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Fukumitsu N, Kubota H, Demizu Y, Suzuki T, Hasegawa D, Kosaka Y, Kawamura A, Soejima T. Comparison of passive-scattered and intensity-modulated proton beam therapy of craniospinal irradiation with proton beams for pediatric and young adult patients with brain tumors. Jpn J Radiol 2024; 42:182-189. [PMID: 37874526 PMCID: PMC10811119 DOI: 10.1007/s11604-023-01499-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2023] [Accepted: 09/06/2023] [Indexed: 10/25/2023]
Abstract
PURPOSE To investigate the dose stability of craniospinal irradiation based on irradiation method of proton beam therapy (PBT). METHODS AND MATERIALS Twenty-four pediatric and young adult brain tumor patients (age: 1-24 years) were examined. Treatment method was passive-scattered PBT (PSPT) in 8 patients and intensity-modulated PBT (IMPT) in 16 patients. The whole vertebral body (WVB) technique was used in 13 patients whose ages were younger than 10, and vertebral body sparing (VBS) technique was used for the remaining 11 patients aged 10 and above. Dose stability of planning target volume (PTV) against set-up error was investigated. RESULTS The minimum dose (Dmin) of IMPT was higher than that of PSPT (p = 0.01). Inhomogeneity index (INH) of IMPT was lower than that of PSPT (p = 0.004). When the irradiation field of the cervical spinal cord level (C level) was shifted, the maximum dose (Dmax) was lower in IMPT, and mean dose (Dmean) was higher than PSPT as movement became greater to the cranial-caudal direction (p = 0.000-0.043). Dmin was higher and INH was lower in IMPT in all directions (p = 0.000-0.034). When the irradiation field of the lumber spinal cord level (L level) was shifted, Dmax was lower in IMPT as movement became greater to the cranial direction (p = 0.000-0.028). Dmin was higher and INH was lower in IMPT in all directions (p = 0.000-0.022). CONCLUSIONS The PTV doses of IMPT and PSPT are robust and stable in both anterior-posterior and lateral directions at both C level and L level, but IMPT is more robust and stable than PSPT for cranial-caudal movements. TRIAL REGISTRY Clinical Trial Registration number: No. 04-03.
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Affiliation(s)
- Nobuyoshi Fukumitsu
- Department of Radiation Oncology, Kobe Proton Center, 1-6-8, Minatojima-Minamimachi, Kobe, 650-0047, Japan.
| | - Hikaru Kubota
- Department of Radiation Oncology, Kobe Proton Center, 1-6-8, Minatojima-Minamimachi, Kobe, 650-0047, Japan
| | - Yusuke Demizu
- Department of Radiation Oncology, Kobe Proton Center, 1-6-8, Minatojima-Minamimachi, Kobe, 650-0047, Japan
| | - Takeshi Suzuki
- Department of Anesthesiology, Kobe Proton Center, Kobe, Japan
| | - Daiichiro Hasegawa
- Department of Hematology and Oncology, Hyogo Children's Hospital, Kobe, Japan
| | - Yoshiyuki Kosaka
- Department of Hematology and Oncology, Hyogo Children's Hospital, Kobe, Japan
| | | | - Toshinori Soejima
- Department of Radiation Oncology, Kobe Proton Center, 1-6-8, Minatojima-Minamimachi, Kobe, 650-0047, Japan
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Weiß A, Löck S, Xu T, Liao Z, Hoffmann AL, Troost EGC. Prediction of radiation pneumonitis using the effective α/β of lungs and heart in NSCLC patients treated with proton beam therapy. Radiother Oncol 2024; 190:110013. [PMID: 37972734 DOI: 10.1016/j.radonc.2023.110013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2023] [Revised: 11/08/2023] [Accepted: 11/09/2023] [Indexed: 11/19/2023]
Abstract
PURPOSE Radiation pneumonitis (RP) remains a major complication in non-small cell lung cancer (NSCLC) patients undergoing radiochemotherapy (RCHT). Traditionally, the mean lung dose (MLD) and the volume of the total lung receiving at least 20 Gy (V20Gy) are used to predict RP in patients treated with normo-fractionated photon therapy. However, other models, including the actual dose-distribution in the lungs using the effective α/β model or a combination of radiation doses to the lungs and heart, have been proposed for predicting RP. Moreover, the models established for photons may not hold for patients treated with passively-scattered proton therapy (PSPT). Therefore, we here tested and validated novel predictive parameters for RP in NSCLC patient treated with PSPT. METHODS Data on the occurrence of RP, structure files and dose-volume histogram parameters for lungs and heart of 96 NSCLC patients, treated with PSPT and concurrent chemotherapy, was retrospectively retrieved from prospective clinical studies of two international centers. Data was randomly split into a training set (64 patients) and a validation set (32 patients). Statistical analyses were performed using