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Parisi A, Furutani KM, Sato T, Beltran CJ. LET-based approximation of the microdosimetric kinetic model for proton radiotherapy. Med Phys 2024. [PMID: 39153222 DOI: 10.1002/mp.17337] [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: 04/26/2024] [Revised: 07/19/2024] [Accepted: 07/19/2024] [Indexed: 08/19/2024] Open
Abstract
BACKGROUND Phenomenological relative biological effectiveness (RBE) models for proton therapy, based on the dose-averaged linear energy transfer (LET), have been developed to address the apparent RBE increase towards the end of the proton range. The results of these phenomenological models substantially differ due to varying empirical assumptions and fitting functions. In contrast, more theory-based approaches are used in carbon ion radiotherapy, such as the microdosimetric kinetic model (MKM). However, implementing microdosimetry-based models in LET-based proton therapy treatment planning systems poses challenges. PURPOSE This work presents a LET-based version of the MKM that is practical for clinical use in proton radiotherapy. METHODS At first, we derived an approximation of the Mayo Clinic Florida (MCF) MKM for relatively-sparsely ionizing radiation such as protons. The mathematical formalism of the proposed model is equivalent to the original MKM, but it maintains some key features of the MCF MKM, such as the determination of model parameters from measurable cell characteristics. Subsequently, we carried out Monte Carlo calculations with PHITS in different simulated scenarios to establish a heuristic correlation between microdosimetric quantities and the dose averaged LET of protons. RESULTS A simple allometric function was found able to describe the relationship between the dose-averaged LET of protons and the dose-mean lineal energy, which includes the contributions of secondary particles. The LET-based MKM was used to model the in vitro clonogenic survival RBE of five human and rodent cell lines (A549, AG01522, CHO, T98G, and U87) exposed to pristine and spread-out Bragg peak (SOBP) proton beams. The results of the LET-based MKM agree well with the biological data in a comparable or better way with respect to the other models included in the study. A sensitivity analysis on the model results was also performed. CONCLUSIONS The LET-based MKM integrates the predictive theoretical framework of the MCF MKM with a straightforward mathematical description of the RBE based on the dose-averaged LET, a physical quantity readily available in modern treatment planning systems for proton therapy.
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Affiliation(s)
- Alessio Parisi
- Department of Radiation Oncology, Mayo Clinic, Jacksonville, Florida, USA
| | - Keith M Furutani
- Department of Radiation Oncology, Mayo Clinic, Jacksonville, Florida, USA
| | - Tatsuhiko Sato
- Nuclear Science and Engineering Center, Japan Atomic Energy Agency, Tokai, Ibaraki, Japan
- Research Center for Nuclear Physics, Osaka University, Suita, Osaka, Japan
| | - Chris J Beltran
- Department of Radiation Oncology, Mayo Clinic, Jacksonville, Florida, USA
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Lyngholm E, Stokkevåg CH, Lühr A, Tian L, Meric I, Tjelta J, Henjum H, Handeland AH, Ytre-Hauge KS. An updated variable RBE model for proton therapy. Phys Med Biol 2024; 69:125025. [PMID: 38527373 DOI: 10.1088/1361-6560/ad3796] [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: 10/17/2023] [Accepted: 03/25/2024] [Indexed: 03/27/2024]
Abstract
Objective.While a constant relative biological effectiveness (RBE) of 1.1 forms the basis for clinical proton therapy, variable RBE models are increasingly being used in plan evaluation. However, there is substantial variation across RBE models, and several newin vitrodatasets have not yet been included in the existing models. In this study, an updatedin vitroproton RBE database was collected and used to examine current RBE model assumptions, and to propose an up-to-date RBE model as a tool for evaluating RBE effects in clinical settings.Approach.A proton database (471 data points) was collected from the literature, almost twice the size of the previously largest model database. Each data point included linear-quadratic model parameters and linear energy transfer (LET). Statistical analyses were performed to test the validity of commonly applied assumptions of phenomenological RBE models, and new model functions were proposed forRBEmaxandRBEmin(RBE at the lower and upper dose limits). Previously published models were refitted to the database and compared to the new model in terms of model performance and RBE estimates.Main results.The statistical analysis indicated that the intercept of theRBEmaxfunction should be a free fitting parameter and RBE estimates were clearly higher for models with free intercept.RBEminincreased with increasing LET, while a dependency ofRBEminon the reference radiation fractionation sensitivity (α/βx) did not significantly improve model performance. Evaluating the models, the new model gave overall lowest RMSE and highest R2 score. RBE estimates in the distal part of a spread-out-Bragg-peak in water (α/βx= 2.1 Gy) were 1.24-1.51 for original models, 1.25-1.49 for refits and 1.42 for the new model.Significance.An updated RBE model based on the currently largest database among published phenomenological models was proposed. Overall, the new model showed better performance compared to refitted published RBE models.
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Affiliation(s)
- Erlend Lyngholm
- Department of Physics and Technology, University of Bergen, Bergen, Norway
| | - Camilla Hanquist Stokkevåg
- Department of Physics and Technology, University of Bergen, Bergen, Norway
- Department of Oncology and Medical Physics, Haukeland University Hospital, Bergen, Norway
| | - Armin Lühr
- Department of Physics, TU Dortmund University, Dortmund, Germany
| | - Liheng Tian
- Department of Physics, TU Dortmund University, Dortmund, Germany
| | - Ilker Meric
- Department of Computer Science, Electrical Engineering and Mathematical Sciences, Western Norway University of Applied Sciences, Bergen, Norway
| | - Johannes Tjelta
- Department of Physics and Technology, University of Bergen, Bergen, Norway
- Department of Oncology and Medical Physics, Haukeland University Hospital, Bergen, Norway
| | - Helge Henjum
- Department of Physics and Technology, University of Bergen, Bergen, Norway
| | - Andreas Havsgård Handeland
- Department of Physics and Technology, University of Bergen, Bergen, Norway
- Department of Oncology and Medical Physics, Haukeland University Hospital, Bergen, Norway
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Jeong S, Kim CE, Kim C, Pak SI, An S, Cheon W, Shin D, Lim YK, Jeong JH, Kim H, Chung Y, Choi SH, Lee SB. Feasibility study for the development of multilayered solar cells for proton linear energy transfer depth profile measurement. Med Phys 2024. [PMID: 38828894 DOI: 10.1002/mp.17234] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2023] [Revised: 05/09/2024] [Accepted: 05/10/2024] [Indexed: 06/05/2024] Open
Abstract
BACKGROUND Previous study proposed a method to measure linear energy transfer (LET) at specific points using the quenching magnitude of thin film solar cells. This study was conducted to propose a more advanced method for measuring the LET distribution. PURPOSE This study focuses on evaluating the feasibility of estimating the proton LET distribution in proton therapy. The feasibility of measuring the proton LET and dose distribution simultaneously using a single-channel configuration comprising two solar cells with distinct quenching constants is investigated with the objective of paving the way for enhanced proton therapy dosimetry. METHODS Two solar cells with different quenching constants were used to estimate the proton LET distribution. Detector characteristics (e.g., dose linearity and dose-rate dependency) of the solar cells were evaluated to assess their suitability for dosimetry applications. First, using a reference beam condition, the quenching constants of the two solar cells were determined according to the modified Birks equation. The signal ratios of the two solar cells were then evaluated according to proton LET in relation to the estimated quenching constants. The proton LET distributions of six test beams were obtained by measuring the signal ratios of the two solar cells at each depth, and the ratios were evaluated by comparing them with those calculated by Monte Carlo simulation. RESULTS The detector characterization of the two solar cells including dose linearity and dose-rate dependence affirmed their suitability for use in dosimetry applications. The maximum difference between the LET measured using the two solar cells and that calculated by Monte Carlo simulation was 2.34 keV/µm. In the case of the dose distribution measured using the method proposed in this study, the maximum difference between range measured using the proposed method and that measured using a multilayered ionization chamber was 0.7 mm. The expected accuracy of simultaneous LET and dose distribution measurement using the method proposed in this study were estimated to be 3.82%. The signal ratios of the two solar cells, which are related to quenching constants, demonstrated the feasibility of measuring LET and dose distribution simultaneously. CONCLUSION The feasibility of measuring proton LET and dose distribution simultaneously using two solar cells with different quenching constants was demonstrated. Although the method proposed in this study was evaluated using a single channel by varying the measuring depth, the results suggest that the proton LET and dose distribution can be simultaneously measured if the detector is configured in a multichannel form. We believe that the results presented in this study provide the envisioned transition to a multichannel configuration, with the promise of substantially advancing proton therapy's accuracy and efficacy in cancer treatment.
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Affiliation(s)
- Seonghoon Jeong
- Department of Neurosurgery, College of Medicine, Ilsan Paik Hospital, Inje University, Goyang, Republic of Korea
| | - Chae-Eon Kim
- Proton Therapy Center, National Cancer Center, Goyang, Republic of Korea
- Department of Nuclear Engineering, Hanyang University, Seoul, Republic of Korea
| | - Chankyu Kim
- Proton Therapy Center, National Cancer Center, Goyang, Republic of Korea
| | - Sang-Il Pak
- Proton Therapy Center, National Cancer Center, Goyang, Republic of Korea
| | - Seohyeon An
- Proton Therapy Center, National Cancer Center, Goyang, Republic of Korea
- Department of Physics, Hanyang University, Seoul, Republic of Korea
| | - Wonjoong Cheon
- Department of Radiation Oncology, Seoul St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea
| | - Dongho Shin
- Proton Therapy Center, National Cancer Center, Goyang, Republic of Korea
| | - Young Kyung Lim
- Proton Therapy Center, National Cancer Center, Goyang, Republic of Korea
| | - Jong Hwi Jeong
- Proton Therapy Center, National Cancer Center, Goyang, Republic of Korea
| | - Haksoo Kim
- Proton Therapy Center, National Cancer Center, Goyang, Republic of Korea
| | - Yoonsun Chung
- Department of Nuclear Engineering, Hanyang University, Seoul, Republic of Korea
| | - Sang Hyoun Choi
- Radiation Therapy Technology and Standards, Korea Institute of Radiological & Medical Sciences, Seoul, Republic of Korea
| | - Se Byeong Lee
- Proton Therapy Center, National Cancer Center, Goyang, Republic of Korea
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Yan N, Wu C, Zhou Y, Liao W, Liu J, Pu Y. A linear energy transfer distributions computation method for inhomogeneous medium by using the water equivalent ratio approximation. RADIATION PROTECTION DOSIMETRY 2024; 200:325-332. [PMID: 37850312 DOI: 10.1093/rpd/ncad273] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2023] [Revised: 07/26/2023] [Accepted: 09/19/2023] [Indexed: 10/19/2023]
Abstract
Dose-averaged linear energy transfer (LET), LETd is widely used in proton therapy. Compared with analytical models, Monte Carlo (MC) simulations are more accurate in obtaining LETd distributions, but they are time-consuming. This study used the 3D LETd distributions of proton beam spots in water by MC simulations as a benchmark data set. Subsequently, by combining the water equivalent ratio of various human tissues, the 3D LETd distributions of clinical cases could be quickly obtained. Our method was applied to a single spot of 160 MeV proton beam in a water-bone phantom and a pelvic case. We also computed the 3D LETd distributions for multiple proton beam spots in the pelvic case and a lung case. The results of our method were compared with the results of MC simulations, demonstrating that our method can rapidly provide 3D LETd distributions of clinical cases with acceptable differences from MC simulations.
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Affiliation(s)
- Nan Yan
- Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Chao Wu
- Medical Equipment Innovation Research Center, West China School of Medicine, Med+X Center for Manufacturing, West China Hospital, Sichuan University, Chengdu 610041, China
| | - Yun Zhou
- Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Wentao Liao
- Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Junya Liu
- Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yuehu Pu
- Medical Equipment Innovation Research Center, West China School of Medicine, Med+X Center for Manufacturing, West China Hospital, Sichuan University, Chengdu 610041, China
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Vieceli M, Park J, Hsi WC, Saki M, Mendenhall NP, Johnson P, Artz M. Potential Therapeutic Improvements in Prostate Cancer Treatment Using Pencil Beam Scanning Proton Therapy with LET d Optimization and Disease-Specific RBE Models. Cancers (Basel) 2024; 16:780. [PMID: 38398171 PMCID: PMC10886728 DOI: 10.3390/cancers16040780] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2024] [Revised: 02/11/2024] [Accepted: 02/12/2024] [Indexed: 02/25/2024] Open
Abstract
PURPOSE To demonstrate the feasibility of improving prostate cancer patient outcomes with PBS proton LETd optimization. METHODS SFO, IPT-SIB, and LET-optimized plans were created for 12 patients, and generalized-tissue and disease-specific LET-dependent RBE models were applied. The mean LETd in several structures was determined and used to calculate mean RBEs. LETd- and dose-volume histograms (LVHs/DVHs) are shown. TODRs were defined based on clinical dose goals and compared between plans. The impact of robust perturbations on LETd, TODRs, and DVH spread was evaluated. RESULTS LETd optimization achieved statistically significant increased target volume LETd of ~4 keV/µm compared to SFO and IPT-SIB LETd of ~2 keV/µm while mitigating OAR LETd increases. A disease-specific RBE model predicted target volume RBEs > 1.5 for LET-optimized plans, up to 18% higher than for SFO plans. LET-optimized target LVHs/DVHs showed a large increase not present in OARs. All RBE models showed a statistically significant increase in TODRs from SFO to IPT-SIB to LET-optimized plans. RBE = 1.1 does not accurately represent TODRs when using LETd optimization. Robust evaluations demonstrated a trade-off between increased mean target LETd and decreased DVH spread. CONCLUSION The demonstration of improved TODRs provided via LETd optimization shows potential for improved patient outcomes.
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Affiliation(s)
- Michael Vieceli
- University of Florida Health Proton Therapy Institute, Jacksonville, FL 32206, USA
- Medical Physics Graduate Program, University of Florida College of Medicine, Gainesville, FL 32610, USA
| | - Jiyeon Park
- University of Florida Health Proton Therapy Institute, Jacksonville, FL 32206, USA
- Department of Radiation Oncology, University of Florida College of Medicine, Gainesville, FL 32610, USA
| | - Wen Chien Hsi
- University of Florida Health Proton Therapy Institute, Jacksonville, FL 32206, USA
- Department of Radiation Oncology, University of Florida College of Medicine, Gainesville, FL 32610, USA
| | - Mo Saki
- University of Florida Health Proton Therapy Institute, Jacksonville, FL 32206, USA
- Department of Radiation Oncology, University of Florida College of Medicine, Gainesville, FL 32610, USA
| | - Nancy P Mendenhall
- University of Florida Health Proton Therapy Institute, Jacksonville, FL 32206, USA
- Department of Radiation Oncology, University of Florida College of Medicine, Gainesville, FL 32610, USA
| | - Perry Johnson
- University of Florida Health Proton Therapy Institute, Jacksonville, FL 32206, USA
- Department of Radiation Oncology, University of Florida College of Medicine, Gainesville, FL 32610, USA
| | - Mark Artz
- University of Florida Health Proton Therapy Institute, Jacksonville, FL 32206, USA
- Department of Radiation Oncology, University of Florida College of Medicine, Gainesville, FL 32610, USA
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Sebastián SM, Alejandro C, Ignacio E, Sophia G, Pía VM, Andrea R. Monte Carlo simulations of cell survival in proton SOBP. Phys Med Biol 2023; 68:195024. [PMID: 37673077 DOI: 10.1088/1361-6560/acf752] [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: 06/28/2023] [Accepted: 09/06/2023] [Indexed: 09/08/2023]
Abstract
Objective. The objective of this study is to develop a multi-scale modeling approach that accurately predicts radiation-induced DNA damage and survival fraction in specific cell lines.Approach. A Monte Carlo based simulation framework was employed to make the predictions. The FLUKA Monte Carlo code was utilized to estimate absorbed doses and fluence energy spectra, which were then used in the Monte Carlo Damage Simulation code to compute DNA damage yields in Chinese hamster V79 cell lines. The outputs were converted into cell survival fractions using a previously published theoretical model. To reduce the uncertainties of the predictions, new values for the parameters of the theoretical model were computed, expanding the database of experimental points considered in the previous estimation. Simulated results were validated against experimental data, confirming the applicability of the framework for proton beams up to 230 MeV. Additionally, the impact of secondary particles on cell survival was estimated.Main results. The simulated survival fraction versus depth in a glycerol phantom is reported for eighteen different configurations. Two proton spread out Bragg peaks at several doses were simulated and compared with experimental data. In all cases, the simulations follow the experimental trends, demonstrating the accuracy of the predictions up to 230 MeV.Significance. This study holds significant importance as it contributes to the advancement of models for predicting biological responses to radiation, ultimately contributing to more effective cancer treatment in proton therapy.
