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Kuhlmann ML, Pojtinger S. Implementation of a new EGSnrc particle source class for computed tomography: validation and uncertainty quantification. Phys Med Biol 2024; 69:095021. [PMID: 38537305 DOI: 10.1088/1361-6560/ad3886] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2023] [Accepted: 03/26/2024] [Indexed: 04/25/2024]
Abstract
Objective. Personalized dose monitoring and risk management are of increasing significance with the growing number of computer tomography (CT) examinations. These require high-quality Monte Carlo (MC) simulations that are of the utmost importance for the new developments in personalized CT dosimetry. This work aims to extend the MC framework EGSnrc source code with a new particle source. This, in turn, allows CT-scanner-specific dose and image calculations for any CT scanner. The novel method can be used with all modern EGSnrc user codes, particularly for the simulation of the effective dose based on DICOM images and the calculation of CT images.Approach. The new particle source can be used with input data derived by the user. The input data can be generated by the user based on a previously developed method for the experimental characterization of any CT scanner (doi.org/10.1016/j.ejmp.2015.09.006). Furthermore, the new particle source was benchmarked by air kerma measurements in an ionization chamber at a clinical CT scanner. For this, the simulated angular distribution and attenuation characteristics were compared to measurements to verify the source output free in air. In a second validation step, simulations of air kerma in a homogenous cylindrical and an anthropomorphic thorax phantom were performed and validated against experimentally determined results. A detailed uncertainty evaluation of the simulated air kerma values was developed.Main results. We successfully implemented a new particle source class for the simulation of realistic CT scans. This method can be adapted to any CT scanner. For the attenuation characteristics, there was a maximal deviation of 6.86% between the measurement and the simulation. The mean deviation for all tube voltages was 2.36% (σ= 1.6%). For the phantom measurements and simulations, all the values agreed within 5.0%. The uncertainty evaluation resulted in an uncertainty of 5.5% (k=1).
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Affiliation(s)
- Marie-Luise Kuhlmann
- Dosimetry for Radiation Therapy and Diagnostic Radiology, Physikalisch-Technische Bundesanstalt (PTB), Braunschweig, D-38116, Germany
- Technische Universität Dortmund, Dortmund, D-44227, Germany
| | - Stefan Pojtinger
- Dosimetry for Radiation Therapy and Diagnostic Radiology, Physikalisch-Technische Bundesanstalt (PTB), Braunschweig, D-38116, Germany
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Lépy MC, Thiam C, Anagnostakis M, Cosar C, de Blas A, Dikmen H, Duch MA, Galea R, Ganea ML, Hurtado S, Karfopoulos K, Luca A, Lutter G, Mitsios I, Persson H, Potiriadis C, Röttger S, Salpadimos N, Savva MI, Sima O, Thanh TT, Townson RW, Vargas A, Vasilopoulou T, Verheyen L, Vidmar T. A benchmark for Monte Carlo simulations in gamma-ray spectrometry Part II: True coincidence summing correction factors. Appl Radiat Isot 2024; 204:111109. [PMID: 38029636 DOI: 10.1016/j.apradiso.2023.111109] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2023] [Revised: 10/31/2023] [Accepted: 11/07/2023] [Indexed: 12/01/2023]
Abstract
The goal of this study is to provide a benchmark for the use of Monte Carlo simulation when applied to coincidence summing corrections. The examples are based on simple geometries: two types of germanium detectors and four kinds of sources, to mimic eight typical measurement conditions. The coincidence corrective factors are computed for four radionuclides. The exercise input files and calculation results with practical recommendations are made available for new users on a dedicated webpage.
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Affiliation(s)
- M-C Lépy
- Université Paris-Saclay, CEA, List, Laboratoire National Henri Becquerel (LNE-LNHB), F-91120, Palaiseau, France.
| | - C Thiam
- Université Paris-Saclay, CEA, List, Laboratoire National Henri Becquerel (LNE-LNHB), F-91120, Palaiseau, France
| | - M Anagnostakis
- Nuclear Engineering Department, School of Mechanical Engineering, National Technical University of Athens, Iroon Polytechniou 9, 15780, Zografou, Athens, Greece
| | - C Cosar
- Horia Hulubei National Institute for R&D in Physics and Nuclear Engineering (IFIN-HH), 30 Reactorului Street, PO Box MG-6, Magurele, Ilfov County, RO-077125, Romania; Physics Department, University of Bucharest, 405 Atomistilor Str., Magurele, Ilfov County, RO-077125, Romania
| | - A de Blas
- Universitat Politècnica de Catalunya (UPC), Avda. Diagonal, 647, 08028, Barcelona, Spain
| | - H Dikmen
- TENMAK-NUKEN, Nuclear Energy Research Institute, Saray Mahallesi Atom Caddesi No:27, 06980 Kahramankazan, Ankara, Turkey
| | - M A Duch
- Universitat Politècnica de Catalunya (UPC), Avda. Diagonal, 647, 08028, Barcelona, Spain
| | - R Galea
- National Research Council of Canada, 1200 Montreal Road, Ottawa, ON, K1A0R6, Canada
| | - M L Ganea
- Horia Hulubei National Institute for R&D in Physics and Nuclear Engineering (IFIN-HH), 30 Reactorului Street, PO Box MG-6, Magurele, Ilfov County, RO-077125, Romania
| | - S Hurtado
- Dpto. Física Aplicada II, ETSA, Universidad de Sevilla, Avda. Reina Mercedes 2, 41012, Seville, Spain
| | - K Karfopoulos
- Greek Atomic Energy Commission (EEAE), Environmental Radioactivity Monitoring Unit, P.O. Box 60092, 153 10, Agia Paraskevi, Athens, Greece
| | - A Luca
- Horia Hulubei National Institute for R&D in Physics and Nuclear Engineering (IFIN-HH), 30 Reactorului Street, PO Box MG-6, Magurele, Ilfov County, RO-077125, Romania
| | - G Lutter
- European Commission, Joint Research Centre, Retieseweg 111, 2440, Geel, Belgium; Belgium and Department of Environmental Engineering, Technical University of Denmark, DTU, Risø Campus, 4000, Roskilde, Denmark
| | - I Mitsios
- Nuclear Engineering Department, School of Mechanical Engineering, National Technical University of Athens, Iroon Polytechniou 9, 15780, Zografou, Athens, Greece
| | - H Persson
- Mirion Technologies, Inc, 800 Research Parkway, Meriden, CT, 06450, USA
| | - C Potiriadis
- Greek Atomic Energy Commission (EEAE), Environmental Radioactivity Monitoring Unit, P.O. Box 60092, 153 10, Agia Paraskevi, Athens, Greece
| | - S Röttger
- Physikalisch-Technische Bundesanstalt (PTB), Bundesallee 100, 38116, Braunschweig, Germany
| | - N Salpadimos
- Greek Atomic Energy Commission (EEAE), Environmental Radioactivity Monitoring Unit, P.O. Box 60092, 153 10, Agia Paraskevi, Athens, Greece
| | - M I Savva
- INRASTES, NCSR "Demokritos", P.O. Box 60037, 15310 Agia Paraskevi, Greece
| | - O Sima
- Horia Hulubei National Institute for R&D in Physics and Nuclear Engineering (IFIN-HH), 30 Reactorului Street, PO Box MG-6, Magurele, Ilfov County, RO-077125, Romania; Physics Department, University of Bucharest, 405 Atomistilor Str., Magurele, Ilfov County, RO-077125, Romania
| | - T T Thanh
- VNUHCM-University of Science, 227, Nguyen Van Cu Street, District 5, Ho Chi Minh City, Viet Nam
| | - R W Townson
- National Research Council of Canada, 1200 Montreal Road, Ottawa, ON, K1A0R6, Canada
| | - A Vargas
- Universitat Politècnica de Catalunya (UPC), Avda. Diagonal, 647, 08028, Barcelona, Spain
| | - T Vasilopoulou
- INRASTES, NCSR "Demokritos", P.O. Box 60037, 15310 Agia Paraskevi, Greece
| | - L Verheyen
- SCK-CEN, Belgian Nuclear Research Centre, Boeretang 200, 2400, Mol, Belgium
| | - T Vidmar
- SCK-CEN, Belgian Nuclear Research Centre, Boeretang 200, 2400, Mol, Belgium
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Iliaskou C, Rossi G, Sachpazidis I, Boronikolas V, Gainey M, Baltas D. Evaluation of RADIANCE Monte Carlo algorithm for treatment planning in electron based Intraoperative Radiotherapy (IOERT). Z Med Phys 2024:S0939-3889(23)00149-6. [PMID: 38182457 DOI: 10.1016/j.zemedi.2023.12.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2023] [Revised: 12/01/2023] [Accepted: 12/04/2023] [Indexed: 01/07/2024]
Abstract
PURPOSE To perform experimental as well as independent Monte Carlo (MC) evaluation of the MC algorithm implemented in RADIANCE version 4.0.8, a dedicated treatment planning system (TPS) for 3D electron dose calculations in intraoperative radiation therapy (IOERT). METHODS AND MATERIALS The MOBETRON 2000 (IntraOp Medical Corporation, Sunnyvale, CA) IOERT accelerator was employed. PDD and profiles for five cylindrical plastic applicators with 50-90 mm diameter and 0°, 30° beveling were measured in a water phantom, at nominal energies of 6, 9 and 12 MeV. Additional PDD measurements were performed for all the energies without applicator. MC modeling of the MOBETRON was performed with the user code BEAMnrc and egs_chamber of the MC simulation toolkit EGSnrc. The generated phase space files of the two 0°-bevel applicators (50 mm, 80 mm) and three energies in both RADIANCE and BEAMnrc, were used to determine PDD and profiles in various set-ups of virtual water phantoms with air and bone inhomogeneities. 3D dose distributions were also calculated in image data sets of an anthropomorphic tissue-equivalent pelvis phantom. Image acquisitions were realized with a CT scanner (Philips Big Bore CT, Netherlands). Gamma analysis was applied to quantify the deviations of the RADIANCE calculations to the measurements and EGSnrc calculations. Gamma criteria normalized to the global maximum were investigated between 2%, 2 mm and 3%, 3 mm. RESULTS RADIANCE MC calculations satisfied the gamma criteria of 3%, 3 mm with a tolerance limit of 85% passing rate compared to in- water phantom measurements, except for the dose profiles of the 30° beveled applicators. Mismatches lay in surface doses, in umbra regions and in the beveled end of the 30° applicators. A very good agreement to the EGSnrc calculations in heterogeneous media was observed. Deviations were more pronounced for the larger applicator diameter and higher electron energy. In 3D dose comparisons in the anthropomorphic phantom, gamma passing rates were higher than 96 % for both simulated applicators. CONCLUSIONS RADIANCE MC algorithm agrees within 3%, 3 mm criteria with in-water phantom measurements and EGSnrc MC dose distributions in heterogeneous media for 0°-bevel applicators. The user should be aware of missing scattering components and the 30° beveled applicators should be used with attention.
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Affiliation(s)
- Charoula Iliaskou
- Division of Medical Physics, Department of Radiation Oncology, University Medical Center, Freiburg 79106, Germany; German Cancer Consortium (DKTK), Partner Site Freiburg, German Cancer Research Center (DKFZ), Heidelberg 69120, Germany.
| | - Giulio Rossi
- Division of Medical Physics, Department of Radiation Oncology, University Medical Center, Freiburg 79106, Germany; German Cancer Consortium (DKTK), Partner Site Freiburg, German Cancer Research Center (DKFZ), Heidelberg 69120, Germany
| | - Ilias Sachpazidis
- Division of Medical Physics, Department of Radiation Oncology, University Medical Center, Freiburg 79106, Germany; German Cancer Consortium (DKTK), Partner Site Freiburg, German Cancer Research Center (DKFZ), Heidelberg 69120, Germany
| | - Vasilios Boronikolas
- Division of Medical Physics, Department of Radiation Oncology, University Medical Center, Freiburg 79106, Germany; German Cancer Consortium (DKTK), Partner Site Freiburg, German Cancer Research Center (DKFZ), Heidelberg 69120, Germany
| | - Mark Gainey
- Division of Medical Physics, Department of Radiation Oncology, University Medical Center, Freiburg 79106, Germany; German Cancer Consortium (DKTK), Partner Site Freiburg, German Cancer Research Center (DKFZ), Heidelberg 69120, Germany
| | - Dimos Baltas
- Division of Medical Physics, Department of Radiation Oncology, University Medical Center, Freiburg 79106, Germany; German Cancer Consortium (DKTK), Partner Site Freiburg, German Cancer Research Center (DKFZ), Heidelberg 69120, Germany
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Thiele M, Galonske K, Ernst I, Mack A. Development of a LINAC head model for the CyberKnife VSI-System using EGSnrc Monte Carlo system. J Appl Clin Med Phys 2023; 24:e14137. [PMID: 37712892 PMCID: PMC10691629 DOI: 10.1002/acm2.14137] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2023] [Revised: 06/04/2023] [Accepted: 08/12/2023] [Indexed: 09/16/2023] Open
Abstract
INTRODUCTION In order to understand the interaction processes of photons and electrons of the CyberKnife VSI-System, a modeling of the LINAC head must take place. Here, a Monte Carlo simulation can help. By comparing the measured data with the simulation data, the agreement can be checked. MATERIALS AND METHODS For the Monte Carlo simulations, the toolkit EGSnrc with the user codes BEAMnrc and DOSXZYnrc was used. The CyberKnife VSI-System has two collimation systems to define the field size of the beam. On the one hand, it has 12 circular collimators and, on the other, an IRIS-aperture. The average energy, final source width, dose profiles, and output factors in a voxel-based water phantom were determined and compared to the measured data. RESULTS The average kinetic energy of the electron beam for the CyberKnife VSI LINAC head is 6.9 MeV, with a final source width of 0.25 cm in x-direction and 0.23 cm in y-direction. All simulated dose profiles for both collimation systems were able to achieve a global gamma criterion of 1%/1 mm to the measured data. For the output factors, the deviation from simulated to measured data is < 1% from a field size of 12.5 mm for the circular collimators and from a field size of 10 mm for the IRIS-aperture. CONCLUSION The beam characteristics of the CyberKnife VSI LINAC head could be exactly simulated with Monte Carlo simulation. Thus, in the future, this model can be used as a basis for electronic patient-specific QA or to determine scattering processes of the LINAC head.
