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Volz L, Korte J, Martire MC, Zhang Y, Hardcastle N, Durante M, Kron T, Graeff C. Opportunities and challenges of upright patient positioning in radiotherapy. Phys Med Biol 2024; 69:18TR02. [PMID: 39159668 DOI: 10.1088/1361-6560/ad70ee] [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: 02/21/2024] [Accepted: 08/19/2024] [Indexed: 08/21/2024]
Abstract
Objective.Upright positioning has seen a surge in interest as a means to reduce radiotherapy (RT) cost, improve patient comfort, and, in selected cases, benefit treatment quality. In particle therapy (PT) in particular, eliminating the need for a gantry can present massive cost and facility footprint reduction. This review discusses the opportunities of upright RT in perspective of the open challenges.Approach.The clinical, technical, and workflow challenges that come with the upright posture have been extracted from an extensive literature review, and the current state of the art was collected in a synergistic perspective from photon and particle therapy. Considerations on future developments and opportunities are provided.Main results.Modern image guidance is paramount to upright RT, but it is not clear which modalities are essential to acquire in upright posture. Using upright MRI or upright CT, anatomical differences between upright/recumbent postures have been observed for nearly all body sites. Patient alignment similar to recumbent positioning was achieved in small patient/volunteer cohorts with prototype upright positioning systems. Possible clinical advantages, such as reduced breathing motion in upright position, have been reported, but limited cohort sizes prevent resilient conclusions on the treatment impact. Redesign of RT equipment for upright positioning, such as immobilization accessories for various body regions, is necessary, where several innovations were recently presented. Few clinical studies in upright PT have already reported promising outcomes for head&neck patients.Significance.With more evidence for benefits of upright RT emerging, several centers worldwide, particularly in PT, are installing upright positioning devices or have commenced upright treatment. Still, many challenges and open questions remain to be addressed to embed upright positioning firmly in the modern RT landscape. Guidelines, professionals trained in upright patient positioning, and large-scale clinical studies are required to bring upright RT to fruition.
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Affiliation(s)
- Lennart Volz
- Biophysics, GSI Helmholtz Center for Heavy Ion Research GmbH, Darmstadt, Germany
| | - James Korte
- Department of Physical Science, Peter MacCallum Cancer Centere, Melbourne, Australia
- Department of Biomedical Engineering, University of Melbourne, Melbourne, Australia
| | - Maria Chiara Martire
- Biophysics, GSI Helmholtz Center for Heavy Ion Research GmbH, Darmstadt, Germany
| | - Ye Zhang
- Center for Proton Therapy, Paul Scherrer Institut, Villigen-PSI, Switzerland
| | - Nicholas Hardcastle
- Department of Physical Science, Peter MacCallum Cancer Centere, Melbourne, Australia
- Sir Peter MacCallum Department of Oncology, University of Melbourne, Melbourne, Australia
- Centre for Medical Radiation Physics, University of Wollongong, Wollongong, Australia
| | - Marco Durante
- Biophysics, GSI Helmholtz Center for Heavy Ion Research GmbH, Darmstadt, Germany
- Institute for Condensed Matter Physics, Technical University Darmstadt, Darmstadt, Germany
| | - Tomas Kron
- Department of Physical Science, Peter MacCallum Cancer Centere, Melbourne, Australia
- Sir Peter MacCallum Department of Oncology, University of Melbourne, Melbourne, Australia
- Centre for Medical Radiation Physics, University of Wollongong, Wollongong, Australia
| | - Christian Graeff
- Biophysics, GSI Helmholtz Center for Heavy Ion Research GmbH, Darmstadt, Germany
- Department for Electronic Engineering and Computer Science, Technical University Darmstadt, Darmstadt, Germany
