Photon Organ and Effective Dose Coefficients for Cranial and Caudal Irradiation Geometries - Paper 148
- Y-12 National Security Complex, Oak Ridge, TN 37831 (United States)
- Center for Radiation Protection Knowledge, Oak Ridge National Laboratory, Oak Ridge, TN, 37831 (United States)
With the introduction of new recommendations of the ICRP in Publication 103 the methodology for determining the protection quantity effective dose has been modified. The modifications include changes in organ/tissue weighting factors as well as some changes in radiation weighting factors. Computations of protection dose coefficients now require the use of reference male and female voxel phantoms, see ICRP Publication 110. Computations of equivalent doses in organs and tissues are now performed in each phantom and the average is used to compute the effective dose. The latest set of external dose coefficients using the new reference phantoms and the latest guidance from the ICRP were performed by the ICRP DOCAL task group and reported in ICRP Publication 116, the revision of ICRP Publication 74 and ICRU Report 57. The coefficients were determined for the following irradiation geometries: anterior-posterior (AP), posterior-anterior (PA), right and left lateral (RLAT and LLAT), rotational (ROT), and isotropic (ISO). For all geometries, except the ISO geometry, parallel beams are used to compute the dose coefficients. In this paper, the methodology of ICRP Publication 116 was used to compute dose coefficients for photons for irradiations of the body with parallel beams directed upward from below the feet (caudal) and directed downward from above the head (cranial). These geometries may be encountered in the workplace for personnel standing on contaminated surfaces or volumes and from overhead sources. In this work calculations of organ and tissue kerma and absorbed doses for caudal and cranial exposures to photons ranging in energy from 10 keV to 10 GeV have been performed using the MCNP6.1 radiation transport code and the adult reference phantoms of ICRP Publication 110. Dose coefficients for caudal and cranial irradiation geometries have been calculated in accordance with ICRP Publication 103. The coefficients differ significantly from AP values for both organ and tissues of ICRP Publication 116, as would be expected. For workers in these scenarios organ and effective doses can differ significantly from AP values. For common photon energies (i.e. 100 keV to a few MeV) the AP effective dose overestimates the caudal and cranial values by about a factor of ten. (authors)
- Research Organization:
- American Nuclear Society - ANS, 555 North Kensington Avenue, La Grange Park, IL 60526 (United States)
- OSTI ID:
- 23082964
- Resource Relation:
- Conference: RPSD 2014: 18. Topical Meeting of the Radiation Protection and Shielding Division of ANS, Knoxville, TN (United States), 14-18 Sep 2014; Other Information: Country of input: France; 6 refs.; available on CD Rom from American Nuclear Society - ANS, 555 North Kensington Avenue, La Grange Park, IL 60526 (US)
- Country of Publication:
- United States
- Language:
- English
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