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Affiliation(s)
| | | | - Iris Ernst
- German Center for Stereotaxy and Precision IrradiationSoestGermany
| | - Andreas Mack
- Swiss Neuro Radiosurgery CenterZurichSwitzerland
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Ferreira CVG, Piedade JS, Prado MRD, Benavente J, Mendes BM, Paixão L, Fonseca TCF. Monte Carlo calculation of whole body counter efficiency factors for different computational phantoms. Appl Radiat Isot 2023; 194:110685. [PMID: 36758323 DOI: 10.1016/j.apradiso.2023.110685] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2022] [Revised: 12/28/2022] [Accepted: 01/15/2023] [Indexed: 02/09/2023]
Abstract
Individual monitoring can provide an estimate of the radioactivity present in the body of the exposed individuals. Periodic monitoring of occupationally exposed individuals is of great importance in case of accidental incorporation. Computational phantoms and Monte Carlo codes are often used to complement the calibration method of counting systems in internal dosimetry. Here, counting efficiency (CE) factors for a WBC system were calculated using MC simulations. The WBC system with a NaI(Tl) detector and the BOMAB phantom was modeled using three MC codes. After validation, the models were used to obtain CE values for a wide range of energies, and a CE curve was generated for the WBC system. To estimate the effects of anatomical differences on the measurement process, two anthropomorphic voxel phantoms were modeled using the VMC code. For the detector position with the highest CE value, the differences when comparing BOMAB results with the MaMP and Yale results were (-1 ± 6)% and (-1 ± 3)%, respectively. The results confirm that the use of the BOMAB phantom is a good approach for the calibration of the whole-body counter system. Measurements should be made at detector position with the highest CE values, and it is recommended to use the mean Monte Carlo CE values calculated in this work.
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Affiliation(s)
- Carlos V G Ferreira
- Universidade Federal de Minas Gerais, Escola de Engenharia - Departamento de Engenharia Nuclear, Programa de Pós-graduação em Ciências e Técnicas Nucleares, Av. Pres. Antônio Carlos 6627, Belo Horizonte MG, Brazil.
| | - Jennifer S Piedade
- Universidade Federal de Minas Gerais, Faculdade de Medicina - Departamento de Anatomia e Imagem, Av. Prof. Alfredo Balena 190, Belo Horizonte, MG, Brazil
| | - Max R D Prado
- Centro universitário de Belo Horizonte, Av. Mário Werneck 1685, Belo Horizonte MG, Brazil
| | - Jhonny Benavente
- Universidade Federal de Minas Gerais, Escola de Engenharia - Departamento de Engenharia Nuclear, Programa de Pós-graduação em Ciências e Técnicas Nucleares, Av. Pres. Antônio Carlos 6627, Belo Horizonte MG, Brazil
| | - Bruno M Mendes
- Centro de Desenvolvimento da Tecnologia Nuclear - CDTN/CNEN, Av. Pres. Antônio Carlos 6627, Belo Horizonte MG, Brazil
| | - Lucas Paixão
- Universidade Federal de Minas Gerais, Faculdade de Medicina - Departamento de Anatomia e Imagem, Av. Prof. Alfredo Balena 190, Belo Horizonte, MG, Brazil
| | - Telma C F Fonseca
- Universidade Federal de Minas Gerais, Escola de Engenharia - Departamento de Engenharia Nuclear, Programa de Pós-graduação em Ciências e Técnicas Nucleares, Av. Pres. Antônio Carlos 6627, Belo Horizonte MG, Brazil.
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Safigholi H, Chamberland MJP, Taylor REP, Martinov MP, Rogers DWO, Thomson RM. Update of the CLRP Monte Carlo TG-43 parameter database for high-energy brachytherapy sources. Med Phys 2023; 50:1928-1941. [PMID: 36542404 DOI: 10.1002/mp.16176] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2022] [Revised: 11/11/2022] [Accepted: 12/06/2022] [Indexed: 12/24/2022] Open
Abstract
PURPOSE To update and extend version 2 of the Carleton Laboratory for Radiotherapy Physics (CLRP) TG-43 dosimetry database (CLRP_TG43v2) for high-energy (HE, ≥50 keV) brachytherapy sources (1 169 Yb, 23 192 Ir, 5 137 Cs, and 4 60 Co) using egs_brachy, an open-source EGSnrc application. A comprehensive dataset of TG-43 parameters is compiled, including detailed source descriptions, dose-rate constants, radial dose functions, 1D and 2D anisotropy functions, along-away dose-rate tables, Primary and Scatter Separated (PSS) dose tables, and mean photon energies escaping each source. The database also documents the source models which are freely distributed with egs_brachy. ACQUISITION AND VALIDATION METHODS Datasets are calculated after a recoding of the source geometries using the egs++ geometry package and its egs_brachy extensions. Air kerma per history is calculated in a 10 × 10 × $\,{\times}\, 10\,{\times}\,$ 0.05 cm3 voxel located 100 cm from the source along the transverse axis and then corrected for the lateral and thickness dimensions of the scoring voxel to give the air kerma on the central axis at a point 100 cm from the source's mid-point. Full-scatter water phantoms with varying voxel resolutions in cylindrical coordinates are used for dose calculations. Most data (except for 60 Co) are based on the assumption of charged particle equilibrium and ignore the potentially large effects of electron transport very close to the source and dose from initial beta particles. These effects are evaluated for four representative sources. For validation, data are compared to those from CLRP_TG43v1 and published data. DATA FORMAT AND ACCESS Data are available at https://physics.carleton.ca/clrp/egs_brachy/seed_database_v2 or http://doi.org/10.22215/clrp/tg43v2 including in Excel (.xlsx) spreadsheets, and are presented graphically in comparisons to previously published data for each source. POTENTIAL APPLICATIONS The CLRP_TG43v2 database has applications in research, dosimetry, and brachytherapy planning. This comprehensive update provides the medical physics community with more precise and in some cases more accurate Monte Carlo (MC) TG-43 dose calculation parameters, as well as fully benchmarked and described source models which are distributed with egs_brachy.
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Affiliation(s)
- Habib Safigholi
- Carleton Laboratory for Radiotherapy Physics (CLRP), Department of Physics, Carleton University, Ottawa, Ontario, Canada
| | - Marc J P Chamberland
- Carleton Laboratory for Radiotherapy Physics (CLRP), Department of Physics, Carleton University, Ottawa, Ontario, Canada
| | - Randle E P Taylor
- Carleton Laboratory for Radiotherapy Physics (CLRP), Department of Physics, Carleton University, Ottawa, Ontario, Canada
| | - Martin P Martinov
- Carleton Laboratory for Radiotherapy Physics (CLRP), Department of Physics, Carleton University, Ottawa, Ontario, Canada
| | - D W O Rogers
- Carleton Laboratory for Radiotherapy Physics (CLRP), Department of Physics, Carleton University, Ottawa, Ontario, Canada
| | - Rowan M Thomson
- Carleton Laboratory for Radiotherapy Physics (CLRP), Department of Physics, Carleton University, Ottawa, Ontario, Canada
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Rogers DWO. Reflections on a life with Monte Carlo in Medical Physics. Med Phys 2023. [PMID: 36779658 DOI: 10.1002/mp.16278] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2022] [Accepted: 01/31/2023] [Indexed: 02/14/2023] Open
Abstract
The author reminisces about some of his experiences working with Monte Carlo techniques for Medical Physics applications.
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Affiliation(s)
- David W O Rogers
- Carleton Laboratory for Radiotherapy Physics, Physics Department, Carleton University, Ottawa, Canada
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Wu J, Kang S, Wang P, Li J, Wang X. Monte Carlo dosimetry of the 60Co sources of a new GZP3 HDR afterloading system. Radiat Oncol 2023; 18:13. [PMID: 36670476 PMCID: PMC9854037 DOI: 10.1186/s13014-023-02207-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2022] [Accepted: 01/14/2023] [Indexed: 01/21/2023] Open
Abstract
BACKGROUND The purpose of this work was to obtain the dosimetric parameters of the new GZP3 60Co high-dose-rate afterloading system launched by the Nuclear Power Institute of China, which is comprised of two different 60Co sources. METHODS The Monte Carlo software Geant4 and EGSnrc were employed to derive accurate calculations of the dosimetric parameters of the new GZP3 60Co brachytherapy source in the range of 0-10 cm, following the formalism proposed by American Association of Physicists in Medicine reports TG43 and TG43U1. Results of the two Monte Carlo codes were compared to verify the accuracy of the data. The source was located in the center of a 30-cm-radius theoretical sphere water phantom. RESULTS For channels 1 and 2 of the new GZP3 60Co afterloading system, the results of the dose-rate constant (Λ) were 1.115 cGy h-1 U-1 and 1.112 cGy h-1 U-1, and for channel 3 they were 1.116 cGy h-1 U-1 and 1.113 cGy h-1 U-1 according to the Geant4 and EGSnrc, respectively. The radial dose function in the range of 0.25-10.0 cm in a longitudinal direction was calculated, and the fitting formulas for the function were obtained. The polynomial function for the radial dose function and the anisotropy function (1D and 2D) with a [Formula: see text] of 0°-175° and an r of 0.5-10.0 cm were obtained. The curves of the radial function and the anisotropy function fitted well compared with the two Monte Carlo software. CONCLUSION These dosimetric data sets can be used as input data for TPS calculations and quality control for the new GZP3 60Co afterloading system.
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Affiliation(s)
- Junxiang Wu
- grid.54549.390000 0004 0369 4060Sichuan Cancer Hospital and Institute, Sichuan Cancer Center, School of Medicine, University of Electronic Science and Technology of China, Radiation Oncology Key Laboratory of Sichuan Province, Chengdu, 610041 China
| | - Shengwei Kang
- grid.54549.390000 0004 0369 4060Sichuan Cancer Hospital and Institute, Sichuan Cancer Center, School of Medicine, University of Electronic Science and Technology of China, Radiation Oncology Key Laboratory of Sichuan Province, Chengdu, 610041 China
| | - Pei Wang
- grid.54549.390000 0004 0369 4060Sichuan Cancer Hospital and Institute, Sichuan Cancer Center, School of Medicine, University of Electronic Science and Technology of China, Radiation Oncology Key Laboratory of Sichuan Province, Chengdu, 610041 China
| | - Jie Li
- grid.54549.390000 0004 0369 4060Sichuan Cancer Hospital and Institute, Sichuan Cancer Center, School of Medicine, University of Electronic Science and Technology of China, Radiation Oncology Key Laboratory of Sichuan Province, Chengdu, 610041 China
| | - Xianliang Wang
- grid.54549.390000 0004 0369 4060Sichuan Cancer Hospital and Institute, Sichuan Cancer Center, School of Medicine, University of Electronic Science and Technology of China, Radiation Oncology Key Laboratory of Sichuan Province, Chengdu, 610041 China
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Failing T, Hartmann GH, Hensley FW, Keil B, Zink K. Enhancement of the EGSnrc code egs_chamber for fast fluence calculations of charged particles. Z Med Phys 2022; 32:417-427. [PMID: 35643800 PMCID: PMC9948836 DOI: 10.1016/j.zemedi.2022.04.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2022] [Revised: 03/29/2022] [Accepted: 04/14/2022] [Indexed: 11/19/2022]
Abstract
PURPOSE Simulation of absorbed dose deposition in a detector is one of the key tasks of Monte Carlo (MC) dosimetry methodology. Recent publications (Hartmann and Zink, 2018; Hartmann and Zink, 2019; Hartmann et al., 2021) have shown that knowledge of the charged particle fluence differential in energy contributing to absorbed dose is useful to provide enhanced insight on how response depends on detector properties. While some EGSnrc MC codes provide output of charged particle spectra, they are often restricted in setup options or limited in calculation efficiency. For detector simulations, a promising approach is to upgrade the EGSnrc code egs_chamber which so far does not offer charged particle calculations. METHODS Since the user code cavity offers charged particle fluence calculation, the underlying algorithm was embedded in egs_chamber. The modified code was tested against two EGSnrc applications and DOSXYZnrc which was modified accordingly by one of the authors. Furthermore, the gain in efficiency achieved by photon cross section enhancement was determined quantitatively. RESULTS Electron and positron fluence spectra and restricted cema calculated by egs_chamber agreed well with the compared applications thus demonstrating the feasibility of the new code. Additionally, variance reduction techniques are now applicable also for fluence calculations. Depending on the simulation setup, considerable gains in efficiency were obtained by photon cross section enhancement. CONCLUSION The enhanced egs_chamber code represents a valuable tool to investigate the response of detectors with respect to absorbed dose and fluence distribution and the perturbation caused by the detector in a reasonable computation time. By using intermediate phase space scoring, egs_chamber offers parallel calculation of charged particle fluence spectra for different detector configurations in one single run.
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Affiliation(s)
- Thomas Failing
- Department for Radiotherapy and Radiooncology, University Medical Center Göttingen, Göttingen 37075, Germany; Institute of Medical Physics and Radiation Protection (IMPS), University of Applied Sciences, Gießen 35390, Germany.
| | | | - Frank W Hensley
- Department for Radiotherapy and Radiooncology, University Medical Center Heidelberg, Heidelberg 69120, Germany
| | - Boris Keil
- Institute of Medical Physics and Radiation Protection (IMPS), University of Applied Sciences, Gießen 35390, Germany; Diagnostic and Interventional Radiology, Philipps-University Marburg, Marburg 35043, Germany
| | - Klemens Zink
- Institute of Medical Physics and Radiation Protection (IMPS), University of Applied Sciences, Gießen 35390, Germany; Department for Radiotherapy and Radiooncology, University Medical Center Giessen-Marburg, Marburg 35043, Germany; Marburg Iontherapy Center (MIT), Marburg 35043, Germany
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10
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Tegaw EM, Geraily G, Gholami S, Shojaei M, Tadesse GF. Gold-nanoparticle-enriched breast tissue in breast cancer treatment using the INTRABEAM® system: a Monte Carlo study. Radiat Environ Biophys 2022; 61:119-131. [PMID: 34860272 DOI: 10.1007/s00411-021-00954-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2021] [Accepted: 11/07/2021] [Indexed: 06/13/2023]
Abstract
Using a 50-kV INTRABEAM® system after breast-conserving surgery, breast skin injury and long treatment time remain the challenging problems when large-size spherical applicators are used. This study has aimed to address these problems using gold (Au) nanoparticles (NPs). For this, surface and isotropic doses were measured using a Gafchromic EBT3 film and a water phantom. The particle propagation code EGSnrc/Epp was used to score the corresponding doses using a geometry similar to that used in the measurements. The simulation was validated using a gamma index of 2%/2 mm acceptance criterion in the gamma analysis. After validation Au-NP-enriched breast tissue was simulated to quantify any breast skin dose reduction and shortening of treatment time. It turned out that the gamma value deduced for validation of the simulation was in an acceptable range (i.e., less than one). For 20 mg-Au/g-breast tissue, the calculated Dose Enhancement Ratio (DER) of the breast skin was 0.412 and 0.414 using applicators with diameters of 1.5 cm and 5 cm, respectively. The corresponding treatment times were shortened by 72.22% and 72.30% at 20 mg-Au/g-breast tissue concentration, respectively. It is concluded that Au-NP-enriched breast tissue shows significant advantages, such as reducing the radiation dose received by the breast skin as well as shortening the treatment time. Additionally, the DERs were not significantly dependent on the size of the applicators.
