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Hu N, Nakao M, Ozawa S, Takata T, Tanaka H, Nihei K, Ono K, Suzuki M. Application of stoichiometric CT number calibration method for dose calculation of tissue heterogeneous volumes in boron neutron capture therapy. Med Phys 2024; 51:4413-4422. [PMID: 38669482 DOI: 10.1002/mp.17093] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2023] [Revised: 04/09/2024] [Accepted: 04/10/2024] [Indexed: 04/28/2024] Open
Abstract
BACKGROUND Monte Carlo simulation code is commonly used for the dose calculation of boron neutron capture therapy. In the past, dose calculation was performed assuming a homogeneous mass density and elemental composition inside the tissue, regardless of the patient's age or sex. Studies have shown that the mass density varies with patient to patient, particularly for those that have undergone surgery or radiotherapy. A method to convert computed tomography numbers into mass density and elemental weights of tissues has been developed and applied in the dose calculation process using Monte Carlo codes. A recent study has shown the variation in the computed tomography number between different scanners for low- and high-density materials. PURPOSE The aim of this study is to investigate the effect of the elemental composition inside each calculation voxel on the dose calculation and the application of the stoichiometric CT number calibration method for boron neutron capture therapy planning. METHODS Monte Carlo simulation package Particle and Heavy Ion Transport code System was used for the dose calculation. Firstly, a homogeneous cubic phantom with the material set to ICRU soft tissue (four component), muscle, fat, and brain was modelled and the NeuCure BNCT system accelerator-based neutron source was used. The central axis depth dose distribution was simulated and compared between the four materials. Secondly, a treatment plan of the brain and the head and neck region was simulated using a dummy patient dataset. Three models were generated; (1) a model where only the fundamental materials were considered (simple model), a model where each voxel was assigned a mass density and elemental weight using (2) the Nakao20 model, and (3) the Schneider00 model. The irradiation conditions were kept the same between the different models (irradiation time and irradiation field size) and the near maximum (D1%) and mean dose to the organs at risk were calculated and compared. RESULTS A maximum percentage difference of approximately 5% was observed between the different materials for the homogeneous phantom. With the dummy patient plan, a large dose difference in the bone (greater than 12%) and region near the low-density material (mucosal membrane, 7%-11%) was found between the different models. CONCLUSIONS A stoichiometric CT number calibration method using the newly developed Nakao20 model was applied to BNCT dose calculation. The results indicate the importance of calibrating the CT number to elemental composition for each individual CT scanner for the purpose of BNCT dose calculation along with the consideration of heterogeneity of the material composition inside the defined region of interest.
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Affiliation(s)
- Naonori Hu
- Institute for Integrated Radiation and Nuclear Science, Kyoto University, Sennangun, Osaka, Japan
- Kansai BNCT Medical Center, Osaka Medical and Pharmaceutical University, Takatsuki, Osaka, Japan
| | - Minoru Nakao
- Hiroshima High-Precision Radiotherapy Cancer Center, Hiroshima, Japan
- Department of Radiation Oncology, Hiroshima University, Hiroshima, Japan
| | - Shuichi Ozawa
- Hiroshima High-Precision Radiotherapy Cancer Center, Hiroshima, Japan
- Department of Radiation Oncology, Hiroshima University, Hiroshima, Japan
| | - Takushi Takata
- Institute for Integrated Radiation and Nuclear Science, Kyoto University, Sennangun, Osaka, Japan
| | - Hiroki Tanaka
- Institute for Integrated Radiation and Nuclear Science, Kyoto University, Sennangun, Osaka, Japan
| | - Keiji Nihei
- Kansai BNCT Medical Center, Osaka Medical and Pharmaceutical University, Takatsuki, Osaka, Japan
