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Kasamatsu K, Matsuura T, Yasuda K, Miyazaki K, Takao S, Tamura M, Otsuka M, Uchinami Y, Aoyama H. Hyperfractionated intensity-modulated proton therapy for pharyngeal cancer with variable relative biological effectiveness: A simulation study. Med Phys 2022; 49:7815-7825. [PMID: 36300598 DOI: 10.1002/mp.16064] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Revised: 10/06/2022] [Accepted: 10/07/2022] [Indexed: 12/27/2022] Open
Abstract
BACKGROUND The relative biological effectiveness (RBE) of proton is considered to be dependent on biological parameters and fractional dose. While hyperfractionated photon therapy was effective in the treatment of patients with head and neck cancers, its effect in intensity-modulated proton therapy (IMPT) under the variable RBE has not been investigated in detail. PURPOSE To study the effect of variable RBE on hyperfractionated IMPT for the treatment of pharyngeal cancer. We investigated the biologically effective dose (BED) to determine the theoretical effective hyperfractionated schedule. METHODS The treatment plans of three pharyngeal cancer patients were used to define the ΔBED for the clinical target volume (CTV) and soft tissue (acute and late reaction) as the difference between the BED for the altered schedule with variable RBE and conventional schedule with constant RBE. The ΔBED with several combinations of parameters (treatment days, number of fractions, and prescribed dose) was comprehensively calculated. Of the candidate schedules, the one that commonly gave a higher ΔBED for CTV was selected as the resultant schedule. The BED volume histogram was used to compare the influence of variable RBE and fractionation. RESULTS In the conventional schedule, compared with the constant RBE, the variable RBE resulted in a mean 2.6 and 2.7 Gy reduction of BEDmean for the CTV and soft tissue (acute reaction) of the three plans, respectively. Moreover, the BEDmean for soft tissue (late reaction) increased by 7.4 Gy, indicating a potential risk of increased RBE. Comprehensive calculation of the ΔBED resulted in the hyperfractionated schedule of 80.52 Gy (RBE = 1.1)/66 fractions in 6.5 weeks. When variable RBE was used, compared with the conventional schedule, the hyperfractionated schedule increased the BEDmean for CTV by 7.6 Gy; however, this was associated with a 7.8 Gy increase for soft tissue (acute reaction). The BEDmean for soft tissue (late reaction) decreased by 2.4 Gy. CONCLUSION The results indicated a potential effect of the variable RBE on IMPT for pharyngeal cancer but with the possibility that hyperfractionation could outweigh this effect. Although biological uncertainties require conservative use of the resultant schedule, hyperfractionation is expected to be an effective strategy in IMPT for pharyngeal cancer.
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Affiliation(s)
- Koki Kasamatsu
- Graduate School of Biomedical Science and Engineering, Hokkaido University, Sapporo, Japan
| | - Taeko Matsuura
- Faculty of Engineering, Hokkaido University, Sapporo, Japan.,Department of Medical Physics, Hokkaido University Hospital, Sapporo, Japan.,Proton Beam Therapy Center, Hokkaido University Hospital, Sapporo, Japan
| | - Koichi Yasuda
- Department of Radiation Oncology, Faculty and Graduate School of Medicine, Hokkaido University, Sapporo, Japan
| | - Koichi Miyazaki
- Faculty of Engineering, Hokkaido University, Sapporo, Japan.,Department of Medical Physics, Hokkaido University Hospital, Sapporo, Japan.,Research and Development Group, Hitachi, Ltd., Hitachi-shi, Japan
| | - Seishin Takao
- Faculty of Engineering, Hokkaido University, Sapporo, Japan.,Department of Medical Physics, Hokkaido University Hospital, Sapporo, Japan.,Proton Beam Therapy Center, Hokkaido University Hospital, Sapporo, Japan
| | - Masaya Tamura
- Department of Medical Physics, Hokkaido University Hospital, Sapporo, Japan
| | - Manami Otsuka
- Department of Radiation Oncology, Faculty and Graduate School of Medicine, Hokkaido University, Sapporo, Japan
| | - Yusuke Uchinami
- Department of Radiation Oncology, Faculty and Graduate School of Medicine, Hokkaido University, Sapporo, Japan
| | - Hidefumi Aoyama
- Department of Radiation Oncology, Faculty and Graduate School of Medicine, Hokkaido University, Sapporo, Japan
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Zhang J, Liang Y, Yang C. A primary proton integral depth dose calculation model corrected with straight scattering track approximation. Radiat Phys Chem Oxf Engl 1993 2022. [DOI: 10.1016/j.radphyschem.2022.110283] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
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Validation and testing of a novel pencil-beam model derived from Monte Carlo simulations in carbon-ion treatment planning for different scenarios. Phys Med 2022; 99:1-9. [PMID: 35576855 DOI: 10.1016/j.ejmp.2022.04.018] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/01/2022] [Revised: 04/27/2022] [Accepted: 04/28/2022] [Indexed: 11/23/2022] Open
Abstract
PURPOSE The calculation ability of the newly-proposed accurate beam model, the double Gaussian-logistic (DG-L) model, was validated in both homogeneous and heterogeneous phantoms to provide helpful information for its future application in clinical carbon-ion treatment planning system (TPS). METHODS MatRad was used as the new algorithm test platform. Based on Monte Carlo (MC) method, the basic database in matRad was generated, then comparative dosimetric analyses between the single Gaussian (SG), double Gaussian (DG) and DG-L models against the MC recalculations were performed on the treatment plans of a cubic water phantom, a TG119 phantom and a liver patient scenario. Absolute dose differences, dose-volume histograms (DVHs) and global γ-index analyses derived from the treatment plans were evaluated. RESULTS Calculated with the DG-L model, the deviations of the target dose coverage (D95) for the cubic water phantom, the TG119 phantom and the liver patient case against the MC recalculations could be reduced from -2.5%, -4.6% and -6.4% to -0.3%, -2.0% and -4.5% respectively compared to the SG model, while the γ pass rates (3%/3mm) could be enhanced from 98.0%, 90.6% and 90.1% to 99.8%, 95.7% and 91.6%, respectively. The novel beam model also shows improved performance compared with the DG model, without substantially increasing the computation time. CONCLUSIONS The DG-L model could effectively improve the dose calculation accuracy and mitigate the delivered dose deficiency in target volumes compared to the SG and DG models. The lateral heterogeneities should be considered for its future implementation in a clinical TPS.
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Fujii Y, Ueda H, Umegaki K, Matsuura T. An initial systematic study of the linear energy transfer distributions of a proton beam under a transverse magnetic field. Med Phys 2022; 49:1839-1852. [DOI: 10.1002/mp.15478] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Revised: 01/11/2022] [Accepted: 01/12/2022] [Indexed: 11/10/2022] Open
Affiliation(s)
- Yusuke Fujii
- Graduate School of Engineering Hokkaido University Sapporo Hokkaido Japan
- Hitachi Ltd. Hitachi Ibaraki Japan
| | - Hideaki Ueda
- Faculty of Engineering Hokkaido University Sapporo Hokkaido Japan
| | - Kikuo Umegaki
- Faculty of Engineering Hokkaido University Sapporo Hokkaido Japan
- Proton Beam Therapy Center Hokkaido University Hospital Sapporo Hokkaido Japan
- Department of Medical Physics Hokkaido University Hospital Sapporo Hokkaido Japan
| | - Taeko Matsuura
- Faculty of Engineering Hokkaido University Sapporo Hokkaido Japan
- Proton Beam Therapy Center Hokkaido University Hospital Sapporo Hokkaido Japan
- Department of Medical Physics Hokkaido University Hospital Sapporo Hokkaido Japan
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5
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Kasamatsu K, Tanaka S, Miyazaki K, Takao S, Miyamoto N, Hirayama S, Nishioka K, Hashimoto T, Aoyama H, Umegaki K, Matsuura T. Impact of a spatially dependent dose delivery time structure on the biological effectiveness of scanning proton therapy. Med Phys 2021; 49:702-713. [PMID: 34796522 DOI: 10.1002/mp.15367] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2021] [Revised: 10/09/2021] [Accepted: 11/02/2021] [Indexed: 11/09/2022] Open
Abstract
PURPOSE In the scanning beam delivery of protons, different portions of the target are irradiated with different linear energy transfer protons with various time intervals and irradiation times. This research aimed to evaluate the spatially dependent biological effectiveness of protracted irradiation in scanning proton therapy. METHODS One and two parallel opposed fields plans were created in water phantom with the prescribed dose of 2 Gy. Three scenarios (instantaneous, continuous, and layered scans) were used with the corresponding beam delivery models. The biological dose (physical dose × relative biological effectiveness) was calculated using the linear quadratic model and the theory of dual radiation action to quantitatively evaluate the dose delivery time effect. In addition, simulations using clinical plans (postoperative seminoma and prostate tumor cases) were conducted to assess the impact of the effects on the dose volume histogram parameters and homogeneity coefficient (HC) in targets. RESULTS In a single-field plan of water phantom, when the treatment time was 19 min, the layered-scan scenario showed a decrease of <0.2% (almost 3.3%) in the biological dose from the plan on the distal (proximal) side because of the high (low) dose rate. This is in contrast to the continuous scenario, where the biological dose was almost uniformly decreased over the target by approximately 3.3%. The simulation with clinical geometry showed that the decrease rates in D99% were 0.9% and 1.5% for every 10 min of treatment time prolongation for postoperative seminoma and prostate tumor cases, respectively, whereas the increase rates in HC were 0.7% and 0.2%. CONCLUSIONS In protracted irradiation in scanning proton therapy, the spatially dependent dose delivery time structure in scanning beam delivery can be an important factor for accurate evaluation of biological effectiveness.
