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Lund CM, Famulari G, Montgomery L, Kildea J. A microdosimetric analysis of the interactions of mono-energetic neutrons with human tissue. Phys Med 2020; 73:29-42. [PMID: 32283505 DOI: 10.1016/j.ejmp.2020.04.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Revised: 03/05/2020] [Accepted: 04/02/2020] [Indexed: 10/24/2022] Open
Abstract
Nuclear reactions induced during high-energy radiotherapy produce secondary neutrons that, due to their carcinogenic potential, constitute an important risk for the development of iatrogenic cancer. Experimental and epidemiological findings indicate a marked energy dependence of neutron relative biological effectiveness (RBE) for carcinogenesis, but little is reported on its physical basis. While the exact mechanism of radiation carcinogenesis is yet to be fully elucidated, numerical microdosimetry can be used to predict the biological consequences of a given irradiation based on its microscopic pattern of energy depositions. Building on recent studies, this work investigated the physics underlying neutron RBE by using the microdosimetric quantity dose-mean lineal energy (y‾D) as a proxy. A simulation pipeline was constructed to explicitly calculate the y‾D of radiation fields that consisted of (i) the open source Monte Carlo toolkit Geant4, (ii) its radiobiological extension Geant4-DNA, and (iii) a weighted track-sampling algorithm. This approach was used to study mono-energetic neutrons with initial kinetic energies between 1 eV and 10 MeV at multiple depths in a tissue-equivalent phantom. Spherical sampling volumes with diameters between 2 nm and 1 μm were considered. To obtain a measure of RBE, the neutron y‾D values were divided by those of 250 keV X-rays that were calculated in the same way. Qualitative agreement was found with published radiation protection factors and simulation data, allowing for the dependencies of neutron RBE on depth and energy to be discussed in the context of the neutron interaction cross sections and secondary particle distributions in human tissue.
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Affiliation(s)
- C M Lund
- Medical Physics Unit, McGill University, Montreal, QC H4A3J1, Canada.
| | - G Famulari
- Medical Physics Unit, McGill University, Montreal, QC H4A3J1, Canada
| | - L Montgomery
- Medical Physics Unit, McGill University, Montreal, QC H4A3J1, Canada
| | - J Kildea
- Medical Physics Unit, McGill University, Montreal, QC H4A3J1, Canada
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Hamada N, Sato T. Cataractogenesis following high-LET radiation exposure. MUTATION RESEARCH-REVIEWS IN MUTATION RESEARCH 2016; 770:262-291. [DOI: 10.1016/j.mrrev.2016.08.005] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2016] [Revised: 08/04/2016] [Accepted: 08/17/2016] [Indexed: 12/24/2022]
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Baiocco G, Barbieri S, Babini G, Morini J, Alloni D, Friedland W, Kundrát P, Schmitt E, Puchalska M, Sihver L, Ottolenghi A. The origin of neutron biological effectiveness as a function of energy. Sci Rep 2016; 6:34033. [PMID: 27654349 PMCID: PMC5032018 DOI: 10.1038/srep34033] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2016] [Accepted: 09/05/2016] [Indexed: 12/22/2022] Open
Abstract
The understanding of the impact of radiation quality in early and late responses of biological targets to ionizing radiation exposure necessarily grounds on the results of mechanistic studies starting from physical interactions. This is particularly true when, already at the physical stage, the radiation field is mixed, as it is the case for neutron exposure. Neutron Relative Biological Effectiveness (RBE) is energy dependent, maximal for energies ~1 MeV, varying significantly among different experiments. The aim of this work is to shed light on neutron biological effectiveness as a function of field characteristics, with a comprehensive modeling approach: this brings together transport calculations of neutrons through matter (with the code PHITS) and the predictive power of the biophysical track structure code PARTRAC in terms of DNA damage evaluation. Two different energy dependent neutron RBE models are proposed: the first is phenomenological and based only on the characterization of linear energy transfer on a microscopic scale; the second is purely ab-initio and based on the induction of complex DNA damage. Results for the two models are compared and found in good qualitative agreement with current standards for radiation protection factors, which are agreed upon on the basis of RBE data.
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Affiliation(s)
- G. Baiocco
- Department of Physics, University of Pavia, Pavia, Italy
| | - S. Barbieri
- Department of Physics, University of Pavia, Pavia, Italy
| | - G. Babini
- Department of Physics, University of Pavia, Pavia, Italy
| | - J. Morini
- Department of Physics, University of Pavia, Pavia, Italy
| | - D. Alloni
- INFN, National Institute of Nuclear Physics, Sezione di Pavia, Pavia, Italy
- LENA, Laboratory of Applied Nuclear Energy, University of Pavia, Pavia, Italy
| | - W. Friedland
- Institute of Radiation Protection, Helmholtz Zentrum München – German Research Center for Environmental Health, Neuherberg, Germany
| | - P. Kundrát
- Institute of Radiation Protection, Helmholtz Zentrum München – German Research Center for Environmental Health, Neuherberg, Germany
| | - E. Schmitt
- Institute of Radiation Protection, Helmholtz Zentrum München – German Research Center for Environmental Health, Neuherberg, Germany
| | | | - L. Sihver
- Technische Universität Wien, Wien, Austria
| | - A. Ottolenghi
- Department of Physics, University of Pavia, Pavia, Italy
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Baiocco G, Alloni D, Babini G, Mariotti L, Ottolenghi A. Reaction mechanism interplay in determining the biological effectiveness of neutrons as a function of energy. RADIATION PROTECTION DOSIMETRY 2015; 166:316-319. [PMID: 25848097 DOI: 10.1093/rpd/ncv134] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Neutron relative biological effectiveness (RBE) is found to be energy dependent, being maximal for energies ∼1 MeV. This is reflected in the choice of radiation weighting factors wR for radiation protection purposes. In order to trace back the physical origin of this behaviour, a detailed study of energy deposition processes with their full dependences is necessary. In this work, the Monte Carlo transport code PHITS was used to characterise main secondary products responsible for energy deposition in a 'human-sized' soft tissue spherical phantom, irradiated by monoenergetic neutrons with energies around the maximal RBE/wR. Thereafter, results on the microdosimetric characterisation of secondary protons were used as an input to track structure calculations performed with PARTRAC, thus evaluating the corresponding DNA damage induction. Within the proposed simplified approach, evidence is suggested for a relevant role of secondary protons in inducing the maximal biological effectiveness for 1 MeV neutrons.
