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Haertter A, Salerno M, Koger B, Kennedy C, Alonso‐Basanta M, Dong L, Teo B, Li T. ACR benchmark testing of a novel high-speed ring-gantry linac kV-CBCT system. J Appl Clin Med Phys 2024; 25:e14299. [PMID: 38520072 PMCID: PMC11087172 DOI: 10.1002/acm2.14299] [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: 04/19/2023] [Revised: 07/21/2023] [Accepted: 01/16/2024] [Indexed: 03/25/2024] Open
Abstract
A new generation cone-beam computed tomography (CBCT) system with new hardware design and advanced image reconstruction algorithms is available for radiation treatment simulation or adaptive radiotherapy (HyperSight CBCT imaging solution, Varian Medical Systems-a Siemens Healthineers company). This study assesses the CBCT image quality metrics using the criteria routinely used for diagnostic CT scanner accreditation as a first step towards the future use of HyperSight CBCT images for treatment planning and target/organ delineations. Image performance was evaluated using American College of Radiology (ACR) Program accreditation phantom tests for diagnostic computed tomography systems (CTs) and compared HyperSight images with a standard treatment planning diagnostic CT scanner (Siemens SOMATOM Edge) and with existing CBCT systems (Varian TrueBeam version 2.7 and Varian Halcyon version 2.0). Image quality performance for all Varian HyperSight CBCT vendor-provided imaging protocols were assessed using ACR head and body ring CT phantoms, then compared to existing imaging modalities. Image quality analysis metrics included contrast-to-noise (CNR), spatial resolution, Hounsfield number (HU) accuracy, image scaling, and uniformity. All image quality assessments were made following the recommendations and passing criteria provided by the ACR. The Varian HyperSight CBCT imaging system demonstrated excellent image quality, with the majority of vendor-provided imaging protocols capable of passing all ACR CT accreditation standards. Nearly all (8/11) vendor-provided protocols passed ACR criteria using the ACR head phantom, with the Abdomen Large, Pelvis Large, and H&N vendor-provided protocols produced HU uniformity values slightly exceeding passing criteria but remained within the allowable minor deviation levels (5-7 HU maximum differences). Compared to other existing CT and CBCT imaging modalities, both HyperSight Head and Pelvis imaging protocols matched the performance of the SOMATOM CT scanner, and both the HyperSight and SOMATOM CT substantially surpassed the performance of the Halcyon 2.0 and TrueBeam version 2.7 systems. Varian HyperSight CBCT imaging system could pass almost all tests for all vendor-provided protocols using ACR accreditation criteria, with image quality similar to those produced by diagnostic CT scanners and significantly better than existing linac-based CBCT imaging systems.
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Affiliation(s)
- Allison Haertter
- Department of Radiation OncologyUniversity of PennsylvaniaPhiladelphiaPennsylvaniaUSA
| | - Michael Salerno
- Department of Radiation OncologyUniversity of PennsylvaniaPhiladelphiaPennsylvaniaUSA
| | - Brandon Koger
- Department of Radiation OncologyUniversity of PennsylvaniaPhiladelphiaPennsylvaniaUSA
| | - Christopher Kennedy
- Department of Radiation OncologyUniversity of PennsylvaniaPhiladelphiaPennsylvaniaUSA
| | | | - Lei Dong
- Department of Radiation OncologyUniversity of PennsylvaniaPhiladelphiaPennsylvaniaUSA
| | - Boon‐Keng Teo
- Department of Radiation OncologyUniversity of PennsylvaniaPhiladelphiaPennsylvaniaUSA
| | - Taoran Li
- Department of Radiation OncologyUniversity of PennsylvaniaPhiladelphiaPennsylvaniaUSA
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Wegener S, Sauer OA. Simulation of consequences of using nonideal detectors during beam data commissioning measurements. Med Phys 2023; 50:8044-8056. [PMID: 37646469 DOI: 10.1002/mp.16675] [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: 12/22/2021] [Revised: 07/03/2023] [Accepted: 07/19/2023] [Indexed: 09/01/2023] Open
Abstract