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Affiliation(s)
- Eyachew Misganew Tegaw
- Department of Physics, Faculty of Natural and Computational Sciences, Debre Tabor University, Debre Tabor, Ethiopia
| | - Ghazale Geraily
- Department of Medical Physics and Biomedical Engineering, School of Medicine, International Campus (TUMS-IC), Tehran University of Medical Sciences, Tehran, Iran.
| | - Somayeh Gholami
- Radiation Oncology Research Center, Cancer Institute, Tehran University of Medical Sciences, Tehran, Iran
| | - Mehdi Shojaei
- Department of Medical Physics and Biomedical Engineering, School of Medicine, International Campus (TUMS-IC), Tehran University of Medical Sciences, Tehran, Iran
| | - Getu Ferenji Tadesse
- Department of Physics, College of Natural and Computational Sciences, Aksum University, Axum, Ethiopia
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11
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McCann A, León Vintró L, Cournane S, Lucey J. Assessment of occupational exposure from shielded and unshielded syringes for clinically relevant positron emission tomography (PET) isotopes-a Monte Carlo approach using EGSnrc. J Radiol Prot 2021; 41:1060-1074. [PMID: 34161938 DOI: 10.1088/1361-6498/ac0df5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Accepted: 06/23/2021] [Indexed: 06/13/2023]
Abstract
18F has been the most widely used radionuclide in positron emission tomography (PET) facilities over the last few decades. However, increased interest in novel PET tracers, theranostics and immuno-PET has led to significant growth in clinically used positron-emitting radionuclides. The decay schemes of each of these radioisotopes are markedly different from18F, with different endpoint energies for the emitted positrons and, in some cases, additional high energy gamma radiation. This has implications for the occupational exposure of personnel involved in the manipulation and dispensing of PET radiopharmaceuticals. The EGSnrc Monte Carlo simulation software was used to estimate the doses to extremities in contact with unshielded and shielded syringes containing64Cu,18F,11C,13N,15O,68Ga and89Zr, respectively. Dose rates at various distances from the syringe were also modelled, with dose rates reported in terms of eye (Hp(3)), skin equivalent (Hp(0.07)) and deep (Hp(10)) doses. The composition and geometry of the simulated syringe shields were based on a selection of commercially available PET shields. Experimental dose rate measurements were performed for validation purposes where possible. Contact skin dose rates for all isotopes, except for64Cu, were found to be higher than18F for the unshielded syringe. The addition of a shield resulted in approximately equal contact skin dose rates for nearly all isotopes, for each shield type, with the exception of89Zr which was notably higher. Dose rate constants (µGy/MBq.hr) for a range of PET isotopes and shields are presented and their significance discussed.
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Affiliation(s)
- Ann McCann
- Department of Medical Physics and Clinical Engineering, St Vincent's University Hospital, Dublin, Ireland
- Centre for Physics in Health and Medicine, School of Physics, University College Dublin, Dublin, Ireland
| | - Luis León Vintró
- Centre for Physics in Health and Medicine, School of Physics, University College Dublin, Dublin, Ireland
| | - Seán Cournane
- Department of Medical Physics and Clinical Engineering, St Vincent's University Hospital, Dublin, Ireland
- Centre for Physics in Health and Medicine, School of Physics, University College Dublin, Dublin, Ireland
| | - Julie Lucey
- Department of Medical Physics and Clinical Engineering, St Vincent's University Hospital, Dublin, Ireland
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12
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Partanen M, Niemelä J, Ojala J, Keyriläinen J, Kapanen M. Properties of IBA Razor Nano Chamber in small-field radiation therapy using 6 MV FF, 6 MV FFF, and 10 MV FFF photon beams. Acta Oncol 2021; 60:1419-1424. [PMID: 34596486 DOI: 10.1080/0284186x.2021.1979644] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
BACKGROUND Small megavoltage photon fields are increasingly used in modern radiotherapy techniques such as stereotactic radiotherapy. Therefore, it is important to study the reliability of dosimetry in the small-field conditions. The IBA Razor Nano Chamber (Nano chamber) ionization chamber is particularly intended for small-field measurements. In this work, properties of the Nano chamber were studied with both measurements and Monte Carlo (MC) simulations. MATERIAL AND METHODS The measurements and MC simulations were performed with 6 MV, 6 MV FFF and 10 MV FFF photon beams from the Varian TrueBeam linear accelerator. The source-to-surface distance was fixed at 100 cm. The measurements and MC simulations included profiles, percentage depth doses (PDD), and output factors (OF) in square jaw-collimated fields. The MC simulations were performed with the EGSnrc software system in a large water phantom. RESULTS The measured profiles and PDDs obtained with the Nano chamber were compared against IBA Razor Diode, PTW microDiamond and the PTW Semiflex ionization chamber. These results indicate that the Nano chamber is a high-resolution detector and thus suitable for small field profile measurements down to field sizes 2 × 2 cm2 and appropriate for the PDD measurements. The field output correction factors kQclin, Qmsrfclin, fmsr and field OFs ΩQclin, Qmsrfclin, fmsr were determined according to TRS-483 protocol In the 6 MV FF and FFF beams, the determined correction factors kQclin, Qmsrfclin, fmsr were within 1.2% for the field sizes of 1 × 1 cm2-3 × 3 cm2 and the experimental and MC defined field output factors ΩQclin,Qmsrfclin,fmsr showed good agreement. CONCLUSION The Nano chamber with its small cavity volume is a potential detector for the small-field dosimetry. In this study, the properties of this detector were characterized with measurements and MC simulations. The determined correction factors kQclin, Qmsrfclin, fmsr are novel results for the NC in the TrueBeam fields.
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Affiliation(s)
- Mari Partanen
- Unit of Radiotherapy, Department of Oncology, Tampere University Hospital, Tampere, Finland
- Department of Medical Physics, Medical Imaging Center, Tampere University Hospital, Tampere, Finland
| | - Jarkko Niemelä
- Department of Medical Physics, Turku University Hospital, Turku, Finland
- Department of Oncology and Radiotherapy, Turku University Hospital, Turku, Finland
- Department of Physics and Astronomy, University of Turku, Turku, Finland
| | - Jarkko Ojala
- Unit of Radiotherapy, Department of Oncology, Tampere University Hospital, Tampere, Finland
- Department of Medical Physics, Medical Imaging Center, Tampere University Hospital, Tampere, Finland
| | - Jani Keyriläinen
- Department of Medical Physics, Turku University Hospital, Turku, Finland
- Department of Oncology and Radiotherapy, Turku University Hospital, Turku, Finland
| | - Mika Kapanen
- Unit of Radiotherapy, Department of Oncology, Tampere University Hospital, Tampere, Finland
- Department of Medical Physics, Medical Imaging Center, Tampere University Hospital, Tampere, Finland
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13
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Tuğrul T. The Effect of Algorithms on Dose Distribution in Inhomogeneous Phantom: Monaco Treatment Planning System versus Monte Carlo Simulation. J Med Phys 2021; 46:111-115. [PMID: 34566291 PMCID: PMC8415246 DOI: 10.4103/jmp.jmp_21_21] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2021] [Revised: 05/05/2021] [Accepted: 05/05/2021] [Indexed: 11/26/2022] Open
Abstract
Background: The aim of this study is to evaluate the dose calculation algorithms commonly used in TPS by using MC simulation in the highly different inhomogeneous region and in the small fields and to provide the following uniquely new information in the study of correction algorithm. Materials and Methods: We compared the dose distribution obtained by Monaco TPS for small fields. Results: When we examine lung medium, for four different fields, we can see that the algorithms begin to differ. In both the lung and bone environment, the percentage differences decrease as the field size increases. In areas less than or equal to 3x3 cm2, there are serious differences between the algorithms. The CC algorithm calculates a low dose value as the photon passes from the lung environment to water environment. We can also see that this algorithm measures a low dose value in voxel as the photon passes from the water medium to the bone medium. In the transition from the water environment to the bone environment or from the bone environment to the water environment, the results of the CC algorithm are not close to MC simulation. Conclusion: The effect of the algorithms used in TPS on dose distribution is very strong, especially in environment with high electron density variation and in applications such as Stereotactic Body Radiotherapy and Intensity Modulated Radiotherapy where small fields are used.
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Affiliation(s)
- Taylan Tuğrul
- Department of Radiation Oncology, Faculty of Medicine, Van Yüzüncü Yıl University, Van, Turkey
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14
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Sahoo S, Selvam TP, Pathan M, Saxena SK, Pandey U, Kumar M, Kumar Y. Monte Carlo-based dosimetric studies of a locally developed 170Tm LDR brachytherapy seed source. J Radiol Prot 2021; 41:197-215. [PMID: 33690175 DOI: 10.1088/1361-6498/abecf6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Accepted: 03/09/2021] [Indexed: 06/12/2023]
Abstract
170Tm is being explored as a source for applications in brachytherapy. Although it has adequate physical properties, such as a short half-life (128.6 d), high specific activity and a mean photon energy of about 66 keV, it has a drawback of low photon yield (only about six photon emissions/100 beta emissions). The objective of this work is to study the dosimetric characteristics of a locally developed170Tm brachytherapy seed source using the Monte Carlo-based EGSnrc code system. In this study, we calculate the dose rate constant, air-kerma strength, radial dose function, anisotropic function and 2D dose-rate distributions in water. Separate simulations are carried out by considering the photon (gamma and characteristic x-ray) and beta spectra of the source. For regions close to the source (surface of the source <r< 0.4 cm), the dose is solely due to direct dose deposition by beta particles. At larger distances (0.4 cm <r<10 cm), the dose is due to bremsstrahlung photons produced by beta particles and photon emissions. The calculated value of the dose rate constant is 1.217 ± 0.052 cGy h-1U-1. The value ofSkper mCi is 0.029 ± 0.0009 U mCi-1. The contributions of the inherent photon emission and the bremsstrahlung photons to the totalSkare 0.58 and 0.42, respectively.
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Affiliation(s)
- Sridhar Sahoo
- Radiological Physics & Advisory Division, Bhabha Atomic Research Centre, Mumbai 400 085, India
| | - T Palani Selvam
- Radiological Physics & Advisory Division, Bhabha Atomic Research Centre, Mumbai 400 085, India
- Homi Bhabha National Institute, Mumbai 400 094, India
| | - Munir Pathan
- Radiological Physics & Advisory Division, Bhabha Atomic Research Centre, Mumbai 400 085, India
| | - S K Saxena
- Radiopharmaceuticals Division, Bhabha Atomic Research Centre, Mumbai 400 085, India
| | - Usha Pandey
- Board of Radiation Isotope and Technology, Vashi, Navi Mumbai 400 705, India
| | - Manoj Kumar
- Radiopharmaceuticals Division, Bhabha Atomic Research Centre, Mumbai 400 085, India
| | - Yogendra Kumar
- Radiopharmaceuticals Division, Bhabha Atomic Research Centre, Mumbai 400 085, India
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15
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Niemelä J, Partanen M, Ojala J, Kapanen M, Keyriläinen J. Dose-area product ratio in external small-beam radiotherapy: beam shape, size and energy dependencies in clinical photon beams. Biomed Phys Eng Express 2021; 7. [PMID: 33836522 DOI: 10.1088/2057-1976/abf6aa] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2021] [Accepted: 04/09/2021] [Indexed: 11/12/2022]
Abstract
In small-field radiotherapy (RT), a significant challenge is to define the amount of radiation dose absorbed in the patient where the quality of the beam has to be measured with high accuracy. The properties of a proposed new beam quality specifier, namely the dose-area-product ratio at 20 and 10 cm depths in water or DAPR20,10, were studied to yield more information on its feasibility over the conventional quality specifier tissue-phantom ratio or TPR20,10. The DAPR20,10may be measured with a large-area ionization chamber (LAC) instead of small volume chambers or semi-conductors where detector, beam and water phantom positioning and beam perturbations introduce uncertainties. The effects of beam shape, size and energy on the DAPR20,10were studied and it was shown that the DAPR20,10increases with increasing beam energy similarly to TPR20,10but in contrast exhibits a small beam size and shape dependence. The beam profile outside the beam limiting devices has been shown to have a large contribution to the DAPR20,10. There is potential in large area chambers to be used in DAPR measurement and its use in dosimetry of small-beam RT for beam quality measurements.
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Affiliation(s)
- Jarkko Niemelä
- University of Turku, Department of Physics and Astronomy, FI-20014 Turku, Finland.,Department of Medical Physics, Turku University Hospital, PO Box 52, FI-20521 Turku, Finland.,Department of Oncology and Radiotherapy, Turku University Hospital, PO Box 52, FI-20521 Turku, Finland
| | - Mari Partanen
- Department of Oncology, Unit of Radiotherapy, Tampere University Hospital, PO Box 2000, FI-33521 Tampere, Finland.,Department of Medical Physics, Medical Imaging Center, Tampere University Hospital, PO Box 2000, FI-33521 Tampere, Finland
| | - Jarkko Ojala
- Department of Oncology, Unit of Radiotherapy, Tampere University Hospital, PO Box 2000, FI-33521 Tampere, Finland.,Department of Medical Physics, Medical Imaging Center, Tampere University Hospital, PO Box 2000, FI-33521 Tampere, Finland
| | - Mika Kapanen
- Department of Oncology, Unit of Radiotherapy, Tampere University Hospital, PO Box 2000, FI-33521 Tampere, Finland.,Department of Medical Physics, Medical Imaging Center, Tampere University Hospital, PO Box 2000, FI-33521 Tampere, Finland
| | - Jani Keyriläinen
- Department of Medical Physics, Turku University Hospital, PO Box 52, FI-20521 Turku, Finland.,Department of Oncology and Radiotherapy, Turku University Hospital, PO Box 52, FI-20521 Turku, Finland
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16
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Yüksel Z, Tufan MÇ. Relationship between dose and stopping power values for electrons in skin and muscle tissues. Radiat Environ Biophys 2021; 60:135-140. [PMID: 33528674 DOI: 10.1007/s00411-020-00888-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Accepted: 12/07/2020] [Indexed: 06/12/2023]
Abstract
Absorbed dose and stopping power of the target material are two important parameters for determining the radiation effects. In this work, the relationship between these two parameters has been investigated for electron beams incident on skin and muscle tissue. Absorbed dose was obtained by using the EGSnrc code and the stopping power values were calculated by considering the velocity-depended effective charge and mean excitation values. To obtain the relationship between absorbed dose and stopping power values, these parameters were graphed together and simple fitting functions have been obtained. The results obtained show that these parameters are linearly correlated with each other.
