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Uvarov VL, Zakharchenko AA, Dikiy NP, Lyashko YV, Pomatsalyuk RI. A method of determining the bremsstrahlung flux-weighted average photonuclear cross section. Appl Radiat Isot 2024; 207:111258. [PMID: 38460484 DOI: 10.1016/j.apradiso.2024.111258] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2023] [Revised: 02/21/2024] [Accepted: 02/25/2024] [Indexed: 03/11/2024]
Abstract
Based on a developed analytical model, a method is proposed for measuring the photonuclear cross section averaged over bremsstrahlung flux without application of additional target-monitor of photon flux. The method involves the use of a thin isotopic target, that completely overlaps the photon beam (a photonuclear converter), as well as an algorithm for processing the data on the yield of a reaction under study in such a target. The novel technique was validated on the reactions 100Mo(γ,n)99Mo and 58Ni(γ,n)57Ni in the range of photon end-point energy of 40.7-93.9 MeV. The photon flux-weighted average cross sections of the reactions measured experimentally are in good agreement with Monte Carlo simulations and TALYS predictions on their excitation functions.
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Affiliation(s)
- V L Uvarov
- NSC Kharkov Institute of Physics and Technology, National Academy of Sciences of Ukraine, Kharkiv, Ukraine.
| | - A A Zakharchenko
- NSC Kharkov Institute of Physics and Technology, National Academy of Sciences of Ukraine, Kharkiv, Ukraine
| | - N P Dikiy
- NSC Kharkov Institute of Physics and Technology, National Academy of Sciences of Ukraine, Kharkiv, Ukraine
| | - Yu V Lyashko
- NSC Kharkov Institute of Physics and Technology, National Academy of Sciences of Ukraine, Kharkiv, Ukraine
| | - R I Pomatsalyuk
- NSC Kharkov Institute of Physics and Technology, National Academy of Sciences of Ukraine, Kharkiv, Ukraine
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2
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Naceur A, Bienvenue C, Romano P, Chilian C, Carrier JF. Extending deterministic transport capabilities for very-high and ultra-high energy electron beams. Sci Rep 2024; 14:2796. [PMID: 38307920 PMCID: PMC11226718 DOI: 10.1038/s41598-023-51143-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2023] [Accepted: 12/31/2023] [Indexed: 02/04/2024] Open
Abstract
Focused Very-High Energy Electron (VHEE, 50-300 MeV) and Ultra-High Energy Electron (UHEE, > 300 MeV) beams can accurately target both large and deeply seated human tumors with high sparing properties, while avoiding the spatial requirements and cost of proton and heavy ion facilities. Advanced testing phases are underway at the CLEAR facilities at CERN (Switzerland), NLCTA at Stanford (USA), and SPARC at INFN (Italy), aiming to accelerate the transition to clinical application. Currently, Monte Carlo (MC) transport is the sole paradigm supporting preclinical trials and imminent clinical deployment. In this paper, we propose an alternative: the first extension of the nuclear-reactor deterministic chain NJOY-DRAGON for VHEE and UHEE applications. We have extended the Boltzmann-Fokker-Planck (BFP) multigroup formalism and validated it using standard radio-oncology benchmarks, complex assemblies with a wide range of atomic numbers, and comprehensive irradiation of the entire periodic table. We report that [Formula: see text] of water voxels exhibit a BFP-MC deviation below [Formula: see text] for electron energies under [Formula: see text]. Additionally, we demonstrate that at least [Formula: see text] of voxels of bone, lung, adipose tissue, muscle, soft tissue, tumor, steel, and aluminum meet the same criterion between [Formula: see text] and [Formula: see text]. For water, the thorax, and the breast intra-operative benchmark, typical average BFP-MC deviations of [Formula: see text] and [Formula: see text] were observed at [Formula: see text] and [Formula: see text], respectively. By irradiating the entire periodic table, we observed similar performance between lithium ([Formula: see text]) and cerium ([Formula: see text]). Deficiencies observed between praseodymium ([Formula: see text]) and einsteinium ([Formula: see text]) have been reported, analyzed, and quantified, offering critical insights for the ongoing development of the Evaluated Nuclear Data File mode in NJOY.
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Affiliation(s)
- Ahmed Naceur
- École Polytechnique, SLOWPOKE Nuclear Reactor Laboratory, Nuclear Engineering Institute, Montréal, H3T1J4, Canada.
- CRCHUM, Centre hospitalier de l'Université de Montréal, Montréal, H2L4M1, Canada.
| | - Charles Bienvenue
- École Polytechnique, Engineering Physics Department, Biomedical Engineering Institute, Montréal, H3T1J4, Canada
| | - Paul Romano
- Computational Science Division, Argonne National Laboratory, Lemont, IL, 60439, USA
| | - Cornelia Chilian
- École Polytechnique, SLOWPOKE Nuclear Reactor Laboratory, Nuclear Engineering Institute, Montréal, H3T1J4, Canada
| | - Jean-François Carrier
- Department of Physics, Université de Montréal, Montréal, H3T1J4, Canada
- CRCHUM, Centre hospitalier de l'Université de Montréal, Montréal, H2L4M1, Canada
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3
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Feasibility of a multigroup Boltzmann-Fokker-Planck solution for electron beam dose calculations. Sci Rep 2023; 13:1310. [PMID: 36693824 PMCID: PMC9873679 DOI: 10.1038/s41598-023-27376-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2022] [Accepted: 01/02/2023] [Indexed: 01/25/2023] Open
Abstract
Legacy nuclear-reactor Boltzmann solvers start clinical deployment as an alternative to Monte Carlo (MC) codes and Fermi-Eyges semiemprical models in radiation oncology treatment planning. Today's certified clinical solvers are limited to photon beams. In this paper, ELECTR, a state-of-the-art multigroup electron cross sections generation module in NJOY is presented and validated against Lockwood's calorimetric measurements, EGS-nrc and GEANT-4 for 1-20 MeV unidirectional electron beams. The nuclear-reactor DRAGON-5 solver is upgraded to access the library and solve the Boltzmann-Fokker-Planck (BFP) equation. A variety of heterogeneous radiotherapy and radiosurgery phantom configurations were used for validation purpose. Case studies include a thorax benchmark, that of a typical breast Intra-Operative Radiotherapy and a high-heterogeneity patient-like benchmark. For all beams, [Formula: see text] of the water voxels satisfied the American Association of Physicists in Medicine accuracy criterion for a BFP-MC dose error below [Formula: see text]. At least, [Formula: see text] of adipose, muscle, bone, lung, tumor and breast voxels satisfied the [Formula: see text] criterion. The average BFP-MC relative error was about [Formula: see text] for all voxels, beams and materials combined. By irradiating homogeneous slabs from [Formula: see text] (hydrogen) to [Formula: see text] (einsteinium), we reported performance and defects of the CEPXS mode [US. Sandia National Lab., SAND-89-1685] in ELECTR for the entire periodic table. For all Lockwood's benchmarks, NJOY-DRAGON dose predictions are within the experimental data precision for [Formula: see text] of voxels.