BACKGROUND Beam data commissioning is a core task of radiotherapy physicists. Despite multiple detectors available, a feasible measurement program compromises between detector properties and time constraints. Therefore, it is important to understand how nonideal measurement data propagates into patient dose calculation. PURPOSE We simulated the effects of realistic errors, due to beam commissioning with presumably nonoptimal detectors, on the resulting patient dose distributions. Additionally, the detectability of such beam commissioning errors during patient plan quality assurance (QA) was evaluated. METHODS A clinically used beam model was re-commissioned introducing changes to depth dose curves, output factors, profiles or combinations of those. Seventeen altered beam models with incremental changes of the modelling parameters were created to analyze dose changes on simplified anatomical phantoms. Additionally, fourteen altered models incorporate changes in the order of signal differences reported for typically used detectors. Eighteen treatment plans of different types were recalculated on patient CT data sets using the altered beam models. RESULTS For the majority of clinical plans, dose distributions in the target volume recalculated on the patient computed tomography data were similar between the original and the modified beam models, yielding global 2%/2 mm gamma pass rates above 98.9%. Larger changes were observed for certain combinations of beam modelling errors and anatomical sites, most extreme for output factor changes in a small target volume plan with a pass rate of 80.6%. Modelling an enlarged penumbra as if measured with a 0.125 cm3 ion chamber had the largest effect on the dose distribution (average pass rate of 96.5%, lowest 85.4%). On different QA phantom geometries, dose distributions between calculations with modified and unmodified models typically changed too little to be detected in actual measurements. CONCLUSION While the simulated errors during beam modelling had little effect on most plans, in some cases changes were considerable. High-quality penumbra and small field output factor should be a main focus of commissioning measurements. Detecting modelling issues using standard patient QA phantoms is unlikely. Verification of a beam model should be performed especially for plans with high modulation and in different depths or geometries representing the variety of situations expected clinically.
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Affiliation(s)
- Sonja Wegener
- Department of Radiation Oncology, University Hospital Wurzburg, Wuerzburg, Germany
| | - Otto A Sauer
- Department of Radiation Oncology, University Hospital Wurzburg, Wuerzburg, Germany
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Huang Y, Liu Z. Dosimetric performance evaluation of the Halcyon treatment platform for stereotactic radiotherapy: A pooled study. Medicine (Baltimore) 2023; 102:e34933. [PMID: 37682167 PMCID: PMC10489306 DOI: 10.1097/md.0000000000034933] [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: 04/13/2023] [Accepted: 08/04/2023] [Indexed: 09/09/2023] Open
Abstract
With the advancement of radiotherapy equipment, stereotactic radiotherapy (SRT) has been increasingly used. Among the many radiotherapy devices, Halcyon shows promising applications. This article reviews the dosimetric performance such as plan quality, plan complexity, and gamma passing rates of SRT plans with Halcyon to determine the effectiveness and safety of Halcyon SRT plans. This article retrieved the last 5 years of PubMed studies on the effectiveness and safety of the Halcyon SRT plans. Two authors independently reviewed the titles and abstracts to decide whether to include the studies. A search was conducted to identify publications relevant to evaluating the dosimetric performance of SRT plans on Halcyon using the key strings Halcyon, stereotactic radiosurgery, SRT, stereotactic body radiotherapy, and stereotactic ablative radiotherapy. A total of 18 eligible publications were retrieved. Compared to SRT plans on the TrueBeam, the Halcyon has advantages in terms of plan quality, plan complexity, and gamma passing rates. The high treatment speed of SRT plans on the Halcyon is impressive, while the results of its plan evaluation are also encouraging. As a result, Halcyon offers a new option for busy radiotherapy units while significantly improving patient comfort in treatment. For more accurate results, additional relevant publications will need to be followed up in subsequent studies.
