constant for Cs-137 of 0.322 R/h at 1  
meter
> per Ci.   I am surprised at such a large difference  (27%) between the
> theoretical value and measurement.  Should I  be?  I know that scatter 
from
> the collimator will affect the  actual exposure rate, but this much?
>
>
>
> Any help  from people with more experience with exposure rate calibrations
> on  this list will be most appreciated.
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