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Affiliation(s)
- Zeynep Yüksel
- Medical Services and Techniques Department, Vocational School of Health Services, Ondokuz Mayıs University, 55139, Samsun, Turkey.
| | - M Çağatay Tufan
- Graduate School, Department of Radiological Sciences, Ondokuz Mayıs University, 55139, Samsun, Turkey
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17
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Tessier F, Ross CK. Technical Note: Implications of using EGSnrc instead of EGS4 for extracting electron stopping powers from measured energy spectra. Med Phys 2021; 48:1996-2003. [PMID: 33125734 DOI: 10.1002/mp.14567] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Revised: 10/05/2020] [Accepted: 10/05/2020] [Indexed: 11/10/2022] Open
Abstract
PURPOSE NRC Report PIRS-0626 (https://doi.org/10.4224/40000364) describes how measured electron energy deposition spectra can be used to determine the electronic stopping power. The stopping power is obtained by comparing measured spectra with spectra calculated using Monte Carlo techniques. The stopping powers reported in PIRS-0626 were obtained using the EGS4 Monte Carlo code. Since then, the EGSnrc code has been released which has more accurate electron transport algorithms. We calculate the effect on the measured stopping powers of using EGSnrc instead of EGS4. METHOD The EGS4 spectra calculated in PIRS-0626 were based on 4 × 10 5 primary electron histories. We first show that those spectra, calculated in 1997, are consistent with current EGS4 spectra calculated using 10 8 histories. EGSnrc spectra are also calculated using 10 8 histories and these high-precision spectra are compared to extract any energy difference. The energy differences between the spectra are used to estimate the effect on the measured electronic stopping powers. RESULTS The energy differences depend on the absorber material, the absorber thickness and the beam energy. The improved electron elastic scattering cross section of EGSnrc accounts for only part of the difference between the two codes. The effect on the extracted stopping power is largest for the lowest electron energies and can be as large as 0.9%. The calculated spectra show differences for lower energies, with the EGSnrc spectra having a larger proportion of low-energy electrons. CONCLUSION The differences introduced by using EGSnrc instead of EGS4 can affect the estimated stopping power by almost 1% in the worst case but generally the effect is much smaller. We report corrections that can be applied to all the stopping power data in PIRS-0626. An experiment to measure the average energy to create an ion pair in air, W air , using aluminum detectors will provide an interesting test of the aluminum stopping power data as reported in PIRS-0626 and revised by this work.
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Affiliation(s)
- Frédéric Tessier
- Ionizing Radiation Standards, Metrology Research Centre, National Research Council Canada, Ottawa, ON, K1A 0R6, Canada
| | - Carl K Ross
- Ionizing Radiation Standards, Metrology Research Centre, National Research Council Canada, Ottawa, ON, K1A 0R6, Canada
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18
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Rostamzadeh M, Ishihara Y, Nakamura M, Popescu IA, Mestrovic A, Gete E, Fedrigo R, Bergman AM. Monte Carlo simulation of 6-MV dynamic wave VMAT deliveries by Vero4DRT linear accelerator using EGSnrc moving sources. J Appl Clin Med Phys 2020; 21:206-218. [PMID: 33219743 PMCID: PMC7769401 DOI: 10.1002/acm2.13090] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2020] [Revised: 08/12/2020] [Accepted: 10/06/2020] [Indexed: 12/02/2022] Open
Abstract
The commissioning and benchmark of a Monte Carlo (MC) model of the 6‐MV Brainlab‐Mitsubishi Vero4DRT linear accelerator for the purpose of quality assurance of clinical dynamic wave arc (DWA) treatment plans is reported. Open‐source MC applications based on EGSnrc particle transport codes are used to simulate the medical linear accelerator head components. Complex radiotherapy irradiations can be simulated in a single MC run using a shared library format combined with BEAMnrc “source20.” Electron energy tuning is achieved by comparing measured vs simulated percentage depth doses (PDDs) for MLC‐defined field sizes in a water phantom. Electron spot size tuning is achieved by comparing measured and simulated inplane and crossplane beam profiles. DWA treatment plans generated from RayStation (RaySearch) treatment planning system (TPS) are simulated on voxelized (2.5 mm3) patient CT datasets. Planning target volume (PTV) and organs at risk (OAR) dose–volume histograms (DVHs) are compared to TPS‐calculated doses for clinically deliverable dynamic volumetric modulated arc therapy (VMAT) trajectories. MC simulations with an electron beam energy of 5.9 MeV and spot size FWHM of 1.9 mm had the closest agreement with measurement. DWA beam deliveries simulated on patient CT datasets results in DVH agreement with TPS‐calculated doses. PTV coverage agreed within 0.1% and OAR max doses (to 0.035 cc volume) agreed within 1 Gy. This MC model can be used as an independent dose calculation from the TPS and as a quality assurance tool for complex, dynamic radiotherapy treatment deliveries. Full patient CT treatment simulations are performed in a single Monte Carlo run in 23 min. Simulations are run in parallel using the Condor High‐Throughput Computing software1 on a cluster of eight servers. Each server has two physical processors (Intel Xeon CPU E5‐2650 0 @2.00 GHz), with 8 cores per CPU and two threads per core for 256 calculation nodes.
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Affiliation(s)
- Maryam Rostamzadeh
- Department of Physics and Astronomy, University of British Columbia, Vancouver, BC, Canada
| | | | | | | | - Ante Mestrovic
- Medical Physics Department, BC Cancer-Vancouver, Vancouver, Canada
| | - Ermias Gete
- Medical Physics Department, BC Cancer-Vancouver, Vancouver, Canada
| | - Roberto Fedrigo
- Department of Physics and Astronomy, University of British Columbia, Vancouver, BC, Canada
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19
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Shukla BK, Spindeldreier CK, Schrenk O, Bakenecker AC, Klüter S, Kawrakow I, Runz A, Burigo L, Karger CP, Greilich S, Pfaffenberger A. Dosimetry in magnetic fields with dedicated MR-compatible ionization chambers. Phys Med 2020; 80:259-266. [PMID: 33220650 DOI: 10.1016/j.ejmp.2020.10.021] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/12/2020] [Revised: 09/20/2020] [Accepted: 10/24/2020] [Indexed: 10/22/2022] Open
Abstract
MR-integrated radiotherapy requires suitable dosimetry detectors to be used in magnetic fields. This study investigates the feasibility of using dedicated MR-compatible ionization chambers at MR-integrated radiotherapy devices. MR-compatible ionization chambers (Exradin A19MR, A1SLMR, A26MR, A28MR) were precisely modeled and their relative response in a 6MV treatment beam in the presence of a magnetic field was simulated using EGSnrc. Monte Carlo simulations were carried out with the magnetic field in three orientations: the magnetic field aligned perpendicular to the chamber and beam axis (transverse orientation), the magnetic field parallel to the chamber as well as parallel to the beam axis. Monte Carlo simulation results were validated with measurements using an electromagnet with magnetic field strength upto 1.1 T with the chambers in transverse orientation. The measurements and simulation results were in good agreement, except for the A26MR ionization chamber in transverse orientation. The maximum increase in response of the ionization chambers observed was 8.6% for the transverse orientation. No appreciable change in chamber response due to the magnetic field was observed for the magnetic field parallel to the ionization chamber and parallel to the photon beam. Polarity and recombination correction factor were experimentally investigated in the transverse orientation. The polarity effect and recombination effect were not altered by a magnetic field. This study further investigates the response of the ionization chambers as a function of the chambers' rotation around their longitudinal axis. A variation in response was observed when the chamber was not rotationally symmetric, which was independent of the magnetic field.
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Affiliation(s)
- Bhargesh K Shukla
- Medical Physics in Radiation Oncology, German Cancer Research Center (DKFZ), Heidelberg, Germany; National Center for Radiation Research in Oncology (NCRO), Heidelberg Institute for Radiooncology (HIRO), Heidelberg, Germany
| | - Claudia Katharina Spindeldreier
- Medical Physics in Radiation Oncology, German Cancer Research Center (DKFZ), Heidelberg, Germany; National Center for Radiation Research in Oncology (NCRO), Heidelberg Institute for Radiooncology (HIRO), Heidelberg, Germany; Department of Radiation Oncology, University Hospital Heidelberg, Heidelberg, Germany
| | - Oliver Schrenk
- Medical Physics in Radiation Oncology, German Cancer Research Center (DKFZ), Heidelberg, Germany; National Center for Radiation Research in Oncology (NCRO), Heidelberg Institute for Radiooncology (HIRO), Heidelberg, Germany; Department of Radiation Oncology, University Hospital Heidelberg, Heidelberg, Germany; Medical Faculty, University of Heidelberg, Heidelberg, Germany
| | - Anna C Bakenecker
- Medical Physics in Radiation Oncology, German Cancer Research Center (DKFZ), Heidelberg, Germany; National Center for Radiation Research in Oncology (NCRO), Heidelberg Institute for Radiooncology (HIRO), Heidelberg, Germany
| | - Sebastian Klüter
- National Center for Radiation Research in Oncology (NCRO), Heidelberg Institute for Radiooncology (HIRO), Heidelberg, Germany; Department of Radiation Oncology, University Hospital Heidelberg, Heidelberg, Germany
| | - Iwan Kawrakow
- Viewray Inc., Thermo Fischer Way, Oakwood village, OH, USA
| | - Armin Runz
- Medical Physics in Radiation Oncology, German Cancer Research Center (DKFZ), Heidelberg, Germany; National Center for Radiation Research in Oncology (NCRO), Heidelberg Institute for Radiooncology (HIRO), Heidelberg, Germany
| | - Lucas Burigo
- Medical Physics in Radiation Oncology, German Cancer Research Center (DKFZ), Heidelberg, Germany; National Center for Radiation Research in Oncology (NCRO), Heidelberg Institute for Radiooncology (HIRO), Heidelberg, Germany
| | - Christian P Karger
- Medical Physics in Radiation Oncology, German Cancer Research Center (DKFZ), Heidelberg, Germany; National Center for Radiation Research in Oncology (NCRO), Heidelberg Institute for Radiooncology (HIRO), Heidelberg, Germany
| | - Steffen Greilich
- Medical Physics in Radiation Oncology, German Cancer Research Center (DKFZ), Heidelberg, Germany; National Center for Radiation Research in Oncology (NCRO), Heidelberg Institute for Radiooncology (HIRO), Heidelberg, Germany
| | - Asja Pfaffenberger
- Medical Physics in Radiation Oncology, German Cancer Research Center (DKFZ), Heidelberg, Germany; National Center for Radiation Research in Oncology (NCRO), Heidelberg Institute for Radiooncology (HIRO), Heidelberg, Germany
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20
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Pojtinger S, Nachbar M, Kapsch RP, Thorwarth D. Influence of beam quality on reference dosimetry correction factors in magnetic resonance guided radiation therapy. Phys Imaging Radiat Oncol 2020; 16:95-98. [PMID: 33458350 PMCID: PMC7807647 DOI: 10.1016/j.phro.2020.10.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Revised: 10/07/2020] [Accepted: 10/07/2020] [Indexed: 01/09/2023] Open
Abstract
Correction factors for reference dosimetry in magnetic resonance (MR) imaging-guided radiation therapy (k B → , M , Q ) are often determined in setups that combine a conventional 6 MV linac with an electromagnet. This study investigated whether results based on these measurements were applicable for a 7 MV MR-linac using Monte Carlo simulations. For a Farmer-type ionization chamber,k B → , M , Q was assessed for different tissue-phantom ratios (TPR 20 , 10 ).k B → , M , Q differed by 0.0029 ( 43 ) betweenTPR 20 , 10 = 0.6790 ( 23 ) (6 MV linac) andTPR 20 , 10 = 0.7028 ( 14 ) (7 MV MR-linac) at 1.5 T . The agreement was best in an orientation in which the secondary electrons were deflected to the stem of the ionization chamber.
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Affiliation(s)
- Stefan Pojtinger
- Physikalisch-Technische Bundesanstalt, Braunschweig, Germany
- Section for Biomedical Physics, Department of Radiation Oncology, University of Tübingen, Germany
| | - Marcel Nachbar
- Section for Biomedical Physics, Department of Radiation Oncology, University of Tübingen, Germany
| | | | - Daniela Thorwarth
- Section for Biomedical Physics, Department of Radiation Oncology, University of Tübingen, Germany
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21
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Bajwa S, Gul A, Ahmed S, Kakakhel MB. Monte Carlo commissioning of radiotherapy LINAC-Introducing an improved methodology. Rep Pract Oncol Radiother 2020; 25:720-724. [PMID: 32684860 DOI: 10.1016/j.rpor.2020.06.009] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2020] [Revised: 05/18/2020] [Accepted: 06/23/2020] [Indexed: 11/15/2022] Open
Abstract
Purpose Monte Carlo (MC) commissioning of medical linear accelerator (LINAC) is a time-consuming process involving a comparison between measured and simulated cross beam/lateral profiles and percentage depth doses (PDDs) for various field sizes. An agreement between these two data sets is sought by trial and error method while varying the incident electron beam parameters, such as electron beam energy or width, etc. This study aims to improve the efficiency of MC commissioning of a LINAC by assessing the feasibility of using a limited number of simulated PDDs. Materials and methods Using EGSnrc codes, a Varian Clinac 2100 unit has been commissioned for 6 MV photon beam, and a methodology has been proposed to identify the incident electron beam parameters in a speedier fashion. Impact of voxel size in 3-dimensions and cost functions used for comparison of the measured and simulated data have been investigated along with the role of interpolation. Results A voxel size of 1 × 1×0.5 cm3 has been identified as suitable for accurate and fast commissioning of the LIANC. The optimum number of simulated PDDs (required for further interpolation) has been found to be five. Conclusion The present study suggests that PDDs alone at times can be insufficient for an unambiguous commissioning process and should be supported by including the lateral beam profiles in the process.