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Affiliation(s)
- Koki Kasamatsu
- Graduate School of Biomedical Science and Engineering, Hokkaido University, Sapporo, Japan
| | - Sodai Tanaka
- Faculty of Engineering, Hokkaido University, Sapporo, Japan.,Department of Medical Physics, Hokkaido University Hospital, Sapporo, Japan
| | - Koichi Miyazaki
- Faculty of Engineering, Hokkaido University, Sapporo, Japan.,Department of Medical Physics, Hokkaido University Hospital, Sapporo, Japan
| | - Seishin Takao
- Faculty of Engineering, Hokkaido University, Sapporo, Japan.,Department of Medical Physics, Hokkaido University Hospital, Sapporo, Japan.,Proton Beam Therapy Center, Hokkaido University Hospital, Sapporo, Japan
| | - Naoki Miyamoto
- Faculty of Engineering, Hokkaido University, Sapporo, Japan.,Department of Medical Physics, Hokkaido University Hospital, Sapporo, Japan
| | | | - Kentaro Nishioka
- Department of Radiation Medical Science and Engineering, Faculty of Medicine, Hokkaido University, Sapporo, Japan
| | - Takayuki Hashimoto
- Department of Radiation Medical Science and Engineering, Faculty of Medicine, Hokkaido University, Sapporo, Japan
| | - Hidefumi Aoyama
- Department of Radiation Oncology, Faculty of Medicine, Hokkaido University, Sapporo, Japan
| | - Kikuo Umegaki
- Faculty of Engineering, Hokkaido University, Sapporo, Japan.,Department of Medical Physics, Hokkaido University Hospital, Sapporo, Japan.,Proton Beam Therapy Center, Hokkaido University Hospital, Sapporo, Japan
| | - Taeko Matsuura
- Faculty of Engineering, Hokkaido University, Sapporo, Japan.,Department of Medical Physics, Hokkaido University Hospital, Sapporo, Japan.,Proton Beam Therapy Center, Hokkaido University Hospital, Sapporo, Japan
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Younkin JE, Morales DH, Shen J, Shan J, Bues M, Lentz JM, Schild SE, Stoker JB, Ding X, Liu W. Clinical Validation of a Ray-Casting Analytical Dose Engine for Spot Scanning Proton Delivery Systems. Technol Cancer Res Treat 2020; 18:1533033819887182. [PMID: 31755362 PMCID: PMC6876166 DOI: 10.1177/1533033819887182] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022] Open
Abstract
Purpose: To describe and validate the dose calculation algorithm of an independent second-dose check software for spot scanning proton delivery systems with full width at half maximum between 5 and 14 mm and with a negligible spray component. Methods: The analytical dose engine of our independent second-dose check software employs an altered pencil beam algorithm with 3 lateral Gaussian components. It was commissioned using Geant4 and validated by comparison to point dose measurements at several depths within spread-out Bragg peaks of varying ranges, modulations, and field sizes. Water equivalent distance was used to compensate for inhomogeneous geometry. Twelve patients representing different disease sites were selected for validation. Dose calculation results in water were compared to a fast Monte Carlo code and ionization chamber array measurements using dose planes and dose profiles as well as 2-dimensional–3-dimensional and 3-dimensional–3-dimensional γ-index analysis. Results in patient geometry were compared to Monte Carlo simulation using dose–volume histogram indices, 3-dimensional–3-dimensional γ-index analysis, and inpatient dose profiles. Results: Dose engine model parameters were tuned to achieve 1.5% agreement with measured point doses. The in-water γ-index passing rates for the 12 patients using 3%/2 mm criteria were 99.5% ± 0.5% compared to Monte Carlo. The average inpatient γ-index analysis passing rate compared to Monte Carlo was 95.8% ± 2.9%. The average difference in mean dose to the clinical target volume between the dose engine and Monte Carlo was −0.4% ± 1.0%. For a typical plan, dose calculation time was 2 minutes on an inexpensive workstation. Conclusions: Following our commissioning process, the analytical dose engine was validated for all treatment sites except for the lung or for calculating dose–volume histogram indices involving point doses or critical structures immediately distal to target volumes. Monte Carlo simulations are recommended for these scenarios.
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Affiliation(s)
- James E Younkin
- Department of Radiation Oncology, Mayo Clinic Arizona, Phoenix, AZ, USA
| | | | - Jiajian Shen
- Department of Radiation Oncology, Mayo Clinic Arizona, Phoenix, AZ, USA
| | - Jie Shan
- Department of Radiation Oncology, Mayo Clinic Arizona, Phoenix, AZ, USA
| | - Martin Bues
- Department of Radiation Oncology, Mayo Clinic Arizona, Phoenix, AZ, USA
| | - Jarrod M Lentz
- Department of Radiation Oncology, Mayo Clinic Arizona, Phoenix, AZ, USA
| | - Steven E Schild
- Department of Radiation Oncology, Mayo Clinic Arizona, Phoenix, AZ, USA
| | - Joshua B Stoker
- Department of Radiation Oncology, Mayo Clinic Arizona, Phoenix, AZ, USA
| | - Xiaoning Ding
- Department of Radiation Oncology, Mayo Clinic Arizona, Phoenix, AZ, USA
| | - Wei Liu
- Department of Radiation Oncology, Mayo Clinic Arizona, Phoenix, AZ, USA
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Hirayama S, Matsuura T, Yasuda K, Takao S, Fujii T, Miyamoto N, Umegaki K, Shimizu S. Difference in LET-based biological doses between IMPT optimization techniques: Robust and PTV-based optimizations. J Appl Clin Med Phys 2020; 21:42-50. [PMID: 32150329 PMCID: PMC7170293 DOI: 10.1002/acm2.12844] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2019] [Revised: 02/01/2020] [Accepted: 02/10/2020] [Indexed: 12/03/2022] Open
Abstract
Purpose While a large amount of experimental data suggest that the proton relative biological effectiveness (RBE) varies with both physical and biological parameters, current commercial treatment planning systems (TPS) use the constant RBE instead of variable RBE models, neglecting the dependence of RBE on the linear energy transfer (LET). To conduct as accurate a clinical evaluation as possible in this circumstance, it is desirable that the dosimetric parameters derived by TPS (DRBE=1.1) are close to the “true” values derived with the variable RBE models (DvRBE). As such, in this study, the closeness of DRBE=1.1 to DvRBE was compared between planning target volume (PTV)‐based and robust plans. Methods Intensity‐modulated proton therapy (IMPT) treatment plans for two Radiation Therapy Oncology Group (RTOG) phantom cases and four nasopharyngeal cases were created using the PTV‐based and robust optimizations, under the assumption of a constant RBE of 1.1. First, the physical dose and dose‐averaged LET (LETd) distributions were obtained using the analytical calculation method, based on the pencil beam algorithm. Next, DvRBE was calculated using three different RBE models. The deviation of DvRBE from DRBE=1.1 was evaluated with D99 and Dmax, which have been used as the evaluation indices for clinical target volume (CTV) and organs at risk (OARs), respectively. The influence of the distance between the OAR and CTV on the results was also investigated. As a measure of distance, the closest distance and the overlapped volume histogram were used for the RTOG phantom and nasopharyngeal cases, respectively. Results As for the OAR, the deviations of DmaxvRBE from DmaxRBE=1.1 were always smaller in robust plans than in PTV‐based plans in all RBE models. The deviation would tend to increase as the OAR was located closer to the CTV in both optimization techniques. As for the CTV, the deviations of D99vRBE from D99RBE=1.1 were comparable between the two optimization techniques, regardless of the distance between the CTV and the OAR. Conclusion Robust optimization was found to be more favorable than PTV‐based optimization in that the results presented by TPS were closer to the “true” values and that the clinical evaluation based on TPS was more reliable.
