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Uddin MF, Akter S, Ahmed M, Sattar BN, Morshed KM, Osman H, Bokhari FF, Alsufyani SJ, Issa SA, Khandaker MU. Photoneutron production mechanisms, their characteristics, and shielding strategies in high-energy linac environment: A review. JOURNAL OF RADIATION RESEARCH AND APPLIED SCIENCES 2024; 17:101031. [DOI: 10.1016/j.jrras.2024.101031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/12/2024]
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Jelínek Michaelidesová A, Kundrát P, Zahradníček O, Danilová I, Pachnerová Brabcová K, Vachelová J, Vilimovský J, David M, Vondráček V, Davídková M. First independent validation of the proton-boron capture therapy concept. Sci Rep 2024; 14:19264. [PMID: 39164312 PMCID: PMC11335746 DOI: 10.1038/s41598-024-69370-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2024] [Accepted: 08/05/2024] [Indexed: 08/22/2024] Open
Abstract
Boron has been suggested to enhance the biological effectiveness of proton beams in the Bragg peak region via the p + 11B → 3α nuclear capture reaction. However, a number of groups have observed no such enhancement in vitro or questioned its proposed mechanism recently. To help elucidate this phenomenon, we irradiated DU145 prostate cancer or U-87 MG glioblastoma cells by clinical 190 MeV proton beams in plateau or Bragg peak regions with or without 10B or 11B isotopes added as sodium mercaptododecaborate (BSH). The results demonstrate that 11B but not 10B or other components of the BSH molecule enhance cell killing by proton beams. The enhancement occurs selectively in the Bragg peak region, is present for boron concentrations as low as 40 ppm, and is not due to secondary neutrons. The enhancement is likely initiated by proton-boron capture reactions producing three alpha particles, which are rare events occurring in a few cells only, and their effects are amplified by intercellular communication to a population-level response. The observed up to 2-3-fold reductions in survival levels upon the presence of boron for the studied prostate cancer or glioblastoma cells suggest promising clinical applications for these tumour types.
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Affiliation(s)
- Anna Jelínek Michaelidesová
- Nuclear Physics Institute of the Czech Academy of Sciences, Husinec - Řež 130, 250 68, Řež, Czech Republic
- Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University in Prague, Břehová 78/7, 115 19, Prague, Czech Republic
| | - Pavel Kundrát
- Nuclear Physics Institute of the Czech Academy of Sciences, Husinec - Řež 130, 250 68, Řež, Czech Republic
| | - Oldřich Zahradníček
- Nuclear Physics Institute of the Czech Academy of Sciences, Husinec - Řež 130, 250 68, Řež, Czech Republic
| | - Irina Danilová
- Nuclear Physics Institute of the Czech Academy of Sciences, Husinec - Řež 130, 250 68, Řež, Czech Republic
- Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University in Prague, Břehová 78/7, 115 19, Prague, Czech Republic
| | | | - Jana Vachelová
- Nuclear Physics Institute of the Czech Academy of Sciences, Husinec - Řež 130, 250 68, Řež, Czech Republic
| | - Jan Vilimovský
- Proton Therapy Center Czech, Prague, Budínova 2437/1a, 180 00, Prague, Czech Republic
| | - Miroslav David
- Thomayer University Hospital, Vídeňská 800, 140 59, Prague, Czech Republic
| | - Vladimír Vondráček
- Proton Therapy Center Czech, Prague, Budínova 2437/1a, 180 00, Prague, Czech Republic
- Thomayer University Hospital, Vídeňská 800, 140 59, Prague, Czech Republic
| | - Marie Davídková
- Nuclear Physics Institute of the Czech Academy of Sciences, Husinec - Řež 130, 250 68, Řež, Czech Republic.
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Saadatmand P, Mahdavi SR, Chegeni N, Karimi AH. Dose equivalent consideration from neutron contamination in modified radiotherapy vault: a Monte Carlo study. Biomed Phys Eng Express 2024; 10:045049. [PMID: 38861949 DOI: 10.1088/2057-1976/ad567c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2023] [Accepted: 06/11/2024] [Indexed: 06/13/2024]
Abstract
Laminated barriers incorporating metal sheets provide effective protection for space-restricted radiotherapy centers. This study aimed to assess photoneutron contamination in smaller vaults protected by different compositions of multilayer barriers during simulated pelvic radiotherapy with 18 MV photon beams. Monte Carlo Simulations of 18 MV LINAC (Varian 2100 C/D) and Medical Internal Radiation Dose (MIRD) phantom were used to assess photoneutron contamination within reconstructed vaults incorporating different combinations of metal sheet and borated polyethylene (BPE) during pelvic radiotherapy. The findings highlight a 3.27 and 2.91 times increase in ambient neutron doseHn*(10) along the maze of reconstructed vaults that use lead and steel sheets, respectively, compared to concrete. TheHn*(10) outside the treatment room increased after incorporating a metal sheet, but it remained within the permissible limit of 20μSv/week for uncontrolled areas adjacent to the LINAC bunker, even with a workload of 1000Gy/week. Neutron equivalent doses in the patient's organs ranged from 0.22 to 0.96 mSv Gy-1. There is no notable distinction in the organ's neutron equivalent dose, fatal cancer risk, secondary radiation-induced cancer risk, and cancer mortality for various laminated barrier compositions. Furthermore, the use of metal sheets for vault wall reconstruction keeps the variation in cancer risk induced by photoneutrons below 6%, while risks of fatal cancer and cancer mortality vary less than 11%. While the metal portion of the laminated barrier raises the neutron dose, the addition of a BPE plate reduces concerns of increased effective dose and secondary malignancy risk.
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Affiliation(s)
- Pegah Saadatmand
- Department of Medical Physics, School of Medicine, Iran University of Medical Sciences, Tehran, Iran
| | - Seied Rabi Mahdavi
- Department of Medical Physics, School of Medicine, Iran University of Medical Sciences, Tehran, Iran
- Radiation Biology Research Center, Iran University of Medical Sciences, Tehran, Iran
| | - Nahid Chegeni
- Department of Medical Physics, Medicine Faculty, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran
| | - Amir Hossein Karimi
- Department of Medical Physics and Biomedical Engineering, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran
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Carlier B, Heymans SV, Nooijens S, Collado-Lara G, Toumia Y, Delombaerde L, Paradossi G, D’hooge J, Van Den Abeele K, Sterpin E, Himmelreich U. A Preliminary Investigation of Radiation-Sensitive Ultrasound Contrast Agents for Photon Dosimetry. Pharmaceuticals (Basel) 2024; 17:629. [PMID: 38794199 PMCID: PMC11125270 DOI: 10.3390/ph17050629] [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: 03/20/2024] [Revised: 04/28/2024] [Accepted: 04/30/2024] [Indexed: 05/26/2024] Open
Abstract
Radiotherapy treatment plans have become highly conformal, posing additional constraints on the accuracy of treatment delivery. Here, we explore the use of radiation-sensitive ultrasound contrast agents (superheated phase-change nanodroplets) as dosimetric radiation sensors. In a series of experiments, we irradiated perfluorobutane nanodroplets dispersed in gel phantoms at various temperatures and assessed the radiation-induced nanodroplet vaporization events using offline or online ultrasound imaging. At 25 °C and 37 °C, the nanodroplet response was only present at higher photon energies (≥10 MV) and limited to <2 vaporization events per cm2 per Gy. A strong response (~2000 vaporizations per cm2 per Gy) was observed at 65 °C, suggesting radiation-induced nucleation of the droplet core at a sufficiently high degree of superheat. These results emphasize the need for alternative nanodroplet formulations, with a more volatile perfluorocarbon core, to enable in vivo photon dosimetry. The current nanodroplet formulation carries potential as an innovative gel dosimeter if an appropriate gel matrix can be found to ensure reproducibility. Eventually, the proposed technology might unlock unprecedented temporal and spatial resolution in image-based dosimetry, thanks to the combination of high-frame-rate ultrasound imaging and the detection of individual vaporization events, thereby addressing some of the burning challenges of new radiotherapy innovations.
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Affiliation(s)
- Bram Carlier
- Department of Oncology, KU Leuven-University of Leuven, 3000 Leuven, Belgium; (B.C.); (L.D.); (E.S.)
- Department of Imaging and Pathology, KU Leuven-University of Leuven, 3000 Leuven, Belgium
- Molecular Small Animal Imaging Center (MoSAIC), KU Leuven-University of Leuven, 3000 Leuven, Belgium
| | - Sophie V. Heymans
- Department of Physics, KU Leuven Campus Kortrijk—KULAK, Etienne Sabbelaan 53, 8500 Kortrijk, Belgium; (S.V.H.); (K.V.D.A.)
- Department of Cardiovascular Sciences, KU Leuven-University of Leuven, 3000 Leuven, Belgium; (S.N.); (J.D.)
| | - Sjoerd Nooijens
- Department of Cardiovascular Sciences, KU Leuven-University of Leuven, 3000 Leuven, Belgium; (S.N.); (J.D.)
| | - Gonzalo Collado-Lara
- Department of Cardiology, Erasmus MC University Medical Center, 3015 GD Rotterdam, The Netherlands;
| | - Yosra Toumia
- National Institute for Nuclear Physics, INFN Sezione di Roma Tor Vergata, 00133 Rome, Italy;
- Department of Chemical Science and Technologies, University of Rome Tor Vergata, 00133 Rome, Italy;
| | - Laurence Delombaerde
- Department of Oncology, KU Leuven-University of Leuven, 3000 Leuven, Belgium; (B.C.); (L.D.); (E.S.)
- Department of Radiotherapy, UH Leuven, 3000 Leuven, Belgium
| | - Gaio Paradossi
- Department of Chemical Science and Technologies, University of Rome Tor Vergata, 00133 Rome, Italy;
| | - Jan D’hooge
- Department of Cardiovascular Sciences, KU Leuven-University of Leuven, 3000 Leuven, Belgium; (S.N.); (J.D.)
| | - Koen Van Den Abeele
- Department of Physics, KU Leuven Campus Kortrijk—KULAK, Etienne Sabbelaan 53, 8500 Kortrijk, Belgium; (S.V.H.); (K.V.D.A.)
| | - Edmond Sterpin
- Department of Oncology, KU Leuven-University of Leuven, 3000 Leuven, Belgium; (B.C.); (L.D.); (E.S.)
