1
|
Gardner LL, O'Connor JD, McMahon SJ. Benchmarking proton RBE models. Phys Med Biol 2024; 69:085022. [PMID: 38471187 DOI: 10.1088/1361-6560/ad3329] [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: 10/03/2023] [Accepted: 03/12/2024] [Indexed: 03/14/2024]
Abstract
Objective.To biologically optimise proton therapy, models which can accurately predict variations in proton relative biological effectiveness (RBE) are essential. Current phenomenological models show large disagreements in RBE predictions, due to different model assumptions and differences in the data to which they were fit. In this work, thirteen RBE models were benchmarked against a comprehensive proton RBE dataset to evaluate predictions when all models are fit using the same data and fitting techniques, and to assess the statistical robustness of the models.Approach.Model performance was initially evaluated by fitting to the full dataset, and then a cross-validation approach was applied to assess model generalisability and robustness. The impact of weighting the fit and the choice of biological endpoint (either single or multiple survival levels) was also evaluated.Main results.Fitting the models to a common dataset reduced differences between their predictions, however significant disagreements remained due to different underlying assumptions. All models performed poorly under cross-validation in the weighted fits, suggesting that some uncertainties on the experimental data were significantly underestimated, resulting in over-fitting and poor performance on unseen data. The simplest model, which depends linearly on the LET but has no tissue or dose dependence, performed best for a single survival level. However, when fitting to multiple survival levels simultaneously, more complex models with tissue dependence performed better. All models had significant residual uncertainty in their predictions compared to experimental data.Significance.This analysis highlights that poor quality of error estimation on the dose response parameters introduces substantial uncertainty in model fitting. The significant residual error present in all approaches illustrates the challenges inherent in fitting to large, heterogeneous datasets and the importance of robust statistical validation of RBE models.
Collapse
Affiliation(s)
- Lydia L Gardner
- Patrick G Johnston Centre for Cancer Research, Queen's University Belfast, Belfast, United Kingdom
| | - John D O'Connor
- School of Engineering, Ulster University, Belfast, United Kingdom
| | - Stephen J McMahon
- Patrick G Johnston Centre for Cancer Research, Queen's University Belfast, Belfast, United Kingdom
| |
Collapse
|
2
|
Denbeigh JM, Howard ME, Garcia DA, Debrot EK, Cole KC, Remmes NB, Beltran CJ. Characterizing Proton-Induced Biological Effects in a Mouse Spinal Cord Model: A Comparison of Bragg Peak and Entrance Beam Response in Single and Fractionated Exposures. Int J Radiat Oncol Biol Phys 2024:S0360-3016(23)08305-0. [PMID: 38310485 DOI: 10.1016/j.ijrobp.2023.12.031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2023] [Revised: 12/19/2023] [Accepted: 12/23/2023] [Indexed: 02/05/2024]
Abstract
PURPOSE Proton relative biological effectiveness (RBE) is a dynamic variable influenced by factors like linear energy transfer (LET), dose, tissue type, and biological endpoint. The standard fixed proton RBE of 1.1, currently used in clinical planning, may not accurately represent the true biological effects of proton therapy (PT) in all cases. This uncertainty can contribute to radiation-induced normal tissue toxicity in patients. In late-responding tissues such as the spinal cord, toxicity can cause devastating complications. This study investigated spinal cord tolerance in mice subjected to proton irradiation and characterized the influence of fractionation on proton- induced myelopathy at entrance (ENT) and Bragg peak (BP) positions. METHODS AND MATERIALS Cervical spinal cords of 8-week-old C57BL/6J female mice were irradiated with single- or multi-fractions (18x) using lateral opposed radiation fields at 1 of 2 positions along the Bragg curve: ENT (dose-mean LET = 1.2 keV/μm) and BP (LET = 6.9 keV/μm). Mice were monitored over 1 year for changes in weight, mobility, and general health, with radiation-induced myelopathy as the primary biological endpoint. Calculations of the RBE of the ENT and BP curve (RBEENT/BP) were performed. RESULTS Single-fraction RBEENT/BP for 50% effect probability (tolerance dose (TD50), grade II paresis, determined using log-logistic model fitting) was 1.10 ± 0.06 (95% CI) and for multifraction treatments it was 1.19 ± 0.05 (95% CI). Higher incidence and faster onset of paralysis were seen in mice treated at the BP compared with ENT. CONCLUSIONS The findings challenge the universally fixed RBE value in PT, indicating up to a 25% mouse spinal cord RBEENT/BP variation for multifraction treatments. These results highlight the importance of considering fractionation in determining RBE for PT. Robust characterization of proton-induced toxicity, aided by in vivo models, is paramount for refining clinical decision-making and mitigating potential patient side effects.