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Affiliation(s)
| | - Carabe Alejandro
- Hampton University Proton Therapy Institute, 40 Enterprise Pkwy Hampton, VA 2366, United States of America
| | - Espinoza Ignacio
- Instituto de Física, Pontificia Universidad Católica de Chile, 7820436 Santiago, Chile
| | - Galvez Sophia
- Instituto de Física, Pontificia Universidad Católica de Chile, 7820436 Santiago, Chile
| | - Valenzuela María Pía
- Instituto de Física, Pontificia Universidad Católica de Chile, 7820436 Santiago, Chile
| | - Russomando Andrea
- Instituto de Física, Pontificia Universidad Católica de Chile, 7820436 Santiago, Chile
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Jeong S, Kim C, An S, Kwon YC, Pak SI, Cheon W, Shin D, Lim Y, Jeong JH, Kim H, Lee SB. Determination of the proton LET using thin film solar cells coated with scintillating powder. Med Phys 2023; 50:1194-1204. [PMID: 36135795 DOI: 10.1002/mp.15977] [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: 03/04/2022] [Revised: 08/30/2022] [Accepted: 08/30/2022] [Indexed: 11/08/2022] Open
Abstract
PURPOSE The amount of luminescent light detected in a scintillator is reduced with increased proton linear energy transfer (LET) despite receiving the same proton dose, through a phenomenon called quenching. This study evaluated the ability of a solar cell coated with scintillating powder (SC-SP) to measure therapeutic proton LET by measuring the quenching effect of the scintillating powder using a solar cell while simultaneously measuring the dose of the proton beam. METHODS SC-SP was composed of a flexible thin film solar cell and scintillating powder. The LET and dose of the pristine Bragg peak in the 14 cm range were calculated using a validated Monte Carlo model of a double scattering proton beam nozzle. The SC-SP was evaluated by measuring the proton beam under the same conditions at specific depths using SC-SP and Markus chamber. Finally, the 10 and 20 cm range pristine Bragg peaks and 5 cm spread-out Bragg peak (SOBP) in the 14 cm range were measured using the SC-SP and the Markus chamber. LETs measured using the SC-SP were compared with those calculated using Monte Carlo simulations. RESULTS The quenching factors of the SC-SP and solar cell alone, which were slopes of linear fit obtained from quenching correction factors according to LET, were 0.027 and 0.070 µm/keV (R2 : 0.974 and 0.975). For pristine Bragg peaks in the 10 and 20 cm ranges, the maximum differences between LETs measured using the SC-SP and calculated using Monte Carlo simulations were 0.5 keV/µm (15.7%) and 1.2 keV/µm (12.0%), respectively. For a 5 cm SOBP proton beam, the LET measured using the SC-SP and calculated using Monte Carlo simulations differed by up to 1.9 keV/µm (18.7%). CONCLUSIONS Comparisons of LETs for pristine Bragg peaks and SOBP between measured using the SC-SP and calculated using Monte Carlo simulations indicated that the solar cell-based system could simultaneously measure both LET and dose in real-time and is cost-effective.
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Affiliation(s)
- Seonghoon Jeong
- Proton Therapy Center, National Cancer Center, Goyang, Korea
| | - Chankyu Kim
- Proton Therapy Center, National Cancer Center, Goyang, Korea
| | - Seohyeon An
- Proton Therapy Center, National Cancer Center, Goyang, Korea.,Department of Physics, Hanyang University, Seoul, Korea
| | - Yong-Cheol Kwon
- Department of Radiation Oncology, Samsung Medical Center, Seoul, Korea
| | - Sang-Il Pak
- Proton Therapy Center, National Cancer Center, Goyang, Korea
| | - Wonjoong Cheon
- Proton Therapy Center, National Cancer Center, Goyang, Korea
| | - Dongho Shin
- Proton Therapy Center, National Cancer Center, Goyang, Korea
| | - Youngkyung Lim
- Proton Therapy Center, National Cancer Center, Goyang, Korea
| | - Jong Hwi Jeong
- Proton Therapy Center, National Cancer Center, Goyang, Korea
| | - Haksoo Kim
- Proton Therapy Center, National Cancer Center, Goyang, Korea
| | - Se Byeong Lee
- Proton Therapy Center, National Cancer Center, Goyang, Korea
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Rana S, Traneus E, Jackson M, Tran L, Rosenfeld AB. Quantitative analysis of dose-averaged linear energy transfer (LET d ) robustness in pencil beam scanning proton lung plans. Med Phys 2022; 49:3444-3456. [PMID: 35194809 DOI: 10.1002/mp.15569] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Revised: 02/14/2022] [Accepted: 02/14/2022] [Indexed: 11/09/2022] Open
Abstract
PURPOSE The primary objective of our study was to perform a quantitative robustness analysis of the dose-averaged linear energy transfer (LETd ) and related RBE-weighted dose in robustly optimized (in terms of the range and set up uncertainties) pencil beam scanning (PBS) proton lung cancer plans. METHODS In this study, we utilized the 4DCT data set of six anonymized lung patients. PBS lung plans were generated using a robust optimization technique (range uncertainty: ±3.5% and setup errors: ±5 mm) on the CTV for a total dose of 5000 cGy(RBE) in 5 fractions using RBE of 1.1. For each patient, the LETd distributions were calculated for the nominal plan and three groups. Group 1: two plan robustness scenarios for range uncertainties of ±3.5%; Group 2: twelve plan robustness scenarios (range uncertainty (±3.5%) in conjunction with setup errors (±5 mm)); and Group 3: ten different breathing phases of the 4DCT data set. RBE-weighted dose to the OARs was evaluated for all robustness scenarios and breathing phases. The variation (∆) in the mean LETd and mean RBE-weighted dose from each group was recorded. RESULTS The mean LETd in the CTV of nominal PBS lung plans among six patients ranged from 2.2 to 2.6 keV/μm. On average, for the combined range and setup uncertainties, the ∆ in the mean LETd among 12 scenarios of all six patients was 0.6 keV/μm, which is slightly higher than when only the range uncertainties were considered (0.4 keV/μm). The ∆ in the mean LETd in a patient was ≤1.7 keV/μm in the heart and ≤1.2 keV/μm in the esophagus and total lung. The ∆ in the mean RBE-weighted dose in a patient was up to 79 cGy for the total lung, 165 cGy for the heart, and 258 cGy for the esophagus. For ten breathing phases, the ∆ in the mean LETd in a patient was ≤0.3 keV/μm in the CTV, ≤0.5 keV/μm in the heart, ≤0.4 keV/μm in the esophagus, and ≤0.7 keV/μm in the total lung. CONCLUSION The addition of setup errors to the range uncertainties resulted in slightly less homogeneous LETd distributions. The variations in the mean LETd among ten breathing phases were slightly larger in the total lung than in the heart and esophagus. The combination of setup and range uncertainties had a greater impact than the effect of breathing phases on the variations in the mean RBE-weighted dose to the OARs. Overall, the LETd distributions in the CTV were less sensitive than those in the OARs to setup errors, range uncertainties, and breathing phases for robustly optimized PBS proton lung cancer plans. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Suresh Rana
- Department of Radiation Oncology, Lynn Cancer Institute, Boca Raton Regional Hospital, Baptist Health South Florida, Boca Raton, Florida, USA.,Department of Medical Physics, The Oklahoma Proton Center, Oklahoma City, Oklahoma, USA.,Centre for Medical Radiation Physics (CMRP), University of Wollongong, Wollongong, NSW, Australia
| | - Erik Traneus
- RaySearch Laboratories, Medical Physics, Stockholm, Sweden
| | - Michael Jackson
- Prince of Wales Hospital, Radiation Oncology, Randwick, Australia
| | - Linh Tran
- Centre for Medical Radiation Physics (CMRP), University of Wollongong, Wollongong, NSW, Australia
| | - Anatoly B Rosenfeld
- Centre for Medical Radiation Physics (CMRP), University of Wollongong, Wollongong, NSW, Australia
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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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10
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Engeseth GM, Hysing LB, Yepes P, Pettersen HES, Mohan R, Fuller CD, Stokkevåg CH, Wu R, Zhang X, Frank SJ, Gunn GB. Impact of RBE variations on risk estimates of temporal lobe necrosis in patients treated with intensity-modulated proton therapy for head and neck cancer. Acta Oncol 2022; 61:215-222. [PMID: 34534047 PMCID: PMC9969227 DOI: 10.1080/0284186x.2021.1979248] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
BACKGROUND Temporal lobe necrosis (TLN) is a potential late effect after radiotherapy for skull base head and neck cancer (HNC). Several photon-derived dose constraints and normal tissue complication probability (NTCP) models have been proposed, however variation in relative biological effectiveness (RBE) may challenge the applicability of these dose constraints and models in proton therapy. The purpose of this study was therefore to investigate the influence of RBE variations on risk estimates of TLN after Intensity-Modulated Proton Therapy for HNC. MATERIAL AND METHODS Seventy-five temporal lobes from 45 previously treated patients were included in the analysis. Sixteen temporal lobes had radiation associated Magnetic Resonance image changes (TLIC) suspected to be early signs of TLN. Fixed (RWDFix) and variable RBE-weighed doses (RWDVar) were calculated using RBE = 1.1 and two RBE models, respectively. RWDFix and RWDVar for temporal lobes were compared using Friedman's test. Based on RWDFix, six NTCP models were fitted and internally validated through bootstrapping. Estimated probabilities from RWDFix and RWDVar were compared using paired Wilcoxon test. Seven dose constraints were evaluated separately for RWDFix and RWDVar by calculating the observed proportion of TLIC in temporal lobes meeting the specific dose constraints. RESULTS RWDVar were significantly higher than RWDFix (p < 0.01). NTCP model performance was good (AUC:0.79-0.84). The median difference in estimated probability between RWDFix and RWDVar ranged between 5.3% and 20.0% points (p < 0.01), with V60GyRBE and DMax at the smallest and largest differences, respectively. The proportion of TLIC was higher for RWDFix (4.0%-13.1%) versus RWDVar (1.3%-5.3%). For V65GyRBE ≤ 0.03 cc the proportion of TLIC was less than 5% for both RWDFix and RWDVar. CONCLUSION NTCP estimates were significantly influenced by RBE variations. Dmax as model predictor resulted in the largest deviations in risk estimates between RWDFix and RWDVar. V65GyRBE ≤ 0.03 cc was the most consistent dose constraint for RWDFix and RWDVar.
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Affiliation(s)
- Grete May Engeseth
- University of Texas MD Anderson Cancer Center, Department of Radiation Oncology, Houston, USA,Haukeland University Hospital, Department of Oncology and Medical Physics, Bergen, Norway,University of Bergen, Department of Clinical Science, Bergen, Norway,Corresponding author: Grete May Engeseth, , Haukeland University Hospital, Department of Oncology and Medical Physics, Postboks 1400, 5021 Bergen
| | - Liv Bolstad Hysing
- Haukeland University Hospital, Department of Oncology and Medical Physics, Bergen, Norway,University of Bergen, Department of Physics and Technology, Bergen, Norway
| | - Pablo Yepes
- Rice University, Physics and Astronomy Department, Houston, USA
| | | | - Rahde Mohan
- University of Texas MD Anderson Cancer Center, Department of Radiation Physics, Houston, USA
| | - Clifton Dave Fuller
- University of Texas MD Anderson Cancer Center, Department of Radiation Oncology, Houston, USA
| | - Camilla Hanquist Stokkevåg
- Haukeland University Hospital, Department of Oncology and Medical Physics, Bergen, Norway,University of Bergen, Department of Physics and Technology, Bergen, Norway
| | - Richard Wu
- University of Texas MD Anderson Cancer Center, Department of Radiation Oncology, Houston, USA
| | - Xiaodong Zhang
- University of Texas MD Anderson Cancer Center, Department of Radiation Oncology, Houston, USA
| | - Steven Jay Frank
- University of Texas MD Anderson Cancer Center, Department of Radiation Oncology, Houston, USA
| | - Gary Brandon Gunn
- University of Texas MD Anderson Cancer Center, Department of Radiation Oncology, Houston, USA
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11
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Paganetti H. Mechanisms and Review of Clinical Evidence of Variations in Relative Biological Effectiveness in Proton Therapy. Int J Radiat Oncol Biol Phys 2022; 112:222-236. [PMID: 34407443 PMCID: PMC8688199 DOI: 10.1016/j.ijrobp.2021.08.015] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Revised: 07/14/2021] [Accepted: 08/10/2021] [Indexed: 01/03/2023]
Abstract
Proton therapy is increasingly being used as a radiation therapy modality. There is uncertainty about the biological effectiveness of protons relative to photon therapies as it depends on several physical and biological parameters. Radiation oncology currently applies a constant and generic value for the relative biological effectiveness (RBE) of 1.1, which was chosen conservatively to ensure tumor coverage. The use of a constant value has been challenged particularly when considering normal tissue constraints. Potential variations in RBE have been assessed in several published reviews but have mostly focused on data from clonogenic cell survival experiments with unclear relevance for clinical proton therapy. The goal of this review is to put in vitro findings in relation to clinical observations. Relevant in vivo pathways determining RBE for tumors and normal tissues are outlined, including not only damage to tumor cells and parenchyma but also vascular damage and immune response. Furthermore, the current clinical evidence of varying RBE is reviewed. The assessment can serve as guidance for treatment planning, personalized dose prescriptions, and outcome analysis.
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Affiliation(s)
- Harald Paganetti
- Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, MA.
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12
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Therapeutic Efficacy of Variable Biological Effectiveness of Proton Therapy in U-CH2 and MUG-Chor1 Human Chordoma Cell Death. Cancers (Basel) 2021; 13:cancers13236115. [PMID: 34885223 PMCID: PMC8656796 DOI: 10.3390/cancers13236115] [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: 07/16/2021] [Revised: 11/22/2021] [Accepted: 11/30/2021] [Indexed: 12/05/2022] Open
Abstract
Simple Summary Chordoma is a rare, slow-growing cancer of the spinal cord. Photon radiation therapy and surgery are the standard of care for chordoma. Proton radiation therapy has become an increasingly common treatment in comparison to photon radiation therapy due to the ability to reduce off-target radiation dose. However, there is still an increased risk of toxicity to the surrounding critical structures that lead to poor treatment outcomes. Moreover, the biologic effectiveness of protons to sterilize chordoma cells remains uncertain and likely varies according to the proton energy spectrum throughout the proton field. We aim to investigate the tumoricidal properties of proton radiation therapy at the middle and end of the proton radiation field and elucidate variations in the relative biological effectiveness for chordoma cells. Our study helps quantify the therapeutic value of treating chordoma near the end of the proton field, where linear energy transfer is relatively high. Abstract Background: Chordoma is a cancer of spinal cord, skull base, and sacral area. Currently, the standard of care to treat chordoma is resection followed by radiation therapy. Since, chordoma is present in the spinal cord and these are very sensitive structures and often complete removal by surgery is not possible. As a result, chordoma has a high chance of recurrence and developing resistance to radiation therapy. In addition, treatment of chordoma by conventional radiation therapy can also damage normal tissues surrounding chordoma. Thus, current therapeutic options to treat chordoma are insufficient and novel therapies are desperately needed to treat locally advanced and metastatic chordoma. (2) Methods: In the present investigation, human chordoma cell lines of sacral origin MUG-Chor1 and U-CH2 were cultured and irradiated with Proton Beam Radiation using the clinical superconducting cyclotron and pencil-beam (active) scanning at Middle and End of the Spread-Out Bragg Peak (SOBP). Proton radiation was given at the following doses: Mug-Chor1 at 0, 1, 2, 4, and 8 Gy and U-CH2 at 0, 4, 8, 12, and 16 Gy. These doses were selected based on a pilot study in our lab and attempted to produce approximate survival fractions in the range of 1, 0.9, 0.5, 0.1, and 0.01, respectively, chosen for linear quadratic model fitting of the dose response. (3) Results: In this study, we investigated relative biological effectiveness (RBE) of proton radiation at the end of Spread Out Bragg Peak assuming that the reference radiation is a proton radiation in the middle of the SOBP. We observed differences in the survival of both Human chordoma cell lines, U-CH2 and MUG-Chor1. The data showed that there was a significantly higher cell death at the end of the Bragg peak as compared to middle of the Bragg peak. Based on the linear quadratic (LQ) fit for cell survival we calculated the RBE between M-SOBP and E-SOBP at 95% CI level and it was observed that RBE was higher than 1 at E-SOBP and caused significantly higher cell killing. Proton field at E-SOBP caused complex DNA damage in comparison to M-EOBP and the genes such as DNA topoisomerase 1, GTSE1, RAD51B were downregulated in E-SOBP treated cells. Thus, we conclude that there seems to be substantial variation in RBE (1.3–1.7) at the E-SOBP compared with the M-SOBP.