- Particle Therapy Interuniversity Center Leuven—PARTICLE, 3000 Leuven, Belgium
| | - Uwe Himmelreich
- Department of Imaging and Pathology, KU Leuven-University of Leuven, 3000 Leuven, Belgium
- Molecular Small Animal Imaging Center (MoSAIC), KU Leuven-University of Leuven, 3000 Leuven, Belgium
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Ramos-Mendez J, Ortiz CR, Schuemann J, Paganetti H, Faddegon B. TOPAS simulation of photoneutrons in radiotherapy: accuracy and speed with variance reduction. Phys Med Biol 2024; 69:10.1088/1361-6560/ad4303. [PMID: 38657630 PMCID: PMC467037 DOI: 10.1088/1361-6560/ad4303] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2024] [Accepted: 04/24/2024] [Indexed: 04/26/2024]
Abstract
Objective. We provide optimal particle split numbers for speeding up TOPAS Monte Carlo simulations of linear accelerator (linac) treatment heads while maintaining accuracy. In addition, we provide a new TOPAS physics module for simulating photoneutron production and transport.Approach.TOPAS simulation of a Siemens Oncor linac was used to determine the optimal number of splits for directional bremsstrahlung splitting as a function of the field size for 6 MV and 18 MV x-ray beams. The linac simulation was validated against published data of lateral dose profiles and percentage depth-dose curves (PDD) for the largest square field (40 cm side). In separate simulations, neutron particle split and the custom TOPAS physics module was used to generate and transport photoneutrons, called 'TsPhotoNeutron'. Verification of accuracy was performed by comparing simulations with published measurements of: (1) neutron yields as a function of beam energy for thick targets of Al, Cu, Ta, W, Pb and concrete; and (2) photoneutron energy spectrum at 40 cm laterally from the isocenter of the Oncor linac from an 18 MV beam with closed jaws and MLC.Main results.The optimal number of splits obtained for directional bremsstrahlung splitting enhanced the computational efficiency by two orders of magnitude. The efficiency decreased with increasing beam energy and field size. Calculated lateral profiles in the central region agreed within 1 mm/2% from measured data, PDD curves within 1 mm/1%. For the TOPAS physics module, at a split number of 146, the efficiency of computing photoneutron yields was enhanced by a factor of 27.6, whereas it improved the accuracy over existing Geant4 physics modules.Significance.This work provides simulation parameters and a new TOPAS physics module to improve the efficiency and accuracy of TOPAS simulations that involve photonuclear processes occurring in high-Zmaterials found in linac components, patient devices, and treatment rooms, as well as to explore new therapeutic modalities such as very-high energy electron therapy.
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Affiliation(s)
- J Ramos-Mendez
- Department of Radiation Oncology, University of California San Francisco, San Francisco CA, United States of America
| | - Catalan R Ortiz
- Department of Radiation Oncology, University of California San Francisco, San Francisco CA, United States of America
| | - J Schuemann
- Department of Radiation Oncology, Physics Division, Massachusetts General Hospital & Harvard Medical School, Boston MA, United States of America
| | - H Paganetti
- Department of Radiation Oncology, Physics Division, Massachusetts General Hospital & Harvard Medical School, Boston MA, United States of America
| | - B Faddegon
- Department of Radiation Oncology, University of California San Francisco, San Francisco CA, United States of America
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Carlone M, Yang R, Hyde D, Becker N, Cocarell J. In reply to Masjedi et al. Med Phys 2024; 51:2352-2353. [PMID: 38573652 DOI: 10.1002/mp.16993] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2023] [Revised: 12/22/2023] [Accepted: 02/01/2024] [Indexed: 04/05/2024] Open
Affiliation(s)
- Marco Carlone
- BC Cancer Kelowna, Kelowna, British Columbia, Canada
- University of British Columbia - Okanagan, Department of Physics, Kelowna, British Columbia, Canada
| | - Ray Yang
- BC Cancer Kelowna, Kelowna, British Columbia, Canada
| | - Derek Hyde
- BC Cancer Kelowna, Kelowna, British Columbia, Canada
- University of British Columbia - Okanagan, Department of Physics, Kelowna, British Columbia, Canada
| | - Nathan Becker
- BC Cancer Kelowna, Kelowna, British Columbia, Canada
- University of British Columbia - Okanagan, Department of Physics, Kelowna, British Columbia, Canada
| | - John Cocarell
- BC Cancer Kelowna, Kelowna, British Columbia, Canada
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Tulik P, Maciak M, Tulik M. A dosimetric comparison of 3D-CRT, IMRT and IMAT treatment techniques - assessment from radiation protection point of view. Rep Pract Oncol Radiother 2024; 29:69-76. [PMID: 39165590 PMCID: PMC11333076 DOI: 10.5603/rpor.99025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2023] [Accepted: 01/09/2024] [Indexed: 08/22/2024] Open
Abstract
Background The purpose was to assess the impact of irradiation technique type and beam energy on the mixed radiation field around the medical linear accelerator (linac) in terms of radiation quality and related radiation protection quantities. Materials and methods Seven radiotherapeutic plans with Alderson-Rando anthropomorphic phantom [different techniques: conventional three-dimensional conformal radiotherapy (3D-CRT), intensity-modulated radiotherapy (IMRT) and intensity modulated arc therapy (IMAT), different beams: 6 MV or 18 MV, and their arrangements) were prepared for the case of prostate malignancy. Recombination chambers REM-2 and GW2 were positioned on the treatment couch 100 cm from the beam axis at the height of the isocentre. Recombination chambers REM-2 and GW2 were used for recombination index of radiation quality Q4 determination, measurement of total tissue dose Dt and calculation of gamma and neutron components to Dt. Estimation of Dt and Q4 allowed for the ambient dose equivalent H*(10) calculations for each plan. Results For plans prepared with 6 MV beams, Q4 values within the limits of uncertainty were equal to one, which confirms the correctness of the measurement method. For plans implemented with 18 MV beams, the value of Q4 was in the range of 3.7-5.7. Comparison between treatment techniques indicates that the lowest exposure resulting from out-of-field doses comes from 6 MV IMAT (0.7 mSv), whereas the highest one is from 18 MV IMRT (55.1 mSv). Conclusion With the recombination chambers technique it was confirmed that the choice of beam energy directly affects the generation of photoneutrons. The treatment plan technique can have a significant impact on the out-of-field dose.
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Affiliation(s)
- Piotr Tulik
- Institute of Metrology and Biomedical Engineering, Faculty of Mechatronics, Warsaw University of Technology, Warsaw, Poland
| | - Maciej Maciak
- Institute of Metrology and Biomedical Engineering, Faculty of Mechatronics, Warsaw University of Technology, Warsaw, Poland
| | - Monika Tulik
- Department of Nuclear Medicine, Medical University of Warsaw, Warsaw, Poland
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Sathian D, Bakshi AK, Kannan U, Beck M, Haneefa A, Cyriac S. FOIL ACTIVATION TECHNIQUE-A TOOL FOR THE EVALUATION OF PHOTO-NEUTRON DOSE IN RADIOTHERAPY. RADIATION PROTECTION DOSIMETRY 2023; 199:603-614. [PMID: 36928532 DOI: 10.1093/rpd/ncad054] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2022] [Revised: 01/25/2023] [Accepted: 02/08/2023] [Indexed: 05/05/2023]
Abstract
Treatment of cancer is carried out using photon beams from high-energy medical linear accelerators. Photo-neutrons are also produced as an unwanted by product in the process of dose delivery to the cancer patients during their radiation treatments. In the present study, photo-neutron dose equivalents (both thermal and fast components) per unit delivered gamma-photon dose were measured at different depths, as function of distances from iso-centre in patient plane, field sizes, wedge angles and at LINAC head for a 15-MV medical linear accelerator model Elekta Precise using multi-foil activation technique. The neutron dose equivalents determined for the above-mentioned parameters were found to be lower (<0.05%) in comparison with the therapeutic photon dose delivered and within the prescribed limits recommended by the national regulatory authority.
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Affiliation(s)
- Deepa Sathian
- Radiological Physics and Advisory Division, Bhabha Atomic Research Centre, Mumbai 400071, India
- Homi Bhabha National Institute, Mumbai 400094, India
| | - Ashok K Bakshi
- Radiological Physics and Advisory Division, Bhabha Atomic Research Centre, Mumbai 400071, India
- Homi Bhabha National Institute, Mumbai 400094, India
| | - Umasankari Kannan
- Homi Bhabha National Institute, Mumbai 400094, India
- Reactor Physics Design Division, Bhabha Atomic Research Centre, Mumbai 400085, India
| | - Mudit Beck
- Radiological Physics and Advisory Division, Bhabha Atomic Research Centre, Mumbai 400071, India
| | - Abdul Haneefa
- Nanavati Super Speciality Hospital, Mumbai 400056, India
| | - Siji Cyriac
- Nanavati Super Speciality Hospital, Mumbai 400056, India
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Carlone M, Yang R, Hyde D, Becker N, Cocarell J. Measurement of neutron yield for a medical linear accelerator below 10 MV. Med Phys 2023. [PMID: 37060574 DOI: 10.1002/mp.16416] [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: 09/14/2022] [Revised: 03/25/2023] [Accepted: 03/30/2023] [Indexed: 04/16/2023] Open
Abstract
BACKGROUND The recent trend toward 10 MV for volumetric radiotherapy treatment such as volumetric modulated arc therapy (VMAT), stereotactic radiosurgery (SRS), and stereotactic ablative body radiotherapy (SABR) introduces photoneutron production, with implications for non-therapeutic patient dose and additional shielding requirements for treatment room design. The sharply nonlinear drop-off in photoneutron production below 10 MV to negligible at 6 MV has scarcely been characterized quantitatively, yet can elucidate important practical insights. PURPOSE To measure photoneutron yields in a medical linac at 8 MV, which may strike a reasonable balance between usefully increased beam penetration and dose rate as compared to 6 MV while reducing photoneutron production which is present at 10 MV. METHODS A Varian iX linear accelerator undergoing decommissioning at our clinic was made to operate over a range of photon energies between 6 and 15 MV by calibrating the bending magnet and adjusting other beam generation parameters. Neutron dose within the treatment room was measured using an Anderson-Braun type detector over a continuum of intermediate energies. RESULTS The photoneutron production for energies below 10 MV was measured, adding to data that is otherwise scarce in the literature. Our results are consistent with previously published results for neutron yield. We found that the photoneutron production at 8 MV was about 1/10 of the value at 10 MV, and about 10 times higher than detector background at 6 MV. CONCLUSIONS Photoneutron production drops off below 10 MV, but is still present at 8 MV. An 8 MV beam is more penetrating than a 6 MV beam, and may offer a suitable tradeoff for modern radiotherapy techniques such as VMAT, SRS, and SABR. Further studies are needed to better understand the impact on treatment plan quality between 8 and 10 MV beams considering the benefits to facility requirements and non-therapeutic patient dose.