Collapse
Affiliation(s)
- Janet M Denbeigh
- Department of Radiation Oncology, Mayo Clinic, Jacksonville, Florida.
| | - Michelle E Howard
- Department of Radiation Oncology, University of Iowa, Iowa City, Iowa
| | - Darwin A Garcia
- Department of Radiation Oncology, Mayo Clinic, Rochester, Minnesota
| | - Emily K Debrot
- St George Cancer Care Centre, Kogarah, New South Wales, Australia
| | - Kristin C Cole
- Department of Radiation Oncology, Mayo Clinic, Rochester, Minnesota
| | | | - Chris J Beltran
- Department of Radiation Oncology, Mayo Clinic, Jacksonville, Florida
| |
Collapse
|
3
|
Parisi A, Beltran CJ, Furutani KM. Variable RBE in proton radiotherapy: a comparative study with the predictive Mayo Clinic Florida microdosimetric kinetic model and phenomenological models of cell survival. Phys Med Biol 2023; 68:185020. [PMID: 38133518 DOI: 10.1088/1361-6560/acf43b] [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: 05/26/2023] [Accepted: 08/25/2023] [Indexed: 12/23/2023]
Abstract
Objectives. (1) To examine to what extent the cell- and exposure- specific information neglected in the phenomenological proton relative biological effectiveness (RBE) models could influence the computed RBE in proton therapy. (2) To explore similarities and differences in the formalism and the results between the linear energy transfer (LET)-based phenomenological proton RBE models and the microdosimetry-based Mayo Clinic Florida microdosimetric kinetic model (MCF MKM). (3) To investigate how the relationship between the RBE and the dose-mean proton LET is affected by the proton energy spectrum and the secondary fragments.Approach. We systematically compared six selected phenomenological proton RBE models with the MCF MKM in track-segment simulations, monoenergetic proton beams in a water phantom, and two spread-out Bragg peaks. A representative comparison within vitrodata for human glioblastoma cells (U87 cell line) is also included.Main results. Marked differences were observed between the results of the phenomenological proton RBE models, as reported in previous studies. The dispersion of these models' results was found to be comparable to the spread in the MCF MKM results obtained by varying the cell-specific parameters neglected in the phenomenological models. Furthermore, while single cell-specific correlation between RBE and the dose-mean proton LET seems reasonable above 2 keVμm-1, caution is necessary at lower LET values due to the relevant contribution of secondary fragments. The comparison within vitrodata demonstrates comparable agreement between the MCF MKM predictions and the results of the phenomenological models.Significance. The study highlights the importance of considering cell-specific characteristics and detailed radiation quality information for accurate RBE calculations in proton therapy. Furthermore, these results provide confidence in the use of the MCF MKM for clonogenic survival RBE calculations in proton therapy, offering a more mechanistic approach compared to phenomenological models.
Collapse
Affiliation(s)
- Alessio Parisi
- Department of Radiation Oncology, Mayo Clinic, Jacksonville, FL, United States of America
| | - Chris J Beltran
- Department of Radiation Oncology, Mayo Clinic, Jacksonville, FL, United States of America
| | - Keith M Furutani
- Department of Radiation Oncology, Mayo Clinic, Jacksonville, FL, United States of America
| |
Collapse
|
4
|
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.
Collapse
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
| |
Collapse
|
5
|
Henthorn NT, Gardner LL, Aitkenhead AH, Rowland BC, Shin J, Smith EAK, Merchant MJ, Mackay RI, Kirkby KJ, Chaudhary P, Prise KM, McMahon SJ, Underwood TSA. Proposing a Clinical Model for RBE Based on Proton Track-End Counts. Int J Radiat Oncol Biol Phys 2023; 116:916-926. [PMID: 36642109 DOI: 10.1016/j.ijrobp.2022.12.056] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2022] [Revised: 12/21/2022] [Accepted: 12/29/2022] [Indexed: 01/15/2023]
Abstract
PURPOSE In proton therapy, the clinical application of linear energy transfer (LET) optimization remains contentious, in part because of challenges associated with the definition and calculation of LET and its exact relationship with relative biological effectiveness (RBE) because of large variation in experimental in vitro data. This has raised interest in other metrics with favorable properties for biological optimization, such as the number of proton track ends in a voxel. In this work, we propose a novel model for clinical calculations of RBE, based on proton track end counts. METHODS AND MATERIALS We developed an effective dose concept to translate between the total proton track-end count per unit mass in a voxel and a proton RBE value. Dose, track end, and dose-averaged LET (LETd) distributions were simulated using Monte Carlo models for a series of water phantoms, in vitro radiobiological studies, and patient treatment plans. We evaluated the correlation between track ends and regions of elevated biological effectiveness in comparison to LETd-based models of RBE. RESULTS Track ends were found to correlate with biological effects in in vitro experiments with an accuracy comparable to LETd. In patient simulations, our track end model identified the same biological hotspots as predicted by LETd-based radiobiological models of proton RBE. CONCLUSIONS These results suggest that, for clinical optimization and evaluation, an RBE model based on proton track end counts may match LETd-based models in terms of information provided while also offering superior statistical properties.