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4
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Kahn Y, Krnjaic G, Mandava B. Dark Matter Detection with Bound Nuclear Targets: The Poisson Phonon Tail. PHYSICAL REVIEW LETTERS 2021; 127:081804. [PMID: 34477403 DOI: 10.1103/physrevlett.127.081804] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/25/2020] [Revised: 05/13/2021] [Accepted: 07/26/2021] [Indexed: 06/13/2023]
Abstract
Dark matter (DM) scattering with nuclei in solid-state systems may produce elastic nuclear recoil at high energies and single-phonon excitation at low energies. When the DM momentum is comparable to the momentum spread of nuclei bound in a lattice, q_{0}=sqrt[2m_{N}ω_{0}] where m_{N} is the mass of the nucleus and ω_{0} is the optical phonon energy, an intermediate scattering regime characterized by multiphonon excitations emerges. We study a greatly simplified model of a single nucleus in a harmonic potential and show that, while the mean energy deposited for a given momentum transfer q is equal to the elastic value q^{2}/(2m_{N}), the phonon occupation number follows a Poisson distribution and thus the energy spread is ΔE=qsqrt[ω_{0}/(2m_{N})]. This observation suggests that low-threshold calorimetric detectors may have significantly increased sensitivity to sub-GeV DM compared to the expectation from elastic scattering, even when the energy threshold is above the single-phonon energy, by exploiting the tail of the Poisson distribution for phonons above the elastic energy. We use a simple model of electronic excitations to argue that this multiphonon signal will also accompany ionization signals induced from DM-electron scattering or the Migdal effect. In well-motivated models where DM couples to a heavy, kinetically mixed dark photon, we show that these signals can probe experimental milestones for cosmological DM production via thermal freeze-out, including the thermal target for Majorana fermion DM.
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Affiliation(s)
- Yonatan Kahn
- Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
- Illinois Center for Advanced Studies of the Universe, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
| | - Gordan Krnjaic
- Fermi National Accelerator Laboratory, Batavia, Illinois 60510, USA
- Kavli Institute for Cosmological Physics, University of Chicago, Chicago, Illinois 60637, USA
| | - Bashi Mandava
- Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
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5
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Semisalov I, Chekhovska A, Skakun Y, Karpus S, Kasilov V. Intensities of the strongest γ-ray transitions originating from the 112gIn decay determined via photoactivation yield measurements. Appl Radiat Isot 2021; 176:109843. [PMID: 34216881 DOI: 10.1016/j.apradiso.2021.109843] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Revised: 06/07/2021] [Accepted: 06/22/2021] [Indexed: 11/25/2022]
Abstract
Analyzing the γ-ray spectra of the decay of the 112m,gIn isomer pair produced by the (γ, n)-reaction the intensities of strongest 606.8, 617.5, 851.2, 1253.5, and 1468.8 keV radiation transitions following the ground state decay were correctly determined. They amounted to 0.87(9), 3.9(4), 0.12(2), 0.17(3), and 0.076(12), respectively, and differ from those given in the current databases.
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Affiliation(s)
- I Semisalov
- National Science Center Kharkiv Institute of Physics and Technology, 1 Akademichna St., Kharkiv, 61108, Ukraine.
| | - A Chekhovska
- National Science Center Kharkiv Institute of Physics and Technology, 1 Akademichna St., Kharkiv, 61108, Ukraine; V. N. Karazin Kharkiv National University, 4 Svobody Sq., Kharkiv, 61022, Ukraine.
| | - Ye Skakun
- National Science Center Kharkiv Institute of Physics and Technology, 1 Akademichna St., Kharkiv, 61108, Ukraine.
| | - S Karpus
- National Science Center Kharkiv Institute of Physics and Technology, 1 Akademichna St., Kharkiv, 61108, Ukraine.
| | - V Kasilov
- National Science Center Kharkiv Institute of Physics and Technology, 1 Akademichna St., Kharkiv, 61108, Ukraine.