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Affiliation(s)
- Yangyang Huang
- Department of Radiotherapy, the Second Affiliated Hospital of Zhengzhou University, Zhengzhou, China
| | - Zongwen Liu
- Department of Radiotherapy, the Second Affiliated Hospital of Zhengzhou University, Zhengzhou, China
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Kawata K, Hirashima H, Tsuruta Y, Sasaki M, Matsushita N, Fujimoto T, Nakamura M, Nakata M. Applicability evaluation of the TRS-483 protocol for the determination of small-field output factors using different multi-leaf collimator and field-shaping types. Phys Med 2023; 113:102664. [PMID: 37573811 DOI: 10.1016/j.ejmp.2023.102664] [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: 10/13/2022] [Revised: 08/06/2023] [Accepted: 08/07/2023] [Indexed: 08/15/2023] Open
Abstract
PURPOSE To evaluate the applicability of TRS-483 output correction factors (CFs) for small-field output factors (OFs) using different multi-leaf collimators (MLC) and field-shaping types. METHODS All measurements were performed on TrueBeam, TrueBeam STx, and Halcyon using 6 MV flattening filter-free energy. Four detectors, including CC01, CC04, microDiamond, and EDGE, were used. Nominal field sizes ranging from 1 × 1 to 4 × 4, and 10 × 10 cm2 were used to measure small-field OFs at source-to-axis distance of 100 cm with a 0° gantry angle in a 3D water phantom. Further, the field-shaping types were defined using jaw collimator or MLC (five different configurations). A field size of 10 × 10 cm2 was used as the reference for calculation of OFs obtained as ratio of detector readings (OFdet). The percentage difference and coefficient of variation of OFdet and OFdet corrected by applying CF were compared for each field size and configuration. RESULTS For OFdet corrected by applying CF, the ranges of percentage difference and coefficient of variation in all configurations for ≥ 2 × 2 cm2 fields were reduced from 1.2-2.2 to 0.8-1.3 percentage points (%pt) and from 0.5-1.0 to 0.4-0.7%, respectively. For 1 × 1 cm2 field, the ranges of percentage difference and coefficient of variation were reduced from 3.3-5.7 to 1.2-2.2 %pt and from 2.2-3.7 to 0.8-1.1%, respectively. CONCLUSIONS The CFs described in TRS-483 dosimetry protocol have broad applicability in reducing OF variations between detectors under different MLC and field-shaping types.
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Affiliation(s)
- Kohei Kawata
- Division of Clinical Radiology Service, Kyoto University Hospital, Kyoto, Japan
| | - Hideaki Hirashima
- Department of Radiation Oncology and Image-Applied Therapy, Graduate School of Medicine, Kyoto University, Sakyo-ku, Kyoto, Japan.
| | - Yusuke Tsuruta
- Division of Clinical Radiology Service, Kyoto University Hospital, Kyoto, Japan; Department of Advanced Medical Physics, Graduate School of Medicine, Kyoto University, Sakyo-ku, Kyoto, Japan
| | - Makoto Sasaki
- Division of Clinical Radiology Service, Kyoto University Hospital, Kyoto, Japan
| | - Norimasa Matsushita
- Division of Clinical Radiology Service, Kyoto University Hospital, Kyoto, Japan
| | - Takahiro Fujimoto
- Division of Clinical Radiology Service, Kyoto University Hospital, Kyoto, Japan
| | - Mitsuhiro Nakamura
- Department of Radiation Oncology and Image-Applied Therapy, Graduate School of Medicine, Kyoto University, Sakyo-ku, Kyoto, Japan; Department of Advanced Medical Physics, Graduate School of Medicine, Kyoto University, Sakyo-ku, Kyoto, Japan
| | - Manabu Nakata
- Division of Clinical Radiology Service, Kyoto University Hospital, Kyoto, Japan
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Jaffray DA, Knaul F, Baumann M, Gospodarowicz M. Harnessing progress in radiotherapy for global cancer control. NATURE CANCER 2023; 4:1228-1238. [PMID: 37749355 DOI: 10.1038/s43018-023-00619-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2021] [Accepted: 06/22/2023] [Indexed: 09/27/2023]
Abstract
The pace of technological innovation over the past three decades has transformed the field of radiotherapy into one of the most technologically intense disciplines in medicine. However, the global barriers to access this highly effective treatment are complex and extend beyond technological limitations. Here, we review the technological advancement and current status of radiotherapy and discuss the efforts of the global radiation oncology community to formulate a more integrative 'diagonal approach' in which the agendas of science-driven advances in individual outcomes and the sociotechnological task of global cancer control can be aligned to bring the benefit of this proven therapy to patients with cancer everywhere.