Collapse
Affiliation(s)
- Nicholas T Henthorn
- Division of Cancer Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, United Kingdom; Manchester Academic Health Science Centre, The Christie NHS Foundation Trust, Manchester, United Kingdom.
| | - Lydia L Gardner
- Patrick G. Johnston Centre for Cancer Research, Queen's University Belfast, Belfast, United Kingdom
| | - Adam H Aitkenhead
- Division of Cancer Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, United Kingdom; Christie Medical Physics and Engineering, The Christie NHS Foundation Trust, Manchester, United Kingdom
| | - Benjamin C Rowland
- Division of Cancer Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, United Kingdom; Manchester Academic Health Science Centre, The Christie NHS Foundation Trust, Manchester, United Kingdom
| | - Jungwook Shin
- Department of Radiation Oncology, Harvard Medical School and Massachusetts General Hospital, Boston, Massachusetts
| | - Edward A K Smith
- Division of Cancer Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, United Kingdom; Manchester Academic Health Science Centre, The Christie NHS Foundation Trust, Manchester, United Kingdom
| | - Michael J Merchant
- Division of Cancer Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, United Kingdom; Manchester Academic Health Science Centre, The Christie NHS Foundation Trust, Manchester, United Kingdom
| | - Ranald I Mackay
- Division of Cancer Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, United Kingdom; Christie Medical Physics and Engineering, The Christie NHS Foundation Trust, Manchester, United Kingdom
| | - Karen J Kirkby
- Division of Cancer Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, United Kingdom; Manchester Academic Health Science Centre, The Christie NHS Foundation Trust, Manchester, United Kingdom
| | - Pankaj Chaudhary
- Patrick G. Johnston Centre for Cancer Research, Queen's University Belfast, Belfast, United Kingdom
| | - Kevin M Prise
- Patrick G. Johnston Centre for Cancer Research, Queen's University Belfast, Belfast, United Kingdom
| | - Stephen J McMahon
- Patrick G. Johnston Centre for Cancer Research, Queen's University Belfast, Belfast, United Kingdom
| | - Tracy S A Underwood
- Division of Cancer Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, United Kingdom; Manchester Academic Health Science Centre, The Christie NHS Foundation Trust, Manchester, United Kingdom; Leo Cancer Care Ltd, Unit 1 Woodbridge House, Chapel Rd, Smallfield, Horley RH6 9NW, United Kingdom
| |
Collapse
|
6
|
Kasamatsu K, Matsuura T, Yasuda K, Miyazaki K, Takao S, Tamura M, Otsuka M, Uchinami Y, Aoyama H. Hyperfractionated intensity-modulated proton therapy for pharyngeal cancer with variable relative biological effectiveness: A simulation study. Med Phys 2022; 49:7815-7825. [PMID: 36300598 DOI: 10.1002/mp.16064] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Revised: 10/06/2022] [Accepted: 10/07/2022] [Indexed: 12/27/2022] Open
Abstract
BACKGROUND The relative biological effectiveness (RBE) of proton is considered to be dependent on biological parameters and fractional dose. While hyperfractionated photon therapy was effective in the treatment of patients with head and neck cancers, its effect in intensity-modulated proton therapy (IMPT) under the variable RBE has not been investigated in detail. PURPOSE To study the effect of variable RBE on hyperfractionated IMPT for the treatment of pharyngeal cancer. We investigated the biologically effective dose (BED) to determine the theoretical effective hyperfractionated schedule. METHODS The treatment plans of three pharyngeal cancer patients were used to define the ΔBED for the clinical target volume (CTV) and soft tissue (acute and late reaction) as the difference between the BED for the altered schedule with variable RBE and conventional schedule with constant RBE. The ΔBED with several combinations of parameters (treatment days, number of fractions, and prescribed dose) was comprehensively calculated. Of the candidate schedules, the one that commonly gave a higher ΔBED for CTV was selected as the resultant schedule. The BED volume histogram was used to compare the influence of variable RBE and fractionation. RESULTS In the conventional schedule, compared with the constant RBE, the variable RBE resulted in a mean 2.6 and 2.7 Gy reduction of BEDmean for the CTV and soft tissue (acute reaction) of the three plans, respectively. Moreover, the BEDmean for soft tissue (late reaction) increased by 7.4 Gy, indicating a potential risk of increased RBE. Comprehensive calculation of the ΔBED resulted in the hyperfractionated schedule of 80.52 Gy (RBE = 1.1)/66 fractions in 6.5 weeks. When variable RBE was used, compared with the conventional schedule, the hyperfractionated schedule increased the BEDmean for CTV by 7.6 Gy; however, this was associated with a 7.8 Gy increase for soft tissue (acute reaction). The BEDmean for soft tissue (late reaction) decreased by 2.4 Gy. CONCLUSION The results indicated a potential effect of the variable RBE on IMPT for pharyngeal cancer but with the possibility that hyperfractionation could outweigh this effect. Although biological uncertainties require conservative use of the resultant schedule, hyperfractionation is expected to be an effective strategy in IMPT for pharyngeal cancer.