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Ebner D, Koto M, Furuichi W, Mori S. Simulation study of comparative dosimetric analysis of coplanar horizontal-port scanned carbon-ion beam therapy in the head and neck. Br J Radiol 2023; 96:20221138. [PMID: 37427708 PMCID: PMC10461273 DOI: 10.1259/bjr.20221138] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2022] [Revised: 06/01/2023] [Accepted: 06/01/2023] [Indexed: 07/11/2023] Open
Abstract
OBJECTIVE Carbon-ion radiotherapy (CIRT) has demonstrated success in treating radioresistant disease within the head and neck, owing to its unique physical and radiobiological properties. Construction cost remains prohibitive; a center offering only a horizontal port may bridge this difficulty, but removal of the vertical port may prohibit treatment of disease near critical organs-at-risk. Building a center only containing a horizontal treatment port has been proposed as one method for cost savings. METHODS 20 complex cases of head and neck cancer previously treated with conventional CIRT were retrospectively planned using horizontal-port-only treatment incorporating non-coplanar treatment angles to achieve greater degrees of freedom. These were dosimetrically compared with the previous plans. RESULTS Comparable D95 coverage of both planning target volume and gross tumor volume with ability to meet organ-at-risk constraints were feasible with horizontal-port-only treatment. Collectively differences were noted in PTV D95, brain stem Dmax, contralateral eye Dmax and V10 Gy (RBE); further qualitative differences were noted on a plan-by-plan basis dependent on disease location. CONCLUSION Horizontal-port-only treatment employing non-coplanar angles was feasible for complicated head and neck disease typically treated with CIRT, though careful consideration is necessary on a plan-by-plan basis. ADVANCES IN KNOWLEDGE It is worth noting that non-coplanar approaches are not typically used with the current treatment gantry and may extend further the difference between horizontal port planning and a gantry-based gold-standard.
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Affiliation(s)
| | - Masashi Koto
- QST Hospital, National Institutes for Quantum Science and Technology, Chiba, Japan
| | - Wataru Furuichi
- Accelerator Engineering Corporation, Konakadai, Inage-Ku, Chiba, Japan
| | - Shinichiro Mori
- Institute for Quantum Medical Science, Quantum Life and Medical Science Directorate, National Institutes for Quantum Science and Technology, Chiba, Japan
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Yan S, Ngoma TA, Ngwa W, Bortfeld TR. Global democratisation of proton radiotherapy. Lancet Oncol 2023; 24:e245-e254. [PMID: 37269856 DOI: 10.1016/s1470-2045(23)00184-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2023] [Revised: 04/05/2023] [Accepted: 04/19/2023] [Indexed: 06/05/2023]
Abstract
Proton radiotherapy is an advanced treatment option compared with conventional x-ray treatment, delivering much lower doses of radiation to healthy tissues surrounding the tumour. However, proton therapy is currently not widely available. In this Review, we summarise the evolution of proton therapy to date, together with the benefits to patients and society. These developments have led to an exponential growth in the number of hospitals using proton radiotherapy worldwide. However, the gap between the number of patients who should be treated with proton radiotherapy and those who have access to it remains large. We summarise the ongoing research and development that is contributing to closing this gap, including the improvement of treatment efficiency and efficacy, and advances in fixed-beam treatments that do not require an enormously large, heavy, and costly gantry. The ultimate goal of decreasing the size of proton therapy machines to fit into standard treatment rooms appears to be within reach, and we discuss future research and development opportunities to achieve this goal.
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Affiliation(s)
- Susu Yan
- Division of Radiation Biophysics, Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA.