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Affiliation(s)
- David A Jaffray
- Departments of Radiation Physics and Imaging Physics, University of Texas MD Anderson Cancer Center, Houston, TX, USA.
| | - Felicia Knaul
- Sylvester Comprehensive Cancer Center, Miller School of Medicine, University of Miami, Miami, FL, USA
| | | | - Mary Gospodarowicz
- Radiation Oncology, Princess Margaret Cancer Centre, University of Toronto, Toronto, Ontario, Canada
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Morel A, Prunaretty J, Trauchessec D, Ailleres N, Fenoglietto P, Azria D. Comprehensive commissioning and quality assurance validation of Ethos™ therapy. Cancer Radiother 2023; 27:355-361. [PMID: 37085341 DOI: 10.1016/j.canrad.2022.10.001] [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: 09/22/2022] [Revised: 10/11/2022] [Accepted: 10/18/2022] [Indexed: 04/23/2023]
Abstract
PURPOSE Adaptive radiotherapy with the Ethos® therapy Varian system has been recently implemented at the Montpellier Cancer Institute, France. This article details the commissioning performed before the implementation of this new treatment planning system (TPS). MATERIAL AND METHODS To validate the golden beam data of the machine (Halcyon linear accelerator), percentage depth doses (PDD) and profiles were measured for several field sizes and at different depths with a microdiamond chamber. The final doses calculated for different plan types with the Ethos Acuros XB algorithm and the Halcyon Eclipse Analytic Anisotropic Algorithm were compared using the gamma index method. Lastly, for the patient quality assurance (QA) process, the patient treatment plan results obtained with the Mobius3D QA platform (Varian) were compared with the portal dosimetry results obtained with Epiqa (Epidos). RESULTS Minor differences were observed for the PDD and profile curves (mean difference of 0.2% and 2%, respectively). The χ index pass rate was above 98% for all measures using the 1%/1mm and 2%/2mm criteria for PDD and profile evaluations. The Ethos AXB algorithm was validated for every configuration (fixed fields, standard IMRT and VMAT fields, and clinical plans) with 2D/3D gamma index values>99%. Seventy-three 3-arcs-VMAT QA plans and 27 9-fields-IMRT QA plans were evaluated. Both showed excellent agreement with the TPS calculations (mean gamma pass rate higher than 99%). No difference was observed between IMRT and VMAT. CONCLUSION The beam delivery, the Ethos AXB algorithm, and the patient QA were comprehensively validated using independent tools.
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Affiliation(s)
- A Morel
- Institut du cancer de Montpellier (ICM), Montpellier, France
| | - J Prunaretty
- Institut du cancer de Montpellier (ICM), Montpellier, France.
| | - D Trauchessec
- Institut du cancer de Montpellier (ICM), Montpellier, France
| | - N Ailleres
- Institut du cancer de Montpellier (ICM), Montpellier, France
| | - P Fenoglietto
- Institut du cancer de Montpellier (ICM), Montpellier, France
| | - D Azria
- Institut du cancer de Montpellier (ICM), Montpellier, France
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Qiu Z, Olberg S, den Hertog D, Ajdari A, Bortfeld T, Pursley J. Online adaptive planning methods for intensity-modulated radiotherapy. Phys Med Biol 2023; 68:10.1088/1361-6560/accdb2. [PMID: 37068488 PMCID: PMC10637515 DOI: 10.1088/1361-6560/accdb2] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2022] [Accepted: 04/17/2023] [Indexed: 04/19/2023]
Abstract
Online adaptive radiation therapy aims at adapting a patient's treatment plan to their current anatomy to account for inter-fraction variations before daily treatment delivery. As this process needs to be accomplished while the patient is immobilized on the treatment couch, it requires time-efficient adaptive planning methods to generate a quality daily treatment plan rapidly. The conventional planning methods do not meet the time requirement of online adaptive radiation therapy because they often involve excessive human intervention, significantly prolonging the planning phase. This article reviews the planning strategies employed by current commercial online adaptive radiation therapy systems, research on online adaptive planning, and artificial intelligence's potential application to online adaptive planning.