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Affiliation(s)
- Saqib Bajwa
- Department of Physics & Applied Mathematics, Pakistan Institute of Engineering & Applied Sciences (PIEAS), Nilore, Islamabad, Pakistan
| | - Attia Gul
- Department of Physics & Applied Mathematics, Pakistan Institute of Engineering & Applied Sciences (PIEAS), Nilore, Islamabad, Pakistan
| | - Shahbaz Ahmed
- Wayne State University School of Medicine Gershenson Radiation Oncology Center Karmanos Cancer Institute, 4100 John R, Detroit, MI 48201.,Department of Physics & Applied Mathematics, Pakistan Institute of Engineering & Applied Sciences (PIEAS), Nilore, Islamabad, Pakistan
| | - Muhammad B Kakakhel
- Department of Physics & Applied Mathematics, Pakistan Institute of Engineering & Applied Sciences (PIEAS), Nilore, Islamabad, Pakistan
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22
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Li R, Tseng W, Wu Q. Validation of the dosimetry of total skin irradiation techniques by Monte Carlo simulation. J Appl Clin Med Phys 2020; 21:107-119. [PMID: 32559022 PMCID: PMC7484841 DOI: 10.1002/acm2.12921] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2019] [Revised: 04/12/2020] [Accepted: 04/29/2020] [Indexed: 11/24/2022] Open
Abstract
Purpose To validate the dose measurements for two total skin irradiation techniques with Monte Carlo simulation, providing more information on dose distributions, and guidance on further technique optimization. Methods Two total skin irradiation techniques (stand‐up and lay‐down) with different setup were simulated and validated. The Monte Carlo simulation was primarily performed within the EGSnrc environment. Parameters of jaws, MLCs, and a customized copper (Cu) filter were first tuned to match the profiles and output measured at source‐to‐skin distance (SSD) of 100 cm where the secondary source is defined. The secondary source was rotated to simulate gantry rotation. VirtuaLinac, a cloud‐based Monte Carlo package, was used for Linac head simulation as a secondary validation. The following quantities were compared with measurements: for each field/direction at the treatment SSDs, the percent depth dose (PDD), the profiles at the depth of maximum, and the absolute dosimetric output; the composite dose distribution on cylindrical phantoms of 20 to 40 cm diameters. Results Cu filter broadened the FWHM of the electron beam by 44% and degraded the mean energy by 0.7 MeV. At SSD = 100 cm, MC calculated PDDs agreed with measured data within 2%/2 mm (except for the surface voxel) and lateral profiles agreed within 3%. At the treatment SSD, profiles and output factors of individual field matched within 4%; dmax and R80 of the simulated PDDs also matched with measurement within 2 mm. When all fields were combined on the cylindrical phantom, the dmax shifted toward the surface. For lay‐down technique, the maximum x‐ray contamination at the central axis was (MC: 2.2; Measurement: 2.1)% and reduced to 0.2% at 40 cm off the central axis. Conclusions The Monte Carlo results in general agree well with the measurement, which provides support in our commissioning procedure, as well as the full three‐dimensional dose distribution of the patient phantom.
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Affiliation(s)
- Ruiqi Li
- Department of Radiation Oncology, Duke University Medical Center, Durham, NC, USA
| | - Wenchih Tseng
- Department of Radiation Oncology, Duke University Medical Center, Durham, NC, USA
| | - Qiuwen Wu
- Department of Radiation Oncology, Duke University Medical Center, Durham, NC, USA
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23
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Martinov MP, Thomson RM. Technical Note: Taking EGSnrc to new lows: Development of egs++ lattice geometry and testing with microscopic geometries. Med Phys 2020; 47:3225-3232. [PMID: 32277472 DOI: 10.1002/mp.14172] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2019] [Revised: 03/10/2020] [Accepted: 03/30/2020] [Indexed: 11/10/2022] Open
Abstract
PURPOSE This work introduces a new lattice geometry library, egs_lattice, into the EGSnrc Monte Carlo code, which can be used for both modeling very large (previously unfeasible) quantities of geometries (e.g., cells or gold nanoparticles (GNPs)) and establishing recursive boundary conditions. The reliability of egs_lattice, as well as EGSnrc in general, is cross-validated and tested at short length scales and low energies. METHODS New Bravais, cubic, and hexagonal lattice geometries are defined in egs_lattice and their transport algorithms are described. Simulations of cells and GNP-containing cavities are implemented to compare to independent, published Geant4-DNA and PENELOPE results. Recursive boundary conditions, implemented through a cubic lattice, are used to perform electron Fano cavity tests. The Fano test is performed on three different-sized cells containing GNPs in the region around the nucleus for three source energies. RESULTS Lattices are successfully implemented in EGSnrc, and are used for validation. EGSnrc calculated the dose to cell cytoplasm and nucleus when irradiated by an internal electron source with a median difference of 0.6% compared to published Geant4-DNA results. EGSnrc calculated the ratio of dose to a microscopic cavity containing GNPs over dose to a cavity containing a homogeneous mixture of gold, and results generally agree (within 1%) with published PENELOPE results. The electron Fano cavity test is passed for all energies and cells considered, with sub-0.1% discrepancies between EGSnrc-calculated and expected values. Additionally, the recursive boundary conditions used for the Fano test provided a factor of over a million increase in efficiency in some cases. CONCLUSIONS The egs_lattice geometry library, currently available as a pull request on the EGSnrc GitHub "develop" branch, is now freely accessible as open-source code. Lattice geometry implementations cross-validated with independent simulations in other MC codes and verified with the electron Fano cavity test demonstrate not only the reliability of egs_lattice, but also, by extension, EGSnrc's ability to simulate transport in nanometer geometries and score in microscopic cavities.
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Affiliation(s)
- Martin P Martinov
- Laboratory for Radiotherapy Physics, Department of Physics, Carleton University, Ottawa, ON, K1S 5B6, Canada
| | - Rowan M Thomson
- Laboratory for Radiotherapy Physics, Department of Physics, Carleton University, Ottawa, ON, K1S 5B6, Canada
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Yani S, Rizkia I, Kamirul, Rhani MF, Haekal M, Haryanto F. EGSnrc application for IMRT planning. Rep Pract Oncol Radiother 2020; 25:217-226. [PMID: 32194347 DOI: 10.1016/j.rpor.2020.01.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2019] [Revised: 11/24/2019] [Accepted: 01/20/2020] [Indexed: 10/25/2022] Open
Abstract
The aim of this study was to describe a detailed instruction of intensity modulated radiotherapy (IMRT) planning simulation using BEAMnrc-DOSXYZnrc code system (EGSnrc package) and present a new graphical user interface based on MATLAB code (The MathWorks) to combine more than one. 3ddose file which were obtained from the IMRT plan. This study was performed in four phases: the commissioning of Varian Clinac iX6 MV, the simulation of IMRT planning in EGSnrc, the creation of in-house VDOSE GUI, and the analysis of the isodose contour and dose volume histogram (DVH) curve from several beam angles. The plan paramaters in sequence and control point files were extracted from the planning data in Tan Tock Seng Hospital Singapore (multileaf collimator (MLC) leaf positions - bank A and bank B, gantry angles, coordinate of isocenters, and MU indexes). VDOSE GUI which was created in this study can display the distribution dose curve in each slice and beam angle. Dose distributions from various MLC settings and beam angles yield different dose distributions even though they used the same number of simulated particles. This was due to the differences in the MLC leaf openings in every field. The value of the relative dose error between the two dose ditributions for "body" was 51.23 %. The Monte Carlo (MC) data was normalized with the maximum dose but the analytical anisotropic algorithm (AAA) data was normalized by the dose in the isocenter. In this study, we have presented a Monte Carlo simulation framework for IMRT dose calculation using DOSXYZnrc source 21. Further studies are needed in conducting IMRT simulations using EGSnrc to minimize the different dose error and dose volume histogram deviation.
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Affiliation(s)
- Sitti Yani
- Department of Physics, Faculty of Mathematics and Natural Sciences, Bogor Agricultural University (IPB University), Jalan Meranti Kampus IPB Dramaga, Bogor 16680, Indonesia.,Department of Physics, Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung, Jalan Ganesa 10, Coblong, Bandung, West Java, 40132, Indonesia
| | - Ilmi Rizkia
- Department of Physics, Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung, Jalan Ganesa 10, Coblong, Bandung, West Java, 40132, Indonesia
| | - Kamirul
- Indonesian National Institute of Aeronautics and Space, Jl. Goa Jepang, Sumberker, Samofa, Kabupaten Biak Numfor, Papua 98118, Indonesia
| | | | - Mohammad Haekal
- Department of Physics, Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung, Jalan Ganesa 10, Coblong, Bandung, West Java, 40132, Indonesia
| | - Freddy Haryanto
- Department of Physics, Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung, Jalan Ganesa 10, Coblong, Bandung, West Java, 40132, Indonesia
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25
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Al Kanti H, El Hajjaji O, El Bardouni T, Mohammed M. An analytical fit and EGSnrc code (MC) calculations of personal dose equivalent conversion coefficients for mono-energetic electrons. Appl Radiat Isot 2019; 154:108906. [PMID: 31586843 DOI: 10.1016/j.apradiso.2019.108906] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2019] [Revised: 09/11/2019] [Accepted: 09/25/2019] [Indexed: 11/20/2022]
Abstract
This study aims for calculating a new set of the personal dose equivalent conversion coefficients Hp(d)/Φ when d = 0.07, 3, and 10 mm, for mono-energetic electron beams ranged from 0.06 MeV to 50 MeV for Hp(0.07), from 0.7 MeV to 50 MeV for Hp(3) and from 2 MeV to 50 MeV for Hp(10), which has incident on ICRU slab phantom. Additionally, we have calculated the conversion coefficients of a dose to the lens eye of into a new cylindrical phantom of the ORAMED project. The cylindrical phantom was proposed for calculating the eye lens dose equivalent as a cylinder much better approximates the form of a head than a slab. The ICRU tissue of density of 1 g/cm3 which is consists of 4-elemental has been used in slab and cylindrical phantoms. The calculations were carried out with EGSnrc code Monte Carlo (MC) and a new an analytical fit is applied to the data. Our results are found in a good agreement with those published by Veinot and Hertel (2012)) , with a local difference less than 1.5%. We have concluded that new analytical fits provide a convenient approach for determining conversion coefficients for discrete incident such as MC.
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Affiliation(s)
- Hassan Al Kanti
- Radiations and Nuclear Systems Laboratory, Abdelmalek Essaadi University, Faculty of Sciences, Tetouan, Morocco.
| | - O El Hajjaji
- Radiations and Nuclear Systems Laboratory, Abdelmalek Essaadi University, Faculty of Sciences, Tetouan, Morocco
| | - T El Bardouni
- Radiations and Nuclear Systems Laboratory, Abdelmalek Essaadi University, Faculty of Sciences, Tetouan, Morocco
| | - Maged Mohammed
- SIMO-LAB, Ibn Tofail University, Faculty of Sciences, Kenitra, Morocco
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26
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Rogers DWO, Townson RW. On calculating kerma, collision kerma and radiative yields. Med Phys 2019; 46:5173-5184. [PMID: 31361030 DOI: 10.1002/mp.13744] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2019] [Revised: 06/10/2019] [Accepted: 07/16/2019] [Indexed: 11/11/2022] Open
Abstract
PURPOSE To study the relationships between dose (D), kerma (K), and collision kerma ( K col ) in photon beams and to investigate total radiative yields for electrons and positrons as a function of energy. To do this accurately required calculating collision kerma directly as a function of position in a phantom and making changes to the EGSnrc package (including DOSRZnrc and g applications). METHODS Changes were made to the EGSnrc system to allow the user to distinguish events according to their initiating process, most importantly relaxation particles initiated by electron impact ionization as opposed to initiated by photons, especially those events depositing energy below energy cutoffs after relaxation events. Appropriate changes were made to the applications DOSRZnrc and g and a new application, DOSRZnrcKcol, was written. RESULTS The modified codes are much more robust against changes in simulation parameters such as ECUT and AE and whether or not electron impact ionization is included in the simulation. The radiative yields for electrons generally differ from values in ICRU Report 371 (1984) which only account for radiative losses due to bremsstrahlung. The Monte Carlo calculated g(brems) values are generally greater than the ICRU 37 values due to energy-loss straggling. Plots of D, K and K col vs depth in megavoltage photon beams show that some "conventional wisdom" does not hold in general (e.g., D is not always greater than K past D max ) and in general at 10 cm depth it is found that D≈K and D > K col . The beam radius at which D / K col reaches its saturation value depends strongly on the threshold used to define reaching saturation and is generally greater than the radius for lateral charged particle equilibrium used in the TRS-483 Code of Practice for small beam dosimetry2 (Palmans et al, Med Phys. 2018;45:e1123-e1145). CONCLUSIONS The changes to EGSnrc make kerma calculations more accurate but previous calculations with electron impact ionization turned off gave close to correct results. The application DOSRZnrcKcol makes calculating collision kerma more efficient and avoids various approximations used in the past although those approximations are shown to be justified. Including energy-loss straggling when calculating bremsstrahlung radiation yield increases the value. Fluorescence losses and annihilation in flight further increase the radiation yield of electrons and positrons. Results demonstrate the effects of EGSnrc using electron bremsstrahlung production cross sections for positrons and failing to model positron impact ionization.
