Re: fluence-to-dose equivalent conversion coefficients

From: Alberto Fasso' (fasso@SLAC.Stanford.EDU)
Date: Mon Jan 01 2007 - 18:14:06 CET

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    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 FassÚ
    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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