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Affiliation(s)
- Marco Carlone
- BC Cancer Kelowna, Kelowna, British Columbia, Canada
| | - Ray Yang
- BC Cancer Kelowna, Kelowna, British Columbia, Canada
| | - Derek Hyde
- BC Cancer Kelowna, Kelowna, British Columbia, Canada
- Department of Physics, University of British Columbia - Okanagan, Kelowna, British Columbia, Canada
| | - Nathan Becker
- BC Cancer Kelowna, Kelowna, British Columbia, Canada
- Department of Physics, University of British Columbia - Okanagan, Kelowna, British Columbia, Canada
| | - John Cocarell
- BC Cancer Kelowna, Kelowna, British Columbia, Canada
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Alghamdi AAA. MCNPX Estimation of Photoneutron Dose to Eye Voxel Anthropomorphic Phantom From 18 MV Linear Accelerator. Dose Response 2023; 21:15593258231169807. [PMID: 37077717 PMCID: PMC10107973 DOI: 10.1177/15593258231169807] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2022] [Accepted: 03/27/2023] [Indexed: 04/21/2023] Open
Abstract
The dose due to photoneutron contamination outside the field of irradiation can be significant when using high-energy linear accelerators. The eye is a radiation-sensitive organ, and this risk increases when high linear energy transfer neutron radiation is involved. This study aimed to provide a fast method to estimate photoneutron dose to the eye during radiotherapy. A typical high-energy linear accelerator operating at 18 MV was simulated using the Monte Carlo N-Particle Transport Code System extended version (MCNPX 2.5.0). The latest International Atomic Energy Agency photonuclear data library release was integrated into the code, accounting for the most known elements and isotopes used in typical linear accelerator construction. The photoneutron flux from a 5 × 5 cm2 field size was scored at the treatment table plane and used as a new source for estimating the absorbed dose in a high-resolution eye voxel anthropomorphic phantom. In addition, common shielding media were tested to reduce the photoneutron dose to the eye using common shielding materials. Introducing a 2 cm thickness of common neutron shielding medium reduced the total dose received in the eye voxel anthropomorphic phantom by 54%. In conclusion, individualized treatment based on photoneutron dose assessment is essential to better estimate the secondary dose inside or outside the field of irradiation.
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Affiliation(s)
- Ali AA Alghamdi
- Department of Radiological
Sciences, College of Applied Medical Science, Imam Abdulrahman Bin Faisal
University, Dammam, Saudi Arabia
- Ali AA Alghamdi, Department of Radiological
Sciences, College of Applied Medical Science, Imam Abdulrahman Bin Faisal
University, P.O. Box 2435, Dammam, Saudi Arabia 31441.
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Akkurt I, Boodaghi Malidarreh P, Boodaghi Malidarre R. Simulation and prediction of the attenuation behaviour of the KNN-LMN-based lead-free ceramics by FLUKA code and artificial neural network (ANN)-based algorithm. ENVIRONMENTAL TECHNOLOGY 2023; 44:1592-1599. [PMID: 34787063 DOI: 10.1080/09593330.2021.2008017] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/13/2021] [Accepted: 10/31/2021] [Indexed: 06/13/2023]
Abstract
The significance and novelty of the present work are the preparation of the non-lead ceramic by the general formula of (1-x) K0.5Na0.5NbO3-xLa Mn0.5Ni0.5O3 (KNN-LMN) with different x (0<x<0.295) (mol) to examine the shielding qualities of KNN-LMN non-lead ceramic via FLUKA code. The obtained results via FLUKA code are used as input data for training the artificial neural network algorithm and prediction. For this purpose, the radio isotopic 252Cf neutron source is simulated by the HI-PROBE, RADDECAY and DCYSCORE cards using the FLUKA code. As a result, the neutron-gamma photon shielding ability of the KNN-LMN lead-free ceramics exposed to the 252Cf neutron source is estimated and predicted. Findings show that by increasing the concentration of the x in (1-x) K0.5Na0.5NbO3-xLa Mn0.5Ni0.5O3 lead-free ceramics results in an ascending trend in density. In addition, the increment of the x rate (x refers to the concentration of La Mn0.5Ni0.5O3 in KNN-LMN non-lead ceramics) causes an increase in the value of the neutron attenuation parameter (∑t), and a strong relationship is monitored between ∑t and density. Moreover, descending order of (HVL)x=0.01>(HVL)x=0.04>(HVL)x=0.07>…>(HVL)x=0.25 is reported for half-value layer values against gamma photon. From the attained results, it can be concluded that increaisng the rate of x results in the better shielding proficiency in terms of neutron and gamma photon for chosen KNN-LMN-based lead-free ceramics.
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Affiliation(s)
- Iskender Akkurt
- Physics Department, Suleyman Demirel University, Isparta, Turkey
| | | | - Roya Boodaghi Malidarre
- Hadaf Institution of Higher Education, Sari, Iran
- Physics Department, Payame Noor University, Tehran, Iran
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Wong YM, Koh CWY, Lew KS, Chua CGA, Nei W, Tan HQ, Lee JCL, Mazonakis M, Damilakis J. A review on fetal dose in Radiotherapy: A historical to contemporary perspective. Phys Med 2023; 105:102513. [PMID: 36565555 DOI: 10.1016/j.ejmp.2022.102513] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/05/2022] [Revised: 11/09/2022] [Accepted: 12/16/2022] [Indexed: 12/24/2022] Open
Abstract
This paper aims to review on fetal dose in radiotherapy and extends and updates on a previous work1 to include proton therapy. Out-of-field doses, which are the doses received by regions outside of the treatment field, are unavoidable regardless of the treatment modalities used during radiotherapy. In the case of pregnant patients, fetal dose is a major concern as it has long been recognized that fetuses exposed to radiation have a higher probability of suffering from adverse effects such as anatomical malformations and even fetal death, especially when the 0.1Gy threshold is exceeded. In spite of the low occurrence of cancer during pregnancy, the radiotherapy team should be equipped with the necessary knowledge to deal with fetal dose. This is crucial so as to ensure that the fetus is adequately protected while not compromising the patient treatment outcomes. In this review paper, various aspects of fetal dose will be discussed ranging from biological, clinical to the physics aspects. Other than fetal dose resulting from conventional photon therapy, this paper will also extend the discussion to modern treatment modalities and techniques, namely proton therapy and image-guided radiotherapy, all of which have seen a significant increase in use in current radiotherapy. This review is expected to provide readers with a comprehensive understanding of fetal dose in radiotherapy, and to be fully aware of the steps to be taken in providing radiotherapy for pregnant patients.
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Affiliation(s)
- Yun Ming Wong
- Division of Physics and Applied Physics, Nanyang Technological University, Singapore
| | | | - Kah Seng Lew
- Division of Radiation Oncology, National Cancer Centre Singapore, Singapore
| | | | - Wenlong Nei
- Division of Radiation Oncology, National Cancer Centre Singapore, Singapore
| | - Hong Qi Tan
- Division of Radiation Oncology, National Cancer Centre Singapore, Singapore.
| | - James Cheow Lei Lee
- Division of Radiation Oncology, National Cancer Centre Singapore, Singapore; Division of Physics and Applied Physics, Nanyang Technological University, Singapore
| | - Michael Mazonakis
- Department of Medical Physics, School of Medicine, University of Crete, Greece
| | - John Damilakis
- Department of Medical Physics, School of Medicine, University of Crete, Greece
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Characterization of photoneutron fluxes emitted by electron accelerators in the 4–20 MeV range using Monte Carlo codes: A critical review. Appl Radiat Isot 2022; 191:110506. [DOI: 10.1016/j.apradiso.2022.110506] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2022] [Revised: 08/23/2022] [Accepted: 09/30/2022] [Indexed: 11/18/2022]
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14
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Kundrát P, Pachnerová Brabcová K, Jelínek Michaelidesová A, Zahradníček O, Danilová I, Štěpán V, Jamborová Z, Davídková M. BORON-ENHANCED BIOLOGICAL EFFECTIVENESS OF PROTON IRRADIATION: STRATEGY TO ASSESS THE UNDERPINNING MECHANISM. RADIATION PROTECTION DOSIMETRY 2022; 198:527-531. [PMID: 36005957 DOI: 10.1093/rpd/ncac093] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2022] [Accepted: 05/22/2022] [Indexed: 06/15/2023]
Abstract
Proton radiotherapy for the treatment of cancer offers an excellent dose distribution. Cellular experiments have shown that in terms of biological effects, the sharp dose distribution is further amplified, by as much as 75%, in the presence of boron. It is a matter of debate whether the underlying physical processes involve the nuclear reaction of 11B with protons or 10B with secondary neutrons, both producing densely ionizing short-ranged particles. Likewise, potential roles of intercellular communication or boron acting as a radiosensitizer are not clear. We present an ongoing research project based on a multiscale approach to elucidate the mechanism by which boron enhances the effectiveness of proton irradiation in the Bragg peak. It combines experimental with simulation tools to study the physics of proton-boron interactions, and to analyze intra- and inter-cellular boron biology upon proton irradiation.