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Affiliation(s)
- Shusuke Hirayama
- Research and Development Group, Center for Technology Innovation-Energy, Hitachi Ltd, Hitachi-shi, Ibaraki-ken, Japan.,Graduate School of Biomedical Science and Engineering, Hokkaido University, Sapporo, Hokkaido, Japan
| | - Taeko Matsuura
- Division of Quantum Science and Engineering, Faculty of Engineering, Hokkaido University, Sapporo, Hokkaido, Japan.,Global Station for Quantum Medical Science and Engineering, Global Institution for Collaborative Research and Education (GI-CoRE), Hokkaido University, Sapporo, Hokkaido, Japan.,Department of Medical Physics, Hokkaido University Hospital, Sapporo, Hokkaido, Japan
| | - Koichi Yasuda
- Global Station for Quantum Medical Science and Engineering, Global Institution for Collaborative Research and Education (GI-CoRE), Hokkaido University, Sapporo, Hokkaido, Japan.,Department of Radiation Oncology, Hokkaido University Hospital, Sapporo, Hokkaido, Japan
| | - Seishin Takao
- Division of Quantum Science and Engineering, Faculty of Engineering, Hokkaido University, Sapporo, Hokkaido, Japan.,Global Station for Quantum Medical Science and Engineering, Global Institution for Collaborative Research and Education (GI-CoRE), Hokkaido University, Sapporo, Hokkaido, Japan.,Department of Medical Physics, Hokkaido University Hospital, Sapporo, Hokkaido, Japan
| | - Takaaki Fujii
- Research and Development Group, Center for Technology Innovation-Energy, Hitachi Ltd, Hitachi-shi, Ibaraki-ken, Japan
| | - Naoki Miyamoto
- Division of Quantum Science and Engineering, Faculty of Engineering, Hokkaido University, Sapporo, Hokkaido, Japan.,Global Station for Quantum Medical Science and Engineering, Global Institution for Collaborative Research and Education (GI-CoRE), Hokkaido University, Sapporo, Hokkaido, Japan.,Department of Medical Physics, Hokkaido University Hospital, Sapporo, Hokkaido, Japan
| | - Kikuo Umegaki
- Division of Quantum Science and Engineering, Faculty of Engineering, Hokkaido University, Sapporo, Hokkaido, Japan.,Global Station for Quantum Medical Science and Engineering, Global Institution for Collaborative Research and Education (GI-CoRE), Hokkaido University, Sapporo, Hokkaido, Japan
| | - Shinichi Shimizu
- Global Station for Quantum Medical Science and Engineering, Global Institution for Collaborative Research and Education (GI-CoRE), Hokkaido University, Sapporo, Hokkaido, Japan.,Department of Medical Physics, Hokkaido University Hospital, Sapporo, Hokkaido, Japan.,Department of Radiation Medical Science and Engineering, Faculty of Medicine, Hokkaido University, Sapporo, Hokkaido, Japan
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Harms J, Chang CW, Zhang R, Lin L. Nuclear halo measurements for accurate prediction of field size factor in a Varian ProBeam proton PBS system. J Appl Clin Med Phys 2019; 21:197-204. [PMID: 31793202 PMCID: PMC6964762 DOI: 10.1002/acm2.12783] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2019] [Revised: 10/15/2019] [Accepted: 10/29/2019] [Indexed: 11/18/2022] Open
Abstract
Purpose For pencil‐beam scanning proton therapy systems, in‐air non‐Gaussian halo can significantly impact output at small field sizes and low energies. Since the low‐intensity tail of spot profile (halo) is not necessarily modeled in treatment planning systems (TPSs), this can potentially lead to significant differences in patient dose distribution. In this work, we report such impact for a Varian ProBeam system. Methods We use a pair magnification technique to measure two‐dimensional (2D) spot profiles of protons from 70 to 242 MeV at the treatment isocenter and 30 cm upstream of the isocenter. Measurements are made with both Gafchromic film and a scintillator detector coupled to a CCD camera (IBA Lynx). Spot profiles are measured down to 0.01% of their maximum intensity. Field size factors (FSFs) are compared among calculation using measured 2D profiles, calculation using a clinical treatment planning algorithm (Raystation 8A clinical Monte Carlo), and a CC04 small‐volume ion chamber. FSFs were measured for square fields of proton energies ranging from 70 to 242 MeV. Results All film and Lynx measurements agree within 1 mm for full width at half maximum beam intensity. The measured radial spot profiles disagree with simple Gaussian approximations, which are used for modeling in the TPS. FSF measurements show the magnitude of disagreements between beam output in reality and in the TPS without modeling halo. We found that the clinical TPS overestimated output by as much as 6% for small field sizes of 2 cm at the lowest energy of 70 MeV while the film and Lynx measurements agreed within 4% and 1%, respectively, for this FSF. Conclusions If the in‐air halo for low‐energy proton beams is not fully modeled by the TPS, this could potentially lead to under‐dosing small, shallow treatment volumes in PBS treatment plans.
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Affiliation(s)
- Joseph Harms
- Department of Radiation Oncology, Emory University, Atlanta, GA, USA
| | - Chih-Wei Chang
- Department of Radiation Oncology, Emory University, Atlanta, GA, USA
| | - Rongxiao Zhang
- Department of Radiation Oncology, Emory University, Atlanta, GA, USA.,Department of Radiation Oncology, Dartmouth University, Hanover, NH, USA
| | - Liyong Lin
- Department of Radiation Oncology, Emory University, Atlanta, GA, USA
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9
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Zhang H, Dai T, Liu X, Chen W, Ma Y, He P, Shen G, Yuan P, Dai Z, Li Q. Dosimetric effect of the low dose envelope associated with different beam models for carbon-ion spot scanning beam delivery. Acta Oncol 2019; 58:1790-1793. [PMID: 31368396 DOI: 10.1080/0284186x.2019.1648863] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Affiliation(s)
- Hui Zhang
- Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, China
- Key Laboratory of Heavy Ion Radiation Biology and Medicine of Chinese Academy of Sciences, Lanzhou, China
- Key Laboratory of Basic Research on Heavy Ion Radiation Application in Medicine, Gansu Province, Lanzhou, China
- School of Nuclear Science and Technology, University of Chinese Academy of Sciences, Beijing, China
| | - Tianyuan Dai
- Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, China
- Key Laboratory of Heavy Ion Radiation Biology and Medicine of Chinese Academy of Sciences, Lanzhou, China
- Key Laboratory of Basic Research on Heavy Ion Radiation Application in Medicine, Gansu Province, Lanzhou, China
- School of Nuclear Science and Technology, University of Chinese Academy of Sciences, Beijing, China
| | - Xinguo Liu
- Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, China
- Key Laboratory of Heavy Ion Radiation Biology and Medicine of Chinese Academy of Sciences, Lanzhou, China
- Key Laboratory of Basic Research on Heavy Ion Radiation Application in Medicine, Gansu Province, Lanzhou, China
- School of Nuclear Science and Technology, University of Chinese Academy of Sciences, Beijing, China
| | - Weiqiang Chen
- Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, China
- Key Laboratory of Heavy Ion Radiation Biology and Medicine of Chinese Academy of Sciences, Lanzhou, China
- Key Laboratory of Basic Research on Heavy Ion Radiation Application in Medicine, Gansu Province, Lanzhou, China
- School of Nuclear Science and Technology, University of Chinese Academy of Sciences, Beijing, China
| | - Yuanyuan Ma
- Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, China
- Key Laboratory of Heavy Ion Radiation Biology and Medicine of Chinese Academy of Sciences, Lanzhou, China
- Key Laboratory of Basic Research on Heavy Ion Radiation Application in Medicine, Gansu Province, Lanzhou, China
- School of Nuclear Science and Technology, University of Chinese Academy of Sciences, Beijing, China
| | - Pengbo He
- Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, China
- Key Laboratory of Heavy Ion Radiation Biology and Medicine of Chinese Academy of Sciences, Lanzhou, China
- Key Laboratory of Basic Research on Heavy Ion Radiation Application in Medicine, Gansu Province, Lanzhou, China
- School of Nuclear Science and Technology, University of Chinese Academy of Sciences, Beijing, China
| | - Guosheng Shen
- Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, China
- Key Laboratory of Heavy Ion Radiation Biology and Medicine of Chinese Academy of Sciences, Lanzhou, China
- Key Laboratory of Basic Research on Heavy Ion Radiation Application in Medicine, Gansu Province, Lanzhou, China
- School of Nuclear Science and Technology, University of Chinese Academy of Sciences, Beijing, China
| | - Ping Yuan
- Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, China
| | - Zhongying Dai
- Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, China
- Key Laboratory of Heavy Ion Radiation Biology and Medicine of Chinese Academy of Sciences, Lanzhou, China
- Key Laboratory of Basic Research on Heavy Ion Radiation Application in Medicine, Gansu Province, Lanzhou, China
- School of Nuclear Science and Technology, University of Chinese Academy of Sciences, Beijing, China
| | - Qiang Li
- Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, China
- Key Laboratory of Heavy Ion Radiation Biology and Medicine of Chinese Academy of Sciences, Lanzhou, China
- Key Laboratory of Basic Research on Heavy Ion Radiation Application in Medicine, Gansu Province, Lanzhou, China
- School of Nuclear Science and Technology, University of Chinese Academy of Sciences, Beijing, China
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10
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Dai T, Li Q, Liu X, Dai Z, He P, Ma Y, Shen G, Chen W, Zhang H, Meng Q, Zhang X. Nanodosimetric quantities and RBE of a clinically relevant carbon-ion beam. Med Phys 2019; 47:772-780. [PMID: 31705768 DOI: 10.1002/mp.13914] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2019] [Revised: 10/09/2019] [Accepted: 11/01/2019] [Indexed: 11/10/2022] Open