Collapse
Affiliation(s)
- Koki Kasamatsu
- Graduate School of Biomedical Science and Engineering, Hokkaido University, Sapporo, Japan
| | - Taeko Matsuura
- Faculty of Engineering, Hokkaido University, Sapporo, Japan.,Department of Medical Physics, Hokkaido University Hospital, Sapporo, Japan.,Proton Beam Therapy Center, Hokkaido University Hospital, Sapporo, Japan
| | - Koichi Yasuda
- Department of Radiation Oncology, Faculty and Graduate School of Medicine, Hokkaido University, Sapporo, Japan
| | - Koichi Miyazaki
- Faculty of Engineering, Hokkaido University, Sapporo, Japan.,Department of Medical Physics, Hokkaido University Hospital, Sapporo, Japan.,Research and Development Group, Hitachi, Ltd., Hitachi-shi, Japan
| | - Seishin Takao
- Faculty of Engineering, Hokkaido University, Sapporo, Japan.,Department of Medical Physics, Hokkaido University Hospital, Sapporo, Japan.,Proton Beam Therapy Center, Hokkaido University Hospital, Sapporo, Japan
| | - Masaya Tamura
- Department of Medical Physics, Hokkaido University Hospital, Sapporo, Japan
| | - Manami Otsuka
- Department of Radiation Oncology, Faculty and Graduate School of Medicine, Hokkaido University, Sapporo, Japan
| | - Yusuke Uchinami
- Department of Radiation Oncology, Faculty and Graduate School of Medicine, Hokkaido University, Sapporo, Japan
| | - Hidefumi Aoyama
- Department of Radiation Oncology, Faculty and Graduate School of Medicine, Hokkaido University, Sapporo, Japan
| |
Collapse
|
7
|
Vaniqui A, Vaassen F, Di Perri D, Eekers D, Compter I, Rinaldi I, van Elmpt W, Unipan M. Linear Energy Transfer and Relative Biological Effectiveness Investigation of Various Structures for a Cohort of Proton Patients With Brain Tumors. Adv Radiat Oncol 2022; 8:101128. [PMID: 36632089 PMCID: PMC9827037 DOI: 10.1016/j.adro.2022.101128] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2022] [Accepted: 10/31/2022] [Indexed: 11/27/2022] Open
Abstract
Purpose The current knowledge on biological effects associated with proton therapy is limited. Therefore, we investigated the distributions of dose, dose-averaged linear energy transfer (LETd), and the product between dose and LETd (DLETd) for a patient cohort treated with proton therapy. Different treatment planning system features and visualization tools were explored. Methods and Materials For a cohort of 24 patients with brain tumors, the LETd, DLETd, and dose was calculated for a fixed relative biological effectiveness value and 2 variable models: plan-based and phenomenological. Dose threshold levels of 0, 5, and 20 Gy were imposed for LETd visualization. The relationship between physical dose and LETd and the frequency of LETd hotspots were investigated. Results The phenomenological relative biological effectiveness model presented consistently higher dose values. For lower dose thresholds, the LETd distribution was steered toward higher values related to low treatment doses. Differences up to 26.0% were found according to the threshold. Maximum LETd values were identified in the brain, periventricular space, and ventricles. An inverse relationship between LETd and dose was observed. Frequency information to the domain of dose and LETd allowed for the identification of clusters, which steer the mean LETd values, and the identification of higher, but sparse, LETd values. Conclusions Identifying, quantifying, and recording LET distributions in a standardized fashion is necessary, because concern exists over a link between toxicity and LET hotspots. Visualizing DLETd or dose × LETd during treatment planning could allow for clinicians to make informed decisions.
