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Rippke C, Renkamp CK, Stahl-Arnsberger C, Miltner A, Buchele C, Hörner-Rieber J, Ristau J, Debus J, Alber M, Klüter S. A body mass index-based method for "MR-only" abdominal MR-guided adaptive radiotherapy. Z Med Phys 2024; 34:456-467. [PMID: 36759229 PMCID: PMC11384073 DOI: 10.1016/j.zemedi.2022.12.001] [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: 08/09/2022] [Revised: 12/08/2022] [Accepted: 12/09/2022] [Indexed: 02/10/2023]
Abstract
PURPOSE Dose calculation for MR-guided radiotherapy (MRgRT) at the 0.35 T MR-Linac is currently based on deformation of planning CTs (defCT) acquired for each patient. We present a simple and robust bulk density overwrite synthetic CT (sCT) method for abdominal treatments in order to streamline clinical workflows. METHOD Fifty-six abdominal patient treatment plans were retrospectively evaluated. All patients had been treated at the MR-Linac using MR datasets for treatment planning and plan adaption and defCT for dose calculation. Bulk density CTs (4M-sCT) were generated from MR images with four material compartments (bone, lung, air, soft tissue). The relative electron densities (RED) for bone and lung were extracted from contoured CT structure average REDs. For soft tissue, a correlation between BMI and RED was evaluated. Dose was recalculated on 4M-sCT and compared to dose distributions on defCTs assessing dose differences in the PTV and organs at risk (OAR). RESULTS Mean RED of bone was 1.17 ± 0.02, mean RED of lung 0.17 ± 0.05. The correlation between BMI and RED for soft tissue was statistically significant (p < 0.01). PTV dose differences between 4M-sCT and defCT were Dmean: -0.4 ± 1.0%, D1%: -0.3 ± 1.1% and D95%: -0.5 ± 1.0%. OARs showed D2%: -0.3 ± 1.9% and Dmean: -0.1 ± 1.4% differences. Local 3D gamma index pass rates (2%/2mm) between dose calculated using 4M-sCT and defCT were 96.8 ± 2.6% (range 89.9-99.6%). CONCLUSION The presented method for sCT generation enables precise dose calculation for MR-only abdominal MRgRT.
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Affiliation(s)
- Carolin Rippke
- Department of Radiation Oncology, Heidelberg University Hospital, Im Neuenheimer Feld 400, 69120 Heidelberg, Germany; Heidelberg Institute of Radiation Oncology (HIRO), National Center for Radiation Oncology (NCRO), Heidelberg, Germany; Medical Faculty, University of Heidelberg, Im Neuenheimer Feld 672, 69120 Heidelberg, Germany.
| | - C Katharina Renkamp
- Department of Radiation Oncology, Heidelberg University Hospital, Im Neuenheimer Feld 400, 69120 Heidelberg, Germany; Heidelberg Institute of Radiation Oncology (HIRO), National Center for Radiation Oncology (NCRO), Heidelberg, Germany
| | - Christiane Stahl-Arnsberger
- Clinical Cooperation Unit Radiation Oncology, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, 69120 Heidelberg, Germany
| | - Annette Miltner
- Clinical Cooperation Unit Radiation Oncology, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, 69120 Heidelberg, Germany
| | - Carolin Buchele
- Department of Radiation Oncology, Heidelberg University Hospital, Im Neuenheimer Feld 400, 69120 Heidelberg, Germany; Heidelberg Institute of Radiation Oncology (HIRO), National Center for Radiation Oncology (NCRO), Heidelberg, Germany; Medical Faculty, University of Heidelberg, Im Neuenheimer Feld 672, 69120 Heidelberg, Germany
| | - Juliane Hörner-Rieber
- Department of Radiation Oncology, Heidelberg University Hospital, Im Neuenheimer Feld 400, 69120 Heidelberg, Germany; Heidelberg Institute of Radiation Oncology (HIRO), National Center for Radiation Oncology (NCRO), Heidelberg, Germany; Medical Faculty, University of Heidelberg, Im Neuenheimer Feld 672, 69120 Heidelberg, Germany; Clinical Cooperation Unit Radiation Oncology, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, 69120 Heidelberg, Germany; National Center for Tumor Diseases (NCT), Im Neuenheimer Feld 460, 69120 Heidelberg, Germany; German Cancer Consortium (DKTK), Core-center Heidelberg, Heidelberg, Germany