Abstract
PURPOSE Although carbon-ion therapy is becoming increasingly attractive to the treatment of tumors, details about the ionization pattern formed by therapeutic carbon-ion beam in tissue have not been fully investigated. In this work, systematic calculations for the nanodosimetric quantities and relative biological effectiveness (RBE) of a clinically relevant carbon-ion beam were studied for the first time. METHODS The method combining both track structure and condensed history Monte Carlo (MC) simulations was adopted to calculate the nanodosimetric quantities. Fragments and energy spectra at different positions of the radiation field of a clinically relevant carbon-ion pencil beam were generated by means of MC simulations in water. Nanodosimetric quantities such as mean ionization cluster size ( M 1 ), the first moment of conditional cluster size ( M 1 C 2 ), cumulative probability ( F 2 ), and conditional cumulative probability ( F 3 C 2 ) at these positions were then acquired based on the spectra and the pre-calculated nanodosimetric database created by track structure MC simulations. What's more, a novel approach to calculate RBE based on the said nanodosimetric quantities was introduced. The RBE calculations were then conducted for the carbon-ion beam at different water-equivalent depths. RESULTS Lateral distributions at various water-equivalent depths of both the nanodosimetric quantities and RBE values were obtained. The values of M 1 , M 1 C 2 , F 2 , and F 3 C 2 were 1.49, 2.67, 0.30, and 0.38 at the plateau at the beam central axis and maximized at 2.79, 5.69, 0.47, and 0.68 at the depths around the Bragg peak, respectively. At a given depth, M 1 and F 2 decreased laterally with increasing the distance to the beam central axis while M 1 C 2 and F 3 C 2 remained nearly unchanged at first and then decreased except for M 1 C 2 at the rising edge of the Bragg peak. The calculated RBE values were 1.07 at the plateau and 3.13 around the Bragg peak. Good agreement between the calculated RBE values and experimental data was obtained. CONCLUSIONS Different nanodosimetric quantities feature the track structure of therapeutic carbon-ion beam in different manners. Detailed ionization patterns generated by carbon-ion beam could be characterized by nanodosimetric quantities. Moreover the combined method adopted in this work to calculate nanodosimetric quantities is not only valid but also convenient. Nanodosimetric quantities are significantly helpful for the RBE calculations in carbon-ion therapy.
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Affiliation(s)
- Tianyuan Dai
- Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, 73000, China.,Key Laboratory of Heavy Ion Radiation Biology and Medicine of Chinese Academy of Science, Lanzhou, 730000, China.,Key Laboratory of Basic Research on Heavy Ion Radiation Application in Medicine Gansu Province, Lanzhou, 730000, China.,University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Qiang Li
- Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, 73000, China.,Key Laboratory of Heavy Ion Radiation Biology and Medicine of Chinese Academy of Science, Lanzhou, 730000, China.,Key Laboratory of Basic Research on Heavy Ion Radiation Application in Medicine Gansu Province, Lanzhou, 730000, China.,University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Xinguo Liu
- Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, 73000, China.,Key Laboratory of Heavy Ion Radiation Biology and Medicine of Chinese Academy of Science, Lanzhou, 730000, China.,Key Laboratory of Basic Research on Heavy Ion Radiation Application in Medicine Gansu Province, Lanzhou, 730000, China.,University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Zhongying Dai
- Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, 73000, China.,Key Laboratory of Heavy Ion Radiation Biology and Medicine of Chinese Academy of Science, Lanzhou, 730000, China.,Key Laboratory of Basic Research on Heavy Ion Radiation Application in Medicine Gansu Province, Lanzhou, 730000, China.,University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Pengbo He
- Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, 73000, China.,Key Laboratory of Heavy Ion Radiation Biology and Medicine of Chinese Academy of Science, Lanzhou, 730000, China.,Key Laboratory of Basic Research on Heavy Ion Radiation Application in Medicine Gansu Province, Lanzhou, 730000, China.,University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Yuanyuan Ma
- Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, 73000, China.,Key Laboratory of Heavy Ion Radiation Biology and Medicine of Chinese Academy of Science, Lanzhou, 730000, China.,Key Laboratory of Basic Research on Heavy Ion Radiation Application in Medicine Gansu Province, Lanzhou, 730000, China.,University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Guosheng Shen
- Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, 73000, China.,Key Laboratory of Heavy Ion Radiation Biology and Medicine of Chinese Academy of Science, Lanzhou, 730000, China.,Key Laboratory of Basic Research on Heavy Ion Radiation Application in Medicine Gansu Province, Lanzhou, 730000, China.,University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Weiqiang Chen
- Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, 73000, China.,Key Laboratory of Heavy Ion Radiation Biology and Medicine of Chinese Academy of Science, Lanzhou, 730000, China.,Key Laboratory of Basic Research on Heavy Ion Radiation Application in Medicine Gansu Province, Lanzhou, 730000, China.,University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Hui Zhang
- Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, 73000, China.,Key Laboratory of Heavy Ion Radiation Biology and Medicine of Chinese Academy of Science, Lanzhou, 730000, China.,Key Laboratory of Basic Research on Heavy Ion Radiation Application in Medicine Gansu Province, Lanzhou, 730000, China.,University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Qianqian Meng
- Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, 73000, China.,Key Laboratory of Heavy Ion Radiation Biology and Medicine of Chinese Academy of Science, Lanzhou, 730000, China.,Key Laboratory of Basic Research on Heavy Ion Radiation Application in Medicine Gansu Province, Lanzhou, 730000, China.,University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Xiaofang Zhang
- Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, 73000, China.,Key Laboratory of Heavy Ion Radiation Biology and Medicine of Chinese Academy of Science, Lanzhou, 730000, China.,Key Laboratory of Basic Research on Heavy Ion Radiation Application in Medicine Gansu Province, Lanzhou, 730000, China.,University of Chinese Academy of Sciences, Beijing, 100049, China
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11
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Experimental characterisation of a proton kernel model for pencil beam scanning techniques. Phys Med 2019; 64:195-203. [DOI: 10.1016/j.ejmp.2019.07.013] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/05/2018] [Revised: 06/20/2019] [Accepted: 07/17/2019] [Indexed: 11/24/2022] Open
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12
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Horita R, Yamamoto S, Yogo K, Komori M, Toshito T. Three-dimensional (3D) dose distribution measurements of proton beam using a glass plate. Biomed Phys Eng Express 2019. [DOI: 10.1088/2057-1976/ab169e] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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13
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Ueno K, Matsuura T, Hirayama S, Takao S, Ueda H, Matsuo Y, Yoshimura T, Umegaki K. Physical and biological impacts of collimator-scattered protons in spot-scanning proton therapy. J Appl Clin Med Phys 2019; 20:48-57. [PMID: 31237090 PMCID: PMC6612695 DOI: 10.1002/acm2.12653] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2019] [Revised: 05/01/2019] [Accepted: 05/04/2019] [Indexed: 11/29/2022] Open
Abstract
To improve the penumbra of low‐energy beams used in spot‐scanning proton therapy, various collimation systems have been proposed and used in clinics. In this paper, focused on patient‐specific brass collimators, the collimator‐scattered protons' physical and biological effects were investigated. The Geant4 Monte Carlo code was used to model the collimators mounted on the scanning nozzle of the Hokkaido University Hospital. A systematic survey was performed in water phantom with various‐sized rectangular targets; range (5–20 cm), spread‐out Bragg peak (SOBP) (5–10 cm), and field size (2 × 2–16 × 16 cm2). It revealed that both the range and SOBP dependences of the physical dose increase had similar trends to passive scattering methods, that is, it increased largely with the range and slightly with the SOBP. The physical impact was maximized at the surface (3%–22% for the tested geometries) and decreased with depth. In contrast, the field size (FS) dependence differed from that observed in passive scattering: the increase was high for both small and large FSs. This may be attributed to the different phase‐space shapes at the target boundary between the two dose delivery methods. Next, the biological impact was estimated based on the increase in dose‐averaged linear energy transfer (LETd) and relative biological effectiveness (RBE). The LETd of the collimator‐scattered protons were several keV/μm higher than that of unscattered ones; however, since this large increase was observed only at the positions receiving a small scattered dose, the overall LETd increase was negligible. As a consequence, the RBE increase did not exceed 0.05. Finally, the effects on patient geometries were estimated by testing two patient plans, and a negligible RBE increase (0.9% at most in the critical organs at surface) was observed in both cases. Therefore, the impact of collimator‐scattered protons is almost entirely attributed to the physical dose increase, while the RBE increase is negligible.