- Department of Radiation Oncology, Osaka Medical and Pharmaceutical University Hospital, Takatsuki, Osaka, Japan
| | - Koji Ono
- Kansai BNCT Medical Center, Osaka Medical and Pharmaceutical University, Takatsuki, Osaka, Japan
| | - Minoru Suzuki
- Institute for Integrated Radiation and Nuclear Science, Kyoto University, Sennangun, Osaka, Japan
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Lee J, Kim G, Chang H, Lee S, Ye SJ. A dose calculation algorithm for boron neutron capture therapy using convolution/superposition method. Appl Radiat Isot 2024; 203:111102. [PMID: 37956512 DOI: 10.1016/j.apradiso.2023.111102] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2021] [Revised: 11/17/2022] [Accepted: 10/31/2023] [Indexed: 11/15/2023]
Abstract
The convolution/superposition (C/S) method originally designed for photon dose calculation was first applied for developing a treatment planning system for boron neutron capture therapy. The original concept of TEGMA (total energy generated per unit mass) was proposed to represent distinctive dose components from neutron reactions with the elements in the patient's tissue. First, neutron fluence distributions in a homogeneous brain phantom irradiated with an energy-groupwise pencil beam of 2.5 × 2.5 mm2 were calculated using the MCNP6.2 code. Then, a library of energy-groupwise TEGMA and KERMA were generated and stored in the developed C/S code. As a benchmark, dose distributions in a cuboid phantom and a human head phantom were calculated using the developed C/S and PHITS Monte Carlo codes. A neutron beam having a continuous epithermal spectrum and a square field of 22.5 × 22.5 mm2 or a circle field of 22.5 mm in diameter was assumed to be incident on the phantoms. The human head phantom was created by the pre-processing including the voxelization and transformation of test DICOM CT images. The differences in boron doses between C/S and MC ranged from 2% to 6%. In nitrogen doses, the differences were from 4% to 9%. A large discrepancy observed in hydrogen lateral dose profiles could be explained by the differences in cross-section data and recoil-proton transport algorithms of MCNP6.2 and PHITS. With isodose curves normalized at the center of the tumor in the human head phantom, they were almost identical in the range of 60%-110% for both cases. The C/S have underestimated the backscattering neutron and showed a larger absorbed dose gradient around 40% region. The calculation time of C/S using Intel i7-10700 processor was less than 1 min for both phantoms. The calculation time of PHITS using three Intel Xeon E5-2640 v4 processors was 15.5 min for the cuboid phantom and ∼380 min for the human head phantom. The proposed algorithm has the advantages of high speed while promising fair accuracy in BNCT dose calculations.
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Affiliation(s)
- Junyoung Lee
- Program in Biomedical Radiation Sciences, Department of Transdisciplinary Studies, Graduate School of Convergence Science and Technology, Seoul National University, Seoul, Republic of Korea
| | - Geunsub Kim
- Department of Applied Bioengineering, Graduate School of Convergence Science and Technology, Seoul National University, Seoul, Republic of Korea
| | - Hyegang Chang
- Program in Biomedical Radiation Sciences, Department of Transdisciplinary Studies, Graduate School of Convergence Science and Technology, Seoul National University, Seoul, Republic of Korea
| | - Sangmin Lee
- Program in Biomedical Radiation Sciences, Department of Transdisciplinary Studies, Graduate School of Convergence Science and Technology, Seoul National University, Seoul, Republic of Korea
| | - Sung-Joon Ye
- Program in Biomedical Radiation Sciences, Department of Transdisciplinary Studies, Graduate School of Convergence Science and Technology, Seoul National University, Seoul, Republic of Korea; Department of Applied Bioengineering, Graduate School of Convergence Science and Technology, Seoul National University, Seoul, Republic of Korea; Research Institute of Convergence Science, Seoul National University, Seoul, Republic of Korea; Advance Institutes of Convergence Technology, Seoul National University, Suwon, Republic of Korea.