| | - Twalib A Ngoma
- Department Clinical Oncology, Muhimbili University of Health and Allied Sciences, Dar es Salaam, Tanzania
| | - Wilfred Ngwa
- Department of Radiation Oncology and Molecular Radiation Sciences, Johns Hopkins School of Medicine, Johns Hopkins University, Baltimore, MD, USA; Department of Information and Sciences, ICT University, Yaoundé, Cameroon
| | - Thomas R Bortfeld
- Division of Radiation Biophysics, Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
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Saini J, Maes D, Regmi R, Fung A, Bloch C, Schwarz M, Stacey A, Chen J, Rengan R, Halasz L. Improved lateral penumbra for proton ocular treatments on a general-purpose spot scanning beamline. Phys Med 2023; 107:102551. [PMID: 36867911 DOI: 10.1016/j.ejmp.2023.102551] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/28/2022] [Revised: 01/31/2023] [Accepted: 02/18/2023] [Indexed: 03/05/2023] Open
Abstract
PURPOSE An ocular applicator that fits a commercial proton snout with an upstream range shifter to allow for treatments with sharp lateral penumbra is described. MATERIALS AND METHODS The validation of the ocular applicator consisted of a comparison of range, depth doses (Bragg peaks and spread out Bragg peaks), point doses, and 2-D lateral profiles. Measurements were made for three field sizes, 1.5, 2, and 3 cm, resulting in 15 beams. Distal and lateral penumbras were simulated in the treatment planning system for seven range-modulation combinations for beams typical of ocular treatments and a field size of 1.5 cm, and penumbra values were compared to published literature. RESULTS All the range errors were within 0.5 mm. The maximum averaged local dose differences for Bragg peaks and SOBPs were 2.6% and 1.1%, respectively. All the 30 measured point doses were within +/-3% of the calculated. The measured lateral profiles, analyzed through gamma index analysis and compared to the simulated, had pass rates greater than 96% for all the planes. The lateral penumbra increased linearly with depth, from 1.4 mm at 1 cm depth to 2.5 mm at 4 cm depth. The distal penumbra ranged from 3.6 to 4.4 mm and increased linearly with the range. The treatment time for a single 10 Gy (RBE) fractional dose ranged from 30 to 120 s, depending on the shape and size of the target. CONCLUSIONS The ocular applicator's modified design allows lateral penumbra similar to dedicated ocular beamlines while enabling planners to use modern treatment tools such as Monte Carlo and full CT-based planning with increased flexibility in beam placement.
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Affiliation(s)
- Jatinder Saini
- Department of Radiation Oncology, University of Washington School of Medicine, 1959 NE Pacific St., Seattle, WA 98195, USA; Fred Hutchinson Cancer Center, 1570 N 115th St., Seattle, WA 98133, USA.
| | - Dominic Maes
- Department of Radiation Oncology, University of Washington School of Medicine, 1959 NE Pacific St., Seattle, WA 98195, USA; Fred Hutchinson Cancer Center, 1570 N 115th St., Seattle, WA 98133, USA
| | - Rajesh Regmi
- Department of Radiation Oncology, University of Washington School of Medicine, 1959 NE Pacific St., Seattle, WA 98195, USA; Fred Hutchinson Cancer Center, 1570 N 115th St., Seattle, WA 98133, USA
| | - Angela Fung
- Fred Hutchinson Cancer Center, 1570 N 115th St., Seattle, WA 98133, USA
| | - Charles Bloch
- Department of Radiation Oncology, University of Washington School of Medicine, 1959 NE Pacific St., Seattle, WA 98195, USA; Fred Hutchinson Cancer Center, 1570 N 115th St., Seattle, WA 98133, USA
| | - Marco Schwarz
- Department of Radiation Oncology, University of Washington School of Medicine, 1959 NE Pacific St., Seattle, WA 98195, USA; Fred Hutchinson Cancer Center, 1570 N 115th St., Seattle, WA 98133, USA
| | - Andrew Stacey
- Department of Ophthalmology, University of Washington School of Medicine, 750 Republican St, Seattle, WA 98109, USA
| | - Jonathan Chen
- Department of Radiation Oncology, University of Washington School of Medicine, 1959 NE Pacific St., Seattle, WA 98195, USA; Fred Hutchinson Cancer Center, 1570 N 115th St., Seattle, WA 98133, USA
| | - Ramesh Rengan
- Department of Radiation Oncology, University of Washington School of Medicine, 1959 NE Pacific St., Seattle, WA 98195, USA; Fred Hutchinson Cancer Center, 1570 N 115th St., Seattle, WA 98133, USA
| | - Lia Halasz
- Department of Radiation Oncology, University of Washington School of Medicine, 1959 NE Pacific St., Seattle, WA 98195, USA; Fred Hutchinson Cancer Center, 1570 N 115th St., Seattle, WA 98133, USA
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Volz L, Sheng Y, Durante M, Graeff C. Considerations for Upright Particle Therapy Patient Positioning and Associated Image Guidance. Front Oncol 2022; 12:930850. [PMID: 35965576 PMCID: PMC9372451 DOI: 10.3389/fonc.2022.930850] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2022] [Accepted: 06/17/2022] [Indexed: 11/16/2022] Open