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Affiliation(s)
- Zihang Qiu
- Department of Business Analytics, University of Amsterdam, The Netherlands
- Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, United States of America
| | - Sven Olberg
- Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, United States of America
| | - Dick den Hertog
- Department of Business Analytics, University of Amsterdam, The Netherlands
| | - Ali Ajdari
- Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, United States of America
| | - Thomas Bortfeld
- Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, United States of America
| | - Jennifer Pursley
- Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, United States of America
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8
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Liu L, Shen L, Yang Y, Schüler E, Zhao W, Wetzstein G, Xing L. Modeling linear accelerator (Linac) beam data by implicit neural representation learning for commissioning and quality assurance applications. Med Phys 2023; 50:3137-3147. [PMID: 36621812 PMCID: PMC10175132 DOI: 10.1002/mp.16212] [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: 09/24/2022] [Revised: 12/21/2022] [Accepted: 01/01/2023] [Indexed: 01/10/2023] Open
Abstract
BACKGROUND Linear accelerator (Linac) beam data commissioning and quality assurance (QA) play a vital role in accurate radiation treatment delivery and entail a large number of measurements using a variety of field sizes. How to optimize the effort in data acquisition while maintaining high quality of medical physics practice has been sought after. PURPOSE We propose to model Linac beam data through implicit neural representation (NeRP) learning. The potential of the beam model in predicting beam data from sparse measurements and detecting data collection errors was evaluated, with the goal of using the beam model to verify beam data collection accuracy and simplify the commissioning and QA process. MATERIALS AND METHODS NeRP models with continuous and differentiable functions parameterized by multilayer perceptrons (MLPs) were used to represent various beam data including percentage depth dose (PDD) and profiles of 6 MV beams with and without flattening filter. Prior knowledge of the beam data was embedded into the MLP network by learning the NeRP of a vendor-provided "golden" beam dataset. The prior-embedded network was then trained to fit clinical beam data collected at one field size and used to predict beam data at other field sizes. We evaluated the prediction accuracy by comparing network-predicted beam data to water tank measurements collected from 14 clinical Linacs. Beam datasets with intentionally introduced errors were used to investigate the potential use of the NeRP model for beam data verification, by evaluating the model performance when trained with erroneous beam data samples. RESULTS Linac beam data predicted by the model agreed well with water tank measurements, with averaged Gamma passing rates (1%/1 mm passing criteria) higher than 95% and averaged mean absolute errors less than 0.6%. Beam data samples with measurement errors were revealed by inconsistent beam predictions between networks trained with correct versus erroneous data samples, characterized by a Gamma passing rate lower than 90%. CONCLUSION A NeRP beam data modeling technique has been established for predicting beam characteristics from sparse measurements. The model provides a valuable tool to verify beam data collection accuracy and promises to simplify commissioning/QA processes by reducing the number of measurements without compromising the quality of medical physics service.