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Affiliation(s)
- D W O Rogers
- Carleton Laboratory for Radiotherapy Physics, Physics Department, Carleton University, Ottawa, K1S 5B6, Canada
| | - Reid W Townson
- Metrology Research Centre, National Research Council Canada, Ottawa, K1A OR6, Canada
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27
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Nicolas JD, Aeffner S, Salditt T. Radiation damage studies in cardiac muscle cells and tissue using microfocused X-ray beams: experiment and simulation. J Synchrotron Radiat 2019; 26:980-990. [PMID: 31274419 DOI: 10.1107/s1600577519006817] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2019] [Accepted: 05/12/2019] [Indexed: 05/27/2023]
Abstract
Soft materials are easily affected by radiation damage from intense, focused synchrotron beams, often limiting the use of scanning diffraction experiments to radiation-resistant samples. To minimize radiation damage in experiments on soft tissue and thus to improve data quality, radiation damage needs to be studied as a function of the experimental parameters. Here, the impact of radiation damage in scanning X-ray diffraction experiments on hydrated cardiac muscle cells and tissue is investigated. It is shown how the small-angle diffraction signal is affected by radiation damage upon variation of scan parameters and dose. The experimental study was complemented by simulations of dose distributions for microfocused X-ray beams in soft muscle tissue. As a simulation tool, the Monte Carlo software package EGSnrc was used that is widely used in radiation dosimetry research. Simulations also give additional guidance for a more careful planning of dose distribution in tissue.
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Affiliation(s)
- Jan David Nicolas
- Georg-August-Universität Göttingen, Institut für Röntgenphysik, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - Sebastian Aeffner
- Georg-August-Universität Göttingen, Institut für Röntgenphysik, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - Tim Salditt
- Georg-August-Universität Göttingen, Institut für Röntgenphysik, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
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28
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Malkov VN, Hackett SL, van Asselen B, Raaymakers BW, Wolthaus JWH. Monte Carlo simulations of out-of-field skin dose due to spiralling contaminant electrons in a perpendicular magnetic field. Med Phys 2019; 46:1467-1477. [PMID: 30666678 PMCID: PMC6850151 DOI: 10.1002/mp.13392] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2018] [Revised: 12/10/2018] [Accepted: 01/09/2019] [Indexed: 11/16/2022] Open
Abstract
Purpose The purpose of this study was to evaluate the potential skin dose toxicity contribution of spiralling contaminant electrons (SCE) generated in the air in an MR‐linac with a 0.35 or 1.5 T magnetic field using the EGSnrc Monte Carlo (MC) code. Comparisons to experimental results at 1.5 T are also performed. Methods An Elekta generated phase space file for the Unity MR‐linac is used in conjunction with the EGSnrc enhanced electric and magnetic field transport macros to simulate surface dose profiles and depth‐dose curves in panels located 5 cm away from the beam edge and positioned either parallel or perpendicular to the magnetic field. Electrons generated in the air will spiral along the magnetic field lines, and though surface doses within the field will be reduced, the electrons can contribute to out‐of‐field surface doses. Results Surface dose profiles showed good agreement with experimental findings and the maximum simulated doses at surfaces perpendicular to the magnetic field were 3.77 ± 0.01% and 3.55 ± 0.01% for 1.5 and 0.35 T. These results are expressed as a percentage of the maximum dose to water delivered by the photon beam. The surface dose variations in the out‐of‐field region converge to the 0 T doses within the first 0.5 cm of material. An asymmetry in the dose distribution in surfaces positioned on either side of the photon beam and aligned parallel to the magnetic field is determined to be due to the magnetic field directing electrons deeper into, or localizing them to the surface of, the measurement panel. Conclusions These results confirm the SCE dose contribution in surfaces perpendicular to the magnetic field and show these doses to be of the order of a few percentage of the maximum dose to water of the beam. Good agreement in the dose profiles is seen in comparisons between the MC simulations and experimental work. The effect is apparent in 0.35 and 1.5 T magnetic fields and dissipates within the first few millimeters of material. It should be noted that only SCEs from beam anteriorly incident on the patient will influence the patient surface dose, and the use of beams incident over different angles will reduce the dose to any particular patient surface.
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Affiliation(s)
- Victor N Malkov
- Department of Radiotherapy, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Sara L Hackett
- Department of Radiotherapy, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Bram van Asselen
- Department of Radiotherapy, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Bas W Raaymakers
- Department of Radiotherapy, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Jochem W H Wolthaus
- Department of Radiotherapy, University Medical Center Utrecht, Utrecht, The Netherlands
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29
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Ghila A, Fallone BG, Rathee S. Technical Note: Experimental verification of EGSnrc calculated depth dose within a parallel magnetic field in a lung phantom. Med Phys 2018; 45:5653-5658. [PMID: 30260003 DOI: 10.1002/mp.13215] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2018] [Revised: 08/17/2018] [Accepted: 09/17/2018] [Indexed: 11/10/2022] Open
Abstract
PURPOSE The calculation of depth doses from a 6 MV photon beam in polystyrene using EGSnrc Monte Carlo, within a parallel magnetic field, has been previously verified against measured data. The current work experimentally investigates the accuracy of EGSnrc calculated depth doses in lung within the same parallel magnetic field. METHODS Two cylindrical bore electromagnets produced a magnetic field parallel to the central axis of a Varian Silhouette beam. A Gammex lung phantom was used, along with a parallel plate ion chamber, for the depth dose measurements. Two experimental setups were investigated: top of phantom coinciding with the top of the magnet's bore, and top of phantom coinciding with the center of the bore. EGSnrc was modified to read the 3D magnetic field distribution and then used to simulate the depth dose in lung. RESULTS The parallel magnetic field caused measurable increases in dose at the surface and in the buildup region for both setups. For the setup where the top of the lung phantom coincides with the top of the magnet, the surface dose increased by ~11% compared to the no magnetic field case but the depth of maximum dose remained unchanged. When the phantom's top surface coincided with the center of the magnet, the surface dose increased by 32% and dose maximum occurred at a shallower depth. EGSnrc was able to calculate these dose increases due to the magnetic field accurately for both setups. All the simulated depth dose values were within 2% (with respect to Dmax ) of the measured ones, and most of the investigated points were within 1.5%. CONCLUSIONS Surface and dose increases due to a parallel magnetic field have been measured in a lung phantom at two separate locations within the magnetic field. EGSnrc has been shown to match these measurements to within 2%.
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Affiliation(s)
- Andrei Ghila
- Department of Oncology, Medical Physics Division, University of Alberta, 11560 University Avenue, Edmonton, Alberta, T6G 1Z2, Canada
| | - B Gino Fallone
- Department of Medical Physics, Cross Cancer Institute, 11560 University Avenue, Edmonton, Alberta, T6G 1Z2, Canada.,Departments of Oncology and Physics, University of Alberta, 11560 University Avenue, Edmonton, Alberta, T6G 1Z2, Canada
| | - Satyapal Rathee
- Department of Oncology, Medical Physics Division, University of Alberta, 11560 University Avenue, Edmonton, Alberta, T6G 1Z2, Canada.,Department of Medical Physics, Cross Cancer Institute, 11560 University Avenue, Edmonton, Alberta, T6G 1Z2, Canada
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30
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Vijayan S, Xiong Z, Guo C, Troville J, Islam N, Rudin S, Bednarek DR. Calculation of Forward Scatter Dose Distribution at the skin entrance from the patient table for fluoroscopically guided interventions using a pencil beam convolution kernel. Proc SPIE Int Soc Opt Eng 2018; 10573. [PMID: 29904230 DOI: 10.1117/12.2294920] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
The forward-scatter dose distribution generated by the patient table during fluoroscopic interventions and its contribution to the skin dose is studied. The forward-scatter dose distribution to skin generated by a water table-equivalent phantom and the patient table are calculated using EGSnrc Monte-Carlo and Gafchromic film as a function of x-ray field size and beam penetrability. Forward scatter point spread function's (PSFn) were generated with EGSnrc from a 1×1 mm simulated primary pencil beam incident on the water model and patient table. The forward-scatter point spread function normalized to the primary is convolved over the primary-dose distribution to generate scatter-dose distributions. The utility of PSFn to calculate the entrance skin dose distribution using DTS (dose tracking system) software is investigated. The forward-scatter distribution calculations were performed for 2.32 mm, 3.10 mm, 3.84 mm and 4.24 mm Al HVL x-ray beams for 5×5 cm, 9×9 cm, 13.5×13.5 cm sized x-ray fields for water and 3.1 mm Al HVL x-ray beam for 16.5×16.5 cm field for the patient table. The skin dose is determined with DTS by convolution of the scatter dose PSFn's and with Gafchromic film under PMMA "patient-simulating" blocks for uniform and for shaped x-ray fields. The normalized forward-scatter distribution determined using the convolution method for water table-equivalent phantom agreed with that calculated for the full field using EGSnrc within ±6%. The normalized forward-scatter dose distribution calculated for the patient table for a 16.5×16.5 cm FOV, agreed with that determined using film within ±2.4%. For the homogenous PMMA phantom, the skin dose using DTS was calculated within ±2 % of that measured with the film for both uniform and non-uniform x-ray fields. The convolution method provides improved accuracy over using a single forward-scatter value over the entire field and is a faster alternative to performing full-field Monte-Carlo calculations.
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Affiliation(s)
- Sarath Vijayan
- Canon Stroke and Vascular Research Center, University at Buffalo, Buffalo, NY, USA
| | - Zhenyu Xiong
- Canon Stroke and Vascular Research Center, University at Buffalo, Buffalo, NY, USA
| | - Chao Guo
- Canon Stroke and Vascular Research Center, University at Buffalo, Buffalo, NY, USA
| | - Jonathan Troville
- Canon Stroke and Vascular Research Center, University at Buffalo, Buffalo, NY, USA
| | - Naveed Islam
- Canon Stroke and Vascular Research Center, University at Buffalo, Buffalo, NY, USA
| | - Stephen Rudin
- Canon Stroke and Vascular Research Center, University at Buffalo, Buffalo, NY, USA.,Department of Radiology, University at Buffalo, Buffalo, NY, USA
| | - Daniel R Bednarek
- Canon Stroke and Vascular Research Center, University at Buffalo, Buffalo, NY, USA.,Department of Radiology, University at Buffalo, Buffalo, NY, USA
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31
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Xiong Z, Vijayan S, Guo C, Rudin S, Bednarek DR. Investigation of organ dose variation with adult head size and pediatric age for neuro-interventional projections. Proc SPIE Int Soc Opt Eng 2018; 10573:105734D. [PMID: 29937616 PMCID: PMC6008644 DOI: 10.1117/12.2293958] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The purpose of this study was to evaluate the effect of patient head size on radiation dose to radiosensitive organs, such as the eye lens, brain and spinal cord in fluoroscopically guided neuro-interventional procedures and CBCT scans of the head. The Toshiba Infinix C-Arm System was modeled in BEAMnrc/EGSnrc Monte-Carlo code and patient organ and effective doses were calculated in DOSxynrc/EGSnrc for CBCT and interventional procedures. X-ray projections from different angles, CBCT scans, and neuro-interventional procedures were simulated on a computational head phantom for the range of head sizes in the adult population and for different pediatric ages. The difference of left-eye lens dose between the mean head size and the mean ± 1 standard deviation (SD) ranges from 20% to 300% for projection angles of 0° to 90° RAO. The differences for other organs do not vary as much and is only about 10% for the brain. For a LCI-High CBCT protocol, the difference between mean and mean ± 1 SD head size is about 100% for lens dose and only 10% for mean and peak brain dose; the difference between 20 and 3 year-old mean head size is an increase of about 200% for the eye lens dose and only 30% for mean and peak brain dose. Dose for all organs increases with decreasing head size for the same reference point air kerma. These results will allow size-specific dose estimates to be made using software such as our dose tracking system (DTS).
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Affiliation(s)
- Zhenyu Xiong
- University at Buffalo, Toshiba (Canon) Stroke and Vascular Research Center, Buffalo, New York, United States
| | - Sarath Vijayan
- University at Buffalo, Toshiba (Canon) Stroke and Vascular Research Center, Buffalo, New York, United States
| | - Chao Guo
- University at Buffalo, Toshiba (Canon) Stroke and Vascular Research Center, Buffalo, New York, United States
| | - Stephen Rudin
- University at Buffalo, Toshiba (Canon) Stroke and Vascular Research Center, Buffalo, New York, United States
- University at Buffalo, Department of Radiology, Buffalo, New York, United States
| | - Daniel R Bednarek
- University at Buffalo, Toshiba (Canon) Stroke and Vascular Research Center, Buffalo, New York, United States
- University at Buffalo, Department of Radiology, Buffalo, New York, United States
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Tessier F, Cojocaru CD, Ross CK. Extracting W air from the electron beam measurements of Domen and Lamperti. Med Phys 2017; 45:370-381. [PMID: 29131343 DOI: 10.1002/mp.12660] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2017] [Revised: 10/10/2017] [Accepted: 10/19/2017] [Indexed: 11/11/2022] Open
Abstract
PURPOSE The average energy expended by an energetic electron to create an ion pair in dry air, Wair , is a key quantity in radiation dosimetry. Although Wair is well established for electron energies up to about 3 MeV, there is limited data for higher energies. The measurements by Domen and Lamperti [Med. Phys. 3, 294-301 (1976)] using electron beams in the energy range from 15 to 50 MeV can, in principle, be used to deduce values for Wair , if the electron stopping power of graphite and air are known. A previous analysis of these data revealed an anomalous variation of 2% in Wair as a function of the electron energy. We use Monte Carlo simulation techniques to reanalyze the original data and obtain new estimates for Wair , and to investigate the source of the reported anomaly. METHODS Domen and Lamperti (DL) reported the ratio of the response of a graphite calorimeter to that of a graphite ionization chamber for broad beams of electrons with energies between 15 and 50 MeV and at different depths in graphite (including depths well beyond the range of the primary electrons, i.e., in the bremsstrahlung photon regime). Using a detailed EGSnrc model of the DL apparatus, as well as up-to-date stopping powers, we compute the dose ratio between the ionization chamber cavity and the calorimeter core, for plane-parallel electron beams. This dose ratio, multiplied by the DL measured ratio, provides a direct estimate for Wair . RESULTS Despite an improved analysis of the original work, the extracted values of Wair still exhibit an increase as the mean electron energy at the point of measurement decreases below about 15 MeV. This anomalous trend is dubious physically, and inconsistent with extensive data for Wair obtained at lower energies. A thorough sensitivity analysis indicates that this trend is unlikely to stem from errors in extrapolation and correction procedures, uncertainties in electron stopping powers, or bias in calorimetry or ionization chamber measurements. However, we find that results are quite sensitive to the intrinsic graphite mass thickness of the detectors and to the incident beam energy. CONCLUSIONS The DL experiment provides data in an energy regime where the electron stopping power is insensitive to the mean excitation energy of graphite - an issue plaguing Wair experiments at lower energies. Unfortunately, state-of-the-art scrutiny of the original data cannot explain the anomalous trend in terms of perturbation effects or extrapolation bias. It can only be understood in terms of speculative offsets in graphite mass thickness or beam energy. Therefore higher accuracy measurements for electron energies above 15 MeV are recommended to further resolve the value of Wair .