Abstract
Particle therapy is a rapidly growing field in cancer therapy. Worldwide, over 100 centers are in operation, and more are currently in construction phase. The interest in particle therapy is founded in the superior target dose conformity and healthy tissue sparing achievable through the particles’ inverse depth dose profile. This physical advantage is, however, opposed by increased complexity and cost of particle therapy facilities. Particle therapy, especially with heavier ions, requires large and costly equipment to accelerate the particles to the desired treatment energy and steer the beam to the patient. A significant portion of the cost for a treatment facility is attributed to the gantry, used to enable different beam angles around the patient for optimal healthy tissue sparing. Instead of a gantry, a rotating chair positioning system paired with a fixed horizontal beam line presents a suitable cost-efficient alternative. Chair systems have been used already at the advent of particle therapy, but were soon dismissed due to increased setup uncertainty associated with the upright position stemming from the lack of dedicated image guidance systems. Recently, treatment chairs gained renewed interest due to the improvement in beam delivery, commercial availability of vertical patient CT imaging and improved image guidance systems to mitigate the problem of anatomical motion in seated treatments. In this review, economical and clinical reasons for an upright patient positioning system are discussed. Existing designs targeted for particle therapy are reviewed, and conclusions are drawn on the design and construction of chair systems and associated image guidance. Finally, the different aspects from literature are channeled into recommendations for potential upright treatment layouts, both for retrofitting and new facilities.
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Affiliation(s)
- Lennart Volz
- Biophysics, GSI Helmholtz Center for Heavy Ion Research GmbH, Darmstadt, Germany.,Department of Medical Physics, Shanghai Proton and Heavy Ion Center, Shanghai, China
| | - Yinxiangzi Sheng
- Biophysics, GSI Helmholtz Center for Heavy Ion Research GmbH, Darmstadt, Germany.,Department of Medical Physics, Shanghai Proton and Heavy Ion Center, Shanghai, China
| | - Marco Durante
- Biophysics, GSI Helmholtz Center for Heavy Ion Research GmbH, Darmstadt, Germany.,Institute of Condensed Matter Physics, Technical University of Darmstadt, Darmstadt, Germany
| | - Christian Graeff
- Biophysics, GSI Helmholtz Center for Heavy Ion Research GmbH, Darmstadt, Germany.,Institute of Electrical Engineering and Information Technology, Technical University of Darmstadt, Darmstadt, Germany
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Hegarty S, Hardcastle N, Korte J, Kron T, Everitt S, Rahim S, Hegi-Johnson F, Franich R. Please Place Your Seat in the Full Upright Position: A Technical Framework for Landing Upright Radiation Therapy in the 21 st Century. Front Oncol 2022; 12:821887. [PMID: 35311128 PMCID: PMC8929673 DOI: 10.3389/fonc.2022.821887] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2021] [Accepted: 01/27/2022] [Indexed: 12/20/2022] Open
Abstract
Delivering radiotherapy to patients in an upright position can allow for increased patient comfort, reduction in normal tissue irradiation, or reduction of machine size and complexity. This paper gives an overview of the requirements for the delivery of contemporary arc and modulated radiation therapy to upright patients. We explore i) patient positioning and immobilization, ii) simulation imaging, iii) treatment planning and iv) online setup and image guidance. Treatment chairs have been designed to reproducibly position seated patients for treatment and can be augmented by several existing immobilisation systems or promising emerging technologies such as soft robotics. There are few solutions for acquiring CT images for upright patients, however, cone beam computed tomography (CBCT) scans of upright patients can be produced using the imaging capabilities of standard Linacs combined with an additional patient rotation device. While these images will require corrections to make them appropriate for treatment planning, several methods indicate the viability of this approach. Treatment planning is largely unchanged apart from translating gantry rotation to patient rotation, allowing for a fixed beam with a patient rotating relative to it. Rotation can be provided by a turntable during treatment delivery. Imaging the patient with the same machinery as used in treatment could be advantageous for online plan adaption. While the current focus is using clinical linacs in existing facilities, developments in this area could also extend to lower-cost and mobile linacs and heavy ion therapy.