| | - Jonas Ristau
- Department of Radiation Oncology, Heidelberg University Hospital, Im Neuenheimer Feld 400, 69120 Heidelberg, Germany; Heidelberg Institute of Radiation Oncology (HIRO), National Center for Radiation Oncology (NCRO), Heidelberg, Germany
| | - Jürgen Debus
- Department of Radiation Oncology, Heidelberg University Hospital, Im Neuenheimer Feld 400, 69120 Heidelberg, Germany; Heidelberg Institute of Radiation Oncology (HIRO), National Center for Radiation Oncology (NCRO), Heidelberg, Germany; Medical Faculty, University of Heidelberg, Im Neuenheimer Feld 672, 69120 Heidelberg, Germany; Clinical Cooperation Unit Radiation Oncology, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, 69120 Heidelberg, Germany; National Center for Tumor Diseases (NCT), Im Neuenheimer Feld 460, 69120 Heidelberg, Germany; Heidelberg Ion-Beam Therapy Center (HIT), Im Neuenheimer Feld 450, 69120 Heidelberg, Germany; German Cancer Consortium (DKTK), Core-center Heidelberg, Heidelberg, Germany
| | - Markus Alber
- Department of Radiation Oncology, Heidelberg University Hospital, Im Neuenheimer Feld 400, 69120 Heidelberg, Germany; Heidelberg Institute of Radiation Oncology (HIRO), National Center for Radiation Oncology (NCRO), Heidelberg, Germany; Medical Faculty, University of Heidelberg, Im Neuenheimer Feld 672, 69120 Heidelberg, Germany
| | - Sebastian Klüter
- Department of Radiation Oncology, Heidelberg University Hospital, Im Neuenheimer Feld 400, 69120 Heidelberg, Germany; Heidelberg Institute of Radiation Oncology (HIRO), National Center for Radiation Oncology (NCRO), Heidelberg, Germany.
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Pouymayou B, Perez-Haas Y, Allemann F, Saguner AM, Andratschke N, Guckenberger M, Tanadini-Lang S, Wilke L. Characterization of spatial integrity with active and passive implants in a low-field magnetic resonance linear accelerator scanner. Phys Imaging Radiat Oncol 2024; 30:100576. [PMID: 38644933 PMCID: PMC11031795 DOI: 10.1016/j.phro.2024.100576] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2023] [Revised: 04/02/2024] [Accepted: 04/05/2024] [Indexed: 04/23/2024] Open
Abstract
Background and Purpose Standard imaging protocols can guarantee the spatial integrity of magnetic resonance (MR) images utilized in radiotherapy. However, the presence of metallic implants can significantly compromise this integrity. Our proposed method aims at characterizing the geometric distortions induced by both passive and active implants commonly encountered in planning images obtained from a low-field 0.35 T MR-linear accelerator (LINAC). Materials and Methods We designed a spatial integrity phantom defining 1276 control points and covering a field of view of 20x20x20 cm3. This phantom was scanned in a water tank with and without different implants used in hip and shoulder arthroplasty procedures as well as with active cardiac stimulators. The images were acquired with the clinical planning sequence (balanced steady-state free-precession, resolution 1.5x1.5x1.5 mm3). Spatial integrity was assessed by the Euclidian distance between the control point detected on the image and their theoretical locations. A first plane free of artefact (FPFA) was defined to evaluate the spatial integrity beyond the larger banding artefact. Results In the region extending up to 20 mm from the largest banding artefacts, the tested passive and active implants could cause distortions up to 2 mm and 3 mm, respectively. Beyond this region the spatial integrity was recovered and the image could be considered as unaffected by the implants. Conclusions We characterized the impact of common implants on a low field MR-LINAC planning sequence. These measurements could support the creation of extra margin while contouring organs at risk and target volumes in the vicinity of implants.