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Affiliation(s)
- Frédéric Tessier
- Ionizing Radiation Standards, Measurement Science and Standards, National Research Council Canada, Ottawa, Ontario, K1A 0R6, Canada
| | - Claudiu D Cojocaru
- Ionizing Radiation Standards, Measurement Science and Standards, National Research Council Canada, Ottawa, Ontario, K1A 0R6, Canada
| | - Carl K Ross
- Ionizing Radiation Standards, Measurement Science and Standards, National Research Council Canada, Ottawa, Ontario, K1A 0R6, Canada
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Townson R, Tessier F, Galea R. EGSnrc calculation of activity calibration factors for the Vinten ionization chamber. Appl Radiat Isot 2017; 134:100-104. [PMID: 29042149 DOI: 10.1016/j.apradiso.2017.10.010] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2017] [Revised: 10/04/2017] [Accepted: 10/04/2017] [Indexed: 11/26/2022]
Abstract
The National Physical Laboratory Vinten 671 chamber was selected as a proving ground for a new radionuclide source model in the EGSnrc software. The computational Vinten model is validated against measurements of radionuclide artifacts whose activities were determined by absolute methods. The response of the Vinten chamber is first calculated as a function of gamma energy, but more strikingly, an explicit simulation of radionuclide decay was implemented and now permits the direct determination of a calibration factor, including additional effects due to all decay paths of the radionuclide. The Monte Carlo and experimental calibration factors are found to agree at the percent level, in absolute terms.
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Affiliation(s)
- R Townson
- Measurement Science and Standards, National Research Council Canada, 1200 Montreal Road, Building M-35, Ottawa, ON, Canada K1A0R6
| | - F Tessier
- Measurement Science and Standards, National Research Council Canada, 1200 Montreal Road, Building M-35, Ottawa, ON, Canada K1A0R6
| | - R Galea
- Measurement Science and Standards, National Research Council Canada, 1200 Montreal Road, Building M-35, Ottawa, ON, Canada K1A0R6.
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Xiong Z, Vijayan S, Rudin S, Bednarek DR. Assessment of organ and effective dose when using region-of-interest attenuators in cone-beam CT and interventional fluoroscopy. J Med Imaging (Bellingham) 2017; 4:031210. [PMID: 28840169 DOI: 10.1117/1.jmi.4.3.031210] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2017] [Accepted: 07/24/2017] [Indexed: 11/14/2022] Open
Abstract
In some medical-imaging procedures using cone-beam CT (CBCT) and fluoroscopy, only the center of the field of view (FOV) may be needed to be visualized with optimal image quality. To reduce the dose to the patient while maintaining visualization of the entire FOV, a Cu attenuator with a circular aperture for the region of interest (ROI) is used. The potential organ and effective dose reductions of ROI imaging when applied to CBCT and interventional fluoroscopic procedures were determined using EGSnrc Monte Carlo code. The Monte Carlo model was first validated by comparing the surface dose distribution in a solid-water block phantom with measurement by Gafchromic film. The dependence of dose reduction on the ROI attenuator thickness, the opening size of the ROI, the axial beam position, and the location of the different organs for both neuro and thoracic imaging was evaluated. The results showed a reduction in most organ doses of 45% to 70% and in effective dose of 46% to 66% compared to the dose in a CBCT scan and in an interventional procedure without the ROI attenuator. This work provides evidence of a substantial reduction of organ and effective doses when using an ROI attenuator during CBCT and fluoroscopic procedures.
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Affiliation(s)
- Zhenyu Xiong
- University at Buffalo, Medical Physics Program, Buffalo, New York, United States.,University at Buffalo, Toshiba Stroke and Vascular Research Center, Buffalo, New York, United States
| | - Sarath Vijayan
- University at Buffalo, Medical Physics Program, Buffalo, New York, United States.,University at Buffalo, Toshiba Stroke and Vascular Research Center, Buffalo, New York, United States
| | - Stephen Rudin
- University at Buffalo, Medical Physics Program, Buffalo, New York, United States.,University at Buffalo, Toshiba Stroke and Vascular Research Center, Buffalo, New York, United States.,University at Buffalo, Department of Radiology, Buffalo, New York, United States
| | - Daniel R Bednarek
- University at Buffalo, Medical Physics Program, Buffalo, New York, United States.,University at Buffalo, Toshiba Stroke and Vascular Research Center, Buffalo, New York, United States.,University at Buffalo, Department of Radiology, Buffalo, New York, United States
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Abstract
PURPOSE The development of magnetic resonance-guided radiation therapy (MRgRT) necessitates accurate Monte Carlo (MC) models of ion chambers for computing ion chamber corrections to compensate for the presence of the magnetic field. This study evaluates the sensitivity of the ion chamber dose response in a magnetic field on the collection volume used in the MC simulation. METHODS The EGSnrc system's egs_chamber application is used with a recently developed and validated magnetic field transport code. The calculated dose to the sensitive volume of the chamber per unit incident photon fluence, normalized to that at 0 T, is evaluated as a function of magnetic field for the PTW 30013, PTW 31006, PTW 31010, Exradin A12S, and Exradin A1SL chambers. The sensitive region is varied by excluding the volume corresponding to either 0, 0.5, or 1 mm of distance away from the stem. The photon field, magnetic field, and ion chamber are all oriented perpendicular to each other as in the majority of published experimental works. RESULTS The calculations for a Co-60 source demonstrate that variations from the 0 mm simulations are on the order of several percent with a maximum deviation, occurring at 0.5 T, of 1.75 ± 0.03% and 3.39 ± 0.06% for the 0.5 mm or 1 mm simulations, respectively, for a 0.057 cm3 A1SL chamber. Larger volume chambers showed smaller, but still non-negligible, variations. Simulations of the A1SL chamber with a 7 MV photon source, corresponding to the Elekta MR-linac machine, demonstrate that the effect is slightly reduced but still persists with a maximum deviation of 1.97 ± 0.08% for the 1 mm reduction. CONCLUSIONS Usually, the geometric sensitive volume of the ion chamber is used in MC calculation as a substitute for the potentially unknown, smaller, true collection volume (governed by the complex electric field distribution inside the chamber). The calculations in this study demonstrate that even a small variation in simulated volume can lead to fairly large variations in the MC calculated ion chamber response in a magnetic field. This is an important effect that must be addressed to ensure proper calibration of MRgRT machines using MC ion chamber correction factors. This effect may play a role, even where there is no magnetic field, in small-field dosimetry when volume averaging effect are important.
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Affiliation(s)
- Victor N Malkov
- Department of Physics, Carleton Laboratory for Radiotherapy Physics, Carleton University, Ottawa, ON, Canada
| | - D W O Rogers
- Department of Physics, Carleton Laboratory for Radiotherapy Physics, Carleton University, Ottawa, ON, Canada
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Xiong Z, Vijayan S, Rudin S, Bednarek DR. Organ and effective dose reduction for region-of-interest (ROI) CBCT and fluoroscopy. Proc SPIE Int Soc Opt Eng 2017; 10132:1013242. [PMID: 28638169 PMCID: PMC5476203 DOI: 10.1117/12.2254061] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
In some medical-imaging procedures using CBCT and fluoroscopy, it may be needed to visualize only the center of the field-of-view with optimal quality. To reduce the dose to the patient as well as enable increased contrast in the region of interest (ROI) during CBCT and fluoroscopy procedures, a 0.7 mm thick Cu ROI attenuator with a circular aperture 12% of the FOV was used. The aim of this study was to quantify the dose-reduction benefit of ROI imaging during a typical CBCT and interventional fluoroscopy procedures in the head and torso. The Toshiba Infinix C-Arm System was modeled in BEAMnrc/EGSnrc with and without the ROI attenuator. Patient organ and effective doses were calculated in DOSXYZnrc/EGSnrc Monte-Carlo software for CBCT and interventional procedures. We first compared the entrance dose with and without the ROI attenuator on a 20 cm thick solid-water block. Then we simulated a CBCT scan and an interventional fluoroscopy procedure on the head and torso with and without an ROI attenuator. The results showed that the entrance-surface dose reduction in the solid water is about 85.7% outside the ROI opening and 10.5% in the ROI opening. The results showed a reduction in most organ doses of 45%-70% and in effective dose of 46%-66% compared to the dose in a CBCT scan and in an interventional procedure without the ROI attenuator. This work provides evidence of substantial reduction of organ and effective doses when using an ROI attenuator during CBCT and fluoroscopic procedures.
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Affiliation(s)
- Zhenyu Xiong
- University at Buffalo, Department of Physiology and Biophysics, 124 Sherman Hall, 3435 Main Street, Buffalo, New York 14214, United States
- Toshiba Stroke & Vascular Research Center, 875 Ellicott Street, Buffalo, New York 14203, United States
| | - Sarath Vijayan
- University at Buffalo, Department of Physiology and Biophysics, 124 Sherman Hall, 3435 Main Street, Buffalo, New York 14214, United States
- Toshiba Stroke & Vascular Research Center, 875 Ellicott Street, Buffalo, New York 14203, United States
| | - Stephen Rudin
- University at Buffalo, Department of Physiology and Biophysics, 124 Sherman Hall, 3435 Main Street, Buffalo, New York 14214, United States
- University at Buffalo, Department of Radiology, 319A Sherman Hall, 3435 Main Street, Buffalo, New York 14214, United States
- Toshiba Stroke & Vascular Research Center, 875 Ellicott Street, Buffalo, New York 14203, United States
| | - Daniel R. Bednarek
- University at Buffalo, Department of Physiology and Biophysics, 124 Sherman Hall, 3435 Main Street, Buffalo, New York 14214, United States
- University at Buffalo, Department of Radiology, 319A Sherman Hall, 3435 Main Street, Buffalo, New York 14214, United States
- Toshiba Stroke & Vascular Research Center, 875 Ellicott Street, Buffalo, New York 14203, United States
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Vijayan S, Xiong Z, Shankar A, Rudin S, Bednarek DR. Skin dose mapping for non-uniform x-ray fields using a backscatter point spread function. Proc SPIE Int Soc Opt Eng 2017; 10132:101320U. [PMID: 28649154 PMCID: PMC5478926 DOI: 10.1117/12.2254257] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
Beam shaping devices like ROI attenuators and compensation filters modulate the intensity distribution of the x-ray beam incident on the patient. This results in a spatial variation of skin dose due to the variation of primary radiation and also a variation in backscattered radiation from the patient. To determine the backscatter component, backscatter point spread functions (PSF) are generated using EGS Monte-Carlo software. For this study, PSF's were determined by simulating a 1 mm beam incident on the lateral surface of an anthropomorphic head phantom and a 20 cm thick PMMA block phantom. The backscatter PSF's for the head phantom and PMMA phantom are curve fit with a Lorentzian function after being normalized to the primary dose intensity (PSFn). PSFn is convolved with the primary dose distribution to generate the scatter dose distribution, which is added to the primary to obtain the total dose distribution. The backscatter convolution technique is incorporated in the dose tracking system (DTS), which tracks skin dose during fluoroscopic procedures and provides a color map of the dose distribution on a 3D patient graphic model. A convolution technique is developed for the backscatter dose determination for the non-uniformly spaced graphic-model surface vertices. A Gafchromic film validation was performed for shaped x-ray beams generated with an ROI attenuator and with two compensation filters inserted into the field. The total dose distribution calculated by the backscatter convolution technique closely agreed with that measured with the film.
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Affiliation(s)
- Sarath Vijayan
- Toshiba Stroke and Vascular Research Center, University at Buffalo, Buffalo, NY, USA
- Department of Physiology and Biophysics, University at Buffalo, Buffalo, NY, USA
| | - Zhenyu Xiong
- Toshiba Stroke and Vascular Research Center, University at Buffalo, Buffalo, NY, USA
- Department of Physiology and Biophysics, University at Buffalo, Buffalo, NY, USA
| | - Alok Shankar
- Toshiba Stroke and Vascular Research Center, University at Buffalo, Buffalo, NY, USA
- Department of Physiology and Biophysics, University at Buffalo, Buffalo, NY, USA
| | - Stephen Rudin
- Toshiba Stroke and Vascular Research Center, University at Buffalo, Buffalo, NY, USA
- Department of Physiology and Biophysics, University at Buffalo, Buffalo, NY, USA
- Department of Radiology, University at Buffalo, Buffalo, NY, USA
| | - Daniel R Bednarek
- Toshiba Stroke and Vascular Research Center, University at Buffalo, Buffalo, NY, USA
- Department of Physiology and Biophysics, University at Buffalo, Buffalo, NY, USA
- Department of Radiology, University at Buffalo, Buffalo, NY, USA
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Hadad K, Saeedi-Moghadam M, Zeinali-Rafsanjani B. Voxel dosimetry: Comparison of MCNPX and DOSXYZnrc Monte Carlo codes in patient specific phantom calculations. Technol Health Care 2016; 25:29-35. [PMID: 27447407 DOI: 10.3233/thc-161240] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
INTRODUCTION Dose evaluation with two Monte Carlo codes using patient specific voxel phantom is presented in this paper. We employ both MCNPX and DOSXYZnrc to perform dosimetry for mathematical voxel phantoms generated by our in-house developed voxel phantom generator and EGSnrc/CTCreate respectively. MATERIAL AND METHOD Our case study was a 2.5 × 2.4 × 2.4 cm3 tumor in the middle lobe of right lung of a male patient exposed to 6MV parallel beam. In order to compare these Monte Carlo codes with together gross tumor volume (GTV) and organ at risks (OAR) doses and dose volume histograms (DVH) were calculated. RESULTS Comparing the mean absorbed dose results (in Gy) from both codes indicates that gross tumor volume, heart and spinal cord have 2% to 10% difference. The 10% difference between the codes were from the spinal cord region where was not in the therapy beam and it just received the scatter radiation. The dose volume DVH obtained from DOSXYZnrc results demonstrate a milder slope compared with MCNPX DVHs. CONCLUSION It was revealed that MCNPX has some advantages in comparison to DOSXYZnrc, but it is important to consider that for equal precision in voxel dosimetry calculation, DOSXYZnrc runs faster than MCNPX and it is a great advantage.