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Affiliation(s)
- Sarah Hegarty
- School of Science, RMIT University, Melbourne, VIC, Australia.,Department of Physical Sciences, Peter MacCallum Cancer Centre, Melbourne, VIC, Australia
| | - Nicholas Hardcastle
- Department of Physical Sciences, Peter MacCallum Cancer Centre, Melbourne, VIC, Australia.,Centre for Medical Radiation Physics, University of Wollongong, Wollongong, NSW, Australia.,Sir Peter MacCallum Department of Oncology, Faculty of Medicine, Dentistry and Health Science, University of Melbourne, Parkville, VIC, Australia
| | - James Korte
- Department of Physical Sciences, Peter MacCallum Cancer Centre, Melbourne, VIC, Australia.,Department of Biomedical Engineering, School of Engineering, University of Melbourne, Melbourne, VIC, Australia
| | - Tomas Kron
- Department of Physical Sciences, Peter MacCallum Cancer Centre, Melbourne, VIC, Australia.,Centre for Medical Radiation Physics, University of Wollongong, Wollongong, NSW, Australia.,Sir Peter MacCallum Department of Oncology, Faculty of Medicine, Dentistry and Health Science, University of Melbourne, Parkville, VIC, Australia
| | - Sarah Everitt
- Sir Peter MacCallum Department of Oncology, Faculty of Medicine, Dentistry and Health Science, University of Melbourne, Parkville, VIC, Australia.,Department of Radiation Therapy, Peter MacCallum Cancer Centre, Melbourne, VIC, Australia
| | - Sulman Rahim
- Department of Radiation Therapy, Peter MacCallum Cancer Centre, Melbourne, VIC, Australia
| | - Fiona Hegi-Johnson
- Sir Peter MacCallum Department of Oncology, Faculty of Medicine, Dentistry and Health Science, University of Melbourne, Parkville, VIC, Australia.,Department of Radiation Oncology, Peter MacCallum Cancer Centre, Melbourne, VIC, Australia
| | - Rick Franich
- School of Science, RMIT University, Melbourne, VIC, Australia.,Department of Physical Sciences, Peter MacCallum Cancer Centre, Melbourne, VIC, Australia
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Treatment of ocular tumors through a novel applicator on a conventional proton pencil beam scanning beamline. Sci Rep 2022; 12:4648. [PMID: 35301371 PMCID: PMC8931109 DOI: 10.1038/s41598-022-08440-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Accepted: 03/03/2022] [Indexed: 11/23/2022] Open
Abstract
Treatment of ocular tumors on dedicated scattering-based proton therapy systems is standard afforded due to sharp lateral and distal penumbras. However, most newer proton therapy centers provide pencil beam scanning treatments. In this paper, we present a pencil beam scanning (PBS)-based ocular treatment solution. The design, commissioning, and validation of an applicator mount for a conventional PBS snout to allow for ocular treatments are given. In contrast to scattering techniques, PBS-based ocular therapy allows for inverse planning, providing planners with additional flexibility to shape the radiation field,
potentially sparing healthy tissues. PBS enables the use of commercial Monte Carlo algorithms resulting in accurate dose calculations in the presence of heterogeneities and fiducials. The validation consisted of small field dosimetry measurements of point doses, depth doses, and lateral profiles relevant to ocular therapy. A comparison of beam properties achieved through the applicator against published literature is presented. We successfully showed the feasibility of PBS-based ocular treatments.