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Affiliation(s)
- Bertrand Pouymayou
- Department of Radiation Oncology, University Hospital Zurich and University of Zurich, Zurich, Switzerland
| | - Yoel Perez-Haas
- Department of Radiation Oncology, University Hospital Zurich and University of Zurich, Zurich, Switzerland
| | - Florin Allemann
- Department of Traumatology, University Hospital Zurich and University of Zurich, Zurich, Switzerland
| | - Ardan M. Saguner
- Department of Cardiology, University Hospital Zurich and University of Zurich, Zurich, Switzerland
| | - Nicolaus Andratschke
- Department of Radiation Oncology, University Hospital Zurich and University of Zurich, Zurich, Switzerland
| | - Matthias Guckenberger
- Department of Radiation Oncology, University Hospital Zurich and University of Zurich, Zurich, Switzerland
| | - Stephanie Tanadini-Lang
- Department of Radiation Oncology, University Hospital Zurich and University of Zurich, Zurich, Switzerland
| | - Lotte Wilke
- Department of Radiation Oncology, University Hospital Zurich and University of Zurich, Zurich, Switzerland
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Marasini S, Cole M, Curcuru A, Dyke LM, Gach HM, Flores R, Kim T. Characterization of real-time cine MR imaging distortion on 0.35 T MRgRT with concentric cine imaging QA phantom. Phys Med Biol 2024; 69:065009. [PMID: 38408387 DOI: 10.1088/1361-6560/ad2d33] [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: 09/18/2023] [Accepted: 02/26/2024] [Indexed: 02/28/2024]
Abstract
Objective. Real-time MRgRT uses 2D-cine imaging for target tracking and motion evaluation. Rotation of gantry inducedB0off-resonance, resulting in image artifacts and imaging isocenter-shift precluding MR-guided arc therapy. Standard MRI phantoms designed for higher resolution images face challenges when low-resolution cine imaging is needed to achieve high frame rates. This work aimed to examine the spatial accuracy including geometric distortion and isocenter shift in real-time during gantry rotation on a 0.35 T MR-Linac using the concentric Cine imaging quality assurance (QA) phantom and its associated image analysis software.Approach. The Cine imaging QA phantom consists of two concentric shells of low-T1mineral oil and a central alignment structure. The phantom was scanned on three different MRI systems; 0.55 T Siemens Free.Max, 1.5 T Philips Ingenia, and 0.35 T ViewRay MRIdian MR-Linac using 2D balanced steady-state free precession (bSSFP) imaging sequence. In addition, bSSFP cine MRI with the banding artifact correction was tested on 0.35 T ViewRay MR-Linac. Images from the MR-Linac were acquired with the Linac gantry stationary and rotating from gantry 300°→ 0° and vice versa. Three orthogonal image planes were scanned excluding the 1.5 T Philips Ingenia, where only the axial plane was scanned. The image analysis software calculated the distortion values as well as the isocenter position for each cine frame.Main results. The geometric distortion of cine imaging on MRIs and MR-Linac at gantry stationary are within 1 mm while the substantial geometric distortion of 2 and 2.2 mm were observed on 0.35 T MR-Linac while rotating the gantry clockwise (300°→ 0°) and counterclockwise 0°→ 300° respectively. The average imaging isocenter shift was 0.1 mm for both MRIs and the static gantry and imaging isocenter shift of ≤1.5 mm was observed during the gantry rotation. The imaging isocenter shift decreased by 1 ± 0.2 mm clockwise and counterclockwise withB0compensation.Significance. The concentric Cine imaging QA phantom and its associated software effectively demonstrate the image distortion on real-time cine imaging on regular MRIs and 0.35 T MR-Linac. The results of significant geometric distortion with a rotating gantry in the MR-Linac system require further investigation to alleviate the extent of the image distortion.
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Affiliation(s)
- Shanti Marasini
- Departments of Radiation Oncology, Washington University School of Medicine, St. Louis, MO,United States of America
| | | | - Austen Curcuru
- Departments of Radiation Oncology, Washington University School of Medicine, St. Louis, MO,United States of America
| | - Lara M Dyke
- Departments of Radiation Oncology, Washington University School of Medicine, St. Louis, MO,United States of America
| | - H Michael Gach
- Departments of Radiation Oncology, Washington University School of Medicine, St. Louis, MO,United States of America
- Department of Radiology, Washington University School of Medicine, St. Louis, MO, United States of America
- Departments of Biomedical Engineering, Washington University in St. Louis, MO, United States of America
| | | | - Taeho Kim
- Departments of Radiation Oncology, Washington University School of Medicine, St. Louis, MO,United States of America
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Wu JK, Lee TY, Yu MC, Kuo MC, Chen WC, Hsiao YC, Wang YJ. Developing a novel quasi-3D movable water phantom for radiation therapy workable in the magnetic resonance environment. Quant Imaging Med Surg 2023; 13:7731-7740. [PMID: 38106241 PMCID: PMC10722017 DOI: 10.21037/qims-23-189] [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: 02/15/2023] [Accepted: 08/25/2023] [Indexed: 12/19/2023]
Abstract
Background The use of magnetic resonance linear accelerators (MR-LINACs) for clinical treatment has opened up new possibilities and challenges in the field of radiation oncology. However, annual quality assurance (QA) is relatively understudied due to practical considerations. Thus, to overcome the difficulty of measuring the dose with a small water phantom for TRS-398 or TG-51 in all external beam radiation treatment unit environments, such as MR compatibility, we designed a remote phantom with a three-axis changeable capacity for QA. Methods The designed water phantom was tested under an MR environment. The water phantom system comprised of three parts: a phantom box, a dose measurement tool, and a PMD401 drive system. The UNIDOSE universal dosimeter was used to collect beam data. The manufacturer's developer tools were utilized to position the measurement. To ensure magnetic field homogeneity, a distortion phantom was prepared using sixty fish oil capsules aligned radially to distinguish the oil and free air. The phantom was scanned in both the MR simulator and computed tomography (CT), and the acquired images were analyzed to determine the position shift. Results The dimensions of the device are 30 cm in the X-axis, 20 cm in the Y-axis, and 17 cm in the Z-axis. Total cost of materials was no more than $10,000 US dollars. Our results indicate that the device can function normally in a regular 1.5 T MR environment without interference from the magnetic field. The water phantom's traveling speed was found to be approximately 5 mm/s with a position difference confined within 6 cm intervals during normal use. The distortion test results showed that the prepared MR environment has uniform magnetic field homogeneity. Conclusions In this study, we constructed a prototype water phantom device that can function in an MR simulator without interference between the magnetic field and electronic components. Compared to other commercially available MR-LINAC water phantoms, our device offers a more cost-effective solution for routine monthly QA. It can shorten the duration of QA tests and relieve the burden on medical physicists.