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Affiliation(s)
- Lianli Liu
- Department of Radiation Oncology, Stanford University, Palo Alto, California, USA
| | - Liyue Shen
- Department of Electrical Engineering, Stanford University, Palo Alto, California, USA
| | - Yong Yang
- Department of Radiation Oncology, Stanford University, Palo Alto, California, USA
| | - Emil Schüler
- Department of Radiation Oncology, Stanford University, Palo Alto, California, USA
| | - Wei Zhao
- Department of Radiation Oncology, Stanford University, Palo Alto, California, USA
| | - Gordon Wetzstein
- Department of Electrical Engineering, Stanford University, Palo Alto, California, USA
| | - Lei Xing
- Department of Radiation Oncology, Stanford University, Palo Alto, California, USA
- Department of Electrical Engineering, Stanford University, Palo Alto, California, USA
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Stanley DN, Harms J, Pogue JA, Belliveau JG, Marcrom SR, McDonald AM, Dobelbower MC, Boggs DH, Soike MH, Fiveash JA, Popple RA, Cardenas CE. A roadmap for implementation of kV-CBCT online adaptive radiation therapy and initial first year experiences. J Appl Clin Med Phys 2023:e13961. [PMID: 36920871 DOI: 10.1002/acm2.13961] [Citation(s) in RCA: 13] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Revised: 01/12/2023] [Accepted: 02/23/2023] [Indexed: 03/16/2023] Open
Abstract
PURPOSE Online Adaptive Radiation Therapy (oART) follows a different treatment paradigm than conventional radiotherapy, and because of this, the resources, implementation, and workflows needed are unique. The purpose of this report is to outline our institution's experience establishing, organizing, and implementing an oART program using the Ethos therapy system. METHODS We include resources used, operational models utilized, program creation timelines, and our institutional experiences with the implementation and operation of an oART program. Additionally, we provide a detailed summary of our first year's clinical experience where we delivered over 1000 daily adaptive fractions. For all treatments, the different stages of online adaption, primary patient set-up, initial kV-CBCT acquisition, contouring review and edit of influencer structures, target review and edits, plan evaluation and selection, Mobius3D 2nd check and adaptive QA, 2nd kV-CBCT for positional verification, treatment delivery, and patient leaving the room, were analyzed. RESULTS We retrospectively analyzed data from 97 patients treated from August 2021-August 2022. One thousand six hundred seventy seven individual fractions were treated and analyzed, 632(38%) were non-adaptive and 1045(62%) were adaptive. Seventy four of the 97 patients (76%) were treated with standard fractionation and 23 (24%) received stereotactic treatments. For the adaptive treatments, the generated adaptive plan was selected in 92% of treatments. On average(±std), adaptive sessions took 34.52 ± 11.42 min from start to finish. The entire adaptive process (from start of contour generation to verification CBCT), performed by the physicist (and physician on select days), was 19.84 ± 8.21 min. CONCLUSION We present our institution's experience commissioning an oART program using the Ethos therapy system. It took us 12 months from project inception to the treatment of our first patient and 12 months to treat 1000 adaptive fractions. Retrospective analysis of delivered fractions showed that the average overall treatment time was approximately 35 min and the average time for the adaptive component of treatment was approximately 20 min.
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Affiliation(s)
- Dennis N Stanley
- Department of Radiation Oncology, University of Alabama, Birmingham, Alabama, USA
| | - Joseph Harms
- Department of Radiation Oncology, University of Alabama, Birmingham, Alabama, USA
| | - Joel A Pogue
- Department of Radiation Oncology, University of Alabama, Birmingham, Alabama, USA
| | - Jean-Guy Belliveau
- Department of Radiation Oncology, University of Alabama, Birmingham, Alabama, USA
| | - Samuel R Marcrom
- Department of Radiation Oncology, University of Alabama, Birmingham, Alabama, USA
| | - Andrew M McDonald
- Department of Radiation Oncology, University of Alabama, Birmingham, Alabama, USA