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Affiliation(s)
- Koki Ueno
- Graduate School of Biomedical Science and Engineering, Hokkaido University, Sapporo, Hokkaido, Japan
| | - Taeko Matsuura
- Faculty of Engineering, Hokkaido University, Sapporo, Hokkaido, Japan.,Proton Beam Therapy Center, Hokkaido University Hospital, Sapporo, Hokkaido, Japan.,Global Station for Quantum Medical Science and Engineering, Global Institution for Collaborative Research and Education (GI-CoRE), Hokkaido University, Sapporo, Japan
| | - Shusuke Hirayama
- Graduate School of Biomedical Science and Engineering, Hokkaido University, Sapporo, Hokkaido, Japan.,Proton Beam Therapy Center, Hokkaido University Hospital, Sapporo, Hokkaido, Japan
| | - Seishin Takao
- Proton Beam Therapy Center, Hokkaido University Hospital, Sapporo, Hokkaido, Japan
| | - Hideaki Ueda
- Faculty of Engineering, Hokkaido University, Sapporo, Hokkaido, Japan
| | - Yuto Matsuo
- Proton Beam Therapy Center, Hokkaido University Hospital, Sapporo, Hokkaido, Japan
| | - Takaaki Yoshimura
- Proton Beam Therapy Center, Hokkaido University Hospital, Sapporo, Hokkaido, Japan
| | - Kikuo Umegaki
- Faculty of Engineering, Hokkaido University, Sapporo, Hokkaido, Japan.,Proton Beam Therapy Center, Hokkaido University Hospital, Sapporo, Hokkaido, Japan.,Global Station for Quantum Medical Science and Engineering, Global Institution for Collaborative Research and Education (GI-CoRE), Hokkaido University, Sapporo, Japan
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14
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Gallagher KJ, Taddei PJ. ANALYTICAL MODEL TO ESTIMATE EQUIVALENT DOSE FROM INTERNAL NEUTRONS IN PROTON THERAPY OF CHILDREN WITH INTRACRANIAL TUMORS. RADIATION PROTECTION DOSIMETRY 2019; 183:459-467. [PMID: 30272222 PMCID: PMC6596440 DOI: 10.1093/rpd/ncy166] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/05/2018] [Revised: 08/15/2018] [Accepted: 08/27/2018] [Indexed: 06/08/2023]
Abstract
This study developed a computationally efficient and easy-to-implement analytical model to estimate the equivalent dose from secondary neutrons originating in the bodies ('internal neutrons') of children receiving intracranial proton radiotherapy. A two-term double-Gaussian mathematical model was fit to previously published internal neutron equivalent dose per therapeutic absorbed dose versus distance from the field edge calculated using Monte Carlo simulations. The model was trained using three intracranial proton fields of a 9-year-old girl. The resulting model was tested against two intracranial fields of a 10-year-old boy by comparing the mean doses in organs at risk of a radiogenic cancer estimated by the model versus those previously calculated by Monte Carlo. On average, the model reproduced the internal neutron organ doses in the 10-year-old boy within 13.5% of the Monte Carlo at 3-10 cm from the field edge and within a factor of 2 of the Monte Carlo at 10-20 cm from the field edge. Beyond 20 cm, the model poorly estimated H/DRx, however, the values were very small, at <0.03 mSv Gy-1.
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Affiliation(s)
- Kyle J Gallagher
- Oregon Health and Science University, Portland, OR, USA
- Oregon State University, Corvallis, OR, USA
| | - Phillip J Taddei
- American University of Beirut Medical Center, Beirut, Lebanon
- Department of Radiation Oncology, University of Washington School of Medicine, 1959 NE Pacific Street, Box 356043, Seattle, WA, USA
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15
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Yasui K, Toshito T, Omachi C, Hayashi K, Kinou H, Katsurada M, Hayashi N, Ogino H. Dosimetric verification of IMPT using a commercial heterogeneous phantom. J Appl Clin Med Phys 2019; 20:114-120. [PMID: 30673145 PMCID: PMC6371016 DOI: 10.1002/acm2.12535] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2018] [Revised: 11/19/2018] [Accepted: 12/30/2018] [Indexed: 11/13/2022] Open
Abstract
The purpose of this study was to propose a verification method and results of intensity‐modulated proton therapy (IMPT), using a commercially available heterogeneous phantom. We used a simple simulated head and neck and prostate phantom. An ionization chamber and radiochromic film were used for measurements of absolute dose and relative dose distribution. The measured doses were compared with calculated doses using a treatment planning system. We defined the uncertainty of the measurement point of the ionization chamber due to the effective point of the chamber and mechanical setup error as 2 mm and estimated the dose variation base on a 2 mm error. We prepared a HU‐relative stopping power conversion table and fluence correction factor that were specific to the heterogeneous phantom. The fluence correction factor was determined as a function of depth and was obtained from the ratio of the doses in water and in the phantom at the same effective depths. In the simulated prostate plan, composite doses of measurements and calculations agreed within ±1.3% and the maximum local dose differences of each field were 10.0%. Composite doses in the simulated head and neck plan agreed within 4.0% and the maximum local dose difference for each field was 12.0%. The dose difference for each field came within 2% when taking the measurement uncertainty into consideration. In the composite plan, the maximum dose uncertainty was estimated as 4.0% in the simulated prostate plan and 5.8% in the simulated head and neck plan. Film measurements showed good agreement, with more than 92.5% of points passing a gamma value (3%/3 mm). From these results, the heterogeneous phantom should be useful for verification of IMPT by using a phantom‐specific HU‐relative stopping power conversion, fluence correction factor, and dose error estimation due to the effective point of the chamber.
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Affiliation(s)
- Keisuke Yasui
- Faculty of Radiological Technology, School of Health Sciences, Fujita Health University, 1-98 Dengakugakubo, Kutsukake-cho, Toyoake, Aichi, 470-1192, Japan
| | - Toshiyuki Toshito
- Nagoya Proton Therapy Center, Nagoya City West Medical Center, 1-1-1, Hirate-cho, Kita-ku, Nagoya, Aichi, 462-8508, Japan
| | - Chihiro Omachi
- Nagoya Proton Therapy Center, Nagoya City West Medical Center, 1-1-1, Hirate-cho, Kita-ku, Nagoya, Aichi, 462-8508, Japan
| | - Kensuke Hayashi
- Nagoya Proton Therapy Center, Nagoya City West Medical Center, 1-1-1, Hirate-cho, Kita-ku, Nagoya, Aichi, 462-8508, Japan
| | - Hideto Kinou
- Nagoya Proton Therapy Center, Nagoya City West Medical Center, 1-1-1, Hirate-cho, Kita-ku, Nagoya, Aichi, 462-8508, Japan
| | - Masaki Katsurada
- Nagoya Proton Therapy Center, Nagoya City West Medical Center, 1-1-1, Hirate-cho, Kita-ku, Nagoya, Aichi, 462-8508, Japan
| | - Naoki Hayashi
- Faculty of Radiological Technology, School of Health Sciences, Fujita Health University, 1-98 Dengakugakubo, Kutsukake-cho, Toyoake, Aichi, 470-1192, Japan
| | - Hiroyuki Ogino
- Nagoya Proton Therapy Center, Nagoya City West Medical Center, 1-1-1, Hirate-cho, Kita-ku, Nagoya, Aichi, 462-8508, Japan
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16
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Zhang H, Dai Z, Liu X, Chen W, Ma Y, He P, Dai T, Shen G, Yuan P, Li Q. A novel pencil beam model for carbon-ion dose calculation derived from Monte Carlo simulations. Phys Med 2018; 55:15-24. [PMID: 30471815 DOI: 10.1016/j.ejmp.2018.10.014] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/11/2018] [Revised: 10/11/2018] [Accepted: 10/16/2018] [Indexed: 11/29/2022] Open
Abstract
An accurate kernel model is of vital importance for pencil-beam dose algorithm in charged particle therapy using precise spot-scanning beam delivery, in which an accurate depiction of the low dose envelope is especially crucial. Based on the Monte Carlo method, we investigated the dose contribution of secondary particles to the total dose and proposed a novel beam model to depict the lateral dose distribution of carbon-ion pencil beam in water. We demonstrated that the low dose envelope in single-spot profiles in water could be adequately modelled with the addition of a logistic distribution to a double Gaussian one, which was verified in both single carbon-ion pencil beam and superposed fields of different sizes with multiple pencil beams. Its superiority was mainly manifested at medium depths especially for high-energy beams with small fields compared with single, double and triple Gaussian models, where the secondary particles influenced the total dose considerably. The double Gaussian-logistic model could reduce the deviations from 4.1%, 1.7% to 0.3% in the plateau and peak regions, and from 19.2%, 4.9% to 1.2% in the tail region compared for the field size factor (FSF) calculations of 344 MeV/u carbon-ion pencil beam with the single and double Gaussian models. Compared with the triple Gaussian one, our newly-proposed model was on a par with it, even better than it in the plateau and peak regions. Thus our work will be helpful for improving the dose calculation accuracy for carbon-ion therapy.
