From: Alberto Fasso' (fasso@SLAC.Stanford.EDU)
Date: Mon Jan 01 2007 - 18:14:06 CET
Hi Stefan,
writing this technical note was really a very good idea (I would like
to get a copy, please).
I would like to take this opportunity to stimulate a discussion with the FLUKA
user community on an issue with which I am struggling since a long time.
On the experimental floor of synchrotron radiation facilities, the radiation
field is composed mainly of low-energy photons. FLUKA can be used to
calculate photon spectra down to 1 keV, but conversion coefficients are
available only for energies > 50 keV or > 10 keV, depending on the type
of dose of interest (effective dose, ambient dose equivalent).
What should one do? As a very crude patch, I have modified your fluscw.f
routine and I have extended the tables to 1 keV using fluence-to-tissue kerma
conversion coefficients. This is equivalent to what I was doing many years ago,
when I was calculating photon dose by scoring energy deposition in a thin tissue
region. This solution is conservative, but I have got objections that it is
_too_ conservative.
I realize that my question goes far beyond FLUKA calculations: the actual
question should be "What dose quantity should we use in radiation protection
around this kind of facilities?". Effective dose should be ok, but there
are no conversion coefficients. H*(10) is clearly not suitable, since most of
the energy is deposited at thicknesses much smaller than 1 cm.
In practical radiation protection, one uses an instrument with a very thin
window. Shall we use H*(0.07) or H*(3)? But again, no conversion coefficients
are available.
I would like to hear from my colleagues who work at photon sources what they
think we should do. If we agree on the dosimetric quantity we want, maybe we
can convince Maurizio Pelliccioni to prepare a special set of conversion
coefficients for synchrotron radiation calculations...
Alberto
On Wed, 20 Dec 2006, Stefan Roesler wrote:
> Dear FLUKA-users,
>
> Some of you are using the routine deq99c.f (a special fluscw.f
> user-routine) to convert fluence into dose equivalent. I have now managed
> to complete a Technical Note which I would kindly ask you to cite if you
> publish dose results based on that routine in the future. In addition,
> please continue to cite also the original work by M.Pelliccioni:
>
> Stefan Roesler and Graham R. Stevenson, "deq99.f - A FLUKA user-routine
> converting fluence into effective dose and ambient dose equivalent",
> Technical Note CERN-SC-2006-070-RP-TN, EDMS No. 809389 (2006)
>
> M. Pelliccioni, "Overview of fluence-to-effective dose and
> fluence-to-ambient dose equivalent conversion coefficients for high
> energy radiation calculated using the FLUKA code", Radiation Protection
> Dosimetry 88 (2000) 279-297
>
> If you are interested in either of the two papers and you do not have
> access or if you are interested in the routine itself please do not
> hesitate to contact me directly.
>
> Best regards,
> Stefan
>
>
-- Alberto Fassò SLAC-RP, MS 48, 2575 Sand Hill Road, Menlo Park CA 94025 Phone: (1 650) 926 4762 Fax: (1 650) 926 3569 fasso@slac.stanford.edu
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