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Affiliation(s)
- Jian-Kuen Wu
- Division of Radiation Oncology, Departments of Oncology, National Taiwan University Hospital, Taipei
| | - Ting-Yen Lee
- Department of Nuclear Medicine, National Taiwan University Hospital, Taipei
| | - Min-Chin Yu
- Department of Radiation Oncology Taipei Medical University Hospital, Taipei
| | - Ming-Chih Kuo
- Department of Medical Imaging, National Taiwan University Cancer Center, Taipei
| | - Wei-Chuan Chen
- Department of Radiation Oncology, China Medical University Beigang Hospital, Yunlin
| | - Yi-Cheng Hsiao
- Department of Medical Imaging, National Taiwan University Hospital, Taipei
| | - Yu-Jen Wang
- Department of Radiation Oncology, Fu Jen Catholic University Hospital, New Taipei City
- School of Medicine, College of Medicine, Fu Jen Catholic University, New Taipei City
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Safari M, Fatemi A, Afkham Y, Archambault L. Patient-specific geometrical distortion corrections of MRI images improve dosimetric planning accuracy of vestibular schwannoma treated with gamma knife stereotactic radiosurgery. J Appl Clin Med Phys 2023; 24:e14072. [PMID: 37345614 PMCID: PMC10562030 DOI: 10.1002/acm2.14072] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2023] [Revised: 05/31/2023] [Accepted: 06/01/2023] [Indexed: 06/23/2023] Open
Abstract
PURPOSE To investigate the impact of MRI patient-specific geometrical distortion (PSD) on the quality of Gamma Knife stereotactic radiosurgery (GK-SRS) plans of the vestibular schwannoma (VS) tumors. METHODS AND MATERIALS Three open access datasets including the MPI-Leipzig Mind-Brain-Body (318 patients), the slow event-related fMRI designs dataset (62 patients), and the VS dataset (242 patients) were used. We used first two datasets to train a 3D convolution network to predict the distortion map of third dataset that were then used to calculate and correct the PSD. GK-SRS plans of VS dataset were used to evaluate dose distribution of PSD-corrected MRI images. GK-SRS prescription dose of VS cases was 12 Gy. Geometric and dosimetric discrepancies were assessed between the dose distributions and contours before and after the PSD corrections. Geometry indices were center of the contours, Dice coefficient (DC), Hausdorff distance (HD), and dosimetric indices wereD μ ${D_\mu }$ ,D m a x ${D_{max}}$ ,D m i n ${D_{min}}$ , andD 95 % ${D_{95{\mathrm{\% }}}}$ doses, target coverage (TC), Paddick's conformity index (PCI), Paddick's gradient index (GI), and homogeneity index (HI). RESULTS Geometric distortions of about 1.2 mm were observed at the air-tissue interfaces at the air canal and nasal cavity borders. Average center of the targets was significantly distorted along the frequency encoding direction after the PSD-correction. Average DC and HD metrics were 0.90 and 2.13 mm. AverageD μ ${D_\mu }$ ,D 95 % , ${D_{95{\mathrm{\% ,}}}}$ andD m i n ${D_{min}}$ in Gy significantly increased after PSD correction from 16.85 to 17.25, 12.30 to 12.77, and from 8.98 to 9.92.D m a x ${D_{max}}$ did not significantly change after the correction. Average TC and PCI significantly increased from 0.97 to 0.98, and 0.94 to 0.96. Average GI decreased significantly from 2.24 to 2.15 after PSD correction. However, HI did not significantly change after the correction. CONCLUSION The proposed method could predict and correct the PSD that indicates the importance of PSD correction before GK-SRS plans of the VS patients.