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6
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Friman-Gayer U, Romig C, Hüther T, Albe K, Bacca S, Beck T, Berger M, Birkhan J, Hebeler K, Hernandez OJ, Isaak J, König S, Pietralla N, Ries PC, Rohrer J, Roth R, Savran D, Scheck M, Schwenk A, Seutin R, Werner V. Role of Chiral Two-Body Currents in ^{6}Li Magnetic Properties in Light of a New Precision Measurement with the Relative Self-Absorption Technique. PHYSICAL REVIEW LETTERS 2021; 126:102501. [PMID: 33784121 DOI: 10.1103/physrevlett.126.102501] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Revised: 01/08/2021] [Accepted: 01/22/2021] [Indexed: 06/12/2023]
Abstract
A direct measurement of the decay width of the excited 0_{1}^{+} state of ^{6}Li using the relative self-absorption technique is reported. Our value of Γ_{γ,0_{1}^{+}→1_{1}^{+}}=8.17(14)_{stat.}(11)_{syst.} eV provides sufficiently low experimental uncertainties to test modern theories of nuclear forces. The corresponding transition rate is compared to the results of ab initio calculations based on chiral effective field theory that take into account contributions to the magnetic dipole operator beyond leading order. This enables a precision test of the impact of two-body currents that enter at next-to-leading order.
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Affiliation(s)
- U Friman-Gayer
- Institut für Kernphysik, Technische Universität Darmstadt, 64289 Darmstadt, Germany
- Department of Physics and Astronomy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
- Triangle Universities Nuclear Laboratory, Duke University, Durham, North Carolina 27708, USA
| | - C Romig
- Institut für Kernphysik, Technische Universität Darmstadt, 64289 Darmstadt, Germany
| | - T Hüther
- Institut für Kernphysik, Technische Universität Darmstadt, 64289 Darmstadt, Germany
| | - K Albe
- Institut für Materialwissenschaft, Technische Universität Darmstadt, 64287 Darmstadt, Germany
| | - S Bacca
- Institut für Kernphysik and PRISMA Cluster of Excellence, Johannes Gutenberg-Universität Mainz, 55128 Mainz, Germany
- Helmholtz Institute Mainz, GSI Helmholtzzentrum für Schwerionenforschung GmbH, 64289 Darmstadt, Germany
| | - T Beck
- Institut für Kernphysik, Technische Universität Darmstadt, 64289 Darmstadt, Germany
| | - M Berger
- Institut für Kernphysik, Technische Universität Darmstadt, 64289 Darmstadt, Germany
| | - J Birkhan
- Institut für Kernphysik, Technische Universität Darmstadt, 64289 Darmstadt, Germany
| | - K Hebeler
- Institut für Kernphysik, Technische Universität Darmstadt, 64289 Darmstadt, Germany
- ExtreMe Matter Institute EMMI, GSI Helmholtzzentrum für Schwerionenforschung GmbH, 64289 Darmstadt, Germany
| | - O J Hernandez
- Institut für Kernphysik and PRISMA Cluster of Excellence, Johannes Gutenberg-Universität Mainz, 55128 Mainz, Germany
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
| | - J Isaak
- Institut für Kernphysik, Technische Universität Darmstadt, 64289 Darmstadt, Germany
| | - S König
- Institut für Kernphysik, Technische Universität Darmstadt, 64289 Darmstadt, Germany
- ExtreMe Matter Institute EMMI, GSI Helmholtzzentrum für Schwerionenforschung GmbH, 64289 Darmstadt, Germany
- Department of Physics, North Carolina State University, Raleigh, North Carolina 27695, USA
| | - N Pietralla
- Institut für Kernphysik, Technische Universität Darmstadt, 64289 Darmstadt, Germany
| | - P C Ries
- Institut für Kernphysik, Technische Universität Darmstadt, 64289 Darmstadt, Germany
| | - J Rohrer
- Institut für Materialwissenschaft, Technische Universität Darmstadt, 64287 Darmstadt, Germany
| | - R Roth
- Institut für Kernphysik, Technische Universität Darmstadt, 64289 Darmstadt, Germany
| | - D Savran
- GSI Helmholtzzentrum für Schwerionenforschung GmbH, 64289 Darmstadt, Germany
| | - M Scheck
- Institut für Kernphysik, Technische Universität Darmstadt, 64289 Darmstadt, Germany
- School of Engineering, University of the West of Scotland, Paisley, PA1 2BE, United Kingdom
- SUPA, Scottish Universities Physics Alliance, Glasgow, G12 8QQ, United Kingdom
| | - A Schwenk
- Institut für Kernphysik, Technische Universität Darmstadt, 64289 Darmstadt, Germany
- ExtreMe Matter Institute EMMI, GSI Helmholtzzentrum für Schwerionenforschung GmbH, 64289 Darmstadt, Germany
- Max-Planck-Institut für Kernphysik, 69117 Heidelberg, Germany
| | - R Seutin
- Institut für Kernphysik, Technische Universität Darmstadt, 64289 Darmstadt, Germany
- ExtreMe Matter Institute EMMI, GSI Helmholtzzentrum für Schwerionenforschung GmbH, 64289 Darmstadt, Germany
- Max-Planck-Institut für Kernphysik, 69117 Heidelberg, Germany
| | - V Werner
- Institut für Kernphysik, Technische Universität Darmstadt, 64289 Darmstadt, Germany
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7
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Osipov S, Usachev E, Chakhlov S, Schetinkin S, Osipov O. Inspection of bulk cargoes and liquids by the dual energy method. Radiat Phys Chem Oxf Engl 1993 2020. [DOI: 10.1016/j.radphyschem.2020.109133] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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8
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Bui HM, Tran TD, Truong AT, Phan CV, Lukyanov SM, Belov AG, Mitrofanov S. The isomeric ratios in (n, γ) neutron capture reactions on 108Pd and 110Pd nuclei. J Radioanal Nucl Chem 2020. [DOI: 10.1007/s10967-020-07344-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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9
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Bezshyyko O, Vodin O, Golinka LB, Kadenko I, Kotenko A, Kushnir V, Mitrochenko V, Olejnik S, Perezhogin S, Povar T. Isomer ratios for products of photonuclear reactions on Rh. EPJ WEB OF CONFERENCES 2020. [DOI: 10.1051/epjconf/202023901026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Over the past several years various preequilibrium models for nuclear reaction mechanisms description were developed. Diversified detailed experimental data in the medium excitation energy region for nuclei are needed for reasonable selection among these theoretical models. Lack of experimental data in this energy region does essentially limit the possibilities for analysis and comparison of different preequilibrium theoretical models. For photonuclear reactions this energy range covers 30-100 MeV. Experimental measurements and estimations of isomer ratios for products of photonuclear reactions with multiple particle escape on antimony were performed using bremsstrahlung spectrum as projectile with end-point energies 74,9 and 85,7 MeV. Method of the induced activity measurement was applied. For acquisition of gamma spectra we used HPGe spectrometer with 20% relative efficiency. Linear accelerator of electrons LU-40 was a source of bremsstrahlung. Energy resolution of electron beam was about 1% and a mean electron current varied within (3.8 - 5.3)μA.