binomial logistic regression. RESULTS The biologically effective dose (BED) of the'lungs - GTV' significantly predicted RP ≥ grade 2 in the training-set using both a univariate model (p = 0.019, AUCtrain = 0.72) and a multivariate model in combination with the effective α/β parameter of the heart (pBED = 0.006, [Formula: see text] = 0.043, AUCtrain = 0.74). However, these results did not hold in the validation-set (AUCval = 0.52 andAUCval = 0.50, respectively). Moreover, these models were found to neither outperform a model built with the MLD (p = 0.015, AUCtrain = 0.73, AUCval = 0.51), nor a multivariate model additionally including the V20Gy of the heart (pMLD = 0.039, pV20Gy,heart = 0.58, AUCtrain = 0.74, AUCval = 0.53). CONCLUSION Using the effective α/β parameter of the lungs and heart we achieved similar performance to commonly used models built for photon therapy, such as MLD, in predicting RP ≥ grade 2. Therefore, prediction models developed for photon RCHT still hold for patients treated with PSPT.
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Affiliation(s)
- Albrecht Weiß
- German Cancer Consortium (DKTK), Partner Site Dresden, and German Cancer Research Center (DKFZ), Heidelberg, 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
| | - Steffen Löck
- German Cancer Consortium (DKTK), Partner Site Dresden, and German Cancer Research Center (DKFZ), Heidelberg, 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
| | - Ting Xu
- Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Zhongxing Liao
- Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Aswin L Hoffmann
- 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
| | - Esther G C Troost
- German Cancer Consortium (DKTK), Partner Site Dresden, and German Cancer Research Center (DKFZ), Heidelberg, 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; National Center for Tumor Diseases (NCT), Partner Site Dresden, Germany: German Cancer Research Center (DKFZ), Heidelberg, Germany, Faculty of Medicine and University Hospital Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany, Helmholtz Association/Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Dresden, Germany; Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiooncology-OncoRay, Dresden, Germany.
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Ebrahimi S, Lim G, Liu A, Lin SH, Ellsworth SG, Grassberger C, Mohan R, Cao W. Radiation-Induced Lymphopenia Risks of Photon Versus Proton Therapy for Esophageal Cancer Patients. Int J Part Ther 2021; 8:17-27. [PMID: 34722808 PMCID: PMC8489492 DOI: 10.14338/ijpt-20-00086] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2020] [Accepted: 02/02/2021] [Indexed: 12/03/2022] Open
Abstract
Purpose To assess possible differences in radiation-induced lymphocyte depletion for esophageal cancer patients being treated with the following 3 treatment modalities: intensity-modulated radiation therapy (IMRT), passive scattering proton therapy (PSPT), and intensity-modulated proton therapy (IMPT). Methods and Materials We used 2 prediction models to estimate lymphocyte depletion based on dose distributions. Model I used a piecewise linear relationship between lymphocyte survival and voxel-by-voxel dose. Model II assumes that lymphocytes deplete exponentially as a function of total delivered dose. The models can be fitted using the weekly absolute lymphocyte counts measurements collected throughout treatment. We randomly selected 45 esophageal cancer patients treated with IMRT, PSPT, or IMPT at our institution (15 per modality) to demonstrate the fitness of the 2 models. A different group of 10 esophageal cancer patients who had received PSPT were included in this study of in silico simulations of multiple modalities. One IMRT and one IMPT plan were created, using our standards of practice for each modality, as competing plans to the existing PSPT plan for each patient. We fitted the models by PSPT plans used in treatment and predicted absolute lymphocyte counts for IMRT and IMPT plans. Results Model validation on each modality group of patients showed good agreement between measured and predicted absolute lymphocyte counts nadirs with mean squared errors from 0.003 to 0.023 among the modalities and models. In the simulation study of IMRT and IMPT on the 10 PSPT patients, the average predicted absolute lymphocyte count (ALC) nadirs were 0.27, 0.35, and 0.37 K/μL after IMRT, PSPT, and IMPT treatments using Model I, respectively, and 0.14, 0.22, and 0.33 K/μL using Model II. Conclusions Proton plans carried a lower predicted risk of lymphopenia after the treatment course than did photon plans. Moreover, IMPT plans outperformed PSPT in terms of predicted lymphocyte preservation.