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Affiliation(s)
- Pavel Kundrát
- Department of Radiation Dosimetry, Nuclear Physics Institute of the CAS, Na Truhlářce 39/64, 180 00 Praha 8, Czech Republic
| | - Kateřina Pachnerová Brabcová
- Department of Radiation Dosimetry, Nuclear Physics Institute of the CAS, Na Truhlářce 39/64, 180 00 Praha 8, Czech Republic
| | - Anna Jelínek Michaelidesová
- Department of Radiation Dosimetry, Nuclear Physics Institute of the CAS, Na Truhlářce 39/64, 180 00 Praha 8, Czech Republic
- Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University in Prague, Břehová 7, 110 00 Praha 1, Czech Republic
| | - Oldřich Zahradníček
- Department of Radiation Dosimetry, Nuclear Physics Institute of the CAS, Na Truhlářce 39/64, 180 00 Praha 8, Czech Republic
| | - Irina Danilová
- Department of Radiation Dosimetry, Nuclear Physics Institute of the CAS, Na Truhlářce 39/64, 180 00 Praha 8, Czech Republic
- Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University in Prague, Břehová 7, 110 00 Praha 1, Czech Republic
| | - Václav Štěpán
- Department of Radiation Dosimetry, Nuclear Physics Institute of the CAS, Na Truhlářce 39/64, 180 00 Praha 8, Czech Republic
- Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University in Prague, Břehová 7, 110 00 Praha 1, Czech Republic
| | - Zuzana Jamborová
- Department of Radiation Dosimetry, Nuclear Physics Institute of the CAS, Na Truhlářce 39/64, 180 00 Praha 8, Czech Republic
- Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University in Prague, Břehová 7, 110 00 Praha 1, Czech Republic
| | - Marie Davídková
- Department of Radiation Dosimetry, Nuclear Physics Institute of the CAS, Na Truhlářce 39/64, 180 00 Praha 8, Czech Republic
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15
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Oflaz U, Sarpün İ, Özdoğan H. Investigation of level density and Gama strength function for photoneutron reaction in medical linacs in Beamline. Appl Radiat Isot 2022; 186:110286. [DOI: 10.1016/j.apradiso.2022.110286] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Accepted: 05/08/2022] [Indexed: 11/29/2022]
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16
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The behavior of the contamination particles appears with the 18 MV photon beam delivered by Elekta Synergy MLCi2. Radiat Phys Chem Oxf Engl 1993 2022. [DOI: 10.1016/j.radphyschem.2022.110384] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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17
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Moghaddasi L, Colyer C. Evaluation of the effectiveness of steel for shielding photoneutrons produced in medical linear accelerators: A Monte Carlo particle transport study. Phys Med 2022; 98:53-62. [DOI: 10.1016/j.ejmp.2022.04.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/05/2022] [Revised: 04/13/2022] [Accepted: 04/22/2022] [Indexed: 10/18/2022] Open
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18
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Esplen N, Egoriti L, Paley B, Planche T, Hoehr C, Gottberg A, Bazalova-Carter M. Design optimization of an electron-to-photon conversion target for ultra-high dose rate x-ray (FLASH) experiments at TRIUMF. Phys Med Biol 2022; 67. [DOI: 10.1088/1361-6560/ac5ed6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2021] [Accepted: 03/17/2022] [Indexed: 12/29/2022]
Abstract
Abstract
Objective. To develop a bremsstrahlung target and megavoltage (MV) x-ray irradiation platform for ultrahigh dose-rate (UHDR) irradiation of small-animals on the Advanced Rare Isotope Laboratory (ARIEL) electron linac (e-linac) at TRIUMF. Approach. An electron-to-photon converter design for UHDR radiotherapy (RT) was centered around optimization of a tantalum–aluminum (Ta–Al) explosion-bonded target. Energy deposition within a homogeneous water-phantom and the target itself were evaluated using EGSnrc and FLUKA MC codes, respectively, for various target thicknesses (0.5–1.5 mm), beam energies (E
e− = 8, 10 MeV) and electron (Gaussian) beam sizes (
2
σ
= 2–10 mm). Depth dose-rates in a 3D-printed mouse phantom were also calculated to infer the compatibility of the 10 MV dose distributions for FLASH-RT in small-animal models. Coupled thermo-mechanical FEA simulations in ANSYS were subsequently used to inform the stress–strain conditions and fatigue life of the target assembly. Main results. Dose-rates of up to 128 Gy s−1 at the phantom surface, or 85 Gy s−1 at 1 cm depth, were obtained for a 1 × 1 cm2 field size, 1 mm thick Ta target and 7.5 cm source-to-surface distance using the FLASH-mode beam (E
e− = 10 MeV, 2
σ
= 5 mm, P = 1 kW); furthermore, removal of the collimation assembly and using a shorter (3.5 cm) SSD afforded dose-rates >600 Gy s−1, albeit at the expense of field conformality. Target temperatures were maintained below the tantalum, aluminum and cooling-water thresholds of 2000 °C, 300 °C and 100 °C, respectively, while the aluminum strain behavior remained everywhere elastic and helped ensure the converter survives its prescribed 5 yr operational lifetime. Significance. Effective design iteration, target cooling and failure mitigation have culminated in a robust target compatible with intensive transient (FLASH) and steady-state (diagnostic) applications. The ARIEL UHDR photon source will facilitate FLASH-RT experiments concerned with sub-second, pulsed or continuous beam irradiations at dose rates in excess of 40 Gy s−1.
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19
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Grebowski J, Litwinienko G. Metallofullerenols in biomedical applications. Eur J Med Chem 2022; 238:114481. [PMID: 35665690 DOI: 10.1016/j.ejmech.2022.114481] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2021] [Revised: 04/30/2022] [Accepted: 05/17/2022] [Indexed: 12/20/2022]
Abstract
Metallofullerenols (MFs) are functionalized endohedral fullerenes connecting at least three levels of organization of matter: atomic, molecular, and supramolecular, resulting in their unique activity at the nanoscale. Biomedical applications of MFs started from gadolinium-containing contrasting agents, but today their potential medical applications go far beyond diagnostics and magnetic resonance imaging. In many cases, preclinical studies have shown a great therapeutic value of MFs, and here we provide an overview of interactions of MFs with high-energy radiation and with reactive oxygen species generated during radiation as a ground for potential applications in modern therapy of cancer patients. We also present the current knowledge on interactions of MFs with proteins and with other components of cells and tissues. Due to their antioxidant properties, as well as their ability to regulate the expression of genes involved in apoptosis, angiogenesis, and stimulation of the immune response, MFs can contribute to inhibition of tumor growth and protection of normal cells. MFs with enclosed gadolinium act as inhibitors of tumor growth in targeted therapy along with imaging techniques, but we hope that the data gathered in this review will help to accelerate further progress in the implementation of MFs, also the ones containing rare earth metals other than gadolinium, in a broad range of bioapplications covering not only diagnostics and bioimaging but also radiation therapy and cancer treatment by not-cytotoxic agents.
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Affiliation(s)
- Jacek Grebowski
- Department of Molecular Biophysics, Faculty of Biology and Environmental Protection, University of Lodz, Pomorska 141/143, 90-236, Lodz, Poland; The Military Medical Training Center, 6-Sierpnia 92, 90-646, Lodz, Poland.
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20
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Measurement of neutron equivalent dose in the thyroid, chiasma, and lens for patients undergoing pelvic radiotherapy: A phantom study. Appl Radiat Isot 2022; 184:110188. [DOI: 10.1016/j.apradiso.2022.110188] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Revised: 01/18/2022] [Accepted: 03/04/2022] [Indexed: 11/20/2022]
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21
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Kwon NH, Shin DO, Kim J, Yoo J, Park MS, Kim KB, Kim DW, Choi SH. Current status of disposal and measurement analysis of radioactive components in linear accelerators in Korea. NUCLEAR ENGINEERING AND TECHNOLOGY 2022. [DOI: 10.1016/j.net.2021.11.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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22
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Elmtalab S, Shanei A, Choopan Dastjerdi MH, Brkić H, Abedi I, Amouheidari A. OUP accepted manuscript. RADIATION PROTECTION DOSIMETRY 2022; 198:129-138. [PMID: 35137234 DOI: 10.1093/rpd/ncac001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2021] [Revised: 12/27/2021] [Accepted: 01/03/2022] [Indexed: 11/12/2022]
Affiliation(s)
- Soheil Elmtalab
- Department of Medical Physics, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Ahmad Shanei
- Department of Medical Physics, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran
| | | | - Hrvoje Brkić
- Department of biophysics and radiology, Faculty of Medicine, J. J. Strossmayer University of Osijek, Osijek, Croatia
- Department of biophysics, biology and chemistry, Faculty of dental medicine and health, J. J. Strossmayer University of Osijek, Osijek, Croatia
| | - Iraj Abedi
- Department of Medical Physics, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Alireza Amouheidari
- Department of Radiation Oncology, Isfahan Milad General Hospital, Isfahan, Iran
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23
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Measurement of Neutron Dose Equivalent within and Outside of a LINAC Treatment Vault Using a Neutron Survey Meter. QUANTUM BEAM SCIENCE 2021. [DOI: 10.3390/qubs5040033] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
This work concerns neutron doses associated with the use of a Siemens Primus M5497 electron accelerator, which is operated in the photon mode at 15 MV. The conditions offer a situation within which a fraction of the bremsstrahlung emission energies exceed the photoneutron threshold. For different field sizes, an investigation has been made of neutron dose equivalent values at various measurement locations, including: (i) At the treatment table, at a source-surface distance of 100 cm; (ii) at the level of the floor directly adjacent to the treatment table; and (iii) in the control room and patient waiting area. The evaluated neutron dose equivalent was found to range from 0.0001 to 8.6 mSv/h, notably with the greatest value at the level of the floor directly adjacent to the treatment couch (8.6 mSv/h) exceeding the greatest value on the treatment table (5.5 mSv/h). Low values ranging from unobservable to between 0.0001 to 0.0002 mSv/h neutron dose were recorded around the control room and patient waiting area. For measurements on the floor, the study showed the dose equivalent to be greatest with the jaws closed. These data, most particularly concerning neutron distribution within the treatment room, are of great importance in making steps towards improving patient safety via the provision of protective measures.
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24
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Prasada DNY, Ciamaudi N, Fadli M, Tursinah R, Pawiro SA. Evaluation of the linac neutron dose profile for various depths and field sizes: a Monte Carlo study. Biomed Phys Eng Express 2021; 7. [PMID: 34619664 DOI: 10.1088/2057-1976/ac2dd5] [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: 06/23/2021] [Accepted: 10/07/2021] [Indexed: 11/12/2022]
Abstract
High-energy medical linear accelerator (Linac) has been widely used for treating cancer patients. However, with its effectiveness, high-energy linac yields an undesirable amount of neutron contamination. An MCNPX code version 2.6.0 was used for calculating photoneutron contamination from Varian Clinac iX 15 MV linac heads in this study. The fast neutrons were dominantly produced inside the linac head. The neutron fluence, absorbed dose, and dose equivalent calculations occurred inside a linac head and a water phantom model. The fast neutrons begin to be moderated after 1 cm inside the water phantom by calculating the energy spectra. Variations in the field sizes from 2 × 2, 5 × 5, 10 × 10, and 15 × 15 cm2show that the neutron production yield would increase for larger field sizes. The maximum neutron dose equivalents are 3.745; 7.687; 11.794 and 14.197μSv/MU for 2 × 2, 5 × 5, 10 × 10 and 15 × 15 cm2field sizes, respectively. These calculations predict the photoneutron characteristics with more detail inside a treated patient during radiation therapy procedures.