Collapse
|
8
|
Hahn C, Heuchel L, Ödén J, Traneus E, Wulff J, Plaude S, Timmermann B, Bäumer C, Lühr A. Comparing biological effectiveness guided plan optimization strategies for cranial proton therapy: potential and challenges. Radiat Oncol 2022; 17:169. [PMID: 36273132 DOI: 10.1186/s13014-022-02143-x] [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: 05/19/2022] [Accepted: 10/10/2022] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND To introduce and compare multiple biological effectiveness guided (BG) proton plan optimization strategies minimizing variable relative biological effectiveness (RBE) induced dose burden in organs at risk (OAR) while maintaining plan quality with a constant RBE. METHODS Dose-optimized (DOSEopt) proton pencil beam scanning reference treatment plans were generated for ten cranial patients with prescription doses ≥ 54 Gy(RBE) and ≥ 1 OAR close to the clinical target volume (CTV). For each patient, four additional BG plans were created. BG objectives minimized either proton track-ends, dose-averaged linear energy transfer (LETd), energy depositions from high-LET protons or variable RBE-weighted dose (DRBE) in adjacent serially structured OARs. Plan quality (RBE = 1.1) was assessed by CTV dose coverage and robustness (2 mm setup, 3.5% density), dose homogeneity and conformity in the planning target volumes and adherence to OAR tolerance doses. LETd, DRBE (Wedenberg model, α/βCTV = 10 Gy, α/βOAR = 2 Gy) and resulting normal tissue complication probabilities (NTCPs) for blindness and brainstem necrosis were derived. Differences between DOSEopt and BG optimized plans were assessed and statistically tested (Wilcoxon signed rank, α = 0.05). RESULTS All plans were clinically acceptable. DOSEopt and BG optimized plans were comparable in target volume coverage, homogeneity and conformity. For recalculated DRBE in all patients, all BG plans significantly reduced near-maximum DRBE to critical OARs with differences up to 8.2 Gy(RBE) (p < 0.05). Direct DRBE optimization primarily reduced absorbed dose in OARs (average ΔDmean = 2.0 Gy; average ΔLETd,mean = 0.1 keV/µm), while the other strategies reduced LETd (average ΔDmean < 0.3 Gy; average ΔLETd,mean = 0.5 keV/µm). LET-optimizing strategies were more robust against range and setup uncertaintes for high-dose CTVs than DRBE optimization. All BG strategies reduced NTCP for brainstem necrosis and blindness on average by 47% with average and maximum reductions of 5.4 and 18.4 percentage points, respectively. CONCLUSIONS All BG strategies reduced variable RBE-induced NTCPs to OARs. Reducing LETd in high-dose voxels may be favourable due to its adherence to current dose reporting and maintenance of clinical plan quality and the availability of reported LETd and dose levels from clinical toxicity reports after cranial proton therapy. These optimization strategies beyond dose may be a first step towards safely translating variable RBE optimization in the clinics.
Collapse
Affiliation(s)
- Christian Hahn
- Department of Physics, TU Dortmund University, Dortmund, Germany. .,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.
| | - Lena Heuchel
- Department of Physics, TU Dortmund University, Dortmund, Germany
| | - Jakob Ödén
- RaySearch Laboratories AB, Stockholm, Sweden
| | | | - Jörg Wulff
- West German Proton Therapy Centre Essen, Essen, Germany.,West German Cancer Center (WTZ), University Hospital Essen, Essen, Germany
| | - Sandija Plaude
- West German Proton Therapy Centre Essen, Essen, Germany.,West German Cancer Center (WTZ), University Hospital Essen, Essen, Germany
| | - Beate Timmermann
- West German Proton Therapy Centre Essen, Essen, Germany.,West German Cancer Center (WTZ), University Hospital Essen, Essen, Germany.,Department of Particle Therapy, University Hospital Essen, Essen, Germany.,German Cancer Consortium (DKTK) and German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Christian Bäumer
- Department of Physics, TU Dortmund University, Dortmund, Germany.,West German Proton Therapy Centre Essen, Essen, Germany.,West German Cancer Center (WTZ), University Hospital Essen, Essen, Germany.,German Cancer Consortium (DKTK) and German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Armin Lühr
- Department of Physics, TU Dortmund University, Dortmund, Germany
| |
Collapse
|
9
|
Flint DB, Ruff CE, Bright SJ, Yepes P, Wang Q, Manandhar M, Kacem MB, Turner BX, Martinus DKJ, Shaitelman SF, Sawakuchi GO. An empirical model of proton RBE based on the linear correlation between x-ray and proton radiosensitivity. Med Phys 2022; 49:6221-6236. [PMID: 35831779 PMCID: PMC10360139 DOI: 10.1002/mp.15850] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2022] [Revised: 06/12/2022] [Accepted: 06/24/2022] [Indexed: 11/08/2022] Open
Abstract
BACKGROUND Proton relative biological effectiveness (RBE) is known to depend on physical factors of the proton beam, such as its linear energy transfer (LET), as well as on cell-line specific biological factors, such as their ability to repair DNA damage. However, in a clinical setting, proton RBE is still considered to have a fixed value of 1.1 despite the existence of several empirical models that can predict proton RBE based on how a cell's survival curve (linear-quadratic model [LQM]) parameters α and β vary with the LET of the proton beam. Part of the hesitation to incorporate variable RBE models in the clinic is due to the great noise in the biological datasets on which these models are trained, often making it unclear which model, if any, provides sufficiently accurate RBE predictions to warrant a departure from RBE = 1.1. PURPOSE Here, we introduce a novel model of proton RBE based on how a cell's intrinsic radiosensitivity varies with LET, rather than its LQM parameters. METHODS AND MATERIALS We performed clonogenic cell survival assays for eight cell lines exposed to 6 MV x-rays and 1.2, 2.6, or 9.9 keV/µm protons, and combined our measurements with published survival data (n = 397 total cell line/LET combinations). We characterized how radiosensitivity metrics of the form DSF% , (the dose required to achieve survival fraction [SF], e.g., D10% ) varied with proton LET, and calculated the Bayesian information criteria associated with different LET-dependent functions to determine which functions best described the underlying trends. This allowed us to construct a six-parameter model that predicts cells' proton survival curves based on the LET dependence of their radiosensitivity, rather than the LET dependence of the LQM parameters themselves. We compared the accuracy of our model to previously established empirical proton RBE models, and implemented our model within a clinical treatment plan evaluation workflow to demonstrate its feasibility in a clinical setting. RESULTS Our analyses of the trends in the data show that DSF% is linearly correlated between x-rays and protons, regardless of the choice of the survival level (e.g., D10% , D37% , or D50% are similarly correlated), and that the slope and intercept of these correlations vary with proton LET. The model we constructed based on these trends predicts proton RBE within 15%-30% at the 68.3% confidence level and offers a more accurate general description of the experimental data than previously published empirical models. In the context of a clinical treatment plan, our model generally predicted higher RBE-weighted doses than the other empirical models, with RBE-weighted doses in the distal portion of the field being up to 50.7% higher than the planned RBE-weighted doses (RBE = 1.1) to the tumor. CONCLUSIONS We established a new empirical proton RBE model that is more accurate than previous empirical models, and that predicts much higher RBE values in the distal edge of clinical proton beams.