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Affiliation(s)
- Saba Ebrahimi
- Department of Industrial Engineering, University of Houston, Houston, TX, USA
| | - Gino Lim
- Department of Industrial Engineering, University of Houston, Houston, TX, USA
| | - Amy Liu
- Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Steven H Lin
- Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | | | - Clemens Grassberger
- Departments of Radiation Oncology, Massachusetts General Hospital, Boston, MA, USA
| | - Radhe Mohan
- Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Wenhua Cao
- Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
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Mohammadbagher D, Noofeli M, Karimi G. Comparative Assessment of the Whole-cell Pertussis Vaccine Potency Using Serological and Intracerebral Mouse Protection Methods. Arch Razi Inst 2019; 74:103-109. [PMID: 31232559 DOI: 10.22092/ari.2018.108852.1096] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 12/24/2016] [Accepted: 05/15/2018] [Indexed: 09/30/2022]
Abstract
One of the most important QC tests of whole-cell pertussis vaccine (WCPV) is potency test. In this regard, mouse protection test (MPT) is the current potency method, which is associated with severe animal distress and large variability in results. The purpose of this study was to assess Pertussis Serological Potency Test (PSPT) as a serological alternative method to intracerebral challenge in MPT assay. In the current study, the potency of three experimental batches of WCPV (1, 2, and 3) and standard vaccine were compared using MPT and PSPT methods. In the MPT method, mice were immunized with tests and standard vaccines. After 2 weeks, they were intracerebrally challenged with Bordetella pertussis strain (18323). The potency was calculated via parallel line analysis based on the numbers of survivors 2 weeks after the challenge. Similar to MPT method, mice were immunized in the PSPT method and bled after 4 weeks. In the next step, sera were titrated by 18323-WCP-ELISA assay and potency values were estimated via parallel line analysis. Pearson correlation test was used to measure the strength of association between MPT and PSPT assay results. The potency values of the experimental laboratory batches 1, 2, and 3 in MPT assays were 11.14, 5.02, and 4.24 Iu/ml, whereas the obtained results of PSPT assays were 10.32, 4.11, and 3.06 Iu/ml, respectively. The correlation of MPT and PSPT results was 0.807. The findings of the present study demonstrated a significant correlation between MPT and PSPT results. The implementation of PSPT was more advantageous, compared to MPT due to its ethical approaches and less variability in results. The PSPT is a promising alternative method for intracerebral challenge. However, additional validation is needed to support the establishment of this method.