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Affiliation(s)
- Dewa Ngurah Yudhi Prasada
- Department of Physics, Faculty of Mathematics and Natural Sciences, Universitas Indonesia, Depok, Indonesia.,Department of Radiation Oncology, MRCCC Siloam Hospitals, Jakarta, Indonesia
| | - Nikita Ciamaudi
- Department of Physics, Faculty of Mathematics and Natural Sciences, Universitas Indonesia, Depok, Indonesia
| | - Muhamad Fadli
- Department of Radiation Oncology, MRCCC Siloam Hospitals, Jakarta, Indonesia
| | - Rasito Tursinah
- Centre for Applied Nuclear Science and Technology, National Nuclear Energy Agency, Bandung, Indonesia
| | - Supriyanto Ardjo Pawiro
- Department of Physics, Faculty of Mathematics and Natural Sciences, Universitas Indonesia, Depok, Indonesia
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25
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26
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Banaee N, Goodarzi K, Nedaie HA. Neutron contamination in radiotherapy processes: a review study. JOURNAL OF RADIATION RESEARCH 2021:rrab076. [PMID: 34467374 DOI: 10.1093/jrr/rrab076] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/12/2021] [Revised: 05/25/2021] [Indexed: 05/27/2023]
Abstract
Using high-energy photon beams is one of the most practical methods in radiotherapy treatment of cases in deep site located tumors. In such treatments, neutron contamination induced through photoneutron interaction of high energy photons (>8 MeV) with high Z materials of LINAC structures is the most crucial issue which should be considered. Generated neutrons will affect shielding calculations and cause extra doses to the patient and the probability of increase induced secondary cancer risks. In this study, different parameters of neutron production in radiotherapy processes will be reviewed.
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Affiliation(s)
- Nooshin Banaee
- Medical Radiation Research Center, Central Tehran Branch, Islamic Azad University, Tehran 1469669191, Iran
| | - Kiarash Goodarzi
- Department of Medical Radiation Engineering, Central Tehran Branch, Islamic Azad University, Tehran 1469669191, Iran
| | - Hassan Ali Nedaie
- Radiation Oncology Research Centre, Cancer Institute, Tehran University of Medical Sciences, Tehran 1417613151, Iran
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27
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Toth A, Marjanovic M, Gencel I, Petrovic B. Novel design of radiotherapy room suggestion - three-band maze. NUCLEAR TECHNOLOGY AND RADIATION PROTECTION 2021. [DOI: 10.2298/ntrp2104371t] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
The objective of this study was to analyze the dependence of the neutron dose
from the geometry of the second band of the maze using dosimetric
measurements of neutrons and Monte Carlo simulations, and based on those
results to design a novel radiotherapy room layout. Measurements of the
neutron dose at a two-band maze therapy room were performed for a 15 MeV
photon beam only. Monte Carlo simulations were performed using the GEANT4
toolkit. In order to obtain the geometry dependence, we were changing the
second band angle while we kept the length, height, and width the same as in
reality. Results show that the highest calculated dose was obtained for
the 60? angle of the second maze. It is 17 % higher than for standard 0?
angle. For 30? it was 30 % smaller and for 90? was 10% smaller. Although
the lowest dose was obtained for 30? band angle with calculations, it is not
very practical for clinical use. Clinically the most interesting would be
the 90? angle which is practically a short three-band maze, which could be
promising from the perspective of neutron radiation protection since it
could offer a compact constructional solution, and better optimization of
the available space.
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Affiliation(s)
- Arpad Toth
- Oncology Institute of Vojvodina, Sremska Kamenica, Serbia + Vin~a Institute of Nuclear Sciences, National Institute of the Republic of Serbia, University of Belgrade, Belgrade, Serbia
| | - Milana Marjanovic
- Oncology Institute of Vojvodina, Sremska Kamenica, Serbia + Department of Physics, Faculty of Sciences, University of Novi Sad, Novi Sad, Serbia
| | - Ivan Gencel
- Oncology Institute of Vojvodina, Sremska Kamenica, Serbia
| | - Borislava Petrovic
- Oncology Institute of Vojvodina, Sremska Kamenica, Serbia + Department of Physics, Faculty of Sciences, University of Novi Sad, Novi Sad, Serbia
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28
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H D, A A M, M G, S M, C K. Study of Photoneutron Production for the 18 MV Photon Beam of the Siemens Medical linac by Monte Carlo Simulation. J Biomed Phys Eng 2020; 10:679-690. [PMID: 33364205 PMCID: PMC7753258 DOI: 10.31661/jbpe.v0i0.939] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2018] [Accepted: 06/05/2018] [Indexed: 11/22/2022]
Abstract
Background: Considering the importance of photoneutron production in linear accelerators, it is necessary to describe and measure the photoneutrons produced around modern linear accelerators. Objective: The aim of the present research is to study photoneutron production for the 18 MV photon beam of a Siemens Primus Plus medical linear accelerator. Material and Methods: This study is an experimental study. The main components of the head of Siemens Primus Plus linac were simulated using MCNPX 2.7.0 code. The contribution of different components of the linac in photoneutron production, neutron source strength, neutron source strength and photon and electron spectra were calculated for the flattening filter and flattening filter free cases for the 18 MV photon beam, and was scored for three fields of 5 × 5 cm2, 10 × 10 cm2 and 20 × 20 cm2 in size. Results: The results show that the primary collimator has the largest contribution to production of neutrons. Moreover, the photon fluence for the flattening filter free case is 8.62, 6.51 and 4.62 times higher than the flattening filter case for the three fields, respectively. The electron fluences for the flattening filter free case are 4.62, 2.93 and 2.79 times higher than with flattening filter case for the three fields under study, respectively. In addition to these cases, by increasing the field size, the contribution of neutron production related to the jaws is reduced, so that when the field size increases from 5 × 5 cm2 to 20 × 20 cm2, a 17.93% decrease in photoneutron production was observed. Conclusion: In all of the accelerators, the neutron strength also increases with increasing energy. The calculated neutron strength was equal to 0.83×1012 neutron Gy −1 at the isocenter.
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Affiliation(s)
- Dowlatabadi H
- PhD, Physics Department, School of Sciences, Payame Noor University of Mashhad, Mashhad, Iran
| | - Mowlavi A A
- PhD, Physics Department, School of Sciences, Hakim Sabzevari University, Sabzevar, Iran
- PhD, International Centre for Theoretical Physics, Associate Federation Scheme, Medical Physics Field, Trieste, Italy
| | - Ghorbani M
- PhD, Biomedical Engineering and Medical Physics Department, Faculty of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Mohammadi S
- PhD, Physics Department, School of Sciences, Payame Noor University of Mashhad, Mashhad, Iran
| | - Knaup C
- PhD, Comprehensive Cancer Centers of Nevada, Las Vegas, Nevada, USA
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Gauter-Fleckenstein B, Barthel C, Büttner S, Wenz F, Borggrefe M, Tülümen E. Effectivity and applicability of the German DEGRO/DGK-guideline for radiotherapy in CIED-bearing patients. Radiother Oncol 2020; 152:208-215. [DOI: 10.1016/j.radonc.2020.01.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2019] [Revised: 12/07/2019] [Accepted: 01/07/2020] [Indexed: 11/26/2022]
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30
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Karaman O, Özdoğan H, Üncü YA, Karaman C, Tanır AG. Investigation of the effects of different composite materials on neutron contamination caused by medical LINAC. KERNTECHNIK 2020. [DOI: 10.3139/124.200022] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Affiliation(s)
- O. Karaman
- Akdeniz University, Vocational School of Health Services Medical Imaging Program, Antalya, 07058 Turkey
| | - H. Özdoğan
- Akdeniz University, Faculty of Medicine Antalya Bilim University, Vocational School of Health Services Department of Medical Imaging Techniques Antalya, 07190 Turkey
| | - Y. A. Üncü
- Akdeniz University, Faculty of Medicine Antalya Bilim University, Vocational School of Health Services Department of Medical Imaging Techniques Antalya, 07190 Turkey
- Akdeniz University, Vocational School of Technical Sciences Department of Biomedical Equipment Technology Antalya, 07070 Turkey
| | - C. Karaman
- Akdeniz University, Vocational School of Technical Sciences Department of Electricity and Energy Antalya, 07070 Turkey
| | - A. G. Tanır
- Gazi University, Faculty of Science, Department of Physics Antalya, 06500 Turkey
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31
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Measurement of the photon and thermal neutron doses of contralateral breast surface in breast cancer radiotherapy. JOURNAL OF RADIOTHERAPY IN PRACTICE 2020. [DOI: 10.1017/s1460396919000578] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
AbstractIntroduction and purpose:During the radiation therapy of tumoral breast, the contralateral breast (CB) will receive scattered doses. In the present study, the photon and thermal neutron dose values received by CB surface during breast cancer radiation therapy were measured.Materials and methods:The right breast region of RANDO phantom was considered as CB, and the measurements of photon and thermal neutron dose values were carried out on this region surface. The phantom was irradiated with 18 MV photon beams, and the dose values were measured with thermoluminescent dosimeter (TLD-600 and TLD-700) chips for 11 × 13, 11 × 17 and 11 × 21 cm2 field sizes in the presence of physical and dynamic wedges.Results:The total dose values (photon + thermal neutron) received by the CB surface in the presence of physical wedge were 12·06%, 15·75% and 33·40% of the prescribed dose, respectively, for 11 × 13, 11 × 17 and 11 × 21 cm2 field sizes. The corresponding dose values for dynamic wedge were 9·18%, 12·92% and 29·26% of the prescribed dose, respectively. Moreover, the results showed that treatment field size and wedge type affect the received photon and thermal neutron doses at CB surface.Conclusion:According to our results, the total dose values received at CB surface during breast cancer radiotherapy with high-energy photon beams are remarkable. In addition, the dose values received at CB surface when using a physical wedge were greater than when using a dynamic wedge, especially for medial tangential fields.