Collapse
Affiliation(s)
- David B. Flint
- Department of Radiation PhysicsThe University of Texas MD Anderson Cancer CenterHoustonTexasUSA
| | - Chase E. Ruff
- Department of Radiation PhysicsThe University of Texas MD Anderson Cancer CenterHoustonTexasUSA
| | - Scott J. Bright
- Department of Radiation PhysicsThe University of Texas MD Anderson Cancer CenterHoustonTexasUSA
| | - Pablo Yepes
- Department of Radiation PhysicsThe University of Texas MD Anderson Cancer CenterHoustonTexasUSA
- Department of Physics and AstronomyRice UniversityHoustonTexasUSA
| | - Qianxia Wang
- Department of Radiation PhysicsThe University of Texas MD Anderson Cancer CenterHoustonTexasUSA
- Department of Physics and AstronomyRice UniversityHoustonTexasUSA
| | - Mandira Manandhar
- Department of Radiation PhysicsThe University of Texas MD Anderson Cancer CenterHoustonTexasUSA
| | - Mariam Ben Kacem
- Department of Radiation PhysicsThe University of Texas MD Anderson Cancer CenterHoustonTexasUSA
| | - Broderick X. Turner
- Department of Radiation PhysicsThe University of Texas MD Anderson Cancer CenterHoustonTexasUSA
- The University of Texas MD Anderson Cancer Center UTHealth Graduate School of Biomedical SciencesHoustonTexasUSA
| | - David K. J. Martinus
- Department of Radiation PhysicsThe University of Texas MD Anderson Cancer CenterHoustonTexasUSA
- The University of Texas MD Anderson Cancer Center UTHealth Graduate School of Biomedical SciencesHoustonTexasUSA
| | - Simona F. Shaitelman
- Department of Radiation OncologyThe University of Texas MD Anderson Cancer CenterHoustonTexasUSA
| | - Gabriel O. Sawakuchi
- Department of Radiation PhysicsThe University of Texas MD Anderson Cancer CenterHoustonTexasUSA
- The University of Texas MD Anderson Cancer Center UTHealth Graduate School of Biomedical SciencesHoustonTexasUSA
| |
Collapse
|
10
|
Tian L, Hahn C, Lühr A. An ion-independent phenomenological relative biological effectiveness (RBE) model for proton therapy. Radiother Oncol 2022; 174:69-76. [PMID: 35803365 DOI: 10.1016/j.radonc.2022.06.023] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2022] [Revised: 06/14/2022] [Accepted: 06/28/2022] [Indexed: 11/17/2022]
Abstract
BACKGROUND A relative biological effectiveness (RBE) of 1.1 is used for proton therapy though clinical evidence of varying RBE was raised. Clinical studies on RBE variability have been conducted for decades for carbon radiation, which could advance the understanding of the clinical proton RBE given an ion-independent RBE model. In this work, such a model, linear and simple, using the beam quantity Q = Z2/E (Z = ion charge, E = kinetic energy per nucleon) was tested and compared to the commonly used, proton-specific and linear energy transfer (LET) based Wedenberg RBE model. MATERIAL AND METHODS The Wedenberg and Q models, both predicting RBEmax and RBEmin (i.e., RBE at vanishing and very high dose, respectively), are compared in terms of ion-dependence and prediction power. An experimental in-vitro data ensemble covering 115 publications for various ions was used as dataset. RESULTS The model parameter of the Q model was observed to be similar for different ions (in contrast to LET). The Q model was trained without any prior knowledge of proton data. For proton RBE, the differences between experimental data and corresponding predictions of the Wedenberg or the Q model were highly comparable. CONCLUSIONS A simple linear RBE model using Q instead of LET was proposed and tested to be able to predict proton RBE using model parameter trained based on only RBE data of other particles in a clinical proton energy range for a large in-vitro dataset. Adding (pre)clinical knowledge from carbon ion therapy may, therefore, reduce the dominating biological uncertainty in proton RBE modelling. This would translate in reduced RBE related uncertainty in proton therapy treatment planning.