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13
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Dell'Oro M, Wilson P, Short M, Hua CH, Merchant TE, Bezak E. Normal tissue complication probability modeling to guide individual treatment planning in pediatric cranial proton and photon radiotherapy. Med Phys 2021; 49:742-755. [PMID: 34796509 DOI: 10.1002/mp.15360] [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: 07/05/2021] [Revised: 11/05/2021] [Accepted: 11/09/2021] [Indexed: 11/10/2022] Open
Abstract
PURPOSE Proton therapy (PT) is broadly accepted as the gold standard of care for pediatric patients with cranial cancer. The superior dose distribution of PT compared to photon radiotherapy reduces normal tissue complication probability (NTCP) for organs at risk. As NTCPs for pediatric organs are not well understood, clinics generally base radiation response on adult data. However, there is evidence that radiation response strongly depends on the age and even sex of a patient. Furthermore, questions surround the influence of individual intrinsic radiosensitivity (α/β ratio) on pediatric NTCP. While the clinical pediatric NTCP data is scarce, radiobiological modeling and sensitivity analyses can be used to investigate the NTCP trends and its dependence on individual modeling parameters. The purpose of this study was to perform sensitivity analyses of NTCP models to ascertain the dependence of radiosensitivity, sex, and age of a child and predict cranial side-effects following intensity-modulated proton therapy (IMPT) and intensity-modulated radiotherapy (IMRT). METHODS Previously, six sex-matched pediatric cranial datasets (5, 9, and 13 years old) were planned in Varian Eclipse treatment planning system (13.7). Up to 108 scanning beam IMPT plans and 108 IMRT plans were retrospectively optimized for a range of simulated target volumes and locations. In this work, dose-volume histograms were extracted and imported into BioSuite Software for radiobiological modeling. Relative-Seriality and Lyman-Kutcher-Burman models were used to calculate NTCP values for toxicity endpoints, where TD50, (based on reported adult clinical data) was varied to simulate sex dependence of NTCP. Plausible parameter ranges, based on published literature for adults, were used in modeling. In addition to sensitivity analyses, a 20% difference in TD50 was used to represent the radiosensitivity between the sexes (with females considered more radiosensitive) for ease of data comparison as a function of parameters such as α/β ratio. RESULTS IMPT plans resulted in lower NTCP compared to IMRT across all models (p < 0.0001). For medulloblastoma treatment, the risk of brainstem necrosis (> 10%) and cochlea tinnitus (> 20%) among females could potentially be underestimated considering a lower TD50 value for females. Sensitivity analyses show that the difference in NTCP between sexes was significant (p < 0.0001). Similarly, both brainstem necrosis and cochlea tinnitus NTCP varied significantly (p < 0.0001) across tested α/β as a function of TD50 values (assumption being that TD50 values are 20% lower in females). If the true α/β of these pediatric tissues is higher than expected (α/β ∼ 3), the risk of tinnitus for IMRT can significantly increase (p < 0.0001). CONCLUSION Due to the scarcity of pediatric NTCP data available, sensitivity analyses were performed using plausible ranges based on published adult data. In the clinical scenario where, if female pediatric patients were 20% more radiosensitive (lower TD50 value), they could be up to twice as likely to experience side-effects of brainstem necrosis and cochlea tinnitus compared to males, highlighting the need for considering the sex in NTCP models. Based on our sensitivity analyses, age and sex of a pediatric patient could significantly affect the resultant NTCP from cranial radiotherapy, especially at higher α/β values.
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Affiliation(s)
- Mikaela Dell'Oro
- Cancer Research Institute, University of South Australia, Adelaide, Australia.,Department of Radiation Oncology, Royal Adelaide Hospital, Adelaide, Australia
| | - Puthenparampil Wilson
- Department of Radiation Oncology, Royal Adelaide Hospital, Adelaide, Australia.,UniSA STEM, University of South Australia, Adelaide, Australia
| | - Michala Short
- Cancer Research Institute, University of South Australia, Adelaide, Australia
| | - Chia-Ho Hua
- Department of Radiation Oncology, St. Jude Children's Research Hospital, Memphis, Tennessee, USA
| | - Thomas E Merchant
- Department of Radiation Oncology, St. Jude Children's Research Hospital, Memphis, Tennessee, USA
| | - Eva Bezak
- Cancer Research Institute, University of South Australia, Adelaide, Australia.,Department of Physics, University of Adelaide, Adelaide, Australia
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14
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Howard ME, Denbeigh JM, Debrot EK, Garcia DA, Remmes NB, Herman MG, Beltran CJ. Dosimetric Assessment of a High Precision System for Mouse Proton Irradiation to Assess Spinal Cord Toxicity. Radiat Res 2021; 195:541-548. [PMID: 33826742 DOI: 10.1667/rade-20-00153.1] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2020] [Accepted: 03/11/2021] [Indexed: 11/03/2022]
Abstract
The uncertainty associated with the relative biological effectiveness (RBE) in proton therapy, particularly near the Bragg peak (BP), has led to the shift towards biological-based treatment planning. Proton RBE uncertainty has recently been reported as a possible cause for brainstem necrosis in pediatric patients treated with proton therapy. Despite this, in vivo studies have been limited due to the complexity of accurate delivery and absolute dosimetry. The purpose of this investigation was to create a precise and efficient method of treating the mouse spinal cord with various portions of the proton Bragg curve and to quantify associated uncertainties for the characterization of proton RBE. Mice were restrained in 3D printed acrylic boxes, shaped to their external contour, with a silicone insert extending down to mold around the mouse. Brass collimators were designed for parallel opposed beams to treat the spinal cord while shielding the brain and upper extremities of the animal. Up to six animals may be accommodated for simultaneous treatment within the restraint system. Two plans were generated targeting the cervical spinal cord, with either the entrance (ENT) or the BP portion of the beam. Dosimetric uncertainty was measured using EBT3 radiochromic film with a dose-averaged linear energy transfer (LETd) correction. Positional uncertainty was assessed by collecting a library of live mouse scans (n = 6 mice, two independent scans per mouse) and comparing the following dosimetric statistics from the mouse cervical spinal cord: Volume receiving 90% of the prescription dose (V90); mean dose to the spinal cord; and LETd. Film analysis results showed the dosimetric uncertainty to be ±1.2% and ±5.4% for the ENT and BP plans, respectively. Preliminary results from the mouse library showed the V90 to be 96.3 ± 4.8% for the BP plan. Positional uncertainty of the ENT plan was not measured due to the inherent robustness of that treatment plan. The proposed high-throughput mouse proton irradiation setup resulted in accurate dose delivery to mouse spinal cords positioned along the ENT and BP. Future directions include adapting the setup to account for weight fluctuations in mice undergoing fractionated irradiation.
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Affiliation(s)
| | - Janet M Denbeigh
- Department of Radiation Oncology, Mayo Clinic, Rochester, Minnesota
| | | | - Darwin A Garcia
- Department of Radiation Oncology, Mayo Clinic, Rochester, Minnesota
| | | | - Michael G Herman
- Department of Radiation Oncology, Mayo Clinic, Rochester, Minnesota
| | - Chris J Beltran
- Department of Radiation Oncology, Mayo Clinic, Rochester, Minnesota
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15
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Yang Y, Vargas CE, Bhangoo RS, Wong WW, Schild SE, Daniels TB, Keole SR, Rwigema JCM, Glass JL, Shen J, DeWees TA, Liu T, Bues M, Fatyga M, Liu W. Exploratory Investigation of Dose-Linear Energy Transfer (LET) Volume Histogram (DLVH) for Adverse Events Study in Intensity Modulated Proton Therapy (IMPT). Int J Radiat Oncol Biol Phys 2021; 110:1189-1199. [PMID: 33621660 DOI: 10.1016/j.ijrobp.2021.02.024] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Revised: 01/25/2021] [Accepted: 02/11/2021] [Indexed: 02/06/2023]
Abstract
PURPOSE We proposed a novel tool-a dose linear energy transfer (LET)-volume histogram (DLVH)-and performed an exploratory study to investigate rectal bleeding in prostate cancer treated with intensity modulated proton therapy. METHODS AND MATERIALS The DLVH was constructed with dose and LET as 2 axes, and the normalized volume of the structure was contoured in the dose-LET plane as isovolume lines. We defined the DLVH index, DLv%(d,l) (ie, v% of the structure) to have a dose of ≥d Gy and an LET of ≥l keV/μm, similar to the dose-volume histogram index Dv%. Nine patients with prostate cancer with rectal bleeding (Common Terminology Criteria for Adverse Events grade ≥2) were included as the adverse event group, and 48 patients with no complications were considered the control group. A P value map was constructed by comparison of the DLVH indices of all patients between the 2 groups using the Mann-Whitney U test. Dose-LET volume constraints (DLVCs) were derived based on the P value map with a manual selection procedure facilitated by Spearman's correlation tests. The obtained DLVCs were further cross-validated using a multivariate support vector machine (SVM)-based normal tissue complication probability (NTCP) model with an independent testing data set composed of 8 adverse event and 13 control patients. RESULTS We extracted 2 DLVC constraints. One DLVC was obtained, Vdose/LETboundary:2.5keVμmat 75 Gy to 3.2keVμmat8.65Gy <1.27% (DLVC1), revealing a high LET volume effect. The second DLVC, V(72.2Gy,0keVμm) < 2.23% (DVLC2), revealed a high dose volume effect. The SVM-based NTCP model with 2 DLVCs provided slightly superior performance than using dose only, with an area under the curve of 0.798 versus 0.779 for the testing data set. CONCLUSIONS Our results demonstrated the importance of rectal "hot spots" in both high LET (DLVC1) and high dose (DLVC2) in inducing rectal bleeding. The SVM-based NTCP model confirmed the derived DLVCs as good predictors for rectal bleeding when intensity modulated proton therapy is used to treat prostate cancer.
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Affiliation(s)
- Yunze Yang
- Department of Radiation Oncology, Mayo Clinic Arizona, Phoenix, Arizona
| | - Carlos E Vargas
- Department of Radiation Oncology, Mayo Clinic Arizona, Phoenix, Arizona
| | - Ronik S Bhangoo
- Department of Radiation Oncology, Mayo Clinic Arizona, Phoenix, Arizona
| | - William W Wong
- Department of Radiation Oncology, Mayo Clinic Arizona, Phoenix, Arizona
| | - Steven E Schild
- Department of Radiation Oncology, Mayo Clinic Arizona, Phoenix, Arizona
| | - Thomas B Daniels
- Department of Radiation Oncology, Mayo Clinic Arizona, Phoenix, Arizona
| | - Sameer R Keole
- Department of Radiation Oncology, Mayo Clinic Arizona, Phoenix, Arizona
| | | | - Jennifer L Glass
- Department of Radiation Oncology, Mayo Clinic Arizona, Phoenix, Arizona
| | - Jiajian Shen
- Department of Radiation Oncology, Mayo Clinic Arizona, Phoenix, Arizona
| | - Todd A DeWees
- Division of Biostatics, Mayo Clinic Arizona, Phoenix, Arizona
| | - Tianming Liu
- Department of Computer Science, the University of Georgia, Athens, Georgia
| | - Martin Bues
- Department of Radiation Oncology, Mayo Clinic Arizona, Phoenix, Arizona
| | - Mirek Fatyga
- Department of Radiation Oncology, Mayo Clinic Arizona, Phoenix, Arizona
| | - Wei Liu
- Department of Radiation Oncology, Mayo Clinic Arizona, Phoenix, Arizona.
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16
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Li X, Ding X, Zheng W, Liu G, Janssens G, Souris K, Barragán-Montero AM, Yan D, Stevens C, Kabolizadeh P. Linear Energy Transfer Incorporated Spot-Scanning Proton Arc Therapy Optimization: A Feasibility Study. Front Oncol 2021; 11:698537. [PMID: 34327139 PMCID: PMC8313436 DOI: 10.3389/fonc.2021.698537] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2021] [Accepted: 06/22/2021] [Indexed: 02/02/2023] Open
Abstract
Purpose To integrate dose-averaged linear energy transfer (LETd) into spot-scanning proton arc therapy (SPArc) optimization and to explore its feasibility and potential clinical benefits. Methods An open-source proton planning platform (OpenREGGUI) has been modified to incorporate LETd into optimization for both SPArc and multi-beam intensity-modulated proton therapy (IMPT) treatment planning. SPArc and multi-beam IMPT plans with different beam configurations for a prostate patient were generated to investigate the feasibility of LETd-based optimization using SPArc in terms of spatial LETd distribution and plan delivery efficiency. One liver and one brain case were studied to further evaluate the advantages of SPArc over multi-beam IMPT. Results With similar dose distributions, the efficacy of spatially optimizing LETd distributions improves with increasing number of beams. Compared with multi-beam IMPT plans, SPArc plans show substantial improvement in LETd distributions while maintaining similar delivery efficiency. Specifically, for the liver case, the average LETd in the GTV was increased by 124% for the SPArc plan, and only 9.6% for the 2-beam IMPT plan compared with the 2-beam non-LETd optimized IMPT plan. In case of LET optimization for the brain case, the SPArc plan could effectively increase the average LETd in the CTV and decrease the values in the critical structures while smaller improvement was observed in 3-beam IMPT plans. Conclusion This work demonstrates the feasibility and significant advantages of using SPArc for LETd-based optimization, which could maximize the LETd distribution wherever is desired inside the target and averts the high LETd away from the adjacent critical organs-at-risk.