| | - Michael C Dobelbower
- Department of Radiation Oncology, University of Alabama, Birmingham, Alabama, USA
| | - Drexell H Boggs
- Department of Radiation Oncology, University of Alabama, Birmingham, Alabama, USA
| | - Michael H Soike
- Department of Radiation Oncology, University of Alabama, Birmingham, Alabama, USA
| | - John A Fiveash
- Department of Radiation Oncology, University of Alabama, Birmingham, Alabama, USA
| | - Richard A Popple
- Department of Radiation Oncology, University of Alabama, Birmingham, Alabama, USA
| | - Carlos E Cardenas
- Department of Radiation Oncology, University of Alabama, Birmingham, Alabama, USA
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Kaur A, Sahani G, Shrivastava A, Pawaskar PN. Optimization of Radiation Shielding Considerations for Designing Halcyon Vault. J Med Phys 2023; 48:1-12. [PMID: 37342599 PMCID: PMC10277303 DOI: 10.4103/jmp.jmp_86_22] [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: 09/20/2022] [Revised: 12/23/2022] [Accepted: 12/30/2022] [Indexed: 06/23/2023] Open
Abstract
Purpose To determine the radiation shielding considerations for optimization of Halcyon vault shielding requirements. Materials and Methods The primary and leakage workloads were estimated using actual clinical treatment planning and treatment delivery data acquired from three busy operational clinical Halcyon facilities. The effective use factor was determined based on a newer approach proposed in this paper using the percentage of patients treated with different treatment techniques. The transmission factor of the primary beam block, maximum head leakage, and patient scatter fractions around the Halcyon machine were experimentally determined. The first tenth-value layer (TVL1) and equilibrium tenth-value layer (TVLe) for 6 MV - flattening-filter-free (FFF) primary X-ray beam for ordinary concrete were measured. Results The primary and leakage workloads are estimated as 1 × 105 cGy/wk and 3.1 × 105 cGy/wk at 1 m respectively. The effective use factor is found as 0.114. The primary beam-block transmission factor is determined as 1.7 × 10-4 at 1 m distance from isocenter along the central beam axis. The maximum head leakage is noted as 6.23 × 10-4. The patient scatter fractions are reported for various planar angles around the Halcyon machine at a radial distance of 1 m in a horizontal plane passing through isocenter. The TVL1 and TVLe of 6 MV-FFF X-ray beam energy for ordinary concrete are found to be 33 and 29 cm, respectively. Conclusion Using experimentally determined shielding considerations, the optimized vault shielding requirements for the Halcyon facility are calculated and a typical layout drawing is proposed.
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Affiliation(s)
- Amanjot Kaur
- Centre for Interdisciplinary Research, D. Y. Patil Education Society (Deemed to be University), Kolhapur, Maharashtra, India
- Department of Radiotherapy, Mahatma Phule Charitable Trust (MPCT) Hospital, Navi Mumbai, Maharashtra, India
| | - G. Sahani
- Radiological Safety Division, Atomic Energy Regulatory Board, Mumbai, Maharashtra, India
| | | | - Padmaja N. Pawaskar
- Centre for Interdisciplinary Research, D. Y. Patil Education Society (Deemed to be University), Kolhapur, Maharashtra, India
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Ju SG, Ahn YC, Kim YB, Kim JM, Kwon DY, Park BS, Yang K. Dosimetric comparison between VMAT plans using the fast-rotating O-ring linac with dual-layer stacked MLC and helical tomotherapy for nasopharyngeal carcinoma. Radiat Oncol 2022; 17:155. [PMID: 36096874 PMCID: PMC9465858 DOI: 10.1186/s13014-022-02124-0] [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: 03/29/2022] [Accepted: 08/30/2022] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND To compare the dosimetric profiles of volumetric modulated arc therapy (VMAT) plans using the fast-rotating O-ring linac (the Halcyon system) based on a dual-layer stacked multi-leaf collimator and helical tomotherapy (HT) for nasopharyngeal cancer (NPCa). METHODS For 30 NPCa patients, three sets of RT plans were generated, under the same policy of contouring and dose constraints: HT plan; Halcyon VMAT plan with two arcs (HL2arc); and Halcyon VMAT plan with four arcs (HL4arc), respectively. The