Collapse
Affiliation(s)
- Liheng Tian
- TU Dortmund University, Department of Physics, Dortmund, Germany.
| | - Christian Hahn
- TU Dortmund University, Department of Physics, Dortmund, Germany; 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
| | - Armin Lühr
- TU Dortmund University, Department of Physics, Dortmund, Germany.
| |
Collapse
|
11
|
Kasamatsu K, Tanaka S, Miyazaki K, Takao S, Miyamoto N, Hirayama S, Nishioka K, Hashimoto T, Aoyama H, Umegaki K, Matsuura T. Impact of a spatially dependent dose delivery time structure on the biological effectiveness of scanning proton therapy. Med Phys 2021; 49:702-713. [PMID: 34796522 DOI: 10.1002/mp.15367] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2021] [Revised: 10/09/2021] [Accepted: 11/02/2021] [Indexed: 11/09/2022] Open
Abstract
PURPOSE In the scanning beam delivery of protons, different portions of the target are irradiated with different linear energy transfer protons with various time intervals and irradiation times. This research aimed to evaluate the spatially dependent biological effectiveness of protracted irradiation in scanning proton therapy. METHODS One and two parallel opposed fields plans were created in water phantom with the prescribed dose of 2 Gy. Three scenarios (instantaneous, continuous, and layered scans) were used with the corresponding beam delivery models. The biological dose (physical dose × relative biological effectiveness) was calculated using the linear quadratic model and the theory of dual radiation action to quantitatively evaluate the dose delivery time effect. In addition, simulations using clinical plans (postoperative seminoma and prostate tumor cases) were conducted to assess the impact of the effects on the dose volume histogram parameters and homogeneity coefficient (HC) in targets. RESULTS In a single-field plan of water phantom, when the treatment time was 19 min, the layered-scan scenario showed a decrease of <0.2% (almost 3.3%) in the biological dose from the plan on the distal (proximal) side because of the high (low) dose rate. This is in contrast to the continuous scenario, where the biological dose was almost uniformly decreased over the target by approximately 3.3%. The simulation with clinical geometry showed that the decrease rates in D99% were 0.9% and 1.5% for every 10 min of treatment time prolongation for postoperative seminoma and prostate tumor cases, respectively, whereas the increase rates in HC were 0.7% and 0.2%. CONCLUSIONS In protracted irradiation in scanning proton therapy, the spatially dependent dose delivery time structure in scanning beam delivery can be an important factor for accurate evaluation of biological effectiveness.
Collapse
Affiliation(s)
- Koki Kasamatsu
- Graduate School of Biomedical Science and Engineering, Hokkaido University, Sapporo, Japan
| | - Sodai Tanaka
- Faculty of Engineering, Hokkaido University, Sapporo, Japan.,Department of Medical Physics, Hokkaido University Hospital, Sapporo, Japan
| | - Koichi Miyazaki
- Faculty of Engineering, Hokkaido University, Sapporo, Japan.,Department of Medical Physics, Hokkaido University Hospital, Sapporo, Japan
| | - Seishin Takao
- Faculty of Engineering, Hokkaido University, Sapporo, Japan.,Department of Medical Physics, Hokkaido University Hospital, Sapporo, Japan.,Proton Beam Therapy Center, Hokkaido University Hospital, Sapporo, Japan
| | - Naoki Miyamoto
- Faculty of Engineering, Hokkaido University, Sapporo, Japan.,Department of Medical Physics, Hokkaido University Hospital, Sapporo, Japan
| | | | - Kentaro Nishioka
- Department of Radiation Medical Science and Engineering, Faculty of Medicine, Hokkaido University, Sapporo, Japan
| | - Takayuki Hashimoto
- Department of Radiation Medical Science and Engineering, Faculty of Medicine, Hokkaido University, Sapporo, Japan
| | - Hidefumi Aoyama
- Department of Radiation Oncology, Faculty of Medicine, Hokkaido University, Sapporo, Japan
| | - Kikuo Umegaki
- Faculty of Engineering, Hokkaido University, Sapporo, Japan.,Department of Medical Physics, Hokkaido University Hospital, Sapporo, Japan.,Proton Beam Therapy Center, Hokkaido University Hospital, Sapporo, Japan
| | - Taeko Matsuura
- Faculty of Engineering, Hokkaido University, Sapporo, Japan.,Department of Medical Physics, Hokkaido University Hospital, Sapporo, Japan.,Proton Beam Therapy Center, Hokkaido University Hospital, Sapporo, Japan
| |
Collapse
|
12
|
Henjum H, Dahle TJ, Fjæra LF, Rørvik E, Pilskog S, Stokkevåg CH, Mairani A, Ytre-Hauge KS. The Organ Sparing Potential of Different Biological Optimization Strategies in Proton Therapy. Adv Radiat Oncol 2021; 6:100776. [PMID: 34765804 PMCID: PMC8573123 DOI: 10.1016/j.adro.2021.100776] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Revised: 06/20/2021] [Accepted: 08/09/2021] [Indexed: 02/03/2023] Open
Abstract