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Affiliation(s)
- Xiaoqiang Li
- Department of Radiation Oncology, Beaumont Health System, Royal Oak, MI, United States
| | - Xuanfeng Ding
- Department of Radiation Oncology, Beaumont Health System, Royal Oak, MI, United States
| | - Weili Zheng
- Department of Radiation Oncology, Beaumont Health System, Royal Oak, MI, United States
| | - Gang Liu
- Department of Radiation Oncology, Beaumont Health System, Royal Oak, MI, United States.,Cancer Center, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Guillaume Janssens
- Advanced Technology Group, Ion Beam Applications SA, Louvain-la-Neuve, Belgium
| | - Kevin Souris
- Center for Molecular Imaging and Experimental Radiotherapy, Institut de Recherche Expérimentale et Clinique, UCLouvain, Brussels, Belgium
| | - Ana M Barragán-Montero
- Center for Molecular Imaging and Experimental Radiotherapy, Institut de Recherche Expérimentale et Clinique, UCLouvain, Brussels, Belgium
| | - Di Yan
- Department of Radiation Oncology, Beaumont Health System, Royal Oak, MI, United States
| | - Craig Stevens
- Department of Radiation Oncology, Beaumont Health System, Royal Oak, MI, United States
| | - Peyman Kabolizadeh
- Department of Radiation Oncology, Beaumont Health System, Royal Oak, MI, United States
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17
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Deng W, Yang Y, Liu C, Bues M, Mohan R, Wong WW, Foote RH, Patel SH, Liu W. A Critical Review of LET-Based Intensity-Modulated Proton Therapy Plan Evaluation and Optimization for Head and Neck Cancer Management. Int J Part Ther 2021; 8:36-49. [PMID: 34285934 PMCID: PMC8270082 DOI: 10.14338/ijpt-20-00049.1] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Accepted: 10/14/2020] [Indexed: 12/15/2022] Open
Abstract
In this review article, we review the 3 important aspects of linear-energy-transfer (LET) in intensity-modulated proton therapy (IMPT) for head and neck (H&N) cancer management. Accurate LET calculation methods are essential for LET-guided plan evaluation and optimization, which can be calculated either by analytical methods or by Monte Carlo (MC) simulations. Recently, some new 3D analytical approaches to calculate LET accurately and efficiently have been proposed. On the other hand, several fast MC codes have also been developed to speed up the MC simulation by simplifying nonessential physics models and/or using the graphics processor unit (GPU)–acceleration approach. Some concepts related to LET are also briefly summarized including (1) dose-weighted versus fluence-weighted LET; (2) restricted versus unrestricted LET; and (3) microdosimetry versus macrodosimetry. LET-guided plan evaluation has been clinically done in some proton centers. Recently, more and more studies using patient outcomes as the biological endpoint have shown a positive correlation between high LET and adverse events sites, indicating the importance of LET-guided plan evaluation in proton clinics. Various LET-guided plan optimization methods have been proposed to generate proton plans to achieve biologically optimized IMPT plans. Different optimization frameworks were used, including 2-step optimization, 1-step optimization, and worst-case robust optimization. They either indirectly or directly optimize the LET distribution in patients while trying to maintain the same dose distribution and plan robustness. It is important to consider the impact of uncertainties in LET-guided optimization (ie, LET-guided robust optimization) in IMPT, since IMPT is sensitive to uncertainties including both the dose and LET distributions. We believe that the advancement of the LET-guided plan evaluation and optimization will help us exploit the unique biological characteristics of proton beams to improve the therapeutic ratio of IMPT to treat H&N and other cancers.
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Affiliation(s)
- Wei Deng
- Department of Radiation Oncology, Mayo Clinic, Phoenix, AZ, USA
| | - Yunze Yang
- Department of Radiation Oncology, Mayo Clinic, Phoenix, AZ, USA
| | - Chenbin Liu
- Department of Radiation Oncology, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital & Shenzhen Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Shenzhen, Guangdong, China
| | - Martin Bues
- Department of Radiation Oncology, Mayo Clinic, Phoenix, AZ, USA
| | - Radhe Mohan
- Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - William W Wong
- Department of Radiation Oncology, Mayo Clinic, Phoenix, AZ, USA
| | - Robert H Foote
- Department of Radiation Oncology, Mayo Clinic, Rochester, MN, USA
| | - Samir H Patel
- Department of Radiation Oncology, Mayo Clinic, Phoenix, AZ, USA
| | - Wei Liu
- Department of Radiation Oncology, Mayo Clinic, Phoenix, AZ, USA
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18
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Otterlei OM, Indelicato DJ, Toussaint L, Ytre-Hauge KS, Pilskog S, Fjaera LF, Rørvik E, Pettersen HES, Muren LP, Lassen-Ramshad Y, Di Pinto M, Stokkevåg CH. Variation in relative biological effectiveness for cognitive structures in proton therapy of pediatric brain tumors. Acta Oncol 2021; 60:267-274. [PMID: 33131367 DOI: 10.1080/0284186x.2020.1840626] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
BACKGROUND Clinically, a constant value of 1.1 is used for the relative biological effectiveness (RBE) of protons, whereas in vitro the RBE has been shown to vary depending on physical dose, tissue type, and linear energy transfer (LET). As the LET increases at the distal end of the proton beam, concerns exist for an elevated RBE in normal tissues. The aim of this study was therefore to investigate the heterogeneity of RBE to brain structures associated with cognition (BSCs) in pediatric suprasellar tumors. MATERIAL AND METHODS Intensity-modulated proton therapy (IMPT) plans for 10 pediatric craniopharyngioma patients were re-calculated using 11 phenomenological and two plan-based variable RBE models. Based on LET, tissue dependence and number of data points used to fit the models, the three RBE models considered the most relevant for the studied endpoint were selected. Thirty BSCs were investigated in terms of RBE and dose/volume parameters. RESULTS For a representative patient, the median (range) dose-weighted mean RBE (RBEd) across all BSCs from the plan-based models was among the lowest (1.09 (1.02-1.52) vs. the phenomenological models at 1.21 (0.78-2.24)). Omitting tissue dependency resulted in RBEd at 1.21 (1.04-2.24). Across all patients, the narrower RBE model selection gave median RBEd values from 1.22 to 1.30. CONCLUSION For all BSCs, there was a systematic model-dependent variation in RBEd, mirroring the uncertainty in biological effects of protons. According to a refined selection of in vitro models, the RBE variation across BSCs was in effect underestimated when using a fixed RBE of 1.1.
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Affiliation(s)
| | | | - Laura Toussaint
- Department of Medical Physics, Aarhus University Hospital, Aarhus, Denmark
| | | | - Sara Pilskog
- Department of Physics and Technology, University of Bergen, Bergen, Norway
- Department of Oncology and Medical Physics, Haukeland University Hospital, Bergen, Norway
| | | | - Eivind Rørvik
- Department of Physics and Technology, University of Bergen, Bergen, Norway
| | | | - Ludvig P. Muren
- Department of Medical Physics, Aarhus University Hospital, Aarhus, Denmark
| | | | - Marcos Di Pinto
- Department of Radiation Oncology, University of Florida, Jacksonville, FL, USA
| | - Camilla H. Stokkevåg
- Department of Physics and Technology, University of Bergen, Bergen, Norway
- Department of Oncology and Medical Physics, Haukeland University Hospital, Bergen, Norway
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19
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Marteinsdottir M, Wang CC, McNamara A, Depauw N, Shin J, Paganetti H. The impact of variable relative biological effectiveness in proton therapy for left-sided breast cancer when estimating normal tissue complications in the heart and lung. Phys Med Biol 2021; 66:035023. [PMID: 33522498 DOI: 10.1088/1361-6560/abd230] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The aim of this study was to evaluate the clinical impact of relative biological effectiveness (RBE) variations in proton beam scanning treatment (PBS) for left-sided breast cancer versus the assumption of a fixed RBE of 1.1, particularly in the context of comparisons with photon-based three-dimensional conformal radiotherapy (3DCRT) and volumetric modulated arc therapy (VMAT). Ten patients receiving radiation treatment to the whole breast/chest wall and regional lymph nodes were selected for each modality. For PBS, the dose distributions were re-calculated with both a fixed RBE and a variable RBE using an empirical RBE model. Dosimetric indices based on dose-volume histogram analysis were calculated for the entire heart wall, left anterior descending artery (LAD) and left lung. Furthermore, normal tissue toxicity probabilities for different endpoints were evaluated. The results show that applying a variable RBE significantly increases the RBE-weighted dose and consequently the calculated dosimetric indices increases for all organs compared to a fixed RBE. The mean dose to the heart and the maximum dose to the LAD and the left lung are significantly lower for PBS assuming a fixed RBE compared to 3DCRT. However, no statistically significant difference is seen when a variable RBE is applied. For a fixed RBE, lung toxicities are significantly lower compared to 3DCRT but when applying a variable RBE, no statistically significant differences are noted. A disadvantage is seen for VMAT over both PBS and 3DCRT. One-to-one plan comparison on 8 patients between PBS and 3DCRT shows similar results. We conclude that dosimetric analysis for all organs and toxicity estimation for the left lung might be underestimated when applying a fixed RBE for protons. Potential RBE variations should therefore be considered as uncertainty bands in outcome analysis.
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Affiliation(s)
- Maria Marteinsdottir
- Department of Radiation Oncology, Massachusetts General Hospital, Boston, MA 02114, United States of America. Faculty of Physical Sciences, University of Iceland, Dunhaga 5, IS-107 Reykjavik, Iceland
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20
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Teoh S, Fiorini F, George B, Vallis KA, Van den Heuvel F. Proton vs photon: A model-based approach to patient selection for reduction of cardiac toxicity in locally advanced lung cancer. Radiother Oncol 2020; 152:151-162. [PMID: 31431365 PMCID: PMC7707354 DOI: 10.1016/j.radonc.2019.06.032] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Revised: 06/25/2019] [Accepted: 06/25/2019] [Indexed: 12/25/2022]
Abstract
PURPOSE/OBJECTIVE To use a model-based approach to identify a sub-group of patients with locally advanced lung cancer who would benefit from proton therapy compared to photon therapy for reduction of cardiac toxicity. MATERIAL/METHODS Volumetric modulated arc photon therapy (VMAT) and robust-optimised intensity modulated proton therapy (IMPT) plans were generated for twenty patients with locally advanced lung cancer to give a dose of 70 Gy (relative biological effectiveness (RBE)) in 35 fractions. Cases were selected to represent a range of anatomical locations of disease. Contouring, treatment planning and organs-at-risk constraints followed RTOG-1308 protocol. Whole heart and ub-structure doses were compared. Risk estimates of grade⩾3 cardiac toxicity were calculated based on normal tissue complication probability (NTCP) models which incorporated dose metrics and patients baseline risk-factors (pre-existing heart disease (HD)). RESULTS There was no statistically significant difference in target coverage between VMAT and IMPT. IMPT delivered lower doses to the heart and cardiac substructures (mean, heart V5 and V30, P < .05). In VMAT plans, there were statistically significant positive correlations between heart dose and the thoracic vertebral level that corresponded to the most inferior limit of the disease. The median level at which the superior aspect of the heart contour began was the T7 vertebrae. There was a statistically significant difference in dose (mean, V5 and V30) to the heart and all substructures (except mean dose to left coronary artery and V30 to sino-atrial node) when disease overlapped with or was inferior to the T7 vertebrae. In the presence of pre-existing HD and disease overlapping with or inferior to the T7 vertebrae, the mean estimated relative risk reduction of grade⩾3 toxicities was 24-59%. CONCLUSION IMPT is expected to reduce cardiac toxicity compared to VMAT by reducing dose to the heart and substructures. Patients with both pre-existing heart disease and tumour and nodal spread overlapping with or inferior to the T7 vertebrae are likely to benefit most from proton over photon therapy.
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Affiliation(s)
- S Teoh
- CRUK/MRC Oxford Institute for Radiation Oncology, Old Road Campus Research Building, University of Oxford, Oxford, OX3 7DQ, UK; Department of Radiotherapy, Oxford Cancer Centre, Oxford University Hospitals NHS Foundation Trust, OX3 7LE, UK.
| | - F Fiorini
- CRUK/MRC Oxford Institute for Radiation Oncology, Old Road Campus Research Building, University of Oxford, Oxford, OX3 7DQ, UK; Department of Radiotherapy, Oxford Cancer Centre, Oxford University Hospitals NHS Foundation Trust, OX3 7LE, UK
| | - B George
- CRUK/MRC Oxford Institute for Radiation Oncology, Old Road Campus Research Building, University of Oxford, Oxford, OX3 7DQ, UK; Department of Radiotherapy, Oxford Cancer Centre, Oxford University Hospitals NHS Foundation Trust, OX3 7LE, UK
| | - K A Vallis
- CRUK/MRC Oxford Institute for Radiation Oncology, Old Road Campus Research Building, University of Oxford, Oxford, OX3 7DQ, UK; Department of Radiotherapy, Oxford Cancer Centre, Oxford University Hospitals NHS Foundation Trust, OX3 7LE, UK
| | - F Van den Heuvel
- CRUK/MRC Oxford Institute for Radiation Oncology, Old Road Campus Research Building, University of Oxford, Oxford, OX3 7DQ, UK; Department of Radiotherapy, Oxford Cancer Centre, Oxford University Hospitals NHS Foundation Trust, OX3 7LE, UK
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21
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Hahn C, Eulitz J, Peters N, Wohlfahrt P, Enghardt W, Richter C, Lühr A. Impact of range uncertainty on clinical distributions of linear energy transfer and biological effectiveness in proton therapy. Med Phys 2020; 47:6151-6162. [PMID: 33118161 DOI: 10.1002/mp.14560] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Revised: 10/01/2020] [Accepted: 10/20/2020] [Indexed: 12/14/2022] Open
Abstract
PURPOSE Increased radiation response after proton irradiation, such as late radiation-induced toxicity, is determined by high dose and elevated linear energy transfer (LET). Steep dose-averaged LET (LETd ) gradients and elevated LETd occur at the end of proton range and might be particularly sensitive to uncertainties in range prediction. Therefore, this study quantified LETd distributions and the impact of range uncertainty in robust dose-optimized proton treatment plans and assessed the biological effect in normal tissues and tumors of patients. METHODS For each of six cancer patients (two brain, head-and-neck, and prostate), two nominal treatment plans were robustly dose optimized using single- and multi-field optimization, respectively. For each plan, two additional scenarios with ±3.5% range deviation relative to the nominal plan were derived by global rescaling of stopping-power ratios. Dose and LETd distributions were calculated for each scenario using the beam parameters of the corresponding nominal plan. The variability in relative biological effectiveness (RBE) and probability of late radiation-induced brain toxicity (PIC ) was assessed. RESULTS The optimization technique (single- vs multi-field) had a negligible impact on the LETd distributions in the clinical target volume (CTV) and in most organs at risk (OARs). LETd distributions in the CTV were rather homogeneous with arithmetic mean of LETd below 3.2 keV/µm and robust against range deviations. The RBE variability within the CTV induced by range uncertainty was small (≤0.05, 95% confidence interval). In OARs, LETd hotspots (>7 keV/µm) occurred and LETd distributions were inhomogeneous and sensitive to range deviations. LETd hotspots and the impact of range deviations were most prominent in OARs of brain tumor patients which translated in RBE values exceeding 1.1 in all brain OARs. The near-maximum predicted PIC in healthy brain tissue of brain tumor patients was smaller than 5% and occurred adjacent to the CTV. Range deviations induced absolute differences in PIC up to 1.2%. CONCLUSIONS Robust dose optimization generates LETd distributions in the target volume robust against range deviations. The current findings support using a constant RBE within the CTV. The impact of range deviations on the considered probability of late radiation-induced toxicity in brain tissue was limited for robust dose-optimized treatment plans. Incorporation of LETd in robust optimization frameworks may further reduce uncertainty related to the RBE-weighted dose estimation in normal tissues.