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Affiliation(s)
- Kamal Hadad
- Department of Nuclear Engineering, School of Mechanical Engineering, Shiraz University, Shiraz, Iran
| | - Mahdi Saeedi-Moghadam
- Medical Imaging Research Center, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Banafsheh Zeinali-Rafsanjani
- Medical Imaging Research Center, Shiraz University of Medical Sciences, Shiraz, Iran.,Nuclear Medicine and Molecular Imaging Research Center, Shiraz University of Medical Sciences, Shiraz, Iran
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Xiong Z, Vijayan S, Rana V, Jain A, Rudin S, Bednarek DR. Lens of the eye dose calculation for neuro-interventional procedures and CBCT scans of the head. Proc SPIE Int Soc Opt Eng 2016. [PMID: 28638173 DOI: 10.1117/12.2216504] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
The aim of this work is to develop a method to calculate lens dose for fluoroscopically-guided neuro-interventional procedures and for CBCT scans of the head. EGSnrc Monte Carlo software is used to determine the dose to the lens of the eye for the projection geometry and exposure parameters used in these procedures. This information is provided by a digital CAN bus on the Toshiba Infinix C-Arm system which is saved in a log file by the real-time skin-dose tracking system (DTS) we previously developed. The x-ray beam spectra on this machine were simulated using BEAMnrc. These spectra were compared to those determined by SpekCalc and validated through measured percent-depth-dose (PDD) curves and half-value-layer (HVL) measurements. We simulated CBCT procedures in DOSXYZnrc for a CTDI head phantom and compared the surface dose distribution with that measured with Gafchromic film, and also for an SK150 head phantom and compared the lens dose with that measured with an ionization chamber. Both methods demonstrated good agreement. Organ dose calculated for a simulated neuro-interventional-procedure using DOSXYZnrc with the Zubal CT voxel phantom agreed within 10% with that calculated by PCXMC code for most organs. To calculate the lens dose in a neuro-interventional procedure, we developed a library of normalized lens dose values for different projection angles and kVp's. The total lens dose is then calculated by summing the values over all beam projections and can be included on the DTS report at the end of the procedure.
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Affiliation(s)
- Zhenyu Xiong
- Toshiba Stroke and Vascular Research Center, University at Buffalo, Buffalo, New York
| | - Sarath Vijayan
- Toshiba Stroke and Vascular Research Center, University at Buffalo, Buffalo, New York
| | - Vijay Rana
- Toshiba Stroke and Vascular Research Center, University at Buffalo, Buffalo, New York
| | - Amit Jain
- Toshiba Stroke and Vascular Research Center, University at Buffalo, Buffalo, New York
| | - Stephen Rudin
- Toshiba Stroke and Vascular Research Center, University at Buffalo, Buffalo, New York
| | - Daniel R Bednarek
- Toshiba Stroke and Vascular Research Center, University at Buffalo, Buffalo, New York
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Hadad K, Zohrevand M, Faghihi R, Sedighi Pashaki A. Accuracy Evaluation of Oncentra™ TPS in HDR Brachytherapy of Nasopharynx Cancer Using EGSnrc Monte Carlo Code. J Biomed Phys Eng 2015; 5:25-30. [PMID: 25973408 PMCID: PMC4417616] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2014] [Indexed: 06/04/2023]
Abstract
BACKGROUND HDR brachytherapy is one of the commonest methods of nasopharyngeal cancer treatment. In this method, depending on how advanced one tumor is, 2 to 6 Gy dose as intracavitary brachytherapy is prescribed. Due to high dose rate and tumor location, accuracy evaluation of treatment planning system (TPS) is particularly important. Common methods used in TPS dosimetry are based on computations in a homogeneous phantom. Heterogeneous phantoms, especially patient-specific voxel phantoms can increase dosimetric accuracy. MATERIALS AND METHODS In this study, using CT images taken from a patient and ctcreate-which is a part of the DOSXYZnrc computational code, patient-specific phantom was made. Dose distribution was plotted by DOSXYZnrc and compared with TPS one. Also, by extracting the voxels absorbed dose in treatment volume, dose-volume histograms (DVH) was plotted and compared with Oncentra™ TPS DVHs. RESULTS The results from calculations were compared with data from Oncentra™ treatment planning system and it was observed that TPS calculation predicts lower dose in areas near the source, and higher dose in areas far from the source relative to MC code. Absorbed dose values in the voxels also showed that TPS reports D90 value is 40% higher than the Monte Carlo method. CONCLUSION Today, most treatment planning systems use TG-43 protocol. This protocol may results in errors such as neglecting tissue heterogeneity, scattered radiation as well as applicator attenuation. Due to these errors, AAPM emphasized departing from TG-43 protocol and approaching new brachytherapy protocol TG-186 in which patient-specific phantom is used and heterogeneities are affected in dosimetry.
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Affiliation(s)
- K. Hadad
- Nuclear Engineering Department, Faculty of Mechanical Engineering, Shiraz University, Shiraz, Iran
| | - M. Zohrevand
- Nuclear Engineering Department, Faculty of Mechanical Engineering, Shiraz University, Shiraz, Iran
| | - R. Faghihi
- Nuclear Engineering Department, Faculty of Mechanical Engineering, Shiraz University, Shiraz, Iran
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Al-Ghorabie FHH. Computer simulation of a backscattered X-ray fluorescence system. J Xray Sci Technol 2015; 23:57-64. [PMID: 25567407 DOI: 10.3233/xst-140470] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
An EGSnrc user code is developed to simulate a backscattered geometry in vivo x-ray fluorescence system for the measurement of platinum concentration in head and neck tumours. The user code is fundamentally based on a previous study which used the EGS4 Monte Carlo code. The new user code, which we have developed in this study, has new improvements which made it able to simulate the process of photon transportation through the different components of the modelled x-ray fluorescence system. The simulation process included modelling of the photon source, collimators, phantoms and detector. Simulation results were compared and evaluated against x-ray fluorescence data obtained experimentally from an existing system developed by the Swansea In vivo Analysis and Cancer Research Group. In addition, simulation results of this study were also compared with our previous study in which the EGS4 user code was used. Comparison between results has shown that the new EGSnrc user code was able to reproduce the spectral shape obtained using the experimental x-ray fluorescence system. The area under the Compton peak differs by 2.5% between the experimental measurement and the EGSnrc simulation. Similarly, the area under the two Pt Kα peaks differs by 2.3% and 2.2%.
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Affiliation(s)
- Fayez H H Al-Ghorabie
- Department of Physics, Faculty of Science, Umm Al-Qura University, Makkah, Saudi Arabia. Tel.: +966 12 5270000; Fax: +966 12 5564560; E-mail:
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Camgöz B, Kumru MN. A Monte Carlo evaluation for effects of probable dimensional uncertainties of low dose rate brachytherapy seeds on dose. Rep Pract Oncol Radiother 2014; 19:301-9. [PMID: 25184054 DOI: 10.1016/j.rpor.2014.01.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2012] [Revised: 09/17/2013] [Accepted: 01/07/2014] [Indexed: 10/25/2022] Open
Abstract
The aim of this study is to determine effects of size deviations of brachytherapy seeds on two dimensional dose distributions around the seed. Although many uncertainties are well known, the uncertainties which stem from geometric features of radiation sources are weakly considered and predicted. Neither TG-43 report which is not completely in common consensus, nor individual scientific MC and experimental studies include sufficient data for geometric uncertainties. Sizes of seed and its components can vary in a manufacturing deviation. This causes geometrical uncertainties, too. In this study, three seeds which have different geometrical properties were modeled using EGSnrc-Code Packages. Seeds were designed with all their details using the geometry package. 5% deviations of seed sizes were assumed. Modified seeds were derived from original seed by changing sizes by 5%. Normalizations of doses which were calculated from three kinds of brachytherapy seed and their derivations were found to be about 3%-20%. It was shown that manufacturing differences of brachytherapy seed cause considerable changes in dose distribution.
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Affiliation(s)
- Berkay Camgöz
- Ege University, Institute of Nuclear Sciences, 35100 Bornova, Izmir, Turkey
| | - Mehmet N Kumru
- Ege University, Institute of Nuclear Sciences, 35100 Bornova, Izmir, Turkey
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Anwarul IM, Akramuzzaman MM, Zakaria GA. EGSnrc Monte Carlo-aided dosimetric studies of the new BEBIG (60)Co HDR brachytherapy source. J Contemp Brachytherapy 2013; 5:148-56. [PMID: 24143150 DOI: 10.5114/jcb.2013.37419] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2013] [Revised: 07/25/2013] [Accepted: 09/26/2013] [Indexed: 11/17/2022] Open
Abstract
PURPOSE The purpose of this study is to obtain the dosimetric parameters of the new BEBIG (60)Co brachytherapy source following by TG-43U1 recommendation with appropriate electron cutoff energy (0.521 MeV). MATERIAL AND METHODS The new BEBIG (60)Co brachytherapy source is used to calculate the TG-43U1 parameters. EGSnrc-based Monte Carlo simulation code has been used to calculate the radial dose functions and anisotropy functions. 2D dose rate table is obtained with Cartesian coordinate system for surrounding the source. RESULTS The radial dose functions are calculated for the distance of 0.06 cm to 100 cm from the source center with different cutoff energies and compared. The anisotropy functions values are calculated with the range of 1° to 179°, and apart from 0.2 cm to 20 cm of radial distances. The along-away dose rate data are calculated for quality assurance purposes. The calculated values are compared with the consensus data set and previous published results. CONCLUSIONS The radial dose function values from 0.06 cm to 0.16 cm are low, and these values gradually increased up to 0.3 cm radial distance. The radial dose function values are compared with the values of consensus data set using EGSnrc code system, and it is in good agreement with the published data range. The data for < 0.1 cm is not available in consensus data set, and extrapolated value is included for 0 distances which is the same as the value of 0.1 cm. In this study, the obtained values are strictly fall-off to < 0.1 cm distances. Good agreement with the published data was observed, except the values less than 40° angle at 0.5 cm distance for anisotropy function values.
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Islam MA, Akramuzzaman MM, Zakaria GA. Dosimetric comparison between the microSelectron HDR (192)Ir v2 source and the BEBIG (60)Co source for HDR brachytherapy using the EGSnrc Monte Carlo transport code. J Med Phys 2013; 37:219-25. [PMID: 23293454 PMCID: PMC3532751 DOI: 10.4103/0971-6203.103608] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2012] [Revised: 08/14/2012] [Accepted: 10/08/2012] [Indexed: 11/11/2022] Open
Abstract
Manufacturing of miniaturized high activity 192Ir sources have been made a market preference in modern brachytherapy. The smaller dimensions of the sources are flexible for smaller diameter of the applicators and it is also suitable for interstitial implants. Presently, miniaturized 60Co HDR sources have been made available with identical dimensions to those of 192Ir sources. 60Co sources have an advantage of longer half life while comparing with 192Ir source. High dose rate brachytherapy sources with longer half life are logically pragmatic solution for developing country in economic point of view. This study is aimed to compare the TG-43U1 dosimetric parameters for new BEBIG 60Co HDR and new microSelectron 192Ir HDR sources. Dosimetric parameters are calculated using EGSnrc-based Monte Carlo simulation code accordance with the AAPM TG-43 formalism for microSlectron HDR 192Ir v2 and new BEBIG 60Co HDR sources. Air-kerma strength per unit source activity, calculated in dry air are 9.698×10-8 ± 0.55% U Bq-1 and 3.039×10-7 ± 0.41% U Bq-1 for the above mentioned two sources, respectively. The calculated dose rate constants per unit air-kerma strength in water medium are 1.116±0.12% cGy h-1U-1 and 1.097±0.12% cGy h-1U-1, respectively, for the two sources. The values of radial dose function for distances up to 1 cm and more than 22 cm for BEBIG 60Co HDR source are higher than that of other source. The anisotropic values are sharply increased to the longitudinal sides of the BEBIG 60Co source and the rise is comparatively sharper than that of the other source. Tissue dependence of the absorbed dose has been investigated with vacuum phantom for breast, compact bone, blood, lung, thyroid, soft tissue, testis, and muscle. No significant variation is noted at 5 cm of radial distance in this regard while comparing the two sources except for lung tissues. The true dose rates are calculated with considering photon as well as electron transport using appropriate cut-off energy. No significant advantages or disadvantages are found in dosimetric aspect comparing with two sources.
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Affiliation(s)
- M Anwarul Islam
- Department of Physics, Jahangirnagar University, Savar, Dhaka, Bangladesh
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Joshi CP, Dhanesar S, Darko J, Kerr A, Vidyasagar PB, Schreiner LJ. Practical and clinical considerations in Cobalt-60 tomotherapy. J Med Phys 2011; 34:137-40. [PMID: 20098560 PMCID: PMC2807678 DOI: 10.4103/0971-6203.54847] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2009] [Revised: 02/19/2009] [Accepted: 04/01/2009] [Indexed: 12/04/2022] Open
Abstract
Cobalt-60 (Co-60) based radiation therapy continues to play a significant role in not only developing countries, where access to radiation therapy is extremely limited, but also in industrialized countries. Howver, technology has to be developed to accommodate modern techniques, including image guided and adaptive radiation therapy (IGART). In this paper we describe some of the practical and clinical considerations for Co-60 based tomotherapy by comparing Co-60 and 6 MV linac-based tomotherapy plans for a head and neck (HandN) cancer and a prostate cancer case. The tomotherapy IMRT plans were obtained by modeling a MIMiC binary multi-leaf collimator attached to a Theratron-780c Co-60 unit and a 6 MV linear accelerator (CL2100EX). The EGSnrc/BEAMnrc Monte Carlo (MC) code was used for the modeling of the treatment units with the MIMiC collimator and EGSnrc/DOSXYZnrc code was used for beamlet dose data. An in-house inverse treatment planning program was then used to generate optimized tomotherapy dose distributions for the H and N and prostate cases. The dose distributions, cumulative dose area histograms (DAHs) and dose difference maps were used to evaluate and compare Co-60 and 6 MV based tomotherapy plans. A quantitative analysis of the dose distributions and dose-volume histograms shows that both Co-60 and 6 MV plans achieve the plan objectives for the targets (CTV and nodes) and OARs (spinal cord in HandN case, and rectum in prostate case).
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Affiliation(s)
- Chandra P Joshi
- Department of Medical Physics, Cancer Centre of Southeastern Ontario (CCSEO), Kingston, ON, Canada
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