Purpose Variable relative biological effectiveness (RBE) models allow for differences in linear energy transfer (LET), physical dose, and tissue type to be accounted for when quantifying and optimizing the biological damage of protons. These models are complex and fraught with uncertainties, and therefore, simpler RBE optimization strategies have also been suggested. Our aim was to compare several biological optimization strategies for proton therapy by evaluating their performance in different clinical cases. Methods and Materials Two different optimization strategies were compared: full variable RBE optimization and differential RBE optimization, which involve applying fixed RBE for the planning target volume (PTV) and variable RBE in organs at risk (OARs). The optimization strategies were coupled to 2 variable RBE models and 1 LET-weighted dose model, with performance demonstrated on 3 different clinical cases: brain, head and neck, and prostate tumors. Results In cases with low (α/β)x in the tumor, the full RBE optimization strategies had a large effect, with up to 10% reduction in RBE-weighted dose to the PTV and OARs compared with the reference plan, whereas smaller variations (<5%) were obtained with differential optimization. For tumors with high (α/β)x, the differential RBE optimization strategy showed a greater reduction in RBE-weighted dose to the OARs compared with the reference plan and the full RBE optimization strategy. Conclusions Differences between the optimization strategies varied across the studied cases, influenced by both biological and physical parameters. Whereas full RBE optimization showed greater OAR sparing, awareness of underdosage to the target must be carefully considered.
Collapse
Affiliation(s)
- Helge Henjum
- Department of Physics and Technology, University of Bergen, Bergen, Norway
- Corresponding author: Helge Henjum, MSc
| | - Tordis J. Dahle
- Department of Physics and Technology, University of Bergen, Bergen, Norway
- Department of Oncology and Medical Physics, Haukeland University Hospital, Bergen, Norway
| | - Lars Fredrik Fjæra
- Department of Physics and Technology, University of Bergen, Bergen, Norway
| | - Eivind Rørvik
- Department of Physics and Technology, University of Bergen, Bergen, Norway
| | - Sara Pilskog
- Department of Physics and Technology, University of Bergen, Bergen, Norway
- Department of Oncology and Medical Physics, Haukeland University Hospital, Bergen, Norway
| | - Camilla H. Stokkevåg
- Department of Physics and Technology, University of Bergen, Bergen, Norway
- Department of Oncology and Medical Physics, Haukeland University Hospital, Bergen, Norway
| | - Andrea Mairani
- Centro Nazionale di Adroterapia Oncologica (CNAO Foundation), Pavia, Italy
- Heidelberg Ion Beam Therapy Center, Heidelberg, Germany
| | | |
Collapse
|
13
|
Predict Treatment Response by Magnetic Resonance Diffusion Weighted Imaging: A Preliminary Study on 46 Meningiomas Treated with Proton-Therapy. Diagnostics (Basel) 2021; 11:diagnostics11091684. [PMID: 34574025 PMCID: PMC8469991 DOI: 10.3390/diagnostics11091684] [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: 08/19/2021] [Revised: 09/10/2021] [Accepted: 09/10/2021] [Indexed: 11/16/2022] Open
Abstract
Objective: a considerable subgroup of meningiomas (MN) exhibit indolent and insidious growth. Strategies to detect earlier treatment responses based on tumour biology rather than on size can be useful. We aimed to characterize therapy-induced changes in the apparent diffusion coefficient (ADC) of MN treated with proton-therapy (PT), determining whether the pre- and early post-treatment ADC values may predict tumour response. Methods: Forty-four subjects with MN treated with PT were retrospectively enrolled. All patients underwent conventional magnetic resonance imaging (MRI) including diffusion-weighted imaging (DWI) at baseline and each 3 months for a follow-up period up to 36 months after the beginning of PT. Mean relative ADC (rADCm) values of 46 MN were measured at each exam. The volume variation percentage (VV) for each MN was calculated. The Wilcoxon test was used to assess the differences in rADCm values between pre-treatment and post-treatment exams. Patients were grouped in terms of VV (threshold −20%). A p < 0.05 was considered statistically significant for all the tests. Results: A significant progressive increase of rADCm values was detected at each time point when compared to baseline rADCm (p < 0.05). Subjects that showed higher pre-treatment rADCm values had no significant volume changes or showed volume increase, while subjects that showed a VV < −20% had significantly lower pre-treatment rADCm values. Higher and earlier rADCm increases (3 months) are related to greater volume reduction. Conclusion: In MN treated with PT, pre-treatment rADCm values and longitudinal rADCm changes may predict treatment response.
Collapse
|