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Affiliation(s)
- Christian Hahn
- OncoRay - National Center for Radiation Research in Oncology, Faculty of Medicine and University Hospital Carl Gustav Carus, Technische Universität Dresden, Helmholtz-Zentrum Dresden-Rossendorf, Dresden, Germany.,Department of Radiotherapy and Radiation Oncology, Faculty of Medicine and University Hospital Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany.,Department of Medical Physics and Radiotherapy, Faculty of Physics, TU Dortmund University, Dortmund, Germany
| | - Jan Eulitz
- OncoRay - National Center for Radiation Research in Oncology, Faculty of Medicine and University Hospital Carl Gustav Carus, Technische Universität Dresden, Helmholtz-Zentrum Dresden-Rossendorf, Dresden, Germany.,Department of Radiotherapy and Radiation Oncology, Faculty of Medicine and University Hospital Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany.,Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiooncology - OncoRay, Dresden, Germany
| | - Nils Peters
- OncoRay - National Center for Radiation Research in Oncology, Faculty of Medicine and University Hospital Carl Gustav Carus, Technische Universität Dresden, Helmholtz-Zentrum Dresden-Rossendorf, Dresden, Germany.,Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiooncology - OncoRay, Dresden, Germany
| | - Patrick Wohlfahrt
- Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, USA
| | - Wolfgang Enghardt
- OncoRay - National Center for Radiation Research in Oncology, Faculty of Medicine and University Hospital Carl Gustav Carus, Technische Universität Dresden, Helmholtz-Zentrum Dresden-Rossendorf, Dresden, Germany.,Department of Radiotherapy and Radiation Oncology, Faculty of Medicine and University Hospital Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany.,Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiooncology - OncoRay, Dresden, Germany.,German Cancer Consortium (DKTK), Partner Site Dresden, and German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Christian Richter
- OncoRay - National Center for Radiation Research in Oncology, Faculty of Medicine and University Hospital Carl Gustav Carus, Technische Universität Dresden, Helmholtz-Zentrum Dresden-Rossendorf, Dresden, Germany.,Department of Radiotherapy and Radiation Oncology, Faculty of Medicine and University Hospital Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany.,Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiooncology - OncoRay, Dresden, Germany.,German Cancer Consortium (DKTK), Partner Site Dresden, and German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Armin Lühr
- OncoRay - National Center for Radiation Research in Oncology, Faculty of Medicine and University Hospital Carl Gustav Carus, Technische Universität Dresden, Helmholtz-Zentrum Dresden-Rossendorf, Dresden, Germany.,Department of Medical Physics and Radiotherapy, Faculty of Physics, TU Dortmund University, Dortmund, Germany.,Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiooncology - OncoRay, Dresden, Germany.,German Cancer Consortium (DKTK), Partner Site Dresden, and German Cancer Research Center (DKFZ), Heidelberg, Germany
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22
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Gu W, Ruan D, Zou W, Dong L, Sheng K. Linear energy transfer weighted beam orientation optimization for intensity-modulated proton therapy. Med Phys 2020; 48:57-70. [PMID: 32542711 DOI: 10.1002/mp.14329] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Revised: 05/19/2020] [Accepted: 06/04/2020] [Indexed: 11/09/2022] Open
Abstract
PURPOSE In intensity-modulated proton therapy (IMPT), unaccounted-for variation in biological effectiveness contributes to the discrepancy between the constant relative biological effectiveness (RBE) model prediction and experimental observation. It is desirable to incorporate biological doses in treatment planning to improve modeling accuracy and consequently achieve a higher therapeutic ratio. This study addresses this demand by developing a method to incorporate linear energy transfer (LET) into beam orientation optimization (BOO). METHODS Instead of RBE-weighted dose, this LET weighted BOO (LETwBOO) framework uses the dose and LET product (LET × D) as the biological surrogate. The problem is formulated with a physical dose fidelity term, a LET × D constraint term, and a group sparsity term. The LET × D of organs at risks is penalized for minimizing the biological effect while maintaining the physical dose objectives. Group sparsity is used to reduce the number of active beams from 600-800 non-coplanar candidate beams to between 2 and 4. This LETwBOO method was tested on three skull base tumor (SBT) patients and three bilateral head-and-neck (H&N) patients. The LETwBOO plans were compared with IMPT plans using manually selected beams with only physical dose constraint (MAN) and the initial MAN plan reoptimized with additional LET × D constraint (LETwMAN). RESULTS The LETwBOO plans show superior physical dose and LET × D sparing. On average, the [mean, maximal] doses of organs at risks (OARs) in LETwBOO are reduced by [2.85, 4.6] GyRBE from the MAN plans in the SBT cases and reduced by [0.9, 2.5] GyRBE in the H&N cases, while LETwMAN is comparable to MAN. cLET × Ds of PTVs are comparable in LETwBOO and LETwMAN, where c is a scaling factor of 0.04 μm/keV. On average, in the SBT cases, LETwBOO reduces the OAR [mean, maximal] cLET × D by [1.1, 2.9] Gy from the MAN plans, compared to the reduction by LETwMAN from MAN of [0.7, 1.7] Gy. In the H&N cases, LETwBOO reduces the OAR [mean, maximal] cLET × D by [0.8, 2.6] Gy from the MAN plans, compared to the reduction by LETwMAN from MAN of [0.3, 1.2] Gy. CONCLUSION We developed a novel LET weighted BOO method for IMPT to generate plans with improved physical and biological OAR sparing compared with the plans unaccounted for biological effects from BOO.
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Affiliation(s)
- Wenbo Gu
- Department of Radiation Oncology, University of California-Los Angeles, Los Angeles, CA, 90095, USA
| | - Dan Ruan
- Department of Radiation Oncology, University of California-Los Angeles, Los Angeles, CA, 90095, USA
| | - Wei Zou
- Department of Radiation Oncology, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Lei Dong
- Department of Radiation Oncology, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Ke Sheng
- Department of Radiation Oncology, University of California-Los Angeles, Los Angeles, CA, 90095, USA
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23
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Liu C, Patel SH, Shan J, Schild SE, Vargas CE, Wong WW, Ding X, Bues M, Liu W. Robust Optimization for Intensity Modulated Proton Therapy to Redistribute High Linear Energy Transfer from Nearby Critical Organs to Tumors in Head and Neck Cancer. Int J Radiat Oncol Biol Phys 2020; 107:181-193. [PMID: 31987967 DOI: 10.1016/j.ijrobp.2020.01.013] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2019] [Revised: 01/08/2020] [Accepted: 01/14/2020] [Indexed: 12/29/2022]
Abstract
PURPOSE We propose linear energy transfer (LET)-guided robust optimization in intensity modulated proton therapy for head and neck cancer. This method simultaneously considers LET and physical dose distributions of tumors and organs at risk (OARs) with uncertainties. METHODS AND MATERIALS Fourteen patients with head and neck cancer were included in this retrospective study. Cord, brain stem, brain, and oral cavity were considered. Two algorithms, voxel-wise worst-case robust optimization and LET-guided robust optimization (LETRO), were used to generate intensity modulated proton therapy plans for each patient. The latter method directly optimized LET distributions rather than indirectly as in previous methods. LET-volume histograms (LETVHs) were generated, and high LET was redistributed from nearby OARs to tumors in a user-defined way via LET-volume constraints. Dose-volume histogram indices, such as clinical target volume (CTV) D98% and D2%-D98%, cord Dmax, brain stem Dmax, brain Dmax, and oral cavity Dmean, were calculated. Plan robustness was quantified using the worst-case analysis method. LETVH indices analogous to dose-volume histogram indices were used to characterize LET distributions. The Wilcoxon signed rank test was performed to measure statistical significance. RESULTS In the nominal scenario, LETRO provided higher LET distributions in the CTV (unit: keV/μm; CTV LET98%: 1.18 vs 1.08, LETRO vs RO, P = .0031) while preserving comparable physical dose and plan robustness. LETRO achieved significantly reduced LET distributions in the cord, brain stem, and oral cavity compared with RO (cord LETmax: 7.20 vs 8.20, P = .0010; brain stem LETmax: 10.95 vs 12.05, P = .0007; oral cavity LETmean: 2.11 vs 3.12, P = .0052) and had comparable physical dose and plan robustness in all OARs. In the worst-case scenario, LETRO achieved significantly higher LETmean in the CTV, reduced LETmax in the brain, and was comparable to other LETVH indices (CTV LETmean: 3.26 vs 3.35, P = .0012; brain LETmax: 24.80 vs 22.00, P = .0016). CONCLUSIONS LETRO robustly optimized LET and physical dose distributions simultaneously. It redistributed high LET from OARs to targets with slightly modified physical dose and plan robustness.
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Affiliation(s)
- Chenbin Liu
- Department of Radiation Oncology, Mayo Clinic in Arizona, Phoenix, Arizona
| | - Samir H Patel
- Department of Radiation Oncology, Mayo Clinic in Arizona, Phoenix, Arizona
| | - Jie Shan
- Department of Radiation Oncology, Mayo Clinic in Arizona, Phoenix, Arizona
| | - Steven E Schild
- Department of Radiation Oncology, Mayo Clinic in Arizona, Phoenix, Arizona
| | - Carlos E Vargas
- Department of Radiation Oncology, Mayo Clinic in Arizona, Phoenix, Arizona
| | - William W Wong
- Department of Radiation Oncology, Mayo Clinic in Arizona, Phoenix, Arizona
| | - Xiaoning Ding
- Department of Radiation Oncology, Mayo Clinic in Arizona, Phoenix, Arizona
| | - Martin Bues
- Department of Radiation Oncology, Mayo Clinic in Arizona, Phoenix, Arizona
| | - Wei Liu
- Department of Radiation Oncology, Mayo Clinic in Arizona, Phoenix, Arizona.
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24
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Parisi A, Olko P, Swakoń J, Horwacik T, Jabłoński H, Malinowski L, Nowak T, Struelens L, Vanhavere F. Modeling the radiation-induced cell death in a therapeutic proton beam using thermoluminescent detectors and radiation transport simulations. ACTA ACUST UNITED AC 2020; 65:015008. [DOI: 10.1088/1361-6560/ab491f] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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25
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Sánchez‐Parcerisa D, López‐Aguirre M, Dolcet Llerena A, Udías JM. MultiRBE: Treatment planning for protons with selective radiobiological effectiveness. Med Phys 2019; 46:4276-4284. [DOI: 10.1002/mp.13718] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2018] [Revised: 06/19/2019] [Accepted: 07/10/2019] [Indexed: 12/12/2022] Open
Affiliation(s)
- Daniel Sánchez‐Parcerisa
- Grupo de Física Nuclear & IPARCOS, Departamento de Estructura de la Materia, Física Térmica y Electrónica CEI Moncloa Universidad Complutense de Madrid 28040Madrid Spain
- Instituto de Investigación Sanitaria del Hospital Clínico San Carlos (IdISSC) Madrid Spain
| | - Miguel López‐Aguirre
- Grupo de Física Nuclear & IPARCOS, Departamento de Estructura de la Materia, Física Térmica y Electrónica CEI Moncloa Universidad Complutense de Madrid 28040Madrid Spain
- Instituto de Investigación Sanitaria del Hospital Clínico San Carlos (IdISSC) Madrid Spain
| | | | - José Manuel Udías
- Grupo de Física Nuclear & IPARCOS, Departamento de Estructura de la Materia, Física Térmica y Electrónica CEI Moncloa Universidad Complutense de Madrid 28040Madrid Spain
- Instituto de Investigación Sanitaria del Hospital Clínico San Carlos (IdISSC) Madrid Spain
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26
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Tensaouti F, Ducassou A, Chaltiel L, Bolle S, Habrand JL, Alapetite C, Coche-Dequeant B, Bernier V, Claude L, Carrie C, Padovani L, Muracciole X, Supiot S, Huchet A, Leseur J, Kerr C, Hangard G, Lisbona A, Goudjil F, Ferrand R, Laprie A. Feasibility of Dose Escalation in Patients With Intracranial Pediatric Ependymoma. Front Oncol 2019; 9:531. [PMID: 31293971 PMCID: PMC6598548 DOI: 10.3389/fonc.2019.00531] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2018] [Accepted: 05/31/2019] [Indexed: 12/25/2022] Open
Abstract
Background and purpose: Pediatric ependymoma carries a dismal prognosis, mainly owing to local relapse within RT fields. The current prospective European approach is to increase the radiation dose with a sequential hypofractionated stereotactic boost. In this study, we assessed the possibility of using a simultaneous integrated boost (SIB), comparing VMAT vs. IMPT dose delivery. Material and methods: The cohort included 101 patients. The dose to planning target volume (PTV59.4) was 59.4/1.8 Gy, and the dose to SIB volume (PTV67.6) was 67.6/2.05 Gy. Gross tumor volume (GTV) was defined as the tumor bed plus residual tumor, clinical target volume (CTV59.4) was GTV + 5 mm, and PTV59.4 was CTV59.4 + 3 mm. PTV67.6 was GTV+ 3 mm. After treatment plan optimization, quality indices and doses to target volume and organs at risk (OARs) were extracted and compared with the standard radiation doses that were actually delivered (median = 59.4 Gy [50.4 59.4]). Results: In most cases, the proton treatment resulted in higher quality indices (p < 0.001). Compared with the doses that were initially delivered, mean, and maximum doses to some OARs were no higher with SIB VMAT, and significantly lower with protons (p < 0.001). In the case of posterior fossa tumor, there was a lower dose to the brainstem with protons, in terms of V59 Gy, mean, and near-maximum (D2%) doses. Conclusion: Dose escalation with intensity-modulated proton or photon SIB is feasible in some patients. This approach could be considered for children with unresectable residue or post-operative FLAIR abnormalities, particularly if they have supratentorial tumors. It should not be considered for infratentorial tumors encasing the brainstem or extending to the medulla.
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Affiliation(s)
- Fatima Tensaouti
- ToNIC, Toulouse NeuroImaging Center, Universite de Toulouse, Inserm, Toulouse, France
- Department of Radiation Oncology, Institut Claudius Regaud, Institut Universitaire du, Cancer de Toulouse-Oncopole, Toulouse, France
| | - Anne Ducassou
- Department of Radiation Oncology, Institut Claudius Regaud, Institut Universitaire du, Cancer de Toulouse-Oncopole, Toulouse, France
| | - Léonor Chaltiel
- Department of Biostatistics, Institut Claudius Regaud, Institut Universitaire du Cancer de Toulouse-Oncopole, Toulouse, France
| | - Stéphanie Bolle
- Department of Radiotherapy Oncology, Institut Gustave Roussy, Villejuif, France
| | - Jean Louis Habrand
- Department of Radiation Oncology, Centre Francois Baclesse, Caen, France
| | | | | | - Valérie Bernier
- Department of Radiation Oncology, Centre Alexis Vautrin, Vandœuvre-lès-Nancy, France
| | - Line Claude
- Department of Radiation Oncology, Centre Léon Bérard, Lyon, France
| | - Christian Carrie
- Department of Radiation Oncology, Centre Léon Bérard, Lyon, France
| | | | | | - Stéphane Supiot
- Department of Radiation Oncology, Institut de Cancerologie de l'Ouest, Nantes, France
| | - Aymeri Huchet
- Department of Radiation Oncology, Centre Hospitalier et Universitaire, Bordeaux, France
| | - Julie Leseur
- Department of Radiation Oncology, Centre Eugéne Marquis, Rennes, France
| | - Christine Kerr
- Department of Radiation Oncology, Institut Regional du Cancer Montpellier, Val d'Aurelle, Montpellier, France
| | - Grégorie Hangard
- Department of Engineering and Medical Physics, Institut Universitaire du Cancer de Toulouse-Oncopole, Toulouse, France
| | - Albert Lisbona
- Department of Radiation Oncology, Institut de Cancerologie de l'Ouest, Nantes, France
| | - Farid Goudjil
- Department of Radiation Oncology, Institut Curie, Paris, France
| | - Régis Ferrand
- Department of Engineering and Medical Physics, Institut Universitaire du Cancer de Toulouse-Oncopole, Toulouse, France
| | - Anne Laprie
- ToNIC, Toulouse NeuroImaging Center, Universite de Toulouse, Inserm, Toulouse, France
- Department of Radiation Oncology, Institut Claudius Regaud, Institut Universitaire du, Cancer de Toulouse-Oncopole, Toulouse, France
- Université Toulouse III Paul Sabatier, Toulouse, France
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27
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Paganetti H, Blakely E, Carabe-Fernandez A, Carlson DJ, Das IJ, Dong L, Grosshans D, Held KD, Mohan R, Moiseenko V, Niemierko A, Stewart RD, Willers H. Report of the AAPM TG-256 on the relative biological effectiveness of proton beams in radiation therapy. Med Phys 2019; 46:e53-e78. [PMID: 30661238 DOI: 10.1002/mp.13390] [Citation(s) in RCA: 191] [Impact Index Per Article: 38.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2018] [Revised: 11/21/2018] [Accepted: 01/13/2019] [Indexed: 12/14/2022] Open
Abstract
The biological effectiveness of proton beams relative to photon beams in radiation therapy has been taken to be 1.1 throughout the history of proton therapy. While potentially appropriate as an average value, actual relative biological effectiveness (RBE) values may differ. This Task Group report outlines the basic concepts of RBE as well as the biophysical interpretation and mathematical concepts. The current knowledge on RBE variations is reviewed and discussed in the context of the current clinical use of RBE and the clinical relevance of RBE variations (with respect to physical as well as biological parameters). The following task group aims were designed to guide the current clinical practice: Assess whether the current clinical practice of using a constant RBE for protons should be revised or maintained. Identifying sites and treatment strategies where variable RBE might be utilized for a clinical benefit. Assess the potential clinical consequences of delivering biologically weighted proton doses based on variable RBE and/or LET models implemented in treatment planning systems. Recommend experiments needed to improve our current understanding of the relationships among in vitro, in vivo, and clinical RBE, and the research required to develop models. Develop recommendations to minimize the effects of uncertainties associated with proton RBE for well-defined tumor types and critical structures.