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10
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Manrique J, Costa A. Reconstruction of X-rays spectra of clinical linear accelerators from transmission data with generalized simulated annealing. Radiat Phys Chem Oxf Engl 1993 2019. [DOI: 10.1016/j.radphyschem.2018.08.018] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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11
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Kato H. [Introduction of Self-made Software on Radiological Technology]. Nihon Hoshasen Gijutsu Gakkai Zasshi 2019; 75:104-110. [PMID: 30662025 DOI: 10.6009/jjrt.2019_jsrt_75.1.104] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Affiliation(s)
- Hideki Kato
- Fujita Health University (Visiting professor)
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12
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Performance of different theories for the angular distribution of bremsstrahlung produced by keV electrons incident upon a target. Radiat Phys Chem Oxf Engl 1993 2018. [DOI: 10.1016/j.radphyschem.2018.02.009] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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13
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14
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Channel effect in isomeric ratio of 137m,gCe produced in different nuclear reactions. J Radioanal Nucl Chem 2017. [DOI: 10.1007/s10967-017-5521-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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15
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Affiliation(s)
- J. Sáfár
- Hungarian Academy of Sciences, Institute of Isotopes, P.O. Box 77, H-1525 Budapest, Hungary
| | - L. Lakosi
- Hungarian Academy of Sciences, Institute of Isotopes, P.O. Box 77, H-1525 Budapest, Hungary
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16
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Bramblett RL, Gozani T, Ginaven RO, Rundquist DE. Low Energy Photofission of Heavy Elements—Experimental Results. NUCL TECHNOL 2017. [DOI: 10.13182/nt72-a31095] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- R. L. Bramblett
- Gulf Radiation Technology, P. O. Box 608, San Diego, California 92112
| | - T. Gozani
- Gulf Radiation Technology, P. O. Box 608, San Diego, California 92112
| | - R. O. Ginaven
- Gulf Radiation Technology, P. O. Box 608, San Diego, California 92112
| | - D. E. Rundquist
- Gulf Radiation Technology, P. O. Box 608, San Diego, California 92112
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17
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Juste B, Miró R, Campayo JM, Diez S, Verdú G. Linear Accelerator Photon Spectra Reconstruction Using a Mixed Experimental Monte Carlo Method. NUCL TECHNOL 2017. [DOI: 10.13182/nt09-a9281] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- B. Juste
- Polytechnic University of Valencia Chemical and Nuclear Engineering Department, Camí de Vera s/n, Valencia 46022, Spain
| | - R. Miró
- Polytechnic University of Valencia Chemical and Nuclear Engineering Department, Camí de Vera s/n, Valencia 46022, Spain
| | - J. M. Campayo
- Hospital Clínic Universitari de Valencia Avda. Blasco Ibáñez, 17, Valencia 46010, Spain
| | - S. Diez
- Hospital Clínic Universitari de Valencia Avda. Blasco Ibáñez, 17, Valencia 46010, Spain
| | - G. Verdú
- Polytechnic University of Valencia Chemical and Nuclear Engineering Department, Camí de Vera s/n, Valencia 46022, Spain
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18
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Isomeric ratio of 137mCe to 137gCe produced in 138Ce(γ, n)137m,gCe photonuclear reaction induced by end-point bremsstrahlung energies from 14 to 17, 21 to 23 and at 19 MeV. J Radioanal Nucl Chem 2017. [DOI: 10.1007/s10967-016-5064-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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19
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Anderson R, Lamey M, MacPherson M, Carlone M. Simulation of a medical linear accelerator for teaching purposes. J Appl Clin Med Phys 2015; 16:5139. [PMID: 26103478 PMCID: PMC5690144 DOI: 10.1120/jacmp.v16i3.5139] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2014] [Revised: 01/27/2015] [Accepted: 01/26/2015] [Indexed: 11/23/2022] Open
Abstract
Simulation software for medical linear accelerators that can be used in a teaching environment was developed. The components of linear accelerators were modeled to first order accuracy using analytical expressions taken from the literature. The expressions used constants that were empirically set such that realistic response could be expected. These expressions were programmed in a MATLAB environment with a graphical user interface in order to produce an environment similar to that of linear accelerator service mode. The program was evaluated in a systematic fashion, where parameters affecting the clinical properties of medical linear accelerator beams were adjusted independently, and the effects on beam energy and dose rate recorded. These results confirmed that beam tuning adjustments could be simulated in a simple environment. Further, adjustment of service parameters over a large range was possible, and this allows the demonstration of linear accelerator physics in an environment accessible to both medical physicists and linear accelerator service engineers. In conclusion, a software tool, named SIMAC, was developed to improve the teaching of linear accelerator physics in a simulated environment. SIMAC performed in a similar manner to medical linear accelerators. The authors hope that this tool will be valuable as a teaching tool for medical physicists and linear accelerator service engineers. PACS number: 87.55Gh, 87.56bd
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Kojima S, Arikawa Y, Nishimura Y, Togawa H, Zhang Z, Ikenouchi T, Ozaki T, Morace A, Nagai T, Abe Y, Sakata S, Inoue H, Utsugi M, Nakai M, Nishimura H, Shiraga H, Kato R, Fujioka S, Azechi H. Accuracy evaluation of a Compton X-ray spectrometer with bremsstrahlung X-rays generated by a 6 MeV electron bunch. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2014; 85:11D634. [PMID: 25430210 DOI: 10.1063/1.4894447] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
A Compton-scattering-based X-ray spectrometer is developed to obtain the energy distribution of fast electrons produced by intense laser and matter interactions. Bremsstrahlung X-rays generated by fast electrons in a material are used to measure fast electrons' energy distribution in matter. In the Compton X-ray spectrometer, X-rays are converted into recoil electrons by Compton scattering in a converter made from fused silica glass, and a magnet-based electron energy analyzer is used to measure the energy distribution of the electrons that recoil in the direction of the incident X-rays. The spectrum of the incident X-rays is reconstructed from the energy distribution of the recoil electrons. The accuracy of this spectrometer is evaluated using a quasi-monoenergetic 6 MeV electron bunch that emanates from a linear accelerator. An electron bunch is injected into a 1.5 mm thick tungsten plate to produce bremsstrahlung X-rays. The spectrum of these bremsstrahlung X-rays is obtained in the range from 1 to 9 MeV. The energy of the electrons in the bunch is estimated using a Monte Carlo simulation of particle-matter interactions. The result shows that the spectrometer's energy accuracy is ±0.5 MeV for 6.0 MeV electrons.
