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Title: Organ and effective dose coefficients for cranial and caudal irradiation geometries: Neutrons

Abstract

Dose coefficients based on the recommendations of International Commission on Radiological Protection (ICRP) Publication 103 were reported in ICRP Publication 116, the revision of ICRP Publication 74 and ICRU Publication 57 for the six reference irradiation geometries: anterior–posterior, posterior–anterior, right and left lateral, rotational and isotropic. In this work, dose coefficients for neutron irradiation of the body with parallel beams directed upward from below the feet (caudal) and downward from above the head (cranial) using the ICRP 103 methodology were computed using the MCNP 6.1 radiation transport code. The dose coefficients were determined for neutrons ranging in energy from 10 –9 MeV to 10 GeV. Here, at energies below about 500 MeV, the cranial and caudal dose coefficients are less than those for the six reference geometries reported in ICRP Publication 116.

Authors:
 [1];  [2];  [3];  [4]
  1. Y-12 National Security Complex, Oak Ridge, TN (United States); Easterly Scientific, Knoxville, TN (United States)
  2. Easterly Scientific, Knoxville, TN (United States)
  3. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Georgia Inst. of Technology, Atlanta, GA (United States)
  4. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
Work for Others (WFO); USDOE
OSTI Identifier:
1356889
Grant/Contract Number:
AC05-00OR22725
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Radiation Protection Dosimetry
Additional Journal Information:
Journal Volume: 175; Journal Issue: 1; Journal ID: ISSN 0144-8420
Publisher:
Oxford University Press
Country of Publication:
United States
Language:
English
Subject:
61 RADIATION PROTECTION AND DOSIMETRY

Citation Formats

Veinot, K. G., Eckerman, K. F., Hertel, N. E., and Hiller, M. M. Organ and effective dose coefficients for cranial and caudal irradiation geometries: Neutrons. United States: N. p., 2016. Web. doi:10.1093/rpd/ncw262.
Veinot, K. G., Eckerman, K. F., Hertel, N. E., & Hiller, M. M. Organ and effective dose coefficients for cranial and caudal irradiation geometries: Neutrons. United States. doi:10.1093/rpd/ncw262.
Veinot, K. G., Eckerman, K. F., Hertel, N. E., and Hiller, M. M. 2016. "Organ and effective dose coefficients for cranial and caudal irradiation geometries: Neutrons". United States. doi:10.1093/rpd/ncw262. https://www.osti.gov/servlets/purl/1356889.
@article{osti_1356889,
title = {Organ and effective dose coefficients for cranial and caudal irradiation geometries: Neutrons},
author = {Veinot, K. G. and Eckerman, K. F. and Hertel, N. E. and Hiller, M. M.},
abstractNote = {Dose coefficients based on the recommendations of International Commission on Radiological Protection (ICRP) Publication 103 were reported in ICRP Publication 116, the revision of ICRP Publication 74 and ICRU Publication 57 for the six reference irradiation geometries: anterior–posterior, posterior–anterior, right and left lateral, rotational and isotropic. In this work, dose coefficients for neutron irradiation of the body with parallel beams directed upward from below the feet (caudal) and downward from above the head (cranial) using the ICRP 103 methodology were computed using the MCNP 6.1 radiation transport code. The dose coefficients were determined for neutrons ranging in energy from 10–9 MeV to 10 GeV. Here, at energies below about 500 MeV, the cranial and caudal dose coefficients are less than those for the six reference geometries reported in ICRP Publication 116.},
doi = {10.1093/rpd/ncw262},
journal = {Radiation Protection Dosimetry},
number = 1,
volume = 175,
place = {United States},
year = 2016,
month = 8
}

Journal Article:
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  • With the introduction of new recommendations of the International Commission on Radiological Protection (ICRP) in Publication 103, the methodology for determining the protection quantity, effective dose, has been modified. The modifications include changes to the defined organs and tissues, the associated tissue weighting factors, radiation weighting factors and the introduction of reference sex-specific computational phantoms. Computations of equivalent doses in organs and tissues are now performed in both the male and female phantoms and the sex-averaged values used to determine the effective dose. Dose coefficients based on the ICRP 103 recommendations were reported in ICRP Publication 116, the revision ofmore » ICRP Publication 74 and ICRU Publication 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). In this work, the methodology of ICRP Publication 116 was used to compute dose coefficients for photon irradiation 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 from personnel standing on contaminated surfaces or volumes and from overhead sources. 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. As with calculations reported in ICRP 116, the effects of charged-particle transport are evident when compared with values obtained by using the kerma approximation. At lower energies the effective dose per particle fluence for cranial and caudal exposures is less than AP orientations while above similar to 30 MeV the cranial and caudal values are greater.« less
  • External dose coefficients for environmental exposure scenarios are often computed using assumption on infinite or semi-infinite radiation sources. For example, in the case of a person standing on contaminated ground, the source is assumed to be distributed at a given depth (or between various depths) and extending outwards to an essentially infinite distance. In the case of exposure to contaminated air, the person is modeled as standing within a cloud of infinite, or semi-infinite, source distribution. However, these scenarios do not mimic common workplace environments where scatter off walls and ceilings may significantly alter the energy spectrum and dose coefficients.more » In this study, dose rate coefficients were calculated using the International Commission on Radiological Protection (ICRP) reference voxel phantoms positioned in rooms of three sizes representing an office, laboratory, and warehouse. For each room size calculations using the reference phantoms were performed for photons, electrons, and positrons as the source particles to derive mono-energetic dose rate coefficients. Since the voxel phantoms lack the resolution to perform dose calculations at the sensitive depth for the skin, a mathematical phantom was developed and calculations were performed in each room size with the three source particle types. Coefficients for the noble gas radionuclides of ICRP Publication 107 (e.g., Ne, Ar, Kr, Xe, and Rn) were generated by folding the corresponding photon, electron, and positron emissions over the mono-energetic dose rate coefficients. Finally, results indicate that the smaller room sizes have a significant impact on the dose rate per unit air concentration compared to the semi-infinite cloud case. For example, for Kr-85 the warehouse dose rate coefficient is 7% higher than the office dose rate coefficient while it is 71% higher for Xe-133.« less
  • Prophylactic cranial irradiation (PCI) for the prevention of brain metastasis in small cell lung cancer remains controversial, both in terms of efficacy and the optimal dose-fractionation scheme. We performed this study to evaluate the efficacy of PCI at low doses. One hundred and ninety-seven patients were referred to our institution for treatment of limited stage small cell carcinoma of the lung between June 1986 and December 1992. Follow-up ranged from 1.1 to 89.8 months, with a mean of 19 months. Eighty-five patients received PCI. Patients receiving PCI exhibited brain failure in 15%, while 38 of untreated patients developed metastases. Thismore » degree of prophylaxis was achieved with a median total dose of 25.20 Gy and a median fraction size of 1.80 Gy. At these doses, acute and late complications were minimal. Patients receiving PCI had significantly better 1-year and 2-year overall survivals (68% and 46% vs. 33% and 13%). However, patients with a complete response (CR) to chemotherapy and better Karnofsky performance status (KPS) were overrepresented in the PCI group. In an attempt to compare similar patients in both groups (PCI vs. no PCI), only patients with KPS {ge} 80, CR or near-CR to chemotherapy, and treatment with attempt to cure, were compared. In this good prognostic group, survival was still better in the PCI group (p = 0.0018). In this patient population, relatively low doses of PCI have accomplished a significant reduction in the incidence of brain metastasis with little toxicity. Whether such treatment truly improves survival awaits the results of additional prospective randomized trials. 44 refs., 4 figs., 2 tabs.« less