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Affiliation(s)
- Harald Paganetti
- Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
| | - Eleanor Blakely
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | | | - David J Carlson
- Department of Therapeutic Radiology, Yale University School of Medicine, New Haven, CT, USA
| | - Indra J Das
- New York University Langone Medical Center & Laura and Isaac Perlmutter Cancer Center, New York, NY, USA
| | - Lei Dong
- Department of Radiation Oncology, Hospital of the University of Pennsylvania, Philadelphia, PA, USA
| | - David Grosshans
- Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Kathryn D Held
- Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
| | - Radhe Mohan
- Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Vitali Moiseenko
- Department of Radiation Medicine and Applied Sciences, University of California San Diego, La Jolla, CA, USA
| | - Andrzej Niemierko
- Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
| | - Robert D Stewart
- Department of Radiation Oncology, School of Medicine, University of Washington, Seattle, WA, USA
| | - Henning Willers
- Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
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Kohno R, Cao W, Yepes P, Bai X, Poenisch F, Grosshans DR, Akimoto T, Mohan R. Biological Dose Comparison between a Fixed RBE and a Variable RBE in SFO and MFO IMPT with Various Multi-Beams for Brain Cancer. ACTA ACUST UNITED AC 2019. [DOI: 10.4236/ijmpcero.2019.81004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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29
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Yepes P, Adair A, Frank SJ, Grosshans DR, Liao Z, Liu A, Mirkovic D, Poenisch F, Titt U, Wang Q, Mohan R. Fixed- versus Variable-RBE Computations for Intensity Modulated Proton Therapy. Adv Radiat Oncol 2018; 4:156-167. [PMID: 30706024 PMCID: PMC6349601 DOI: 10.1016/j.adro.2018.08.020] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2018] [Revised: 08/16/2018] [Accepted: 08/16/2018] [Indexed: 11/30/2022] Open
Abstract
Purpose To evaluate how using models of proton therapy that incorporate variable relative biological effectiveness (RBE) versus the current practice of using a fixed RBE of 1.1 affects dosimetric indices on treatment plans for large cohorts of patients treated with intensity modulated proton therapy (IMPT). Methods and Materials Treatment plans for 4 groups of patients who received IMPT for brain, head-and-neck, thoracic, or prostate cancer were selected. Dose distributions were recalculated in 4 ways: 1 with a fast-dose Monte Carlo calculator with fixed RBE and 3 with RBE calculated to 3 different models—McNamara, Wedenberg, and repair-misrepair-fixation. Differences among dosimetric indices (D02, D50, D98, and mean dose) for target volumes and organs at risk (OARs) on each plan were compared between the fixed-RBE and variable-RBE calculations. Results In analyses of all target volumes, for which the main concern is underprediction or RBE less than 1.1, none of the models predicted an RBE less than 1.05 for any of the cohorts. For OARs, the 2 models based on linear energy transfer, McNamara and Wedenberg, systematically predicted RBE >1.1 for most structures. For the mean dose of 25% of the plans for 2 OARs, they predict RBE equal to or larger than 1.4, 1.3, 1.3, and 1.2 for brain, head-and-neck, thorax, and prostate, respectively. Systematically lower increases in RBE are predicted by repair-misrepair-fixation, with a few cases (eg, femur) in which the RBE is less than 1.1 for all plans. Conclusions The variable-RBE models predict increased doses to various OARs, suggesting that strategies to reduce high-dose linear energy transfer in critical structures should be developed to minimize possible toxicity associated with IMPT.
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Affiliation(s)
- Pablo Yepes
- Physics and Astronomy Department, Rice University, Houston, Texas.,Department of Radiation Physics, The University of Texas MD Anderson Cancer, Houston, Texas
| | - Antony Adair
- Physics and Astronomy Department, Rice University, Houston, Texas.,Department of Radiation Physics, The University of Texas MD Anderson Cancer, Houston, Texas
| | - Steven J Frank
- Department of Radiation Oncology, The University of Texas MD Anderson Cancer, Houston, Texas
| | - David R Grosshans
- Department of Radiation Oncology, The University of Texas MD Anderson Cancer, Houston, Texas.,Experimental Radiation Oncology, The University of Texas MD Anderson Cancer, Houston, Texas
| | - Zhongxing Liao
- Department of Radiation Oncology, The University of Texas MD Anderson Cancer, Houston, Texas
| | - Amy Liu
- Department of Radiation Oncology, The University of Texas MD Anderson Cancer, Houston, Texas
| | - Dragan Mirkovic
- Department of Radiation Physics, The University of Texas MD Anderson Cancer, Houston, Texas
| | - Falk Poenisch
- Department of Radiation Physics, The University of Texas MD Anderson Cancer, Houston, Texas
| | - Uwe Titt
- Department of Radiation Physics, The University of Texas MD Anderson Cancer, Houston, Texas
| | - Qianxia Wang
- Physics and Astronomy Department, Rice University, Houston, Texas.,Department of Radiation Physics, The University of Texas MD Anderson Cancer, Houston, Texas
| | - Radhe Mohan
- Department of Radiation Physics, The University of Texas MD Anderson Cancer, Houston, Texas
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Abstract
Accurate prediction of tumor control and toxicities in radiation therapy faces many uncertainties. Besides interpatient variability in the response to radiation, there are also dosimetric uncertainties, that is, differences between the dose displayed in a treatment planning system and the dose actually delivered to the patient. These uncertainties originate from several sources including imperfect knowledge of the patient geometry, approximation in the physics of radiation interaction with tissues, and uncertainties in the biological effectiveness of radiation. Generally, uncertainties are considered in the treatment planning process by applying margins. In intensity-modulated radiotherapy (IMRT), this leads to the planning target volume (PTV) concept. Intensity-modulated proton therapy (IMPT) is widely considered as the future of proton therapy. The treatment planning methods for IMPT and IMRT are similar and based on mathematical optimization techniques for both modalities. However, the PTV concept has fundamental limitations in IMPT. Therefore, researchers have developed robust optimization methods that directly incorporate uncertainties into the IMPT optimization problem. In recent years, vendors of commercial planning systems have started to implement these methods so that robust IMPT planning becomes available in clinical practice. This article summarizes uncertainties in proton therapy and the limitations of the PTV concept to deal with them. Subsequently, robust optimization techniques to overcome these limitations are reviewed.
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31
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Paganetti H. Proton Relative Biological Effectiveness - Uncertainties and Opportunities. Int J Part Ther 2018; 5:2-14. [PMID: 30370315 DOI: 10.14338/ijpt-18-00011.1] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Proton therapy treatments are prescribed using a biological effectiveness relative to photon therapy of 1.1, that is, proton beams are considered to be 10% more biologically effective. Debate is ongoing as to whether this practice needs to be revised. This short review summarizes current knowledge on relative biological effectiveness variations and uncertainties in vitro and in vivo. Clinical relevance is discussed and strategies toward biologically guided treatment planning are presented.
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Affiliation(s)
- Harald Paganetti
- Department of Radiation Oncology, Massachusetts General Hospital, and Harvard Medical School, Boston, MA, USA
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Rørvik E, Fjæra LF, Dahle TJ, Dale JE, Engeseth GM, Stokkevåg CH, Thörnqvist S, Ytre-Hauge KS. Exploration and application of phenomenological RBE models for proton therapy. Phys Med Biol 2018; 63:185013. [PMID: 30102240 DOI: 10.1088/1361-6560/aad9db] [Citation(s) in RCA: 77] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The relative biological effectiveness (RBE) of protons varies with multiple physical and biological factors. Phenomenological RBE models have been developed to include such factors in the estimation of a variable RBE, in contrast to the clinically applied constant RBE of 1.1. In this study, eleven published phenomenological RBE models and two plan-based models were explored and applied to simulated patient cases. All models were analysed with respect to the distribution and range of linear energy transfer (LET) and reference radiation fractionation sensitivity ((α/β) x ) of their respective experimental databases. Proton therapy plans for a spread-out Bragg peak in water and three patient cases (prostate adenocarcinoma, pituitary adenoma and thoracic sarcoma) were optimised using an RBE of 1.1 in the Eclipse™ treatment planning system prior to recalculation and modelling in the FLUKA Monte Carlo code. Model estimated dose-volume parameters for the planning target volumes (PTVs) and organs at risk (OAR) were compared. The experimental in vitro databases for the various models differed greatly in the range of (α/β) x values and dose-averaged LET (LETd). There were significant variations between the model estimations, which arose from fundamental differences in the database definitions and model assumptions. The greatest variations appeared in organs with low (α/β) x and high LETd, e.g. biological doses given to late responding OARs located distal to the target in the treatment field. In general, the variation in maximum dose (D2%) was larger than the variation in mean dose and other dose metrics, with D2% of the left optic nerve ((α/β) x = 2.1 Gy) in the pituitary adenoma case showing the greatest discrepancies between models: 28-52 Gy(RBE), while D2% for RBE1.1 was 30 Gy(RBE). For all patient cases, the estimated mean RBE to the PTV was in the range 1.09-1.29 ((α/β) x = 1.5/3.1/10.6 Gy). There were considerable variations between the estimations of RBE and RBE-weighted doses from the different models. These variations were a consequence of fundamental differences in experimental databases, model assumptions and regression techniques. The results from the implementation of RBE models in dose planning studies should be evaluated in light of these deviations.
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Affiliation(s)
- Eivind Rørvik
- Department of Physics and Technology, University of Bergen, Bergen, Norway. Author to whom any correspondence should be addressed
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Villegas F, Tilly N, Ahnesjö A. Target Size Variation in Microdosimetric Distributions and its Impact on the Linear-Quadratic Parameterization of Cell Survival. Radiat Res 2018; 190:504-512. [PMID: 30106343 DOI: 10.1667/rr15089.1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
The linear-quadratic (LQ) parameterization of survival fraction [SF( D)] inherently assumes that all cells in a population receive the same dose ( D), albeit the distribution of specific energy z over the individual cells f( z, D) can be very wide. From these microdosimetric distributions, which are target size dependent, we estimate the size of the cellular sensitive volume by analyzing its influence on the LQ parameterization of cell survival. A Monte Carlo track structure code was used to simulate detailed tracks from a 60Co source as well as proton and carbon ions of various energies. From these tracks, f( z, D) distributions were calculated for spherical targets with diameters ranging from 10 nm to 12 μm. A cell survival function based on f( z, D) was fitted to experimental LQ α values, revealing an intrinsic limitation that target size imposes on the usage of f( z, D) to describe the linear term of the LQ parameterization. The results indicate that such threshold volume arises naturally from the relationship between the particle's probability of no-hit and the probability of cell survival. Further analysis led to the proposal of a radiobiological property [Formula: see text], defined as the mean lineal energy corresponding to the target size that allows equivalence between the mean inactivation dose (MID) and the mean specific energy [Formula: see text]. The fact that [Formula: see text] is an increasing continuous function of target size within the range of biological targets of interest in radiobiology, ensures the uniqueness of [Formula: see text] for any radiation quality, thus, its potential usefulness in modeling. In conclusion, an accurate estimation of such threshold volumes may be useful for improving modeling of cell survival curves.
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Affiliation(s)
- Fernanda Villegas
- a Medical Radiation Physics, Department of Immunology, Genetics and Pathology, Uppsala University, Akademiska Sjukhuset, Uppsala SE-75185, Sweden
| | - Nina Tilly
- a Medical Radiation Physics, Department of Immunology, Genetics and Pathology, Uppsala University, Akademiska Sjukhuset, Uppsala SE-75185, Sweden.,b Elekta Instrument AB, Stockholm SE-10393, Sweden
| | - Anders Ahnesjö
- a Medical Radiation Physics, Department of Immunology, Genetics and Pathology, Uppsala University, Akademiska Sjukhuset, Uppsala SE-75185, Sweden
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Relative Biological Effectiveness Uncertainties and Implications for Beam Arrangements and Dose Constraints in Proton Therapy. Semin Radiat Oncol 2018; 28:256-263. [DOI: 10.1016/j.semradonc.2018.02.010] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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35
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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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36
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Alsanea F, Therriault-Proulx F, Sawakuchi G, Beddar S. A real-time method to simultaneously measure linear energy transfer and dose for proton therapy using organic scintillators. Med Phys 2018; 45:1782-1789. [PMID: 29446078 DOI: 10.1002/mp.12815] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2017] [Revised: 01/18/2018] [Accepted: 02/05/2018] [Indexed: 11/05/2022] Open
Abstract
PURPOSE Currently, no detectors are capable of simultaneously measuring dose and linear energy transfer (LET) in real time. In this study, we evaluated the feasibility of exploiting the difference in the response of various organic plastic scintillation detectors to measure LET and dose in therapeutic proton beams. The hypothesis behind this work was that the ratio of the responses of different scintillators exposed to the same proton beam can be used to obtain a LET vs ratio calibration curve that can then be used to infer LET under any other measurement conditions. METHODS We first used similar scintillators with different ionization quenching factors. LET values for different irradiation conditions were calculated using a validated Monte Carlo model of the proton beam line. The quenching factors in the Birks equation for different scintillators as a function of LET were obtained from measurements in a 100-MeV pristine proton beam. We then used four different organic scintillation materials - polystyrene (BCF-12), poly (methyl methacrylate), polyvinyltoluene, and a liquid scintillator - for which the LET response varied with regard to not only quenching but also differences in material density and relative stopping power. We simultaneously exposed the four different organic scintillators and a plane-parallel ion chamber to passively scattered proton beams at fluence-averaged LET. Comparisons to the expected values obtained from the Monte Carlo simulations were made on the basis of both dose and LET. RESULTS The maximum difference in the quenching factor was 20%, resulting in a 5% change in LET with a response ratio over a range of 5 keV/μm. Among all the scintillators investigated, the ratio of PMMA to BCF-12 provided the best correlation with LET values and was therefore used to construct the LET calibration curve. The expected LET values in the validation set were within 2% ± 6%, which resulted in dose accuracy of 1.5% ± 5.8% for the range of LET values investigated in this work. CONCLUSIONS We demonstrated the feasibility of using the ratio of the light outputs of two organic scintillators to simultaneously measure LET and dose in therapeutic proton beams for fluence-averaged LET values from 0.47 to 1.26 keV/μm. Further studies are needed to verify the response for higher LET values and the reproducibility of this method.
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Affiliation(s)
- Fahed Alsanea
- Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, TX, 77030, USA.,The University of Texas Graduate School of Biomedical Sciences at Houston, Houston, TX, 77030, USA
| | - Francois Therriault-Proulx
- Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, TX, 77030, USA
| | - Gabriel Sawakuchi
- Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, TX, 77030, USA.,The University of Texas Graduate School of Biomedical Sciences at Houston, Houston, TX, 77030, USA
| | - Sam Beddar
- Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, TX, 77030, USA.,The University of Texas Graduate School of Biomedical Sciences at Houston, Houston, TX, 77030, USA
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37
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Cao W, Khabazian A, Yepes PP, Lim G, Poenisch F, Grosshans DR, Mohan R. Linear energy transfer incorporated intensity modulated proton therapy optimization. Phys Med Biol 2017; 63:015013. [PMID: 29131808 PMCID: PMC5815879 DOI: 10.1088/1361-6560/aa9a2e] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The purpose of this study was to investigate the feasibility of incorporating linear energy transfer (LET) into the optimization of intensity modulated proton therapy (IMPT) plans. Because increased LET correlates with increased biological effectiveness of protons, high LETs in target volumes and low LETs in critical structures and normal tissues are preferred in an IMPT plan. However, if not explicitly incorporated into the optimization criteria, different IMPT plans may yield similar physical dose distributions but greatly different LET, specifically dose-averaged LET, distributions. Conventionally, the IMPT optimization criteria (or cost function) only includes dose-based objectives in which the relative biological effectiveness (RBE) is assumed to have a constant value of 1.1. In this study, we added LET-based objectives for maximizing LET in target volumes and minimizing LET in critical structures and normal tissues. Due to the fractional programming nature of the resulting model, we used a variable reformulation approach so that the optimization process is computationally equivalent to conventional IMPT optimization. In this study, five brain tumor patients who had been treated with proton therapy at our institution were selected. Two plans were created for each patient based on the proposed LET-incorporated optimization (LETOpt) and the conventional dose-based optimization (DoseOpt). The optimized plans were compared in terms of both dose (assuming a constant RBE of 1.1 as adopted in clinical practice) and LET. Both optimization approaches were able to generate comparable dose distributions. The LET-incorporated optimization achieved not only pronounced reduction of LET values in critical organs, such as brainstem and optic chiasm, but also increased LET in target volumes, compared to the conventional dose-based optimization. However, on occasion, there was a need to tradeoff the acceptability of dose and LET distributions. Our conclusion is that the inclusion of LET-dependent criteria in the IMPT optimization could lead to similar dose distributions as the conventional optimization but superior LET distributions in target volumes and normal tissues. This may have substantial advantages in improving tumor control and reducing normal tissue toxicities.