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Affiliation(s)
- Hui Zhang
- Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 73000, China; Key Laboratory of Heavy Ion Radiation Biology and Medicine of Chinese Academy of Science, Lanzhou 730000, China; Key Laboratory of Basic Research on Heavy Ion Radiation Application in Medicine, Gansu Province, Lanzhou 730000, China; University of Chinese Academy of Sciences, Beijing 100049, China.
| | - Zhongying Dai
- Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 73000, China; Key Laboratory of Heavy Ion Radiation Biology and Medicine of Chinese Academy of Science, Lanzhou 730000, China; Key Laboratory of Basic Research on Heavy Ion Radiation Application in Medicine, Gansu Province, Lanzhou 730000, China.
| | - Xinguo Liu
- Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 73000, China; Key Laboratory of Heavy Ion Radiation Biology and Medicine of Chinese Academy of Science, Lanzhou 730000, China; Key Laboratory of Basic Research on Heavy Ion Radiation Application in Medicine, Gansu Province, Lanzhou 730000, China.
| | - Weiqiang Chen
- Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 73000, China; Key Laboratory of Heavy Ion Radiation Biology and Medicine of Chinese Academy of Science, Lanzhou 730000, China; Key Laboratory of Basic Research on Heavy Ion Radiation Application in Medicine, Gansu Province, Lanzhou 730000, China.
| | - Yuanyuan Ma
- Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 73000, China; Key Laboratory of Heavy Ion Radiation Biology and Medicine of Chinese Academy of Science, Lanzhou 730000, China; Key Laboratory of Basic Research on Heavy Ion Radiation Application in Medicine, Gansu Province, Lanzhou 730000, China.
| | - Pengbo He
- Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 73000, China; Key Laboratory of Heavy Ion Radiation Biology and Medicine of Chinese Academy of Science, Lanzhou 730000, China; Key Laboratory of Basic Research on Heavy Ion Radiation Application in Medicine, Gansu Province, Lanzhou 730000, China.
| | - Tianyuan Dai
- Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 73000, China; Key Laboratory of Heavy Ion Radiation Biology and Medicine of Chinese Academy of Science, Lanzhou 730000, China; Key Laboratory of Basic Research on Heavy Ion Radiation Application in Medicine, Gansu Province, Lanzhou 730000, China; University of Chinese Academy of Sciences, Beijing 100049, China.
| | - Guosheng Shen
- Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 73000, China; Key Laboratory of Heavy Ion Radiation Biology and Medicine of Chinese Academy of Science, Lanzhou 730000, China; Key Laboratory of Basic Research on Heavy Ion Radiation Application in Medicine, Gansu Province, Lanzhou 730000, China.
| | - Ping Yuan
- Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 73000, China.
| | - Qiang Li
- Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 73000, China; Key Laboratory of Heavy Ion Radiation Biology and Medicine of Chinese Academy of Science, Lanzhou 730000, China; Key Laboratory of Basic Research on Heavy Ion Radiation Application in Medicine, Gansu Province, Lanzhou 730000, China.
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17
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Huang S, Kang M, Souris K, Ainsley C, Solberg TD, McDonough JE, Simone CB, Lin L. Validation and clinical implementation of an accurate Monte Carlo code for pencil beam scanning proton therapy. J Appl Clin Med Phys 2018; 19:558-572. [PMID: 30058170 PMCID: PMC6123159 DOI: 10.1002/acm2.12420] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2018] [Revised: 05/02/2018] [Accepted: 06/21/2018] [Indexed: 11/12/2022] Open
Abstract
Monte Carlo (MC)‐based dose calculations are generally superior to analytical dose calculations (ADC) in modeling the dose distribution for proton pencil beam scanning (PBS) treatments. The purpose of this paper is to present a methodology for commissioning and validating an accurate MC code for PBS utilizing a parameterized source model, including an implementation of a range shifter, that can independently check the ADC in commercial treatment planning system (TPS) and fast Monte Carlo dose calculation in opensource platform (MCsquare). The source model parameters (including beam size, angular divergence and energy spread) and protons per MU were extracted and tuned at the nozzle exit by comparing Tool for Particle Simulation (TOPAS) simulations with a series of commissioning measurements using scintillation screen/CCD camera detector and ionization chambers. The range shifter was simulated as an independent object with geometric and material information. The MC calculation platform was validated through comprehensive measurements of single spots, field size factors (FSF) and three‐dimensional dose distributions of spread‐out Bragg peaks (SOBPs), both without and with the range shifter. Differences in field size factors and absolute output at various depths of SOBPs between measurement and simulation were within 2.2%, with and without a range shifter, indicating an accurate source model. TOPAS was also validated against anthropomorphic lung phantom measurements. Comparison of dose distributions and DVHs for representative liver and lung cases between independent MC and analytical dose calculations from a commercial TPS further highlights the limitations of the ADC in situations of highly heterogeneous geometries. The fast MC platform has been implemented within our clinical practice to provide additional independent dose validation/QA of the commercial ADC for patient plans. Using the independent MC, we can more efficiently commission ADC by reducing the amount of measured data required for low dose “halo” modeling, especially when a range shifter is employed.
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Affiliation(s)
- Sheng Huang
- Department of Radiation Oncology, University of Pennsylvania, Philadelphia, PA, USA.,Department of Medical Physics, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Minglei Kang
- Department of Radiation Oncology, MedStar Georgetown University Hospital, Washington, DC, USA
| | - Kevin Souris
- Center for Molecular Imaging and Experimental Radiotherapy, Institut de Recherche Expérimentale et Clinique, Université catholique de Louvain, Brussels, Belgium
| | - Christopher Ainsley
- Department of Radiation Oncology, University of Pennsylvania, Philadelphia, PA, USA
| | - Timothy D Solberg
- Department of Radiation Oncology, University of California, San Francisco, CA, USA
| | - James E McDonough
- Department of Radiation Oncology, University of Pennsylvania, Philadelphia, PA, USA
| | - Charles B Simone
- Department of Radiation Oncology, University of Maryland Medical Center, Baltimore, MD, USA
| | - Liyong Lin
- Department of Radiation Oncology, University of Pennsylvania, Philadelphia, PA, USA.,Emory Proton Therapy Center, Emory University, Atlanta, GA, USA
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18
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Hirayama S, Matsuura T, Ueda H, Fujii Y, Fujii T, Takao S, Miyamoto N, Shimizu S, Fujimoto R, Umegaki K, Shirato H. An analytical dose‐averagedLETcalculation algorithm considering the off‐axisLETenhancement by secondary protons for spot‐scanning proton therapy. Med Phys 2018; 45:3404-3416. [DOI: 10.1002/mp.12991] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2017] [Revised: 04/27/2018] [Accepted: 05/14/2018] [Indexed: 11/06/2022] Open
Affiliation(s)
- Shusuke Hirayama
- Faculty of Medicine Hokkaido University Sapporo Hokkaido 0608638 Japan
- Graduate School of Biomedical Science and Engineering Hokkaido University Sapporo Hokkaido 0608638 Japan
- Hitachi Ltd. Research and Development Group Center for Technology Innovation‐Energy Hitachi‐shi Ibaraki‐ken 3191221 Japan
| | - Taeko Matsuura
- Faculty of Engineering Hokkaido University Sapporo Hokkaido 0608628 Japan
- Global Station for Quantum Medical Science and Engineering Global Institution for Collaborative Research and Education (GI‐CoRE) Hokkaido University Sapporo Hokkaido 0608648 Japan
| | - Hideaki Ueda
- Faculty of Engineering Hokkaido University Sapporo Hokkaido 0608628 Japan
| | - Yusuke Fujii
- Hitachi Ltd. Research and Development Group Center for Technology Innovation‐Energy Hitachi‐shi Ibaraki‐ken 3191221 Japan
| | - Takaaki Fujii
- Faculty of Medicine Hokkaido University Sapporo Hokkaido 0608638 Japan
- Hitachi Ltd. Research and Development Group Center for Technology Innovation‐Energy Hitachi‐shi Ibaraki‐ken 3191221 Japan
| | - Seishin Takao
- Proton Beam Therapy Center Hokkaido University Hospital Sapporo Hokkaido 0608638 Japan
| | - Naoki Miyamoto
- Proton Beam Therapy Center Hokkaido University Hospital Sapporo Hokkaido 0608638 Japan
| | - Shinichi Shimizu
- Faculty of Medicine Hokkaido University Sapporo Hokkaido 0608638 Japan
- Global Station for Quantum Medical Science and Engineering Global Institution for Collaborative Research and Education (GI‐CoRE) Hokkaido University Sapporo Hokkaido 0608648 Japan
| | - Rintaro Fujimoto