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Sharifzadehgan A, Laurans M, Thuillot M, Huertas A, Baudinaud P, Narayanan K, Mirabel M, Bibault JE, Frey P, Waldmann V, Varlet E, Amet D, Juin C, Lavergne T, Jouven X, Giraud P, Durdux C, Marijon E. Radiotherapy in Patients With a Cardiac Implantable Electronic Device. Am J Cardiol 2020; 128:196-201. [PMID: 32650920 DOI: 10.1016/j.amjcard.2020.04.045] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/21/2020] [Revised: 04/20/2020] [Accepted: 04/27/2020] [Indexed: 10/24/2022]
Abstract
Recently, the Heart Rhythm Society published recommendations on management of patients with cardiac implantable electronic device (CIED) who require radiotherapy (RT). We aimed to report the experience of a teaching hospital, and discuss our practice in the context of recently published guidelines. We identified all consecutive CIED recipients (12,736 patients) who underwent RT between March 2006 and June 2017. Among them, 90 (1%) patients (78.2 ± 10 years, 73% male) had a CIED: 82 pacemakers and 8 implantable cardioverter-defibrillators. Two patients required CIED extraction prior to RT for ipsilateral breast cancer (no device replacement in 1 patient). Four patients (5%) were considered at high-risk, 35 (39%) at intermediate-risk, and the remaining 50 (56%) at low-risk for CIED dysfunction. Overall, only a minority of patients followed recommended local protocol during RT delivery (31%) and during follow-up (56%). CIED malfunction was detected in 5 patients (6%), mainly back-up mode resetting (80%), with 4 (including 3 pelvic cancer location) patients initially classified as being at intermediate-risk and 1 at low-risk. Four out of the 5 patients with CEID malfunction had received neutron producing beams. In conclusion, our findings underline the lack of rigorous monitoring of patients undergoing RT (though CIED malfunction appears to be rare and relatively benign in nature), and emphasize the interest of considering neutron producing beam for risk stratification as recommended in recent guidelines. Optimization of patient's management requires a close collaboration between both CIED clinicians and radiation oncologists, and more systematic remote CIED monitoring may be helpful.
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Sekar N, Ganesan B, Sahib khilafath HA, Krishnamoorthy K, Prakasarao A, Singaravelu G. Analysis of structural, morphological and dosimetric parameters of HfO2 NPs in clinical 60Co beam. Radiat Phys Chem Oxf Engl 1993 2020. [DOI: 10.1016/j.radphyschem.2020.108833] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Afkham Y, Mesbahi A, Alemi A, Zolfagharpour F, Jabbari N. Design and fabrication of a Nano-based neutron shield for fast neutrons from medical linear accelerators in radiation therapy. Radiat Oncol 2020; 15:105. [PMID: 32393290 PMCID: PMC7216519 DOI: 10.1186/s13014-020-01551-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Accepted: 04/27/2020] [Indexed: 11/24/2022] Open
Abstract
BACKGROUND Photo-neutrons are produced at the head of the medical linear accelerators (linac) by the interaction of high-energy photons, and patients receive a whole-body-absorbed dose from these neutrons. The current study aimed to find an efficient shielding material for fast neutrons. METHODS Nanoparticles (NPs) of Fe3O4 and B4C were applied in a matrix of silicone resin to design a proper shield against fast neutrons produced by the 18 MeV photon beam of a Varian 2100 C/D linac. Neutron macroscopic cross-sections for three types of samples were calculated by the Monte Carlo (MC) method and experimentally measured for neutrons of an Am-Be source. The designed shields in different concentrations were tested by MCNPX MC code, and the proper concentration was chosen for the experimental test. A shield was designed with two layers, including nano-iron oxide and a layer of nano-boron carbide for eliminating fast neutrons. RESULTS MC simulation results with uncertainty less than 1% showed that for discrete energies and 50% nanomaterial concentration, the macroscopic cross-sections for iron oxide and boron carbide at the energy of 1 MeV were 0.36 cm- 1 and 0.32 cm- 1, respectively. For 30% nanomaterial concentration, the calculated macroscopic cross-sections for iron oxide and boron carbide shields for Am-Be spectrum equaled 0.12 cm- 1 and 0.15 cm- 1, respectively, while they are 0.15 cm- 1 and 0.18 cm- 1 for the linac spectrum. In the experiment with the Am-Be spectrum, the macroscopic cross-sections for 30% nanomaterial concentration were 0.17 ± 0.01 cm- 1 for iron oxide and 0.21 ± 0.02 cm- 1 for boron carbide. The measured transmission factors for 30% nanomaterial concentration with the Am-Be spectrum were 0.71 ± 0.01, 0.66 ± 0.02, and 0.62 ± 0.01 for the iron oxide, boron carbide, and double-layer shields, respectively. In addition, these values were 0.74, 0.69, and 0.67, respectively, for MC simulation for the linac spectrum at the same concentration and thickness of 2 cm. CONCLUSION Results achieved from MC simulation and experimental tests were in a satisfactory agreement. The difference between MC and measurements was in the range of 10%. Our results demonstrated that the designed double-layer shield has a superior macroscopic cross-section compared with two single-layer nanoshields and more efficiently eliminates fast photo-neutrons.
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Affiliation(s)
- Younes Afkham
- Department of Medical Physics, Faculty of Medicine, Urmia University of Medical Sciences, Urmia, Iran
| | - Asghar Mesbahi
- Molecular Medicine Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Abdolali Alemi
- Department of Inorganic Chemistry, Faculty of chemistry, Tabriz University, Tabriz, Iran
| | - Farhad Zolfagharpour
- Department of Physics, Faculty of Basic Sciences, University Of Mohaghegh Ardebili, Ardabil, Iran
| | - Nasrollah Jabbari
- Solid Tumor Research Center, Cellular and Molecular Medicine Institute, Urmia University of Medical Sciences, Urmia, Iran.
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Method to quickly and accurately calculate absorbed dose from therapeutic and stray photon exposures throughout the entire body in individual patients. Med Phys 2020; 47:2254-2266. [DOI: 10.1002/mp.14018] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Revised: 12/11/2019] [Accepted: 12/24/2019] [Indexed: 01/26/2023] Open
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Ghasemi-Jangjoo A, Ghiasi H. Monte Carlo study on the secondary cancer risk estimations for patients undergoing prostate radiotherapy: A humanoid phantom study. Rep Pract Oncol Radiother 2020; 25:187-192. [PMID: 32021575 PMCID: PMC6994283 DOI: 10.1016/j.rpor.2019.12.029] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2019] [Revised: 12/04/2019] [Accepted: 12/30/2019] [Indexed: 10/25/2022] Open
Abstract
AIM The aim of this study was to estimate the secondary malignancy risk from the radiation in FFB prostate linac-based radiotherapy for different organs of the patient. BACKGROUND Radiation therapy is one of the main procedures of cancer treatment. However, the application the radiation may impose dose to organs of the patient which can be the cause of some malignancies. MATERIALS AND METHODS Monte Carlo (MC) simulation was used to calculate radiation doses to patient organs in 18 MV linear accelerator (linac) based radiotherapy. A humanoid MC phantom was used to calculate the equivalent dose s for different organs and probability of secondary cancer, fatal and nonfatal risk, and other risks and parameters related to megavoltage radiation therapy. In out-of-field radiation calculation, it could be seen that neutrons imparted a higher dose to distant organs, and the dose to surrounding organs was mainly due to absorbed scattered photons and electron contamination. RESULTS Our results showed that the bladder and skin with 54.89 × 10-3 mSv/Gy and 46.09 × 10-3 mSv/Gy, respectively, absorbed the highest equivalent dose s from photoneutrons, while a lower dose was absorbed by the lung at 3.42 × 10-3 mSv/Gy. The large intestine and bladder absorbed 55.00 × 10-3 mSv/Gy and 49.08 × 10-3, respectively, which were the highest equivalent dose s due to photons. The brain absorbed the lowest out-of-field dose, at 1.87 × 10-3 mSv/Gy. CONCLUSIONS We concluded that secondary neutron portion was higher than other radiation. Then, we recommended more attention to neutrons in the radiation protection in linac based high energy radiotherapy.
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Affiliation(s)
- Amir Ghasemi-Jangjoo
- Medical Radiation Sciences Research Team, Imam Hospital, Tabriz University of Medical Sciences, Imam Hospital, Tabriz, Iran
- Department of Radiology and Radiotherapy, Medicine School, Tabriz University of Medical Sciences, Imam Hospital, Tabriz, Iran
| | - Hosein Ghiasi
- Medical Radiation Sciences Research Team, Imam Hospital, Tabriz University of Medical Sciences, Imam Hospital, Tabriz, Iran
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Gauter-Fleckenstein B, Nguyen J, Jahnke L, Gaiser T, Rudic B, Büttner S, Wenz F, Borggrefe M, Tülümen E. Interaction between CIEDs and modern radiotherapy techniques: Flattening filter free-VMAT, dose-rate effects, scatter radiation, and neutron-generating energies. Radiother Oncol 2020; 152:196-202. [PMID: 31973882 DOI: 10.1016/j.radonc.2019.12.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2019] [Revised: 12/07/2019] [Accepted: 12/12/2019] [Indexed: 10/25/2022]
Abstract
BACKGROUND AND PURPOSE Providing evidence for radiotherapy (RT)-induced effects on cardiac implantable electric devices (CIEDs) with focus on flattening filter free-volumetric modulated arc therapy (FFF-VMAT) at 6 and 10 MV as well as 3D-conformal radiotherapy (3D-CRT) at 18 MV. MATERIALS AND METHODS 68 CIEDs (64 implantable cardioverter-defibrillators (ICDs) and 4 cardiac pacemakers (PMs)) were located on the left chest position on a slab phantom and irradiated under telemetrical surveillance either directly, or distant to 3D-CRT or FFF-VMAT, dose-rate 2500 cGy/min, and target dose of 150 Gy. Devices were placed within, close by (2.5 cm and 5 cm), and distant (35 cm) to the radiation field. Scatter radiation (SR) and photon neutrons (PN) were recorded. CIEDs were investigated in following groups: 1a) 18 MV 3D-CRT - 4 ICDs/4 PMs out of radiation field, 1b) 18 MV open field - 4 ICDs/4 PMs within radiation field, 2) 6 MV FFF-VMAT, 15 ICDs in 35 cm distance to VMAT, 3) 10 MV-FFF VMAT, 15 ICDs in 35 cm distance to VMAT, 4) 6 MV FFF-VMAT, 15 ICDs in 2.5 cm distance to VMAT, 5) 10 MV FFF-VMAT, 15 ICDs in 2.5 cm distance to VMAT. RESULTS No incidents occurred at 6 MV FFF. 10 MV FFF-VMAT and 18 MV 3D-CRT resulted in data loss, reset, and erroneous sensing with inhibition of pacing (leading to inadequate defibrillation) in 8/34 ICDs and 2/4 PMs which were not located within radiation. Direct radiation triggered instantaneous defibrillation in 3/4 ICDs. CONCLUSIONS 6 MV FFF-VMAT is safe even at high dose-rates of 2500 cGy/min, regardless whether CIEDs are located close (2.5 cm) or distant (35 cm) to the radiation beam. CIEDs should never be placed within radiation and energy should always be limited to 6 MV. At 6 MV, VMAT at high dose-rates can be used to treat tumors, which are located close to CIEDs.