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Affiliation(s)
- Mojtaba Safari
- Département de physiquede génie physique et d'optiqueet Centre de recherche sur le cancerUniversité LavalQuébecQuébecCanada
- Service de physique médicale et de radioprotectionCentre Intégré de CancérologieCHU de Québec‐Université Laval et Centre de recherche du CHU de QuébecQuébecQuébecCanada
| | - Ali Fatemi
- Department of PhysicsJackson State UniversityMississippiUSA
- Merit Health CentralDepartment of Radiation OncologyGamma Knife CenterMississippiUSA
| | - Younes Afkham
- Clinical Research Development Unit of Tabriz Valiasr HospitalTabriz University of Medical ScienceTabrizIran
| | - Louis Archambault
- Département de physiquede génie physique et d'optiqueet Centre de recherche sur le cancerUniversité LavalQuébecQuébecCanada
- Service de physique médicale et de radioprotectionCentre Intégré de CancérologieCHU de Québec‐Université Laval et Centre de recherche du CHU de QuébecQuébecQuébecCanada
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Neylon J, Cook KA, Yang Y, Du D, Sheng K, Chin RK, Kishan AU, Lamb JM, Low DA, Cao M. Clinical assessment of geometric distortion for a 0.35T MR-guided radiotherapy system. J Appl Clin Med Phys 2021; 22:303-309. [PMID: 34231963 PMCID: PMC8364259 DOI: 10.1002/acm2.13340] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Purpose To estimate the overall spatial distortion on clinical patient images for a 0.35 T MR‐guided radiotherapy system. Methods Ten patients with head‐and‐neck cancer underwent CT and MR simulations with identical immobilization. The MR images underwent the standard systematic distortion correction post‐processing. The images were rigidly registered and landmark‐based analysis was performed by an anatomical expert. Distortion was quantified using Euclidean distance between each landmark pair and tagged by tissue interface: bone‐tissue, soft tissue, or air‐tissue. For baseline comparisons, an anthropomorphic phantom was imaged and analyzed. Results The average spatial discrepancy between CT and MR landmarks was 1.15 ± 1.14 mm for the phantom and 1.46 ± 1.78 mm for patients. The error histogram peaked at 0–1 mm. 66% of the discrepancies were <2 mm and 51% <1 mm. In the patient data, statistically significant differences (p‐values < 0.0001) were found between the different tissue interfaces with averages of 0.88 ± 1.24 mm, 2.01 ± 2.20 mm, and 1.41 ± 1.56 mm for the air/tissue, bone/tissue, and soft tissue, respectively. The distortion generally correlated with the in‐plane radial distance from the image center along the longitudinal axis of the MR. Conclusion Spatial distortion remains in the MR images after systematic distortion corrections. Although the average errors were relatively small, large distortions observed at bone/tissue interfaces emphasize the need for quantitative methods for assessing and correcting patient‐specific spatial distortions.
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Affiliation(s)
- John Neylon
- Department of Radiation Oncology, University of California, Los Angeles (UCLA), Los Angeles, CA, USA
| | - Kiri A Cook
- Department of Radiation Medicine, Oregon Health & Science University, Oregon, Portland, OR, USA
| | - Yingli Yang
- Department of Radiation Oncology, University of California, Los Angeles (UCLA), Los Angeles, CA, USA
| | - Dongsu Du
- Department of Radiation Oncology, City of Hope Cancer Center, Los Angeles, CA, USA
| | - Ke Sheng
- Department of Radiation Oncology, University of California, Los Angeles (UCLA), Los Angeles, CA, USA
| | - Robert K Chin
- Department of Radiation Oncology, University of California, Los Angeles (UCLA), Los Angeles, CA, USA
| | - Amar U Kishan
- Department of Radiation Oncology, University of California, Los Angeles (UCLA), Los Angeles, CA, USA
| | - James M Lamb
- Department of Radiation Oncology, University of California, Los Angeles (UCLA), Los Angeles, CA, USA
| | - Daniel A Low
- Department of Radiation Oncology, University of California, Los Angeles (UCLA), Los Angeles, CA, USA
| | - Minsong Cao
- Department of Radiation Oncology, University of California, Los Angeles (UCLA), Los Angeles, CA, USA
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