[ RadSafe ] FW: OSL/TLD Comparison Experience

[Perle, Sandy]

Thanks Neill,

Correct as always.

In our program with the Thermo (Harshaw) TLD we make assumptions to middle of wear period for both the pre and post fade, and can make the very adjustments you mentioned depending on when the majority of the irradiation occurs. This is quite accurate with expected uncertainty. If one does not perform this adjustment, the reported data can be quite inaccurate. Dosimetry is not simply reading a badge, there is a lot more to it, as you well know from your many years of experience!!!

Regards,

Sandy

-----------------------------------
Sander C. Perle
President
Mirion Technologies
Dosimetry Services Division
2652 McGaw Avenue
Irvine, CA 92614

+1 (949) 296-2306 (Office)
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-----Original Message-----
From: Neill Stanford [mailto:stanford at stanforddosimetry.com]
Sent: Tuesday, April 27, 2010 1:18 PM
To: 'Michael McNaughton'; Perle, Sandy; 'Brennan, Mike (DOH)'; radsafe at health.phys.iit.edu
Subject: RE: [ RadSafe ] FW: OSL/TLD Comparison Experience

Mike,
LiF definitely fades. The pre-heat that Sandy described takes care (removes)
of a big portion of the signal that fades, but there is still pre- and
post-irradiation fading in the region of interest.
In my post, I referred to corrections that manufacturers and others have
incorporated into their programs to correct for the fade. Thermo in
particular has a sophisticated routine to correct for both pre and post
irradiation fade.
With any fade corrections, inaccuracies arise from inaccurate assumptions.
If the correction assumes an acute exposure at the midpoint of the period
but the actual exposure was received at the beginning or the end of the
period then the correction will be inaccurate. Typically in these
situations, when we know it, a more appropriate correction can be applied.
But for most situations, we assume chronic exposure conditions and the
corrections do well.


Sincerely,

Neill Stanford, CHP
Stanford Dosimetry, LLC
stanford at stanforddosimetry.com
www.stanforddosimetry.com
(360) 733-7367 (V)
(360) 933 1794 (F)


-----Original Message-----
From: Michael McNaughton [mailto:mcnaught at lanl.gov]
Sent: Tuesday, April 27, 2010 12:50 PM
To: Perle, Sandy; Neill Stanford; 'Brennan, Mike (DOH)';
radsafe at health.phys.iit.edu
Subject: Re: [ RadSafe ] FW: OSL/TLD Comparison Experience

Sandy

I have about 10 years of data from more than 100 environmental
dosimeters. With LiF, I measure 5% to 10% fade in 3 months. If this
is surprising, let me know so we can discuss it.

mike

At 03:07 PM 4/23/2010, Perle, Sandy wrote:
>Environmental heat, leaving dosimeter in hot car, is generally not
>going to cause any appreciably fading/annealing effect.
>
>Sandy Perle
>Sent from my Windows phone from AT&T

Mike McNaughton
Los Alamos National Lab.
email: mcnaught at LANL.gov or mcnaughton at LANL.gov
phone: 505-667-6130; page: 505-664-7733




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