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Affiliation(s)
- Sadaoki Kojima
- Institute of Laser Engineering, Osaka University, 2-6 Yamada-oka, Suita, Osaka 565-0871, Japan
| | - Yasunobu Arikawa
- Institute of Laser Engineering, Osaka University, 2-6 Yamada-oka, Suita, Osaka 565-0871, Japan
| | - Yasuhiko Nishimura
- Toyota Technical Development Corporation, 1-21 Imae, Hanamoto-cho, Toyota, Aichi 470-0334, Japan
| | - Hiromi Togawa
- Toyota Technical Development Corporation, 1-21 Imae, Hanamoto-cho, Toyota, Aichi 470-0334, Japan
| | - Zhe Zhang
- Institute of Laser Engineering, Osaka University, 2-6 Yamada-oka, Suita, Osaka 565-0871, Japan
| | - Takahito Ikenouchi
- Institute of Laser Engineering, Osaka University, 2-6 Yamada-oka, Suita, Osaka 565-0871, Japan
| | - Tetsuo Ozaki
- National Institute for Fusion Science, 322-6 Oroshicho, Toki, Gifu 509-5292, Japan
| | - Alessio Morace
- Institute of Laser Engineering, Osaka University, 2-6 Yamada-oka, Suita, Osaka 565-0871, Japan
| | - Takahiro Nagai
- Institute of Laser Engineering, Osaka University, 2-6 Yamada-oka, Suita, Osaka 565-0871, Japan
| | - Yuki Abe
- Institute of Laser Engineering, Osaka University, 2-6 Yamada-oka, Suita, Osaka 565-0871, Japan
| | - Shouhei Sakata
- Institute of Laser Engineering, Osaka University, 2-6 Yamada-oka, Suita, Osaka 565-0871, Japan
| | - Hiroaki Inoue
- Institute of Laser Engineering, Osaka University, 2-6 Yamada-oka, Suita, Osaka 565-0871, Japan
| | - Masaru Utsugi
- Institute of Laser Engineering, Osaka University, 2-6 Yamada-oka, Suita, Osaka 565-0871, Japan
| | - Mitsuo Nakai
- Institute of Laser Engineering, Osaka University, 2-6 Yamada-oka, Suita, Osaka 565-0871, Japan
| | - Hiroaki Nishimura
- Institute of Laser Engineering, Osaka University, 2-6 Yamada-oka, Suita, Osaka 565-0871, Japan
| | - Hiroyuki Shiraga
- Institute of Laser Engineering, Osaka University, 2-6 Yamada-oka, Suita, Osaka 565-0871, Japan
| | - Ryukou Kato
- The Institute of Science and Industrial Research, Osaka University, 2-6 Yamada-oka, Suita, Osaka, Japan
| | - Shinsuke Fujioka
- Institute of Laser Engineering, Osaka University, 2-6 Yamada-oka, Suita, Osaka 565-0871, Japan
| | - Hiroshi Azechi
- Institute of Laser Engineering, Osaka University, 2-6 Yamada-oka, Suita, Osaka 565-0871, Japan
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Sáfár J, Lakosi L. Integrated cross sections for excitation of nuclear isomers by inelastic photon scattering at giant resonance. Radiat Phys Chem Oxf Engl 1993 2014. [DOI: 10.1016/j.radphyschem.2012.12.016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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22
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Kato H, Hayashi N, Kuroki R, Adachi Y, Suzuki S. [Presumption of the energy-spectrum of high-energy electron beam based on the beta-distribution model]. Nihon Hoshasen Gijutsu Gakkai Zasshi 2013; 69:1387-93. [PMID: 24366559 DOI: 10.6009/jjrt.2013_jsrt_69.12.1387] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The energy spectra of high-energy electron beams used in radiotherapy are the most important data for evaluating absorbed doses and/or dose distributions in the body of a patient. However, it is impossible to measure the actual spectra of a high-energy electron beam. In this study, we suggest a method to presume the spectra of high-energy electron beams by use of the beta distribution model. The procedure of this method is as follows: (1) the spectrum of the high-energy electron beam was assumed to have a maximum energy Emax, and α, β parameters of the beta probability density function. (2) The percentage depth dose (PDD) based on the assumed spectrum was calculated by a Monte Carlo simulation. (3) The best matching energy spectrum was searched in comparison with the experimental PDD curves. Finally, the optimal energy spectrum of the electron beam was estimated after reiterating the process from (1) to (3). With our method, the measured PDD curves were optimally simulated following the experimental data. It appeared that the assumed spectra approximated well to the actual spectra. However, the error between the assumed and experimental data was observed in the region under the incident surface. We believe this was due to the influence of low-energy electrons scattered at installed collimators, etc. In order to simulate PDDs in this region accurately, a further correction process is required for a spectrum based on the beta distribution model.