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Affiliation(s)
- Wenhua Cao
- Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, United States of America. Author to whom any correspondence should be addressed
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Trott KR. Special radiobiological features of second cancer risk after particle radiotherapy. Phys Med 2017; 42:221-227. [PMID: 29103987 DOI: 10.1016/j.ejmp.2017.05.002] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/30/2016] [Revised: 04/18/2017] [Accepted: 05/01/2017] [Indexed: 11/24/2022] Open
Abstract
In absolute terms: second cancer risks from radiotherapy of first cancers in adults are small compared to the benefits from radiotherapy but this is not so for radiotherapy of childhood cancers. Moreover, the radiation dose dependence of cancer induction differs between organs and tissues. The organ-specific dose dependence of second cancer risks may indicate the existence of different radiobiological mechanisms. As an inevitable consequence of the age dependence of organ sensitivity to second cancer induction, the organ/tissue weighting factors which have been proposed by ICRP for calculating effective dose (the dose unit Sv) and for risk estimation in the general population should not be used in medical radiation exposures. In adult cancer radiotherapy, the most common unwanted effect is local tumour recurrence whereas both, severe late normal tissue damage and radiation-induced second cancers are rare, around 1% of locally controlled cancer patients. In childhood cancers, local failures are rare (<10% in some cancers) yet second cancers are more common than uncontrolled primaries. The main reason for considering particle radiotherapy for childhood cancers is the possibility to exploit their physical characteristics to reduce the radiation exposure to organs and tissues close to and distant from the primary cancer which is to be targeted. However, the relative biological effectiveness of the radiation doses within the proton beam is not a constant and the relative biological effectiveness of the neutrons is not known as far as the mechanisms of late normal tissue damage and second cancer risk are concerned. In view of the highly charged discussions of the potential risks of treatment-induced seecond cancers from the neutron contamination of exposure doses in out-of-PTV critical organs a comprehensive European project called ANDANTE was performed which integrated the disciplines of radiation physics, molecular biology, systems biology modelling and epidemiology in order to investigate the RBE of induction of cancer from exposure to neutrons compared to photons. Since out-of-field "effective" neutron doses from proton therapy are smaller than the photon stray doses whichever reasonable RBE is chosen for comparison, and since the absolute risk of radiation-induced second cancer rates are in the order of 1% in the cohorts of adult patients who have been treated in the past with methods which caused relatively high out-of-field doses to large body volumes, it is highly unlikely that such patients treated in future with highly conformal particle therapy are at a higher radiation-induced second cancer risk than those patients treated with photons and described before. Still, the potential risks of second cancers from scattered proton radiotherapy for childhood cancers may cause concern. Yet, the overall risk of undesired consequences of radiation exposure of children which are more complex and manifold than in adult patients (including developmental, neurocognitive, hormonal and growth impairment effects) are likely to be very much reduced by the better focussing of the radiation dose in the target offered by particle radioherapy. This benefit may far outweigh the still hypothetical second cancer risk from particle radiotherapy in pediatric radiotherapy.
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An Y, Shan J, Patel SH, Wong W, Schild SE, Ding X, Bues M, Liu W. Robust intensity-modulated proton therapy to reduce high linear energy transfer in organs at risk. Med Phys 2017; 44:6138-6147. [PMID: 28976574 DOI: 10.1002/mp.12610] [Citation(s) in RCA: 67] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2017] [Revised: 09/25/2017] [Accepted: 09/26/2017] [Indexed: 11/11/2022] Open
Abstract
PURPOSE We propose a robust treatment planning model that simultaneously considers proton range and patient setup uncertainties and reduces high linear energy transfer (LET) exposure in organs at risk (OARs) to minimize the relative biological effectiveness (RBE) dose in OARs for intensity-modulated proton therapy (IMPT). Our method could potentially reduce the unwanted damage to OARs. METHODS We retrospectively generated plans for 10 patients including two prostate, four head and neck, and four lung cancer patients. The "worst-case robust optimization" model was applied. One additional term as a "biological surrogate (BS)" of OARs due to the high LET-related biological effects was added in the objective function. The biological surrogate was defined as the sum of the physical dose and extra biological effects caused by the dose-averaged LET. We generated nine uncertainty scenarios that considered proton range and patient setup uncertainty. Corresponding to each uncertainty scenario, LET was obtained by a fast LET calculation method developed in-house and based on Monte Carlo simulations. In each optimization iteration, the model used the worst-case BS among all scenarios and then penalized overly high BS to organs. The model was solved by an efficient algorithm (limited-memory Broyden-Fletcher-Goldfarb-Shanno) in a parallel computing environment. Our new model was benchmarked with the conventional robust planning model without considering BS. Dose-volume histograms (DVHs) of the dose assuming a fixed RBE of 1.1 and BS for tumor and organs under nominal and uncertainty scenarios were compared to assess the plan quality between the two methods. RESULTS For the 10 cases, our model outperformed the conventional robust model in avoidance of high LET in OARs. At the same time, our method could achieve dose distributions and plan robustness of tumors assuming a fixed RBE of 1.1 almost the same as those of the conventional robust model. CONCLUSIONS Explicitly considering LET in IMPT robust treatment planning can reduce the high LET to OARs and minimize the possible toxicity of high RBE dose to OARs without sacrificing plan quality. We believe this will allow one to design and deliver safer proton therapy.
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Affiliation(s)
- Yu An
- Department of Radiation Oncology, Mayo Clinic Hospital, Phoenix, Arizona
| | - Jie Shan
- Department of Biomedical Informatics, Arizona State University, Tempe, Arizona
| | - Samir H Patel
- Department of Radiation Oncology, Mayo Clinic Hospital, Phoenix, Arizona
| | - William Wong
- Department of Radiation Oncology, Mayo Clinic Hospital, Phoenix, Arizona
| | - Steven E Schild
- Department of Radiation Oncology, Mayo Clinic Hospital, Phoenix, Arizona
| | - Xiaoning Ding
- Department of Radiation Oncology, Mayo Clinic Hospital, Phoenix, Arizona
| | - Martin Bues
- Department of Radiation Oncology, Mayo Clinic Hospital, Phoenix, Arizona
| | - Wei Liu
- Department of Radiation Oncology, Mayo Clinic Hospital, Phoenix, Arizona
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Jasińska-Konior K, Pochylczuk K, Czajka E, Michalik M, Romanowska-Dixon B, Swakoń J, Urbańska K, Elas M. Proton beam irradiation inhibits the migration of melanoma cells. PLoS One 2017; 12:e0186002. [PMID: 29016654 PMCID: PMC5634624 DOI: 10.1371/journal.pone.0186002] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2017] [Accepted: 09/22/2017] [Indexed: 12/12/2022] Open
Abstract
Purpose In recent years experimental data have indicated that low-energy proton beam radiation might induce a difference in cellular migration in comparison to photons. We therefore set out to compare the effect of proton beam irradiation and X-rays on the survival and long-term migratory properties of two cell lines: uveal melanoma Mel270 and skin melanoma BLM. Materials and methods Cells treated with either proton beam or X-rays were analyzed for their survival using clonogenic assay and MTT test. Long-term migratory properties were assessed with time-lapse monitoring of individual cell movements, wound test and transpore migration, while the expression of the related proteins was measured with western blot. Results Exposure to proton beam and X-rays led to similar survival but the quality of the cell colonies was markedly different. More paraclones with a low proliferative activity and fewer highly-proliferative holoclones were found after proton beam irradiation in comparison to X-rays. At 20 or 40 days post-irradiation, migratory capacity was decreased more by proton beam than by X-rays. The beta-1-integrin level was decreased in Mel270 cells after both types of radiation, while vimentin, a marker of EMT, was increased in BLM cells only. Conclusions We conclude that proton beam irradiation induced long-term inhibition of cellular motility, as well as changes in the level of beta-1 integrin and vimentin. If confirmed, the change in the quality, but not in the number of colonies after proton beam irradiation might favor tumor growth inhibition after fractionated proton therapy.
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Affiliation(s)
| | - Katarzyna Pochylczuk
- Department of Biophysics, Faculty of Biochemistry, Biophysics and Biotechnology, Cracow, Poland
| | - Elżbieta Czajka
- Department of Biophysics, Faculty of Biochemistry, Biophysics and Biotechnology, Cracow, Poland
| | - Marta Michalik
- Department of Cell Biology, Faculty of Biochemistry, Biophysics and Biotechnology, Cracow, Poland
| | - Bożena Romanowska-Dixon
- Department of Ophthalmology and Ophthalmic Oncology, Jagiellonian University Medical College, Cracow, Poland
| | - Jan Swakoń
- Institute of Nuclear Physics, PAS, Cracow, Poland
| | - Krystyna Urbańska
- Department of Biophysics, Faculty of Biochemistry, Biophysics and Biotechnology, Cracow, Poland
| | - Martyna Elas
- Department of Biophysics, Faculty of Biochemistry, Biophysics and Biotechnology, Cracow, Poland
- * E-mail:
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Vassiliev ON, Grosshans DR, Mohan R. A new formalism for modelling parameters α and β of the linear-quadratic model of cell survival for hadron therapy. Phys Med Biol 2017; 62:8041-8059. [PMID: 28832343 PMCID: PMC5737022 DOI: 10.1088/1361-6560/aa8804] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
We propose a new formalism for calculating parameters α and β of the linear-quadratic model of cell survival. This formalism, primarily intended for calculating relative biological effectiveness (RBE) for treatment planning in hadron therapy, is based on a recently proposed microdosimetric revision of the single-target multi-hit model. The main advantage of our formalism is that it reliably produces α and β that have correct general properties with respect to their dependence on physical properties of the beam, including the asymptotic behavior for very low and high linear energy transfer (LET) beams. For example, in the case of monoenergetic beams, our formalism predicts that, as a function of LET, (a) α has a maximum and (b) the α/β ratio increases monotonically with increasing LET. No prior models reviewed in this study predict both properties (a) and (b) correctly, and therefore, these prior models are valid only within a limited LET range. We first present our formalism in a general form, for polyenergetic beams. A significant new result in this general case is that parameter β is represented as an average over the joint distribution of energies E 1 and E 2 of two particles in the beam. This result is consistent with the role of the quadratic term in the linear-quadratic model. It accounts for the two-track mechanism of cell kill, in which two particles, one after another, damage the same site in the cell nucleus. We then present simplified versions of the formalism, and discuss predicted properties of α and β. Finally, to demonstrate consistency of our formalism with experimental data, we apply it to fit two sets of experimental data: (1) α for heavy ions, covering a broad range of LETs, and (2) β for protons. In both cases, good agreement is achieved.
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Affiliation(s)
- Oleg N Vassiliev
- Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, United States of America
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Quantification of the uncertainties of a biological model and their impact on variable RBE proton treatment plan optimization. Phys Med 2017; 36:91-102. [PMID: 28410691 DOI: 10.1016/j.ejmp.2017.03.013] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/14/2016] [Revised: 03/14/2017] [Accepted: 03/20/2017] [Indexed: 01/12/2023] Open
Abstract
PURPOSE In proton radiation therapy, a relative biological effectiveness (RBE) equal to 1.1 is currently assumed, although biological experiments show that it is not constant. The purpose of this study was to quantify the uncertainties of a published biological model and explore their impact on variable RBE treatment plan (TP) optimization. METHODS Two patient cases with a high and a low (α/β)x tumor were investigated. Firstly, intensity modulated proton therapy TPs assuming constant RBE were derived, and subsequently the variable RBE weighted dose (RWD), including the uncertainty originating in the fit to the experimental data and the uncertainty of the (α/β)x, were calculated. Secondly, TPs optimized for uniform biological effect assuming a variable RBE were created using the worst case tissue specific (α/β)x. RESULTS For the nasopharyngeal cancer patient, the uncertainty of (α/β)x corresponded to a CTV D98 confidence interval (CI) of (-2, +4)% while for the fit parameter CI was (-2,+1)%. For the standard fractionation prostate case the (α/β)x CI was (-7,+5)% and the fit parameter CI was (-3,+3)%. For the hypofractionated case both CIs were (-1,+1)%. In both patient cases, the RBE in most organs at risk (OARs) was significantly underestimated by the constant RBE approximation, whereas the situation was not as definite in the target volumes. Overdosage of OARs was reduced by using the biological effect optimization. CONCLUSION For the two patient cases, the RWD uncertainty from the fit parameter in the biological model contributed non-negligibly to the total uncertainty, depending on the patient case and the organ. The presented optimization strategy is a basic method for robust biological effect optimization to reduce potential consequences caused by the (α/β)x uncertainty.
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Ödén J, Eriksson K, Toma-Dasu I. Inclusion of a variable RBE into proton and photon plan comparison for various fractionation schedules in prostate radiation therapy. Med Phys 2017; 44:810-822. [PMID: 28107554 DOI: 10.1002/mp.12117] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2016] [Revised: 11/29/2016] [Accepted: 01/12/2017] [Indexed: 11/06/2022] Open
Abstract
PURPOSE A constant relative biological effectiveness (RBE) of 1.1 is currently used in proton radiation therapy to account for the increased biological effectiveness compared to photon therapy. However, there is increasing evidence that proton RBE vary with the linear energy transfer (LET), the dose per fraction, and the type of the tissue. Therefore, this study aims to evaluate the impact of disregarding variations in RBE when comparing proton and photon dose plans for prostate treatments for various fractionation schedules using published RBE models and several α/β assumptions. METHODS Photon and proton dose plans were created for three generic prostate cancer cases. Three BED3Gy equivalent schedules were studied, 78, 57.2, and 42.8 Gy in 39, 15, and 7 fractions, respectively. The proton plans were optimized assuming a constant RBE of 1.1. By using the Monte Carlo calculated dose-averaged LET (LETd ) distribution and assuming α/β values on voxel level, three variable RBE models were applied to the proton dose plans. The impact of the variable RBE was studied in the plan comparison, which was based on the dose distribution, DVHs, and normal tissue complication probabilities (NTCP) for the rectum. Subsequently, the physical proton dose was reoptimized for each proton plan based on the LETd distribution, to achieve a homogeneous RBE-weighted target dose when applying a specific RBE model and still fulfill the clinical goals for the rectum and bladder. RESULTS All the photon and proton plans assuming RBE = 1.1 met the clinical goals with similar target coverage. The proton plans fulfilled the robustness criteria in terms of range and setup uncertainty. Applying the variable RBE models generally resulted in higher target doses and rectum NTCP compared to the photon plans. The increase was most pronounced for the fractionation dose of 2 Gy(RBE), whereas it was of less magnitude and more dependent on model and α/β assumption for the hypofractionated schedules. The reoptimized proton plans proved to be robust and showed similar target coverage and doses to the organs at risk as the proton plans optimized with a constant RBE. CONCLUSIONS Model predicted RBE values may differ substantially from 1.1. This is most pronounced for fractionation doses of around 2 Gy(RBE) with higher doses to the target and the OARs, whereas the effect seems to be of less importance for the hypofractionated schedules. This could result in misleading conclusions when comparing proton plans to photon plans. By accounting for a variable RBE in the optimization process, robust and clinically acceptable dose plans, with the potential of lowering rectal NTCP, may be generated by reoptimizing the physical dose. However, the direction and magnitude of the changes in the physical proton dose to the prostate are dependent on RBE model and α/β assumptions and should therefore be used conservatively.