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Tsujiguchi T, Suzuki Y, Sakamoto M, Narumi K, Ito K, Yasuda H, Tokonami S, Kashiwakura I. Simulation study on radiation exposure of emergency medical responders from radioactively contaminated patients. Sci Rep 2021; 11:6162. [PMID: 33731779 PMCID: PMC7971051 DOI: 10.1038/s41598-021-85635-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Accepted: 02/19/2021] [Indexed: 11/30/2022] Open
Abstract
Emergency medical responders (EMRs) who treat victims during a radiation emergency are at risk of radiation exposure. In this study, the exposure dose to EMRs treating hypothetically contaminated patients was estimated using a Monte Carlo simulation, and the findings may be useful for educating EMRs and reducing their anxiety. The Monte Carlo simulation estimated radiation doses for adult computational phantoms based on radioactive contamination conditions and radiation dosages from previous studies. At contamination conditions below the typical upper limit of general Geiger-Müller survey meters, the radiation doses to EMRs were estimated to be less than 1 μSv per hour. In cases with greater contamination due to mishandling of an intense radioactive source (hundreds of GBq), the radiation doses to EMRs could reach approximately 100 mSv per hour. These results imply that a radiological accident with a highly radioactive source could expose EMR to significant radiation that exceeds their dose limit. Thus, authorities and other parties should ensure that EMRs receive appropriate education and training regarding measures that can be taken to protect themselves from the possibility of excessive radiation exposure. The results of this study may provide EMRs with information to take appropriate protective measures, although it is also important that they not hesitate to perform lifesaving measures because of concerns regarding radiation.
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Affiliation(s)
- Takakiyo Tsujiguchi
- Graduate School of Health Sciences, Hirosaki University, 66-1 Hon-cho, Hirosaki, 036-8564, Japan
| | - Yoko Suzuki
- Graduate School of Health Sciences, Hirosaki University, 66-1 Hon-cho, Hirosaki, 036-8564, Japan
| | - Mizuki Sakamoto
- Graduate School of Health Sciences, Hirosaki University, 66-1 Hon-cho, Hirosaki, 036-8564, Japan
| | - Kazuki Narumi
- Graduate School of Health Sciences, Hirosaki University, 66-1 Hon-cho, Hirosaki, 036-8564, Japan
| | - Katsuhiro Ito
- Advance Emergency and Critical Care Center, Hirosaki University Hospital, 5 Zaifu-cho, Hirosaki, 036-8562, Japan
| | - Hiroshi Yasuda
- Research Institute for Radiation Biology and Medicine, Hiroshima University, 1 Kasumi 2-3, Minami-ku, Hiroshima, 734-8553, Japan
| | - Shinji Tokonami
- Institute of Radiation Emergency Medicine, Hirosaki University, 66-1 Hon-cho, Hirosaki, 036-8564, Japan
| | - Ikuo Kashiwakura
- Graduate School of Health Sciences, Hirosaki University, 66-1 Hon-cho, Hirosaki, 036-8564, Japan.
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Takata T, Shiraishi K, Kumagai S, Arai N, Kobayashi T, Oba H, Okamoto T, Kotoku J. Calculating and estimating second cancer risk from breast radiotherapy using Monte Carlo code with internal body scatter for each out-of-field organ. J Appl Clin Med Phys 2020; 21:62-73. [PMID: 33128332 PMCID: PMC7769416 DOI: 10.1002/acm2.13060] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Revised: 04/03/2020] [Accepted: 09/17/2020] [Indexed: 11/20/2022] Open
Abstract
Out-of-field organs are not commonly designated as dose calculation targets during radiation therapy treatment planning, but they might entail risks of second cancer. Risk components include specific internal body scatter, which is a dominant source of out-of-field doses, and head leakage, which can be reduced by external shielding. Our simulation study quantifies out-of-field organ doses and estimates second cancer risks attributable to internal body scatter in whole-breast radiotherapy (WBRT) with or without additional regional nodal radiotherapy (RNRT), respectively, for right and left breast cancer using Monte Carlo code PHITS. Simulations were conducted using a complete whole-body female model. Second cancer risk was estimated using the calculated doses with a concept of excess absolute risk. Simulation results revealed marked differences between WBRT alone and WBRT plus RNRT in out-of-field organ doses. The ratios of mean doses between them were as large as 3.5-8.0 for the head and neck region and about 1.5-6.6 for the lower abdominal region. Potentially, most out-of-field organs had excess absolute risks of less than 1 per 10,000 persons-year. Our study surveyed the respective contributions of internal body scatter to out-of-field organ doses and second cancer risks in breast radiotherapy on this intact female model.