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Affiliation(s)
- Hideki Kato
- Faculty of Radiological Technology, School of Health Sciences, Fujita Health University
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Thiep TD, An TT, Cuong PV, Vinh NT, Belov AG. Study of the isomeric ratios in photonuclear reactions of natural holmium and lutetium induced by bremsstrahlungs with endpoint energies in the giant dipole resonance region. J Radioanal Nucl Chem 2011. [DOI: 10.1007/s10967-011-1257-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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25
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Thiep TD, An TT, Cuong PV, Khai NT, Vinh NT, Belov AG, Maslov OD. The isomeric ratios in photonuclear reactions of natural tellurium induced by bremsstrahlungs with endpoint energies in the giant dipole resonance region. J Radioanal Nucl Chem 2011. [DOI: 10.1007/s10967-011-1137-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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26
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The isomeric ratios in photonuclear reactions of natural strontium induced by bremsstrahlungs in the giant dipole resonance region and by 65 MeV bremsstrahlung. J Radioanal Nucl Chem 2010. [DOI: 10.1007/s10967-010-0630-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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27
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Koenig T, Oelfke U. Single crystal targets may improve soft-tissue contrast in megavoltage imaging by means of coherent bremsstrahlung. Phys Med Biol 2010; 55:1327-41. [DOI: 10.1088/0031-9155/55/5/005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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28
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Hashimoto M, Tomita T, Sawada K, Fujibuchi T, Nishio T, Nakagawa K. Dose profile measurement using an imaging plate: Evaluation of filters using Monte Carlo simulation of 4 MV x-rays. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2009; 80:045101. [PMID: 19405685 DOI: 10.1063/1.3103572] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Computed radiography (CR) is gradually replacing film. The application of CR for two-dimensional profiles and off-axis ratio (OAR) measurement using an imaging plate (IP) in a CR system is currently under discussion. However, a well known problem for IPs in dosimetry is that they use high atomic number (Z) materials, such as Ba, which have an energy dependency in a photon interaction. Although there are some reports that it is possible to compensate for the energy dependency with metal filters, the appropriate thicknesses of these filters and where they should be located have not been investigated. The purpose of this study is to find the most suitable filter for use with an IP as a dosimetric tool. Monte Carlo simulation (Geant4 8.1) was used to determine the filter to minimize the measurement error in OAR measurements of 4 MV x-rays. In this simulation, the material and thickness of the filter and distance between the IP and the filter were varied to determine most suitable filter conditions that gave the best fit to the MC calculated OAR in water. With regard to changing the filter material, we found that using higher Z and higher density material increased the effectiveness of the filter. Also, increasing the distance between the filter and the IP reduced the effectiveness, whereas increasing the thickness of the filter increased the effectiveness. The result of this study showed that the most appropriate filter conditions consistent with the calculated OAR in water were the ones with the IP sandwiched between two 2 mm thick lead filters at a distance of 5 mm from the IP or the IP sandwiched directly between two 1 mm lead filters. Using these filters, we measured the OAR at 10 cm depth with 100 cm source-to-surface distance and surface 10x10 cm(2) field size. The results of this measurement represented that it is possible to achieve measurements with less than within 2.0% and 2.0% in the field and with less than 1.1% and 0.6% out of the field by using 2 and 1 mm lead filters, respectively.
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Affiliation(s)
- Masatoshi Hashimoto
- Division of Radiology and Biomedical Engineering, Graduate School of Medicine, The University of Tokyo, Bunkyo-ku, Tokyo 113-8655, Japan.
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29
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Bulmahn A, Reno MH. Cross sections and energy loss for lepton pair production in muon transport. Int J Clin Exp Med 2009. [DOI: 10.1103/physrevd.79.053008] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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30
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Ehlotzky F, Sheppey GC. Numerical calculations of the Delbrück scattering amplitude. ACTA ACUST UNITED AC 2008. [DOI: 10.1007/bf02749627] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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31
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Zhidkov A, Nemoto K, Nayuki T, Oishi Y, Fuji T. Giant electromagnetic vortex and MeV monoenergetic electrons generated by short laser pulses in underdense plasma near quarter critical density region. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2007; 76:016401. [PMID: 17677573 DOI: 10.1103/physreve.76.016401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2006] [Revised: 02/06/2007] [Indexed: 05/16/2023]
Abstract
Very efficient generation of monoenergetic, about 1MeV , electrons from underdense plasma with its electron density close to the critical, when irradiated by an intense femtosecond laser pulse, is found via two dimensional particle-in-cell simulation. The stimulated Raman scattering of a laser pulse with frequency omega< or =2omega(pl max) gives rise to a giant electromagnetic vortex. In contrast to electron acceleration by the well-known laser pulse wake, injected plasma electrons are accelerated up to vortex ponderomotive potential forming a quite monoenergetic distribution. A relatively high charge of such an electron source makes very efficient generation of soft gamma rays with homega>300 keV .