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Affiliation(s)
- Jakob Ödén
- Department of Physics, Medical Radiation Physics, Stockholm University, Stockholm, 17176, Sweden.,RaySearch Laboratories, Stockholm, 11134, Sweden
| | | | - Iuliana Toma-Dasu
- Department of Physics, Medical Radiation Physics, Stockholm University, Stockholm, 17176, Sweden.,Department of Oncology and Pathology, Medical Radiation Physics, Karolinska Institutet, Stockholm, 17176, Sweden
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Li Y, Tian Z, Song T, Wu Z, Liu Y, Jiang S, Jia X. A new approach to integrate GPU-based Monte Carlo simulation into inverse treatment plan optimization for proton therapy. Phys Med Biol 2017; 62:289-305. [PMID: 27991456 DOI: 10.1088/1361-6560/62/1/289] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Monte Carlo (MC)-based spot dose calculation is highly desired for inverse treatment planning in proton therapy because of its accuracy. Recent studies on biological optimization have also indicated the use of MC methods to compute relevant quantities of interest, e.g. linear energy transfer. Although GPU-based MC engines have been developed to address inverse optimization problems, their efficiency still needs to be improved. Also, the use of a large number of GPUs in MC calculation is not favorable for clinical applications. The previously proposed adaptive particle sampling (APS) method can improve the efficiency of MC-based inverse optimization by using the computationally expensive MC simulation more effectively. This method is more efficient than the conventional approach that performs spot dose calculation and optimization in two sequential steps. In this paper, we propose a computational library to perform MC-based spot dose calculation on GPU with the APS scheme. The implemented APS method performs a non-uniform sampling of the particles from pencil beam spots during the optimization process, favoring those from the high intensity spots. The library also conducts two computationally intensive matrix-vector operations frequently used when solving an optimization problem. This library design allows a streamlined integration of the MC-based spot dose calculation into an existing proton therapy inverse planning process. We tested the developed library in a typical inverse optimization system with four patient cases. The library achieved the targeted functions by supporting inverse planning in various proton therapy schemes, e.g. single field uniform dose, 3D intensity modulated proton therapy, and distal edge tracking. The efficiency was 41.6 ± 15.3% higher than the use of a GPU-based MC package in a conventional calculation scheme. The total computation time ranged between 2 and 50 min on a single GPU card depending on the problem size.
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Affiliation(s)
- Yongbao Li
- Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX 75390-8542, USA. Department of Engineering Physics, Key Laboratory of Particle & Radiation Imaging (Tsinghua University), Ministry of Education, Tsinghua University, Beijing 10084, People's Republic of China
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Unkelbach J, Botas P, Giantsoudi D, Gorissen BL, Paganetti H. Reoptimization of Intensity Modulated Proton Therapy Plans Based on Linear Energy Transfer. Int J Radiat Oncol Biol Phys 2016; 96:1097-1106. [PMID: 27869082 PMCID: PMC5133459 DOI: 10.1016/j.ijrobp.2016.08.038] [Citation(s) in RCA: 135] [Impact Index Per Article: 16.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2016] [Revised: 08/19/2016] [Accepted: 08/25/2016] [Indexed: 01/20/2023]
Abstract
PURPOSE We describe a treatment plan optimization method for intensity modulated proton therapy (IMPT) that avoids high values of linear energy transfer (LET) in critical structures located within or near the target volume while limiting degradation of the best possible physical dose distribution. METHODS AND MATERIALS To allow fast optimization based on dose and LET, a GPU-based Monte Carlo code was extended to provide dose-averaged LET in addition to dose for all pencil beams. After optimizing an initial IMPT plan based on physical dose, a prioritized optimization scheme is used to modify the LET distribution while constraining the physical dose objectives to values close to the initial plan. The LET optimization step is performed based on objective functions evaluated for the product of LET and physical dose (LET×D). To first approximation, LET×D represents a measure of the additional biological dose that is caused by high LET. RESULTS The method is effective for treatments where serial critical structures with maximum dose constraints are located within or near the target. We report on 5 patients with intracranial tumors (high-grade meningiomas, base-of-skull chordomas, ependymomas) in whom the target volume overlaps with the brainstem and optic structures. In all cases, high LET×D in critical structures could be avoided while minimally compromising physical dose planning objectives. CONCLUSION LET-based reoptimization of IMPT plans represents a pragmatic approach to bridge the gap between purely physical dose-based and relative biological effectiveness (RBE)-based planning. The method makes IMPT treatments safer by mitigating a potentially increased risk of side effects resulting from elevated RBE of proton beams near the end of range.
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Affiliation(s)
- Jan Unkelbach
- Department of Radiation Oncology, Massachusetts General Hospital, Boston, Massachusetts.
| | - Pablo Botas
- Department of Radiation Oncology, Massachusetts General Hospital, Boston, Massachusetts; Faculty of Physics, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Germany
| | - Drosoula Giantsoudi
- Department of Radiation Oncology, Massachusetts General Hospital, Boston, Massachusetts
| | - Bram L Gorissen
- Department of Radiation Oncology, Massachusetts General Hospital, Boston, Massachusetts
| | - Harald Paganetti
- Department of Radiation Oncology, Massachusetts General Hospital, Boston, Massachusetts
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Guan F, Peeler C, Bronk L, Geng C, Taleei R, Randeniya S, Ge S, Mirkovic D, Grosshans D, Mohan R, Titt U. Analysis of the track- and dose-averaged LET and LET spectra in proton therapy using the geant4 Monte Carlo code. Med Phys 2016; 42:6234-47. [PMID: 26520716 DOI: 10.1118/1.4932217] [Citation(s) in RCA: 93] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE The motivation of this study was to find and eliminate the cause of errors in dose-averaged linear energy transfer (LET) calculations from therapeutic protons in small targets, such as biological cell layers, calculated using the geant 4 Monte Carlo code. Furthermore, the purpose was also to provide a recommendation to select an appropriate LET quantity from geant 4 simulations to correlate with biological effectiveness of therapeutic protons. METHODS The authors developed a particle tracking step based strategy to calculate the average LET quantities (track-averaged LET, LETt and dose-averaged LET, LETd) using geant 4 for different tracking step size limits. A step size limit refers to the maximally allowable tracking step length. The authors investigated how the tracking step size limit influenced the calculated LETt and LETd of protons with six different step limits ranging from 1 to 500 μm in a water phantom irradiated by a 79.7-MeV clinical proton beam. In addition, the authors analyzed the detailed stochastic energy deposition information including fluence spectra and dose spectra of the energy-deposition-per-step of protons. As a reference, the authors also calculated the averaged LET and analyzed the LET spectra combining the Monte Carlo method and the deterministic method. Relative biological effectiveness (RBE) calculations were performed to illustrate the impact of different LET calculation methods on the RBE-weighted dose. RESULTS Simulation results showed that the step limit effect was small for LETt but significant for LETd. This resulted from differences in the energy-deposition-per-step between the fluence spectra and dose spectra at different depths in the phantom. Using the Monte Carlo particle tracking method in geant 4 can result in incorrect LETd calculation results in the dose plateau region for small step limits. The erroneous LETd results can be attributed to the algorithm to determine fluctuations in energy deposition along the tracking step in geant 4. The incorrect LETd values lead to substantial differences in the calculated RBE. CONCLUSIONS When the geant 4 particle tracking method is used to calculate the average LET values within targets with a small step limit, such as smaller than 500 μm, the authors recommend the use of LETt in the dose plateau region and LETd around the Bragg peak. For a large step limit, i.e., 500 μm, LETd is recommended along the whole Bragg curve. The transition point depends on beam parameters and can be found by determining the location where the gradient of the ratio of LETd and LETt becomes positive.
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Affiliation(s)
- Fada Guan
- Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, Texas 77030
| | - Christopher Peeler
- Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, Texas 77030
| | - Lawrence Bronk
- Department of Experimental Radiation Oncology, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, Texas 77030
| | - Changran Geng
- Department of Nuclear Science and Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China and Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114
| | - Reza Taleei
- Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, Texas 77030
| | - Sharmalee Randeniya
- Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, Texas 77030
| | - Shuaiping Ge
- Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, Texas 77030
| | - Dragan Mirkovic
- Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, Texas 77030
| | - David Grosshans
- Department of Experimental Radiation Oncology, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, Texas 77030 and Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, Texas 77030
| | - Radhe Mohan
- Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, Texas 77030
| | - Uwe Titt
- Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, Texas 77030
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Marsolat F, De Marzi L, Pouzoulet F, Mazal A. Analytical linear energy transfer model including secondary particles: calculations along the central axis of the proton pencil beam. Phys Med Biol 2016; 61:740-57. [PMID: 26732530 DOI: 10.1088/0031-9155/61/2/740] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
In proton therapy, the relative biological effectiveness (RBE) depends on various types of parameters such as linear energy transfer (LET). An analytical model for LET calculation exists (Wilkens' model), but secondary particles are not included in this model. In the present study, we propose a correction factor, L sec, for Wilkens' model in order to take into account the LET contributions of certain secondary particles. This study includes secondary protons and deuterons, since the effects of these two types of particles can be described by the same RBE-LET relationship. L sec was evaluated by Monte Carlo (MC) simulations using the GATE/GEANT4 platform and was defined by the ratio of the LET d distributions of all protons and deuterons and only primary protons. This method was applied to the innovative Pencil Beam Scanning (PBS) delivery systems and L sec was evaluated along the beam axis. This correction factor indicates the high contribution of secondary particles in the entrance region, with L sec values higher than 1.6 for a 220 MeV clinical pencil beam. MC simulations showed the impact of pencil beam parameters, such as mean initial energy, spot size, and depth in water, on L sec. The variation of L sec with these different parameters was integrated in a polynomial function of the L sec factor in order to obtain a model universally applicable to all PBS delivery systems. The validity of this correction factor applied to Wilkens' model was verified along the beam axis of various pencil beams in comparison with MC simulations. A good agreement was obtained between the corrected analytical model and the MC calculations, with mean-LET deviations along the beam axis less than 0.05 keV μm(-1). These results demonstrate the efficacy of our new correction of the existing LET model in order to take into account secondary protons and deuterons along the pencil beam axis.
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Affiliation(s)
- F Marsolat
- Institut Curie, Centre de Protonthérapie d'Orsay, France. Institut Curie, Centre de Recherche, Plateforme de Radiothérapie Expérimentale, France
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Russo G, Attili A, Battistoni G, Bertrand D, Bourhaleb F, Cappucci F, Ciocca M, Mairani A, Milian FM, Molinelli S, Morone MC, Muraro S, Orts T, Patera V, Sala P, Schmitt E, Vivaldo G, Marchetto F. A novel algorithm for the calculation of physical and biological irradiation quantities in scanned ion beam therapy: the beamlet superposition approach. Phys Med Biol 2015; 61:183-214. [DOI: 10.1088/0031-9155/61/1/183] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Giantsoudi D, Sethi RV, Yeap BY, Eaton BR, Ebb DH, Caruso PA, Rapalino O, Chen YLE, Adams JA, Yock TI, Tarbell NJ, Paganetti H, MacDonald SM. Incidence of CNS Injury for a Cohort of 111 Patients Treated With Proton Therapy for Medulloblastoma: LET and RBE Associations for Areas of Injury. Int J Radiat Oncol Biol Phys 2015; 95:287-296. [PMID: 26691786 DOI: 10.1016/j.ijrobp.2015.09.015] [Citation(s) in RCA: 93] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2015] [Revised: 09/03/2015] [Accepted: 09/11/2015] [Indexed: 12/17/2022]
Abstract
BACKGROUND Central nervous system (CNS) injury is a rare complication of radiation therapy for pediatric brain tumors, but its incidence with proton radiation therapy (PRT) is less well defined. Increased linear energy transfer (LET) and relative biological effectiveness (RBE) at the distal end of proton beams may influence this risk. We report the incidence of CNS injury in medulloblastoma patients treated with PRT and investigate correlations with LET and RBE values. METHODS AND MATERIALS We reviewed 111 consecutive patients treated with PRT for medulloblastoma between 2002 and 2011 and selected patients with clinical symptoms of CNS injury. Magnetic resonance imaging (MRI) findings for all patients were contoured on original planning scans (treatment change areas [TCA]). Dose and LET distributions were calculated for the treated plans using Monte Carlo system. RBE values were estimated based on LET-based published models. RESULTS At a median follow-up of 4.2 years, the 5-year cumulative incidence of CNS injury was 3.6% for any grade and 2.7% for grade 3+. Three of 4 symptomatic patients were treated with a whole posterior fossa boost. Eight of 10 defined TCAs had higher LET values than the target but statistically nonsignificant differences in RBE values (P=.12). CONCLUSIONS Central nervous system and brainstem injury incidence for PRT in this series is similar to that reported for photon radiation therapy. The risk of CNS injury was higher for whole posterior fossa boost than for involved field. Although no clear correlation with RBE values was found, numbers were small and additional investigation is warranted to better determine the relationship between injury and LET.
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Affiliation(s)
- Drosoula Giantsoudi
- Department of Radiation Oncology, Massachusetts General Hospital, Boston, Massachusetts
| | - Roshan V Sethi
- Department of Radiation Oncology, Massachusetts General Hospital, Boston, Massachusetts
| | - Beow Y Yeap
- Department of Medicine, Massachusetts General Hospital, Boston, Massachusetts
| | - Bree R Eaton
- Department of Radiation Oncology, Massachusetts General Hospital, Boston, Massachusetts
| | - David H Ebb
- Department of Pediatrics, Massachusetts General Hospital, Boston, Massachusetts
| | - Paul A Caruso
- Department of Radiology (O.R.) at the Massachusetts General Hospital, Boston, Massachusetts
| | - Otto Rapalino
- Department of Radiology (O.R.) at the Massachusetts General Hospital, Boston, Massachusetts
| | - Yen-Lin E Chen
- Department of Radiation Oncology, Massachusetts General Hospital, Boston, Massachusetts
| | - Judith A Adams
- Department of Radiation Oncology, Massachusetts General Hospital, Boston, Massachusetts
| | - Torunn I Yock
- Department of Radiation Oncology, Massachusetts General Hospital, Boston, Massachusetts
| | - Nancy J Tarbell
- Department of Radiation Oncology, Massachusetts General Hospital, Boston, Massachusetts
| | - Harald Paganetti
- Department of Radiation Oncology, Massachusetts General Hospital, Boston, Massachusetts
| | - Shannon M MacDonald
- Department of Radiation Oncology, Massachusetts General Hospital, Boston, Massachusetts.
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Qutub MAZ, Klein SB, Buchsbaum JC. Rapid RBE-Weighted Proton Radiation Dosimetry Risk Assessment. Technol Cancer Res Treat 2015; 15:NP1-7. [PMID: 26283051 DOI: 10.1177/1533034615599313] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2014] [Accepted: 07/01/2015] [Indexed: 11/17/2022] Open
Abstract
Proton therapy dose is affected by relative biological effectiveness differently than X-ray therapies. The current clinically accepted weighting factor is 1.1 at all positions along the depth-dose profile. However, the relative biological effectiveness correlates with the linear energy transfer, cell or tissue type, and the dose per fraction causing variation of relative biological effectiveness along the depth-dose profile. In this article, we present a simple relative biological effectiveness-weighted treatment planning risk assessment algorithm in 2-dimensions and compare the results with those derived using the standard relative biological effectiveness of 1.1. The isodose distribution profiles for beams were accomplished using matrices that represent coplanar intersecting beams. These matrices were combined and contoured using MATLAB to achieve the distribution of dose. There are some important differences in dose distribution between the dose profiles resulting from the use of relative biological effectiveness = 1.1 and the empirically derived depth-dependent values of relative biological effectiveness. Significant hot spots of up to twice the intended dose are indicated in some beam configurations. This simple and rapid risk analysis could quickly evaluate the safety of various dose delivery schema.
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Affiliation(s)
- Mohammad A Z Qutub
- Department of Physics, Indiana University School of Arts and Sciences, Indianapolis, IN, USA
| | - Susan B Klein
- Department of Physics, Indiana University School of Arts and Sciences, Indianapolis, IN, USA
| | - Jeffrey C Buchsbaum
- Department of Physics, Indiana University School of Arts and Sciences, Indianapolis, IN, USA Departments of Radiation Oncology, Pediatrics, and Neurological Surgery, Indiana University School of Medicine, Indianapolis, IN, USA
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