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Affiliation(s)
- D Mohammadbagher
- Blood Transfusion Research Center, High Institute for Research and Education in Transfusion Medicine, Tehran, Iran.,Department of Human Viral Vaccine Production, Razi Vaccine and Serum Research Institute, Agricultural Research, Education and Extension Organization, Karaj, Iran
| | - M Noofeli
- Department of Human Viral Vaccine Production, Razi Vaccine and Serum Research Institute, Agricultural Research, Education and Extension Organization (AREEO), Karaj, Iran.,Department of Human Viral Vaccine Production, Razi Vaccine and Serum Research Institute, Agricultural Research, Education and Extension Organization (AREEO), Karaj, Iran
| | - G Karimi
- Blood Transfusion Research Center, High Institute for Research and Education in Transfusion Medicine, Tehran, Iran
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Polamraju P, Bagley AF, Williamson T, Zhu XR, Frank SJ. Hydrogel Spacer Reduces Rectal Dose during Proton Therapy for Prostate Cancer: A Dosimetric Analysis. Int J Part Ther 2019; 5:23-31. [PMID: 31773038 DOI: 10.14338/ijpt-18-00041.1] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2018] [Accepted: 03/18/2019] [Indexed: 12/24/2022] Open
Abstract
Purpose Proton therapy for prostate cancer may reduce bowel dose and risk of bowel symptoms relative to photon-based methods. Here, we determined the effect of using a biodegradable, injectable hydrogel spacer on rectal dose on plans for treating prostate cancer with intensity-modulated proton therapy (IMPT) or passive scattering proton therapy (PSPT). Materials and Methods Pairs of IMPT and PSPT plans for 9 patients were created from fused computed tomography/magnetic resonance imaging scans obtained before and after spacer injection. Calculated values of rectal V40, V60, V70, V80, and maximum dose (Dmax) were compared with Wilcoxon signed rank tests. Displacements at the base (BP), midgland (MP), and apex (AP) of the prostate relative to the anterior rectal wall with the spacer in place were averaged for each patient and correlated with V70 by using linear regression models. Results The presence of a spacer reduced all dosimetric parameters for both PSPT and IMPT, with the greatest difference in V70, which was 81.1% lower for PSPT-with-spacer than for IMPT-without-spacer. Median displacements at BP, MP, and AP were 12 mm (range 7-19), 2 mm (range 0-4), and 1 mm (range 0-5) without the spacer and 19 mm (range 12-23), 10 mm (range 8-16), and 7 mm (range 2-12) with the spacer. Modest linear trends were noted between rectal V70 and displacement for IMPT-with-spacer and PSPT-with-spacer. When displacement was ≥8 mm, V70 was ≤5.1% for IMPT-with-spacer and PSPT-with-spacer. Conclusion Use of biodegradable hydrogel spacers for prostate cancer treatment provides a significant reduction of radiation dose to the rectum with proton therapy. Significant reductions in rectal dose occurred in both PSPT and IMPT plans, with the greatest reduction for IMPT-with-spacer relative to PSPT alone. Prospective studies are ongoing to assess the clinical impact of reducing rectal dose with hydrogel spacers.
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Affiliation(s)
- Praveen Polamraju
- University of Texas Medical Branch at Galveston School of Medicine, Galveston, TX, USA
| | - Alexander F Bagley
- Department of Radiation Oncology, University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Tyler Williamson
- Department of Radiation Oncology, University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - X Ronald Zhu
- Department of Radiation Physics, University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Steven J Frank
- Department of Radiation Oncology, University of Texas MD Anderson Cancer Center, Houston, TX, USA
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Giaddui T, Chen W, Yu J, Lin L, Simone CB, Yuan L, Gong YUT, Wu QJ, Mohan R, Zhang X, Bluett JB, Gillin M, Moore K, O'Meara E, Presley J, Bradley JD, Liao Z, Galvin J, Xiao Y. Establishing the feasibility of the dosimetric compliance criteria of RTOG 1308: phase III randomized trial comparing overall survival after photon versus proton radiochemotherapy for inoperable stage II-IIIB NSCLC. Radiat Oncol 2016; 11:66. [PMID: 27142674 PMCID: PMC4855766 DOI: 10.1186/s13014-016-0640-8] [Citation(s) in RCA: 72] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2016] [Accepted: 04/23/2016] [Indexed: 11/10/2022] Open
Abstract
Background To establish the feasibility of the dosimetric compliance criteria of the RTOG 1308 trial through testing against Intensity Modulation Radiation Therapy (IMRT) and Passive Scattering Proton Therapy (PSPT) plans. Methods Twenty-six lung IMRT and 26 proton PSPT plans were included in the study. Dose Volume Histograms (DVHs) for targets and normal structures were analyzed. The quality of IMRT plans was assessed using a knowledge-based engineering tool. Results Most of the RTOG 1308 dosimetric criteria were achieved. The deviation unacceptable rates were less than 10 % for most criteria; however, a deviation unacceptable rate of more than 20 % was computed for the planning target volume minimum dose compliance criterion. Dose parameters for the target volume were very close for the IMRT and PSPT plans. However, the PSPT plans led to lower dose values for normal structures. The dose parameters in which PSPT plans resulted in lower values than IMRT plans were: lung V5Gy (%) (34.4 in PSPT and 47.2 in IMRT); maximum spinal cord dose (31.7 Gy in PSPT and 43.5 Gy in IMRT); heart V5Gy (%) (19 in PSPT and 47 in IMRT); heart V30Gy (%) (11 in PSPT and 19 in IMRT); heart V45Gy (%) (7.8 in PSPT and 12.1 in IMRT); heart V50% (Gy) (7.1 in PSPT and 9.8 in IMRT) and mean heart dose (7.7 Gy in PSPT and 14.9 Gy in IMRT). Conclusions The revised RTOG 1308 dosimetric compliance criteria are feasible and achievable.