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Affiliation(s)
- Alexei Zhidkov
- Central Research Institute of Electric Power Industry, 2-6-1 Nagasaka, Yokosuka-shi, Kanagawa-Ken 240-0196, Japan
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Fujibuchi T, Funabashi N, Hashimoto M, Abe Y, Iimori T, Matsubayashi F, Sawada K, Kurokawa M, Isobe T, Kikawa T, Komuro I. Examination of beam profile measurement using an imaging plate by the light exposure fading method for quality assurance of external radiation therapy. Nihon Hoshasen Gijutsu Gakkai Zasshi 2006; 62:1697-706. [PMID: 17189937 DOI: 10.6009/jjrt.62.1697] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
High-resolution film dosimetry has been used for several decades to check and to measure two-dimensional dose distributions. However, in recent years, the automatic processor has been replaced by the spread of computed radiography, or has been little used hospitals. In this study, we measured the off-center ratio (OCR) of the open field, after an irradiating radiation beam was delivered to the imaging plate (IP) under conditions in which the IP was exposed to a fixed amount of light with fading, and compared these data with the OCR measured by an ionization-chamber dosimeter, which is the standard method used for measuring radiation dose. Profile measurement using IP could be achieved by performing light fading, even at a range of more than 100 MU. Further, by using a metallic filter, we succeeded in demonstrating that the profile measurement of IP in an open irradiation field could approximate the values of those obtained by an ionization chamber dosimeter. This method can serve as a simple, easy-to-use method for evaluating the QA of dose distribution in radiation therapy.
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Affiliation(s)
- Toshioh Fujibuchi
- Department of Cardiovascular Science and Medicine, Chiba University Graduate School of Medicine
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33
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Kato H. [Differential dose albedo for high-energy X-rays on concrete slab]. Nihon Hoshasen Gijutsu Gakkai Zasshi 2006; 62:1135-9. [PMID: 16957669 DOI: 10.6009/jjrt.62.1135] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
We computed the differential dose albedo (alpha(D)) for high-energy X-rays on a concrete slab when the incident angle, reflection angle, and azimuth angle were changed, by means of Monte Carlo simulation. We found that alpha(D) changed with incident, reflection, and azimuth angles to the concrete slab. On the whole, the larger the incident angle, the larger alpha(D) tended to become. If the incident angle and reflection angle were the same, the larger the azimuth angle, the smaller alpha(D) tended to become. When the incident, reflection, and azimuth angles were the same, the smaller the X-ray energy was, the larger alpha(D) became, in the order of 10 MV, 6 MV, and 4 MV X-rays.
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Kato H. [Air kerma transmission factors of Scattered X-rays in the maze of a Linac room for lead shield]. Nihon Hoshasen Gijutsu Gakkai Zasshi 2005; 61:96-103. [PMID: 15682037 DOI: 10.6009/jjrt.kj00003326619] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Spectra of scattered X-rays in the maze of a Linac (X-ray energies of 4, 6, and 10 MV) room were estimated by means of the Monte Carlo simulation, and air kerma transmission factors of the X-rays scattered through a lead shield were evaluated based on those spectra. Spectra of scattered X-rays showed a maximum in the energy area below 200 keV. The higher the accelerated electron energy, also, the smaller the scattering angle that tended to spread to the higher energy area of the distribution of spectra. The air kerma transmission factor of 120 degrees scattered X-rays of 4 MV X-rays obtained in this study was larger than the transmission factors of 124 degrees scattered photons of (60)Co gamma rays through a lead shield given in ICRP. The air kerma transmission factors of 120 degrees scattered X-rays of 6 MV X-rays were smaller than the transmission factors of 90 degrees scattered photons of (60)Co gamma rays. The air kerma transmission factors of 120 degrees scattered X-rays of 10 MV X-rays was slightly larger than transmission factors of 90 degrees scattered photons of (60)Co gamma rays. Therefore, in the case of a 4 MV X-ray Linac room, the calculation method given in the "Manual of Practical Shield Calculation of Radiation Facilities (2000)" causes underestimation of leakage doses.
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Ajaj FA, Ghassal NM. An MCNP-based model of a medical linear accelerator x-ray photon beam. AUSTRALASIAN PHYSICAL & ENGINEERING SCIENCES IN MEDICINE 2004; 26:140-4. [PMID: 14626854 DOI: 10.1007/bf03178784] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The major components in the x-ray photon beam path of the treatment head of the VARIAN Clinac 2300 EX medical linear accelerator were modeled and simulated using the Monte Carlo N-Particle radiation transport computer code (MCNP). Simulated components include x-ray target, primary conical collimator, x-ray beam flattening filter and secondary collimators. X-ray photon energy spectra and angular distributions were calculated using the model. The x-ray beam emerging from the secondary collimators were scored by considering the total x-ray spectra from the target as the source of x-rays at the target position. The depth dose distribution and dose profiles at different depths and field sizes have been calculated at a nominal operating potential of 6 MV and found to be within acceptable limits. It is concluded that accurate specification of the component dimensions, composition and nominal accelerating potential gives a good assessment of the x-ray energy spectra.
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Affiliation(s)
- F A Ajaj
- Department of Physics, Faculty of Applied Sciences, Umm Al-Qura University, Makkah, Saudi Arabia, P.O. Box 10130.
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Bentley RE, Jones JC, Lillicrap SC. X-Ray Spectra from Accelerators in the range 2 to 6 MeV. Phys Med Biol 2002. [DOI: 10.1088/0031-9155/12/3/302] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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39
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WARD G, DOLPHIN GW. Energy and Angular Distribution of X-rays Produced by 13 MeV Electrons at a Thick Target. Phys Med Biol 2002; 4:391-401. [PMID: 13842865 DOI: 10.1088/0031-9155/4/4/309] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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40
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Krmar M, Nikolić D, Krstonosić P, Cora S, Francescon P, Chiovati P, Rudić A. A simple method for bremsstrahlung spectra reconstruction from transmission measurements. Med Phys 2002; 29:932-8. [PMID: 12094987 DOI: 10.1118/1.1469632] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
A new method for evaluation of bremsstrahlung spectra from transmission measurements has been developed. In this method some very well known facts relating to thick target bremsstrahlung spectra are a priori included in the calculation procedure. Some characteristics of the method are preliminarily illustrated on a 6 MV therapy linear accelerator.