- Hitachi Ltd. Research and Development Group Center for Technology Innovation‐Energy Hitachi‐shi Ibaraki‐ken 3191221 Japan
| | - Kikuo Umegaki
- Faculty of Engineering Hokkaido University Sapporo Hokkaido 0608628 Japan
- Global Station for Quantum Medical Science and Engineering Global Institution for Collaborative Research and Education (GI‐CoRE) Hokkaido University Sapporo Hokkaido 0608648 Japan
| | - Hiroki Shirato
- Faculty of Medicine Hokkaido University Sapporo Hokkaido 0608638 Japan
- Global Station for Quantum Medical Science and Engineering Global Institution for Collaborative Research and Education (GI‐CoRE) Hokkaido University Sapporo Hokkaido 0608648 Japan
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19
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Takayanagi T, Hirayama S, Fujitaka S, Fujimoto R. A simplified Monte Carlo algorithm considering large-angle scattering for fast and accurate calculation of proton dose. J Appl Clin Med Phys 2017; 19:60-72. [PMID: 29178595 PMCID: PMC5768009 DOI: 10.1002/acm2.12221] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2017] [Revised: 08/09/2017] [Accepted: 09/28/2017] [Indexed: 11/09/2022] Open
Abstract
PURPOSE The purpose of this study is to improve dose calculation accuracy of the simplified Monte Carlo (SMC) algorithm in the low-dose region. Because conventional SMC algorithms calculate particle scattering in consideration of multiple Coulomb scattering (MCS) only, they approximate lateral dose profiles by a single Gaussian function. However, it is well known that the low-dose region spreads away from the beam axis, and it has been pointed out that modeling of the low-dose region is important to calculated dose accurately. METHODS A SMC algorithm, which is named modified SMC and considers not only MCS but also large angle scattering resembling hadron elastic scattering, was developed. In the modified SMC algorithm, the particle fluence varies in the longitudinal direction because the large-angle scattering decreases residual range of particles in accordance with their scattering angle and tracking of the particles with large scattering angle is terminated at a short distance downstream from the scattering. Therefore, modified integrated depth dose (m-IDD) tables, which are converted from measured IDD in consideration of the fluence loss, are used to calculate dose. RESULTS In the case of a 1-liter cubic target, the calculation accuracy was improved in comparison with that of a conventional algorithm, and the modified algorithm results agreed well with Geant4-based simulation results; namely, 98.8% of the points satisfied the 2% dose/2 mm distance-to-agreement (DTA) criterion. The calculation time of the modified SMC algorithm was 1972 s in the case of 4.4 × 108 particles and 16-threading operation of an Intel Xeon E5-2643 (3.3-GHz clock). CONCLUSIONS An SMC algorithm that can reproduce a laterally widespread low-dose region was developed. According to the comparison with a Geant4-based simulation, it was concluded that the modified SMC algorithm is useful for calculating dose of proton radiotherapy.
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Affiliation(s)
- Taisuke Takayanagi
- Hitachi, Ltd., Research & Development Group, Center for Technology Innovation - Energy, Hitachi, Japan
| | - Shusuke Hirayama
- Hitachi, Ltd., Research & Development Group, Center for Technology Innovation - Energy, Hitachi, Japan
| | - Shinichiro Fujitaka
- Hitachi, Ltd., Research & Development Group, Center for Technology Innovation - Energy, Hitachi, Japan
| | - Rintaro Fujimoto
- Hitachi, Ltd., Research & Development Group, Center for Technology Innovation - Energy, Hitachi, Japan
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20
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Yasui K, Toshito T, Omachi C, Hayashi K, Tanaka K, Asai K, Shimomura A, Muramatsu R, Hayashi N. Evaluation of dosimetric advantages of using patient-specific aperture system with intensity-modulated proton therapy for the shallow depth tumor. J Appl Clin Med Phys 2017; 19:132-137. [PMID: 29178546 PMCID: PMC5768032 DOI: 10.1002/acm2.12231] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2017] [Revised: 09/22/2017] [Accepted: 10/23/2017] [Indexed: 11/11/2022] Open
Abstract
In this study, we evaluate dosimetric advantages of using patient-specific aperture system with intensity-modulated proton therapy (IMPT) for head and neck tumors at the shallow depth. We used four types of patient-specific aperture system (PSAS) to irradiate shallow regions less than 4 g/cm2 with a sharp lateral penumbra. Ten head and neck IMPT plans with or without aperture were optimized separately with the same 95% prescription dose and same dose constraint for organs at risk (OARs). The plans were compared using dose volume histograms (DVHs), dose distributions, and some dose indexes such as volume receiving 50% of the prescribed dose (V50 ), mean or maximum dose (Dmean and Dmax ) to the OARs. All examples verified in this study had decreased V50 and OAR doses. Average, maximum, and minimum relative reductions of V50 were 15.4%, 38.9%, and 1.0%, respectively. Dmax and Dmean of OARs were decreased by 0.3% to 25.7% and by 1.0% to 46.3%, respectively. The plans with the aperture over more than half of the field showed decreased V50 or OAR dose by more than 10%. The dosimetric advantage of patient-specific apertures with IMPT was clarified in many cases. The PSAS has some dosimetric advantages for clinical use, and in some cases, it enables to fulfill dose constraints.
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Affiliation(s)
- Keisuke Yasui
- Nagoya Proton Therapy Center, Nagoya City West Medical Center, Nagoya, Japan.,School of Health Sciences, Faculty of Radiological Technology, Fujita Health University, Toyoake, Japan
| | - Toshiyuki Toshito
- Nagoya Proton Therapy Center, Nagoya City West Medical Center, Nagoya, Japan
| | - Chihiro Omachi
- Nagoya Proton Therapy Center, Nagoya City West Medical Center, Nagoya, Japan
| | - Kensuke Hayashi
- Nagoya Proton Therapy Center, Nagoya City West Medical Center, Nagoya, Japan
| | - Kenichiro Tanaka
- Nagoya Proton Therapy Center, Nagoya City West Medical Center, Nagoya, Japan
| | - Kumiko Asai
- Nagoya Proton Therapy Center, Nagoya City West Medical Center, Nagoya, Japan
| | - Akira Shimomura
- Nagoya Proton Therapy Center, Nagoya City West Medical Center, Nagoya, Japan
| | - Rie Muramatsu
- Nagoya Proton Therapy Center, Nagoya City West Medical Center, Nagoya, Japan
| | - Naoki Hayashi
- School of Health Sciences, Faculty of Radiological Technology, Fujita Health University, Toyoake, Japan
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21
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Trnková P, Bolsi A, Albertini F, Weber DC, Lomax AJ. Factors influencing the performance of patient specific quality assurance for pencil beam scanning IMPT fields. Med Phys 2017; 43:5998. [PMID: 27806620 DOI: 10.1118/1.4964449] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE A detailed analysis of 2728 intensity modulated proton therapy (IMPT) fields that were clinically delivered to patients between 2007 and 2013 at Paul Scherrer Institute (PSI) was performed. The aim of this study was to analyze the results of patient specific dosimetric verifications and to assess possible correlation between the quality assurance (QA) results and specific field metrics. METHODS Dosimetric verifications were performed for every IMPT field prior to patient treatment. For every field, a steering file was generated containing all the treatment unit information necessary for treatment delivery: beam energy, beam angle, dose, size of air gap, nuclear interaction (NI) correction factor, number of range shifter plates, number of Bragg peaks (BPs) with their position and weight. This information was extracted and correlated to the results of dosimetric verification of each field which was a measurement of two orthogonal profiles using an orthogonal ionization chamber array in a movable water column. RESULTS The data analysis has shown more than 94% of all verified plans were within defined clinical tolerances. The differences between measured and calculated dose depend critically on the number of BPs, total thickness of all range shifter plates inserted in the beam path, and maximal range. An increase of the dose difference was observed with smaller number of BPs (i.e., smaller tumor) and smaller ranges (i.e., superficial tumors). The results of the verification do not depend, however, on the prescribed dose, NI correction, or the size of the air gap. There is no dependency of the transversal and longitudinal spot position precision on the beam angle. The value of NI correction depends on the number of spots and number of range shifter plates. CONCLUSIONS The presented study has shown that the verification method used at Centre for Proton Therapy at Paul Scherrer Institute is accurate and reproducible for performing patient specific QA. The results confirmed that the dose discrepancy is dependent on the size and location of the tumor.