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Sun J, Kong L, Chen Z, You D, Mao J, Guan X, Wu X, Sheng Y. Clinical Implementation of a 6D Treatment Chair for Fixed Ion Beam Lines. Front Oncol 2021; 11:694749. [PMID: 34249751 PMCID: PMC8260974 DOI: 10.3389/fonc.2021.694749] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Accepted: 05/31/2021] [Indexed: 11/13/2022] Open
Abstract
Purpose To verify the practicality and safety of a treatment chair with six degrees of freedom (6DTC) through demonstrating the efficacy of the workflow in clinical settings and analyzing the obtained technical data, including intra-fraction patient movement during the use of the 6DTC. Materials and Methods A clinical study was designed and conducted to test the clinical treatment workflow and the safety of the 6DTC. Based on the demonstrated dosimetric advantages, fifteen patients with head and neck tumors were selected and treated with the 6DTC. The positional error at the first beam position (PE-B1) and the second beam position (PE-B2) were analyzed and compared with the results from daily quality assurance (QA) procedures of the 6DTC and imaging system performed each day before clinical treatment. The intra-fraction patient movement was derived from the total patient alignment positional error and the QA data based on a Gaussian distribution formulism. Results The QA results showed sub-millimeter mechanical accuracy of the 6DTC over the course of the clinical study. For 150 patient treatment fractions, the mean deviations between PE-B1 and PE-B2 were 0.13mm (SD 0.88mm), 0.25mm (SD 1.17mm), -0.57mm (SD 0.85mm), 0.02° (SD 0.35°), 0.00° (SD 0.37°), and -0.02° (SD 0.37°) in the x, y, z (translational), and u, v, w (rotational) directions, respectively. The calculated intra-fraction patient movement was -0.08mm (SD 0.56mm), 0.71mm (SD 1.12mm), -0.52mm (SD 0.84mm), 0.10° (SD 0.32°), 0.09° (SD 0.36°), and -0.04° (SD 0.36°) in the x, y, z, u, v, w directions, respectively. Conclusions The performance stability of the 6DTC was satisfactory. The position accuracy and intra-fraction patient movement in an upright posture with the 6DTC were verified and found adequate for clinical implementation.
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Affiliation(s)
- Jiayao Sun
- Department of Medical Physics, Shanghai Proton and Heavy Ion Center, Shanghai, China.,Shanghai Key Laboratory of Radiation Oncology (20dz2261000), Shanghai, China.,Shanghai Engineering Research Center of Proton and Heavy Ion Radiation Therapy, Shanghai, China
| | - Lin Kong
- Shanghai Key Laboratory of Radiation Oncology (20dz2261000), Shanghai, China.,Shanghai Engineering Research Center of Proton and Heavy Ion Radiation Therapy, Shanghai, China.,Department of Radiation Oncology, Shanghai Proton and Heavy Ion Center, Fudan University Cancer Hospital, Shanghai, China
| | - Zhi Chen
- Department of Medical Physics, Shanghai Proton and Heavy Ion Center, Shanghai, China.,Shanghai Key Laboratory of Radiation Oncology (20dz2261000), Shanghai, China.,Shanghai Engineering Research Center of Proton and Heavy Ion Radiation Therapy, Shanghai, China
| | - Dan You
- Shanghai Key Laboratory of Radiation Oncology (20dz2261000), Shanghai, China.,Shanghai Engineering Research Center of Proton and Heavy Ion Radiation Therapy, Shanghai, China.,Department of Medical Physics, Shanghai Proton and Heavy Ion Center, Fudan University Cancer Hospital, Shanghai, China
| | - Jingfang Mao
- Shanghai Key Laboratory of Radiation Oncology (20dz2261000), Shanghai, China.,Shanghai Engineering Research Center of Proton and Heavy Ion Radiation Therapy, Shanghai, China.,Department of Radiation Oncology, Shanghai Proton and Heavy Ion Center, Fudan University Cancer Hospital, Shanghai, China
| | - Xiyin Guan
- Shanghai Key Laboratory of Radiation Oncology (20dz2261000), Shanghai, China.,Shanghai Engineering Research Center of Proton and Heavy Ion Radiation Therapy, Shanghai, China.,Department of Radiation Oncology, Shanghai Proton and Heavy Ion Center, Shanghai, China
| | - Xiaodong Wu
- Department of Medical Physics, Shanghai Proton and Heavy Ion Center, Shanghai, China.,Shanghai Key Laboratory of Radiation Oncology (20dz2261000), Shanghai, China.,Shanghai Engineering Research Center of Proton and Heavy Ion Radiation Therapy, Shanghai, China
| | - Yinxiangzi Sheng
- Department of Medical Physics, Shanghai Proton and Heavy Ion Center, Shanghai, China.,Shanghai Key Laboratory of Radiation Oncology (20dz2261000), Shanghai, China.,Shanghai Engineering Research Center of Proton and Heavy Ion Radiation Therapy, Shanghai, China
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