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Affiliation(s)
- M Krmar
- Institute of Physics, University of Novi Sad, Yugoslavia.
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41
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YAMANA H, YAMAMOTO T, KOBAYASHI K, MITSUGASHIRA T, MORIYAMA H. Production of Pure236Pu Tracer for the Assessment of Plutonium in the Environment. J NUCL SCI TECHNOL 2001. [DOI: 10.1080/18811248.2001.9715106] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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42
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YAMANA H, YAMAMOTO T, KOBAYASHI K, MITSUGASHIRA T, MORIYAMA H. Production of Pure 236Pu Tracer for the Assessment of Plutonium in the Environment. J NUCL SCI TECHNOL 2001. [DOI: 10.3327/jnst.38.859] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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43
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Chvetsov AV, Sandison GA, Yeboah C. The energy-dependent electron loss model for pencil beam dose kernels. Phys Med Biol 2000; 45:2913-30. [PMID: 11049180 DOI: 10.1088/0031-9155/45/10/313] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The 'monoenergetic' electron loss model was derived in a previous work to account for pathlength straggling in the Fermi-Eyges pencil beam problem. In this paper, we extend this model to account for energy-loss straggling and secondary knock-on electron transport in order to adequately predict a depth dose curve. To model energy-loss straggling, we use a weighted superposition of a discrete number of monoenergetic pencil beams with different initial energies where electrons travel along the depth-energy characteristics in the continuous slowing down approximation (CSDA). The energy straggling spectrum at depth determines the weighting assigned to each monoenergetic pencil beam. Supplemented by a simple transport model for the secondary knock-on electrons, the 'energy-dependent' electron loss model predicts both lateral and depth dose distributions from the electron pencil beams in good agreement with Monte Carlo calculations and measurements. The calculation of dose distribution from a pencil beam takes 0.2 s on a Pentium III 500 MHz computer. Being computationally fast, the 'energy-dependent' electron loss model can be used for the calculation of 3D energy deposition kernels in dose optimization schemes without using precalculated or measured data.
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Affiliation(s)
- A V Chvetsov
- Department of Medical Physics, Tom Baker Cancer Centre, Alberta, Canada
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44
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Partridge M. Reconstruction of megavoltage photon spectra from electronic portal imager derived transmission measurements. Phys Med Biol 2000; 45:N115-31. [PMID: 11049192 DOI: 10.1088/0031-9155/45/10/401] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Three variants of the Schiff equation are investigated to model the spectra produced by megavoltage linear accelerators. These models are tested against well-validated Monte Carlo (MC) generated spectra on the central axis of large-area fields, and show excellent agreement. Numerical reconstructions of 6 and 10 MV spectra using the same models are then presented, using experimental attenuation data derived from an electronic portal imager. The process of deriving spectra from experimental attenuation data is shown to be inherently badly constrained mathematically, with the derived spectrum being highly sensitive to noise in the source data, and non-unique. By placing a priori constraints on the Schiff model from both physical knowledge of the construction of the accelerator and MC data, physically useful results are gained and presented for both the energy dependence and off-axis behaviour of photon spectra.
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Affiliation(s)
- M Partridge
- Joint Department of Physics, Institute of Cancer Research/Royal Marsden NHS Trust, Sutton, UK
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45
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Allen PD, Chaudhri MA. Neutron yields from selected materials irradiated with high energy photons. Phys Med Biol 2000. [DOI: 10.1088/0031-9155/36/12/009] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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46
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Rogers DWO, Faddegon BA. Re-evaluation of the total stopping power of polystyrene for 5.3 MeV electrons. Phys Med Biol 2000. [DOI: 10.1088/0031-9155/37/4/011] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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47
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Abstract
The Monte Carlo N-Particle radiation transport computer code (MCNP) has been employed on a personal computer to develop a simple model simulating the major components within the beam path of a linear accelerator radiation head, namely the electron target, primary conical collimator, beam flattening filter, wedge filter and the secondary collimators. The model was initially used to calculate the energy spectra and angular distributions of the x-ray beam for the Philips SL 75/5 linear accelerator, in a plane immediately beneath the flattening filter. These data were subsequently used as a 'source' of x-rays at the target position, to assess the emergent beam from the secondary collimators. The depth dose distributions and dose profiles at constant depth for various field sizes have been calculated for a nominal operating potential of 4 MV and found to be within acceptable limits. It is concluded that the technique may be used to calculate the energy spectra of any linear accelerator upon specification of the component dimensions, materials and nominal accelerating potential. It is anticipated that this work will serve as the basis of a quality control tool for linear accelerators and treatment planning systems.
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Affiliation(s)
- R D Lewis
- Department of Medical Physics and Clinical Engineering, Singleton Hospital, Swansea, UK
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Krmar M, Slivka J, Bikit I, Conkić L, Rudić A. 115In as a probe for the characterization of therapy bremsstrahlung beams and the detection of photoneutrons. Med Phys 1999; 26:564-9. [PMID: 10227360 DOI: 10.1118/1.598558] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
Variation of the photoactivation rate across radiation fields of three different bremsstrahlung beams of two medical accelerators has been measured, making use of the photonuclear reactions in natural indium probes: 115In(y,y')115mIn and 115In(y,n)114mIn. The third nuclear reaction, 115In(n,y)116mIn, was used to detect the presence of neutrons in the photon beam and to estimate the spatial distribution of thermal and fast neutrons in the patient plane as a function of collimator opening.
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Affiliation(s)
- M Krmar
- Institute of Physics, University of Novi Sad, Yugoslavia
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