Re: Radon vs. LNT - [CUT TO] the Chase

["Ron L. Kathren" <rkathren@tricity.wsu.edu>]

There have been a number of papers published with resepct to the angular
dependence of film and TL dosimeters, some of which goes back several
decades.  I suggest that you do a literature search in Health Physics; there
you will find a paper by Alun Jones written about 35 years ago that
discusses the problem in some depth and provided correction factors.  Greta
Ehrlich in one of the early NBS handbooks and in separate publications also
described angular dependence of film badges and ways to correct for it.
Years ago when I was first starting out in the field we studied but never
published calibration of film badges on and off a phantom, and compared a
rotating badge to one exposed head on.  The descriptions/evaluations of
various badges including the Hanford badge usually contain information about
energy and angular dependence, as do various books including the work by
Klaus Becker, Photographic Film Dosimetry.

But I would ask you this question:  If a badge is worn on the front of the
body, upper portion, which is the portion of the body (other than the hands,
perhaps) most likely to receive the highest external exposure, would not the
badge dose actually be an overstatement of the average depth dose received
by the body?  Only in the case of a nonuniform field in which the badge is
basically 'missed' by a beam can I think of a badge worn on the upper torso
registering only 10% of the average whole body dose.  In such cases, proper
health physics practice is to badge differently to ensure that the exposures
are not missed.

Ron Kathren, CHP



----- Original Message -----
From: Thomas Gleich Harrison <tomh@jove.acs.unt.edu>
To: Multiple recipients of list <radsafe@romulus.ehs.uiuc.edu>
Sent: Thursday, March 09, 2000 2:26 AM
Subject: Re: Radon vs. LNT - [CUT TO] the Chase


>
> You know.. in my very, very humble opinion,.. I do wish we could simply
> ignore the so called "radon health threat" that we seem to be so
> mesmerized by these days. Other than for a very few specific environmental
> situations such as for uranium miners where it need be addressed, we have
> lived with uranium and it's progeny in our environment for how long
> now...... and if radon is a "problem", how are we going to solve it....
> "clean up" radon in our air ????  Is that the suggested solution ????
>
> But let me ask about another situation... does anybody in the RADSAFE
> community know about any quantitative work that has been done on
> evaluating the gross underestimate for torso dose that can be expected
> from single TLD or film badge display orientation to a unidirectional
> radiation field ????  It seems to me that due to variable geometrical
> orientation and body shielding, wearing a single film tab anywhere on the
> upper torso undoubtedly results in a gross underestimate of realistic
> whole body doses, possibly recording only 10% or maybe even less of the
> actual dose received by the body in a unidirectional field. I've had
> several students express an interest in looking into this problem if in
> fact it is a problem.... simply stated, they've asked that if their TLD
> reports a  WB dose of 100 mrem which of course is a minimum dose, is there
> a correction factor which would give them a more realistic WB
> dose estimate?? My only answer is I don't know of one.....
>
> Thanks in advance for yor help.....
>
> Tom Harrison, Ph.D.
> Radiation Safety Officer
> Physics Dept
> University of North texas
>
> e-mail: tomh@facstaff.cas.unt.edu
>
>
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