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Affiliation(s)
- G Baiocco
- Department of Physics, University of Pavia, Pavia, Italy INFN, National Institute of Nuclear Physics, Sezione di Pavia, Pavia, Italy
| | - D Alloni
- Department of Physics, University of Pavia, Pavia, Italy INFN, National Institute of Nuclear Physics, Sezione di Pavia, Pavia, Italy LENA, Laboratory of Applied Nuclear Energy, University of Pavia, Pavia, Italy
| | - G Babini
- Department of Physics, University of Pavia, Pavia, Italy INFN, National Institute of Nuclear Physics, Sezione di Pavia, Pavia, Italy
| | - L Mariotti
- Department of Physics, University of Pavia, Pavia, Italy INFN, National Institute of Nuclear Physics, Sezione di Pavia, Pavia, Italy Department of Oncology, Gray Institute, University of Oxford, Old Road Campus, Oxford OX3 7DQ, UK
| | - A Ottolenghi
- Department of Physics, University of Pavia, Pavia, Italy INFN, National Institute of Nuclear Physics, Sezione di Pavia, Pavia, Italy
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Nakao M, Baba H, Oishi A, Onizuka Y. Microdosimetric investigation of the spectra from YAYOI by use of the Monte Carlo code PHITS. Radiol Phys Technol 2010; 3:144-50. [PMID: 20821088 DOI: 10.1007/s12194-010-0089-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2009] [Revised: 03/04/2010] [Accepted: 03/05/2010] [Indexed: 11/30/2022]
Abstract
The purpose of this study was to obtain the neutron energy spectrum on the surface of the moderator of the Tokyo University reactor YAYOI and to investigate the origins of peaks observed in the neutron energy spectrum by use of the Monte Carlo Code PHITS for evaluating biological studies. The moderator system was modeled with the use of details from an article that reported a calculation result and a measurement result for a neutron spectrum on the surface of the moderator of the reactor. Our calculation results with PHITS were compared to those obtained with the discrete ordinate code ANISN described in the article. In addition, the changes in the neutron spectrum at the boundaries of materials in the moderator system were examined with PHITS. Also, microdosimetric energy distributions of secondary charged particles from neutron recoil or reaction were calculated by use of PHITS and compared with a microdosimetric experiment. Our calculations of the neutron energy spectrum with PHITS showed good agreement with the results of ANISN in terms of the energy and structure of the peaks. However, the microdosimetric dose distribution spectrum with PHITS showed a remarkable discrepancy with the experimental one. The experimental spectrum could not be explained by PHITS when we used neutron beams of two mono-energies.
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Affiliation(s)
- Minoru Nakao
- Department of Health Sciences, Graduate School of Medical Sciences, Kyushu University, 3-1-1, Maidashi, Higashi-ku, Fukuoka City, 812-8582, Japan.
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SATOH D, SATO K, TAKAHASHI F, ENDO A. Monte Carlo Simulation Using Japanese Voxel Phantoms to Analyze the Contribution ofParticle Types and Their Energy Distributions to Organ Doses upon External Neutron Exposure. J NUCL SCI TECHNOL 2010. [DOI: 10.1080/18811248.2010.9711928] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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Yasuda H. Effective dose measured with a life size human phantom in a low Earth orbit mission. JOURNAL OF RADIATION RESEARCH 2009; 50:89-96. [PMID: 19202325 DOI: 10.1269/jrr.08105] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
The biggest concern about the health risk to astronauts is how large the stochastic effects (cancers and hereditary effects) of space radiation could be. The practical goal is to determine the "effective dose" precisely, which is difficult for each crew because of the complex transport processes of energetic secondary particles. The author and his colleagues thus attempted to measure an effective dose in space using a life-size human phantom torso in the STS-91 Shuttle-Mir mission, which flew at nearly the same orbit as that of the International Space Station (ISS). The effective dose for about 10-days flight was 4.1 mSv, which is about 90% of the dose equivalent (H) at the skin; the lowest H values were seen in deep, radiation-sensitive organs/tissues such as the bone marrow and colon. Succeeding measurements and model calculations show that the organ dose equivalents and effective dose in the low Earth orbit mission are highly consistent, despite the different dosimetry methodologies used to determine them.
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Affiliation(s)
- Hiroshi Yasuda
- National Institute of Radiological Sciences, Anagawa, Anage-ku, Chiba, Japan.
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