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Affiliation(s)
- Tawfik Giaddui
- Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA, USA.
| | - Wenzhou Chen
- Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA, USA
| | - Jialu Yu
- Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA, USA
| | - Liyong Lin
- University of Pennsylvania, Philadelphia, PA, USA
| | | | | | - Yutao U T Gong
- Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA, USA
| | | | | | | | | | | | - Kevin Moore
- University of California, San Diego, CA, USA
| | - Elizabeth O'Meara
- Imaging and Radiation Oncology Core (IROC) Philadelphia-RT QA Center, Philadelphia, PA, USA
| | - Jennifer Presley
- Imaging and Radiation Oncology Core (IROC) Philadelphia-RT QA Center, Philadelphia, PA, USA
| | | | | | - James Galvin
- Imaging and Radiation Oncology Core (IROC) Philadelphia-RT QA Center, Philadelphia, PA, USA
| | - Ying Xiao
- University of Pennsylvania, Philadelphia, PA, USA
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Wink KCJ, Roelofs E, Solberg T, Lin L, Simone CB, Jakobi A, Richter C, Lambin P, Troost EGC. Particle therapy for non-small cell lung tumors: where do we stand? A systematic review of the literature. Front Oncol 2014; 4:292. [PMID: 25401087 PMCID: PMC4212620 DOI: 10.3389/fonc.2014.00292] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2014] [Accepted: 10/07/2014] [Indexed: 12/25/2022] Open
Abstract
This review article provides a systematic overview of the currently available evidence on the clinical effectiveness of particle therapy for the treatment of non-small cell lung cancer and summarizes findings of in silico comparative planning studies. Furthermore, technical issues and dosimetric uncertainties with respect to thoracic particle therapy are discussed.
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Affiliation(s)
- Krista C J Wink
- Department of Radiation Oncology (MAASTRO Clinic), GROW - School for Oncology and Developmental Biology, Maastricht University Medical Centre , Maastricht , Netherlands
| | - Erik Roelofs
- Department of Radiation Oncology (MAASTRO Clinic), GROW - School for Oncology and Developmental Biology, Maastricht University Medical Centre , Maastricht , Netherlands
| | - Timothy Solberg
- Department of Radiation Oncology, Hospital of the University of Pennsylvania , Philadelphia, PA , USA
| | - Liyong Lin
- Department of Radiation Oncology, Hospital of the University of Pennsylvania , Philadelphia, PA , USA
| | - Charles B Simone
- Department of Radiation Oncology, Hospital of the University of Pennsylvania , Philadelphia, PA , USA
| | - Annika Jakobi
- OncoRay - National Center for Radiation Research in Oncology, Faculty of Medicine and University Hospital Carl Gustav Carus, Technische Universität Dresden and Helmholtz-Zentrum Dresden-Rossendorf , Dresden , Germany
| | - Christian Richter
- OncoRay - National Center for Radiation Research in Oncology, Faculty of Medicine and University Hospital Carl Gustav Carus, Technische Universität Dresden and Helmholtz-Zentrum Dresden-Rossendorf , Dresden , Germany ; German Cancer Consortium (DKTK) Dresden and German Cancer Research Center (DKFZ) , Heidelberg , Germany
| | - Philippe Lambin
- Department of Radiation Oncology (MAASTRO Clinic), GROW - School for Oncology and Developmental Biology, Maastricht University Medical Centre , Maastricht , Netherlands
| | - Esther G C Troost
- Department of Radiation Oncology (MAASTRO Clinic), GROW - School for Oncology and Developmental Biology, Maastricht University Medical Centre , Maastricht , Netherlands
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