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Affiliation(s)
- P Trnková
- Centre for Proton Therapy, Paul Scherrer Institute, PSI West, Villigen 5232, Switzerland
| | - A Bolsi
- Centre for Proton Therapy, Paul Scherrer Institute, PSI West, Villigen 5232, Switzerland
| | - F Albertini
- Centre for Proton Therapy, Paul Scherrer Institute, PSI West, Villigen 5232, Switzerland
| | - D C Weber
- Centre for Proton Therapy, Paul Scherrer Institute, PSI West, Villigen 5232, Switzerland and Radiation Oncology Department, University of Zürich, Rämistrasse 71, Zürich 8006, Switzerland
| | - A J Lomax
- Centre for Proton Therapy, Paul Scherrer Institute, PSI West, Villigen 5232, Switzerland and Department of Physics, ETH Zürich, Rämistrasse 101, Zürich 8092, Switzerland
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Hashimoto S, Shibamoto Y, Iwata H, Ogino H, Shibata H, Toshito T, Sugie C, Mizoe JE. Whole-pelvic radiotherapy with spot-scanning proton beams for uterine cervical cancer: a planning study. JOURNAL OF RADIATION RESEARCH 2016; 57:524-532. [PMID: 27380800 PMCID: PMC5045079 DOI: 10.1093/jrr/rrw052] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2015] [Revised: 02/05/2016] [Accepted: 03/31/2016] [Indexed: 05/20/2023]
Abstract
The aim of this study was to compare the dosimetric parameters of whole-pelvic radiotherapy (WPRT) for cervical cancer among plans involving 3D conformal radiotherapy (3D-CRT), intensity-modulated radiotherapy (IMRT), or spot-scanning proton therapy (SSPT). The dose distributions of 3D-CRT-, IMRT-, and SSPT-based WPRT plans were compared in 10 patients with cervical cancer. All of the patients were treated with a prescribed dose of 50.4 Gy in 1.8-Gy daily fractions, and all of the plans involved the same planning target volume (PTV) constrictions. A 3D-CRT plan involving a four-field box, an IMRT plan involving seven coplanar fields, and an SSPT plan involving four fields were created. The median PTV D95% did not differ between the 3D-CRT, IMRT and SSPT plans. The median conformity index 95% and homogeneity index of the IMRT and SSPT were better than those of the 3D-CRT. The homogeneity index of the SSPT was better than that of the IMRT. SSPT resulted in lower median V20 values for the bladder wall, small intestine, colon, bilateral femoral heads, skin, and pelvic bone than IMRT. Comparing the Dmean values, SSPT spared the small intestine, colon, bilateral femoral heads, skin and pelvic bone to a greater extent than the other modalities. SSPT can reduce the irradiated volume of the organs at risk compared with 3D-CRT and IMRT, while maintaining excellent PTV coverage. Further investigations of SSPT are warranted to assess its role in the treatment of cervical cancer.
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Affiliation(s)
- Shingo Hashimoto
- Department of Radiation Oncology, Nagoya Proton Therapy Center, 1-1-1 Hirate-cho, Kita-ku, Nagoya 462-8508, Japan Department of Radiation Oncology, Nagoya City West Medical Center, 1-1-1 Hirate-cho, Kita-ku, Nagoya 462-8508, Japan Department of Radiology, Nagoya City University Graduate School of Medical Sciences, 1 Kawasumi, Mizuho-cho, Mizuho-ku, Nagoya 467-8601, Japan
| | - Yuta Shibamoto
- Department of Radiology, Nagoya City University Graduate School of Medical Sciences, 1 Kawasumi, Mizuho-cho, Mizuho-ku, Nagoya 467-8601, Japan
| | - Hiromitsu Iwata
- Department of Radiation Oncology, Nagoya Proton Therapy Center, 1-1-1 Hirate-cho, Kita-ku, Nagoya 462-8508, Japan
| | - Hiroyuki Ogino
- Department of Radiation Oncology, Nagoya Proton Therapy Center, 1-1-1 Hirate-cho, Kita-ku, Nagoya 462-8508, Japan
| | - Hiroki Shibata
- Department of Proton Therapy Technology, Nagoya Proton Therapy Center, 1-1-1 Hirate-cho, Kita-ku, Nagoya 462-8508, Japan
| | - Toshiyuki Toshito
- Department of Proton Therapy Physics, Nagoya Proton Therapy Center, 1-1-1 Hirate-cho, Kita-ku, Nagoya 462-8508, Japan
| | - Chikao Sugie
- Department of Radiology, Nagoya City University Graduate School of Medical Sciences, 1 Kawasumi, Mizuho-cho, Mizuho-ku, Nagoya 467-8601, Japan
| | - Jun-Etsu Mizoe
- Department of Radiation Oncology, Nagoya Proton Therapy Center, 1-1-1 Hirate-cho, Kita-ku, Nagoya 462-8508, Japan
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Takayanagi T, Nihongi H, Nishiuchi H, Tadokoro M, Ito Y, Nakashima C, Fujitaka S, Umezawa M, Matsuda K, Sakae T, Terunuma T. Dual ring multilayer ionization chamber and theory-based correction technique for scanning proton therapy. Med Phys 2016; 43:4150. [PMID: 27370135 DOI: 10.1118/1.4953633] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE To develop a multilayer ionization chamber (MLIC) and a correction technique that suppresses differences between the MLIC and water phantom measurements in order to achieve fast and accurate depth dose measurements in pencil beam scanning proton therapy. METHODS The authors distinguish between a calibration procedure and an additional correction: 1-the calibration for variations in the air gap thickness and the electrometer gains is addressed without involving measurements in water; 2-the correction is addressed to suppress the difference between depth dose profiles in water and in the MLIC materials due to the nuclear interaction cross sections by a semiempirical model tuned by using measurements in water. In the correction technique, raw MLIC data are obtained for each energy layer and integrated after multiplying them by the correction factor because the correction factor depends on incident energy. The MLIC described here has been designed especially for pencil beam scanning proton therapy. This MLIC is called a dual ring multilayer ionization chamber (DRMLIC). The shape of the electrodes allows the DRMLIC to measure both the percentage depth dose (PDD) and integrated depth dose (IDD) because ionization electrons are collected from inner and outer air gaps independently. RESULTS IDDs for which the beam energies were 71.6, 120.6, 159, 180.6, and 221.4 MeV were measured and compared with water phantom results. Furthermore, the measured PDDs along the central axis of the proton field with a nominal field size of 10 × 10 cm(2) were compared. The spread out Bragg peak was 20 cm for fields with a range of 30.6 and 3 cm for fields with a range of 6.9 cm. The IDDs measured with the DRMLIC using the correction technique were consistent with those that of the water phantom; except for the beam energy of 71.6 MeV, all of the points satisfied the 1% dose/1 mm distance to agreement criterion of the gamma index. The 71.6 MeV depth dose profile showed slight differences in the shallow region, but 94.5% of the points satisfied the 1%/1 mm criterion. The 90% ranges, defined at the 90% dose position in distal fall off, were in good agreement with those in the water phantom, and the range differences from the water phantom were less than ±0.3 mm. The PDDs measured with the DRMLIC were also consistent with those that of the water phantom; 97% of the points passed the 1%/1 mm criterion. CONCLUSIONS It was demonstrated that the new correction technique suppresses the difference between the depth dose profiles obtained with the MLIC and those obtained from a water phantom, and a DRMLIC enabling fast measurements of both IDD and PDD was developed. The IDDs and PDDs measured with the DRMLIC and using the correction technique were in good agreement with those that of the water phantom, and it was concluded that the correction technique and DRMLIC are useful for depth dose profile measurements in pencil beam scanning proton therapy.
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Affiliation(s)
| | | | | | | | - Yuki Ito
- Hitachi Ltd., Hitachi Works, Hitachi 317-8511, Japan
| | | | | | - Masumi Umezawa
- Hitachi Ltd., Hitachi Research Laboratory, Hitachi 319-1221, Japan
| | - Koji Matsuda
- Hitachi Ltd., Hitachi Works, Hitachi 317-8511, Japan
| | - Takeji Sakae
- Proton Medical Research Center, University of Tsukuba, Tsukuba 305-8576, Japan
| | - Toshiyuki Terunuma
- Proton Medical Research Center, University of Tsukuba, Tsukuba 305-8576, Japan
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