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Affiliation(s)
- Takeshi Takata
- Graduate School of Medical Care and TechnologyTeikyo University2‐11‐1 Kaga, Itabashi‐kuTokyo173‐8605Japan
| | - Kenshiro Shiraishi
- Department of RadiologyTeikyo University School of Medicine2‐11‐1 Kaga, Itabashi‐kuTokyo173‐8605Japan
| | - Shinobu Kumagai
- Central Radiology DivisionTeikyo University Hospital2‐11‐1 Kaga, Itabashi‐kuTokyo173‐8605Japan
| | - Norikazu Arai
- Central Radiology DivisionTeikyo University Hospital2‐11‐1 Kaga, Itabashi‐kuTokyo173‐8605Japan
| | - Takenori Kobayashi
- Graduate School of Medical Care and TechnologyTeikyo University2‐11‐1 Kaga, Itabashi‐kuTokyo173‐8605Japan
| | - Hiroshi Oba
- Department of RadiologyTeikyo University School of Medicine2‐11‐1 Kaga, Itabashi‐kuTokyo173‐8605Japan
| | - Takahide Okamoto
- Graduate School of Medical Care and TechnologyTeikyo University2‐11‐1 Kaga, Itabashi‐kuTokyo173‐8605Japan
- Central Radiology DivisionTeikyo University Hospital2‐11‐1 Kaga, Itabashi‐kuTokyo173‐8605Japan
| | - Jun’ichi Kotoku
- Graduate School of Medical Care and TechnologyTeikyo University2‐11‐1 Kaga, Itabashi‐kuTokyo173‐8605Japan
- Central Radiology DivisionTeikyo University Hospital2‐11‐1 Kaga, Itabashi‐kuTokyo173‐8605Japan
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Kumada H, Saito K, Nakamura T, Sakae T, Sakurai H, Matsumura A, Ono K. Multistep Lattice-Voxel method utilizing lattice function for Monte-Carlo treatment planning with pixel based voxel model. Appl Radiat Isot 2011; 69:1866-9. [DOI: 10.1016/j.apradiso.2011.03.023] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2010] [Revised: 03/04/2011] [Accepted: 03/15/2011] [Indexed: 11/29/2022]
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He W, Vazquez LA, Shi C, Papanikolaou N. Sensitivity study to evaluate the dosimetric impact of off-axis ratio profiles misalignment on TomoTherapy second dose validation. Technol Cancer Res Treat 2010; 9:515-22. [PMID: 20815423 DOI: 10.1177/153303461000900510] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Accurate dose planning and delivery are very important in the intensity modulated radiation therapy. For helical TomoTherapy dose validation, a TomoTherapy second check software, called MU-Tomo, has been developed using archived patient documents, initial coordinates and planned dose of the point of calculation, and common dosimetric functions. Based on this software, sensitivity studies on 50 patient cases have been evaluated to show the impact of off-axis ratio profile misalignment on point dose calculation. Off-axis ratio is defined as the dose profile normalized to its maximum dose value. Sensitivity studies were done for three scenarios: oscillating the fluctuation regions of two off-axis profiles, shifting the profiles, and rotating the profiles. The result of the oscillation trial is linear along the change of longitudinal off-axis ratio (OARy), while oscillating the lateral off-axis ratio (OARx) has little influence on the dose calculation. For shifting, the variation in the percentage difference from the non-shifting value is about 15 times larger in OARy modification than in OARx modification. Rotating OARx by +/- 6' gave less than 1.5% +/- 0.20% difference compared to the non-rotating value. Rotating OARy by +/- 1' changes the result more than 5% +/- 2.69%. Therefore, for helical TomoTherapy dose validation, commissioned OARy profiles are more sensitive than OARx to oscillation, shifting and rotating. As a result, different tolerances for OARx and OARy may be required for annual quality assurance.
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Affiliation(s)
- Weihong He
- 7979 Wurzbach Rd Ste 240, Cancer Therapy and Research Center, Department of Radiation Oncology, University of Texas Health Science Center at San Antonio, TX 78229, USA
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