Re: radiographer "overexposure"

On 29 Jul 2003 at 22:17, BLHamrick@aol.com wrote:

> I was wondering about this. Thanks for chiming in. Would that also be the case for other types of common dosimeters

> (TLD's, OSL's, etc.)? I mean, obviously, they wouldn't be "dark," but what is the upper range for the other technologies?

Hi Barbara,

I'll address the TLD only. TLDs, be they LiBO, LiF, CaF or CaSO (we use them all)

can accurately measure and report dose well above 1000 rads, for personnel

dosimetry. In fact, we have a dosimeter that uses LiF (TLD-100 elements) that

measure and reports exposure up to 1 KGy (100,000 rads for those who don't like SI

units), NOT a personnel dosimeter.

Film is unique due to the technology and the film itself. It simply darkens with

exposure, like a camera film, and when it approaches 500 rads or so, the sensitive

and non-sensitive emulsions are simply too dark, and, the OD slope is almost

vertical, whereby a slight move up or down the scale results in 10s up to 100s of

rads. Obviously it is almost impossible to do any dose assessment. As far as the

~1400 rads (if the report is accurate in stating the assumed dose), I say that anyone

who states that they can assess film OD and report a dose at that level, is simply

making a ludicrous assertion, or, has not handle on reality when it comes to film

dosimetry. I don't know who assessed it, but I hope that NVLAP takes a close look at

their overall program, technical staff and QA program. Again, that assumes that they

in fact did report and stand behind a reported dose of ~1400 rads.

***************************************************************

Sandy Perle

Director, Technical

ICN Worldwide Dosimetry Service

ICN Plaza, 3300 Hyland Avenue

Costa Mesa, CA 92626

Tel: (714) 545-0100 / (800) 548-5100 Extension 2306

Fax: (714) 668-3149

E-Mail: sperle@icnpharm.com

E-Mail: sandyfl@earthlink.net

Personal Website: http://sandy-travels.com/

ICN Worldwide Dosimetry Website: http://www.dosimetry.com/

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References:
- Re: radiographer "overexposure"
  - From: BLHamrick@AOL.COM