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Affiliation(s)
- Benjamin Gauter-Fleckenstein
- Department of Radiation Oncology, University Medical Center Mannheim, Medical Faculty Mannheim, Heidelberg University, Germany.
| | - Julia Nguyen
- Medical Faculty Mannheim, Heidelberg University, Germany
| | - Lennart Jahnke
- Department of Radiation Oncology, University Medical Center Mannheim, Medical Faculty Mannheim, Heidelberg University, Germany
| | - Timo Gaiser
- Institute of Pathology, University Medical Center Mannheim, Medical Faculty Mannheim, Heidelberg University, Germany
| | - Boris Rudic
- First Department of Medicine, University Medical Center Mannheim, Medical Faculty Mannheim, Heidelberg University, Germany; DZHK (German Centre for Cardiovascular Research) partner site, Mannheim, Germany
| | - Sylvia Büttner
- Department of Biomathematics and Medical Statistics, University Medical Center Mannheim, University of Heidelberg, Germany
| | - Frederik Wenz
- Department of Radiation Oncology, University Medical Center Mannheim, Medical Faculty Mannheim, Heidelberg University, Germany
| | - Martin Borggrefe
- First Department of Medicine, University Medical Center Mannheim, Medical Faculty Mannheim, Heidelberg University, Germany; DZHK (German Centre for Cardiovascular Research) partner site, Mannheim, Germany
| | - Erol Tülümen
- First Department of Medicine, University Medical Center Mannheim, Medical Faculty Mannheim, Heidelberg University, Germany; DZHK (German Centre for Cardiovascular Research) partner site, Mannheim, Germany
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Midhun CV, Musthafa MM, Akbar S, Cyriac SL, Sajeev S, Joseph A, Jagadeesan KC, Suryanarayana SV, Ganesan S. Spectroscopy of High-Intensity Bremsstrahlung Using Compton Recoiled Electrons. NUCL SCI ENG 2019. [DOI: 10.1080/00295639.2019.1681210] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Affiliation(s)
- C. V. Midhun
- University of Calicut, Department of Physics, Malappuram, Kerala, India
| | - M. M. Musthafa
- University of Calicut, Department of Physics, Malappuram, Kerala, India
| | - Shaima Akbar
- University of Calicut, Department of Physics, Malappuram, Kerala, India
| | - Swapna Lilly Cyriac
- Kerala Institute of Medical Sciences, Cancer Care and Research Center, Department of Radiation Oncology, Thiruvanandapuram, Kerala, India
| | - S. Sajeev
- Kerala Institute of Medical Sciences, Cancer Care and Research Center, Department of Radiation Oncology, Thiruvanandapuram, Kerala, India
| | - Antony Joseph
- University of Calicut, Department of Physics, Malappuram, Kerala, India
| | - K. C. Jagadeesan
- Bhabha Atomic Research Centre, Radiopharmaceuticals Division, Mumbai, India
| | | | - S. Ganesan
- Bhabha Atomic Research Centre, Raja Ramanna Fellow, Department of Atomic Energy, Mumbai, India
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Delany R, Tudor GSJ. A relative comparison of neutron production between conventional and energy-matched flattening-filter-free (FFF) 10MV modes for an elekta linear accelerator. Biomed Phys Eng Express 2019. [DOI: 10.1088/2057-1976/ab2c6f] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Ghorbani M, Azizi M, Mowlavi AA, Azadegan B. Experimental study of the influence of dental restorations on thermal and fast photo-neutron production in radiotherapy with a high-energy photon beam. Appl Radiat Isot 2019; 147:113-120. [PMID: 30870764 DOI: 10.1016/j.apradiso.2019.03.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2018] [Revised: 02/01/2019] [Accepted: 03/04/2019] [Indexed: 10/27/2022]
Abstract
In head and neck radiation therapy, the presence of dental restorations can increase unwanted neutron dose to the patient. This study aimed at the measurement of secondary neutron production induced by irradiation of a healthy tooth, Amalgam, Ni-Cr alloy and Ceramco with a photon beam generated in the treatment head of a Siemens Primus linac at a voltage of 15 MV. The irradiation field amounted to 10 × 10 cm2. The measurements of thermal and fast-neutron equivalent doses were performed by means of CR-39 detectors positioned in various depths of a Perspex (polymethyl methacrylate) phantom as at open field as at presence of corresponding dental restorations. The general trend of thermal neutron as well as fast-neutron equivalent dose behind the denture samples reveals their reduction with increasing depth. The maximum values of thermal-neutron dose related to Amalgam, Ceramco and Ni-Cr alloy amount to 1.45 mSv/100 MU, 1.38 mSv/100 MU and 1.32 mSv/100 MU, whereas the corresponding maximum values of fast-neutron dose at the depth of 1.8 cm amount to 0.19 mSv/100 MU, 1.04 mSv/100 MU and 0.97 mSv/100 MU, respectively. The present study investigates the neutron dose accompanied with radiotherapy. It is recommended that attempts have to be made to ensure that dental restorations are not in the path of the primary high-energy photon beam. Considering treatment planning, the guidelines of radiation protection should be improved.
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Affiliation(s)
- Mahdi Ghorbani
- Medical Physics Research Center, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Mona Azizi
- Physics Department, School of Sciences, Hakim Sabzevari University, Sabzevar, Iran.
| | - Ali Asghar Mowlavi
- Physics Department, School of Sciences, Hakim Sabzevari University, Sabzevar, Iran; Associate Federation Scheme, Medical Physics Field, International Centre for Theoretical Physics (ICTP), Trieste, Italy
| | - Behnam Azadegan
- Physics Department, School of Sciences, Hakim Sabzevari University, Sabzevar, Iran
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41
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Evaluation of in-field neutron production for medical LINACs with and without flattening filter for various beam parameters - Experiment and Monte Carlo simulation. RADIAT MEAS 2018. [DOI: 10.1016/j.radmeas.2018.04.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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42
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Haddad K, Anjak O, Yousef B. Neutron and high energy photon fluence estimation in CLINAC using gold activation foils. Rep Pract Oncol Radiother 2018; 24:41-46. [PMID: 30337847 DOI: 10.1016/j.rpor.2018.08.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2018] [Revised: 07/05/2018] [Accepted: 08/31/2018] [Indexed: 10/28/2022] Open
Abstract
Aim The thermal neutron, epithermal neutron and high-energy photon fluence were measured in this work around the Varian 21EX 23 MV CLINAC, which is operated in Albairouni hospital in Damascus, Syria. Background Photoneutron measurements around medical CLINAC aim to protect both patients and staff from unwanted radiation. Materials and methods Neutron and photon activation techniques were applied using gold foils. Results It was found that high-energy photons fluence has practically a constant value in the field size. The thermal and epithermal neutron fluence along ox and oy axes has the same order of magnitude. Conclusion Gold foils have been used successfully to measure neutron flux and high-energy photons simultaneously using activation techniques.
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Affiliation(s)
- Kh Haddad
- Protection & Safety Department, Atomic Energy Commission of Syria, P.O. Box 6091, Damascus, Syria
| | - O Anjak
- Protection & Safety Department, Atomic Energy Commission of Syria, P.O. Box 6091, Damascus, Syria
| | - B Yousef
- Protection & Safety Department, Atomic Energy Commission of Syria, P.O. Box 6091, Damascus, Syria
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Neutron production in the interaction of 12 and 18 MeV electrons with a scattering foil inside a simple LINAC head. Appl Radiat Isot 2018; 139:46-52. [DOI: 10.1016/j.apradiso.2018.04.024] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2017] [Revised: 04/17/2018] [Accepted: 04/17/2018] [Indexed: 11/20/2022]
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Elazhar H, Deschler T, Létang JM, Nourreddine A, Arbor N. Neutron track length estimator for GATE Monte Carlo dose calculation in radiotherapy. Phys Med Biol 2018; 63:125018. [PMID: 29790859 DOI: 10.1088/1361-6560/aac768] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The out-of-field dose in radiation therapy is a growing concern in regards to the late side-effects and secondary cancer induction. In high-energy x-ray therapy, the secondary neutrons generated through photonuclear reactions in the accelerator are part of this secondary dose. The neutron dose is currently not estimated by the treatment planning system while it appears to be preponderant for distances greater than 50 cm from the isocenter. Monte Carlo simulation has become the gold standard for accurately calculating the neutron dose under specific treatment conditions but the method is also known for having a slow statistical convergence, which makes it difficult to be used on a clinical basis. The neutron track length estimator, a neutron variance reduction technique inspired by the track length estimator method has thus been developped for the first time in the Monte Carlo code GATE to allow a fast computation of the neutron dose in radiotherapy. The details of its implementation, as well as the comparison of its performances against the analog MC method, are presented here. A gain of time from 15 to 400 can be obtained by our method, with a mean difference in the dose calculation of about 1% in comparison with the analog MC method.
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Affiliation(s)
- H Elazhar
- Université de Strasbourg, CNRS, IPHC UMR 7178, F-67000 Strasbourg, France
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Nourmohammadi B, Mesbahi A. A REVIEW ON THE RADIATION THERAPY TECHNOLOGIST RECEIVED DOSE FROM INDUCED ACTIVATION IN HIGH-ENERGY MEDICAL LINEAR ACCELERATORS. RADIATION PROTECTION DOSIMETRY 2018; 179:333-348. [PMID: 29309661 DOI: 10.1093/rpd/ncx292] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/19/2017] [Accepted: 12/02/2017] [Indexed: 06/07/2023]
Abstract
Despite all advantages for using high-energy photons for radiotherapy, high-energy photon beams (≥10 MV) induce photonuclear and neutron capture interactions, which result in producing radionuclide byproducts inside the Linac head and bunker, exposing radiation therapy technologists (RTTs) and patients to excessive dose. By the use of higher photon energy, greater number of monitor unit, greater field size and adding treatment accessories, induced dose rate become greater in the isocenter mainly due to activation of high-Z materials inside the Linac head. Activated radionuclides disintegrate with γ, β+ and β- rays with half-lives between 2 min up to more than 5 years. Several researches estimated additional exposure to an RTT depend on treatment strategies, beam energy, and delay time before entrance to the treatment room between 0.1 and 4.9 mSv/y and proposed at least 2 min delay before entrance to the treatment room after treatments with high-energy photon beams.
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Affiliation(s)
- Bahareh Nourmohammadi
- Medical Radiation Sciences Research Team, Tabriz University of Medical Sciences, Tabriz, Iran
- Department of Medical Physics, Medical School, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Asghar Mesbahi
- Medical Radiation Sciences Research Team, Tabriz University of Medical Sciences, Tabriz, Iran
- Department of Medical Physics, Medical School, Tabriz University of Medical Sciences, Tabriz, Iran
- Molecular Medicine Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
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Choi CH, Park SY, Park JM, Chun M, Kim JI. Monte Carlo simulation of neutron dose equivalent by photoneutron production inside the primary barriers of a radiotherapy vault. Phys Med 2018; 48:1-5. [PMID: 29728220 DOI: 10.1016/j.ejmp.2018.03.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Revised: 03/06/2018] [Accepted: 03/13/2018] [Indexed: 01/09/2023] Open
Abstract
PURPOSE To evaluate the neutron dose equivalent produced by photoneutrons inside the primary barriers of a radiotherapy vault. METHODS Monte Carlo simulations were performed for investigating the production of photoneutrons as well as neutron shielding requirements. Two photon beams of 15 and 18 MV struck sheets of steel and lead, and the neutron doses were calculated at the isocenter (Piso) and at a distance of 50 cm from the inside wall (Pwall) while delivering 1 Gy to the patient. The proper thicknesses of borated polyethylene (BPE) and concrete were simulated to reduce neutron contamination. RESULTS When the primary barrier consisted of a concrete alone, the neutron doses at Piso were 0.5 μSv/Gy and 12.8 μSv/Gy for 15- and 18-MV, respectively. At Pwall, the neutron doses were 15.8 μSv/Gy and 318.4 μSv/Gy for 15- and 18-MV, respectively. When 15 MV photons interacted with metal sheets, the neutron doses were 0.4-22.2 μSv/Gy at Piso and 15.8-812.5 μSv/Gy at Pwall, depending on the thickness and material of the metal sheets and neutron shielding. In the case of 18 MV photons with the same configuration, the neutron doses were 0.9-59.5 μSv/Gy and 73.9-5006.1 μSv/Gy for Piso and Pwall, respectively. The neutron dose delivered to the patient was reduced to the level of the dose delivered with a concrete barrier by including a 10-cm-thick BPE for each beam. CONCLUSIONS When the primary barrier shielding is designed with a metal sheet inside for high energy, proper neutron shielding should be constructed to avoid undesirable photoneutron dose.
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Affiliation(s)
- Chang Heon Choi
- Department of Radiation Oncology, Seoul National University Hospital, Seoul, Republic of Korea; Institute of Radiation Medicine, Seoul National University Medical Research Center, Seoul, Republic of Korea; Biomedical Research Institute, Seoul National University Hospital, Seoul, Republic of Korea
| | - So-Yeon Park
- Department of Radiation Oncology, Seoul National University Hospital, Seoul, Republic of Korea; Institute of Radiation Medicine, Seoul National University Medical Research Center, Seoul, Republic of Korea; Biomedical Research Institute, Seoul National University Hospital, Seoul, Republic of Korea
| | - Jong Min Park
- Department of Radiation Oncology, Seoul National University Hospital, Seoul, Republic of Korea; Institute of Radiation Medicine, Seoul National University Medical Research Center, Seoul, Republic of Korea; Biomedical Research Institute, Seoul National University Hospital, Seoul, Republic of Korea; Center for Convergence Research on Robotics, Advanced Institutes of Convergence Technology, Suwon, Republic of Korea
| | - Minsoo Chun
- Department of Radiation Oncology, Seoul National University Hospital, Seoul, Republic of Korea; Interdisciplinary Program of Radiation Applied Life Science, Seoul National University College of Medicine, Seoul, Republic of Korea
| | - Jung-In Kim
- Department of Radiation Oncology, Seoul National University Hospital, Seoul, Republic of Korea; Institute of Radiation Medicine, Seoul National University Medical Research Center, Seoul, Republic of Korea; Biomedical Research Institute, Seoul National University Hospital, Seoul, Republic of Korea.
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Effect of each component of a LINAC therapy head on neutron and photon spectra. Appl Radiat Isot 2018; 139:40-45. [PMID: 29704704 DOI: 10.1016/j.apradiso.2018.04.022] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2017] [Revised: 04/07/2018] [Accepted: 04/16/2018] [Indexed: 11/22/2022]
Abstract
Linear accelerators (LINACs) are widely applied in radiotherapy for their versatility and flexibility. Monte Carlo simulations were made to find the neutron and photon spectra at the isocenter (IC) of a LINAC operating at 10, 15, 18, and 24 MV by the MCNPX code. A detailed model of the LINAC head, consisting of flattening filter, secondary collimator, primary collimator, and multi-leaf collimator were used in the calculations. The effect of eliminating any of these components on contamination of a neutron spectrum and a photon spectrum was assessed. Photon and neutron ambient equivalent doses were found, and comparisons were made for the various structures. Lethargy neutron spectra at the IC were compared with spectra computed with the function reported by Tosi et al., which describes well neutron spectra for the energy region beyond 1 MeV, although tending to undervalue energy spectra below 1 MeV. The findings show that the photon and neutron fluences are enhanced when eliminating a LINAC component. The neutron and photon doses increased except when removing the primary collimator.
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Dosimetric Analysis of Unflattened (FFFB) and Flattened (FB) Photon Beam Energy for Gastric Cancers Using IMRT and VMAT-a Comparative Study. J Gastrointest Cancer 2018. [PMID: 29520733 DOI: 10.1007/s12029-018-0080-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
PURPOSE To evaluate the feasibility of flattening filter free beam (FFFB) for the treatment of gastric tumors and to review their benefits over 6MV flatten beam (6MV_FFB). METHODS Fifteen patients with histologically proven gastric carcinoma were selected. CT scans with slice thickness of 0.3 cm were acquired and planning target volume (PTV) and organ at risk (OAR) were delineated. Plans were made retrospectively for each patient for the prescription dose of 45 Gy/25 fractions to the PTV. Four isocentric plans were compared in the present study on Varian TrueBeam linear accelerator (Varian Medical Systems, Palo Alto, CA, USA). RESULTS PTV D98% was 44.41 ± 0.12, 44.38 ± 0.13, 44.59 ± 0.14, and 44.49 ± 0.19 Gy for IMRT 6MV_FFB, IMRT 6MV_FFFB, VMAT 6MV_FFB, and VMAT 6MV_FFFB respectively. 6MV_FFFB beam minimizes the mean heart dose Dmean (P = 0.001). VMAT dominates over IMRT when it came to kidney doses V12Gy (P = 0.02), V23Gy (P = 0.015), V28Gy (P = 0.011), and Dmax (P < 0.01). VMAT has significantly reduced the doses to kidneys. It was analyzed that 6MV_FFFB significantly reduces the dose to normal tissues (P = 0.006 and P = 0.018). VMAT significantly reduces the TMU, which is required to deliver the similar dose by IMRT (P < 0.01). CONCLUSIONS Unflattened beam spares the organs at risk significantly to avoid the chances of secondary malignancies and reduces the intra-fraction motion during treatment due to provision of higher dose rate. Hence, we conclude that 6MV unflattened beam can be used to treat gastric carcinoma.
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Khabaz R, Boodaghi R, Benam MR, Zanganeh V. Estimation of photoneutron dosimetric characteristics in tissues/organs using an improved simple model of linac head. Appl Radiat Isot 2018; 133:88-94. [DOI: 10.1016/j.apradiso.2017.12.023] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2017] [Revised: 12/24/2017] [Accepted: 12/27/2017] [Indexed: 10/18/2022]
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Hosseinzadeh E, Banaee N, Nedaie HA. Monte Carlo calculation of photo-neutron dose produced by circular cones at 18 MV photon beams. Rep Pract Oncol Radiother 2018; 23:39-46. [PMID: 29348733 DOI: 10.1016/j.rpor.2017.12.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2017] [Revised: 08/14/2017] [Accepted: 12/11/2017] [Indexed: 11/17/2022] Open
Abstract
Aim The aim of this study is to calculate neutron contamination at the presence of circular cones irradiating by 18 MV photons using Monte Carlo code. Background Small photon fields are one of the most useful methods in radiotherapy. One of the techniques for shaping small photon beams is applying circular cones made of lead. Using this method in high energy photon due to neutron contamination is a crucial issue. Materials and methods Initially, Varian linac producing 18 MV photons was simulated and after validating the code, various circular cones were also simulated. Then, the number of neutrons, neutron equivalent dose and absorbed dose per Gy of photon dose were calculated along the central axis. Results Number of neutrons per Gy of photon dose had their maximum value at depth of 2 cm and these values for 5, 10, 15, 20 and 30 mm circular cones were 9.02, 7.76, 7.61, 6.02 and 5.08 (n cm-2 Gy-1), respectively. Neutron equivalent doses per Gy of photon dose had their maximum at the surface of the phantom and these values for mentioned collimators were 1.48, 1.33, 1.31, 1.12 and 1.08 (mSv Gy-1), respectively. Neutron absorbed doses had their maximum at the surface of the phantom and these values for mentioned collimators sizes were 103.74, 99.71, 95.77, 81.46 and 78.20 (μGy/Gy), respectively. Conclusions As the field size gets smaller, number of neutrons, equivalent and absorbed dose per Gy of photon increase. Also, neutron equivalent dose and absorbed dose are maximum at the surface of phantom and then these values will be decreased.
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Affiliation(s)
- Elham Hosseinzadeh
- Department of Medical Radiation, Engineering Faculty, Central Tehran Branch, Islamic Azad University, Tehran, Iran
| | - Nooshin Banaee
- Department of Medical Radiation, Engineering Faculty, Central Tehran Branch, Islamic Azad University, Tehran, Iran
| | - Hassan Ali Nedaie
- Odette Cancer Centre, University of Toronto, Toronto, Canada
- Joint Cancer Research Center, Radiotherapy Oncology & Radiobiology Research Center, Cancer Institute, Tehran University of Medical Sciences, Tehran, Iran
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