intended dose schedule was to deliver 67.2 Gy to the planning gross target volume (P-GTV) and 56.0 Gy to the planning clinical target volume (P-CTV) in 28 fractions using the simultaneously integrated boost concept. Target volumes and organ at risks dose metrics were evaluated for all plans. Normal tissue complication probabilities (NTCP) for esophagus, parotid glands, spinal cord, and brain stem were compared. RESULTS The HT plan achieved the best dose homogeneity index for both P_GTV and P_CTV, followed by the HL4arc and L2arc plans. No significant difference in the dose conformity index (CI) for P_GTV was observed between the HT plan (0.80) and either the HL2arc plan (0.79) or the HL4arc plan (0.83). The HL4arc plan showed the best CI for P_CTV (0.88), followed by the HL2arc plan (0.83) and the HT plan (0.80). The HL4arc plan (median, interquartile rage (Q1, Q3): 25.36 (22.22, 26.89) Gy) showed the lowest Dmean in the parotid glands, followed by the HT (25.88 (23.87, 27.87) Gy) and HL2arc plans (28.00 (23.24, 33.99) Gy). In the oral cavity (OC) dose comparison, the HT (22.03 (19.79, 24.85) Gy) plan showed the lowest Dmean compared to the HL2arc (23.96 (20.84, 28.02) Gy) and HL4arc (24.14 (20.17, 27.53) Gy) plans. Intermediate and low dose regions (40-65% of the prescribed dose) were well fit to the target volume in HL4arc, compared to the HT and HL2arc plans. All plans met the dose constraints for the other OARs with sufficient dose margins. The between-group differences in the median NTCP values for the parotid glands and OC were < 3.47% and < 1.7% points, respectively. CONCLUSIONS The dosimetric profiles of Halcyon VMAT plans were comparable to that of HT, and HL4arc showed better dosimetric profiles than HL2arc for NPCa.
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Affiliation(s)
- Sang Gyu Ju
- Department of Radiation Oncology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Irwon-Ro 81, Gangnam-Gu, Seoul, 06351, Republic of Korea
| | - Yong Chan Ahn
- Department of Radiation Oncology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Irwon-Ro 81, Gangnam-Gu, Seoul, 06351, Republic of Korea.
| | - Yeong-Bi Kim
- Department of Radiation Oncology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Irwon-Ro 81, Gangnam-Gu, Seoul, 06351, Republic of Korea
| | - Jin Man Kim
- Department of Radiation Oncology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Irwon-Ro 81, Gangnam-Gu, Seoul, 06351, Republic of Korea
| | - Dong Yeol Kwon
- Department of Radiation Oncology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Irwon-Ro 81, Gangnam-Gu, Seoul, 06351, Republic of Korea
| | - Byoung Suk Park
- Department of Radiation Oncology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Irwon-Ro 81, Gangnam-Gu, Seoul, 06351, Republic of Korea
| | - Kyungmi Yang
- Department of Radiation Oncology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Irwon-Ro 81, Gangnam-Gu, Seoul, 06351, Republic of Korea
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Geurts MW, Jacqmin DJ, Jones LE, Kry SF, Mihailidis DN, Ohrt JD, Ritter T, Smilowitz JB, Wingreen NE. AAPM MEDICAL PHYSICS PRACTICE GUIDELINE 5.b: Commissioning and QA of treatment planning dose calculations-Megavoltage photon and electron beams. J Appl Clin Med Phys 2022; 23:e13641. [PMID: 35950259 PMCID: PMC9512346 DOI: 10.1002/acm2.13641] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2021] [Revised: 04/04/2022] [Accepted: 04/06/2022] [Indexed: 11/23/2022] Open
Abstract
The American Association of Physicists in Medicine (AAPM) is a nonprofit professional society whose primary purposes are to advance the science, education, and professional practice of medical physics. The AAPM has more than 8000 members and is the principal organization of medical physicists in the United States. The AAPM will periodically define new practice guidelines for medical physics practice to help advance the science of medical physics and to improve the quality of service to patients throughout the United States. Existing medical physics practice guidelines will be reviewed for the purpose of revision or renewal, as appropriate, on their fifth anniversary or sooner. Each medical physics practice guideline represents a policy statement by the AAPM, has undergone a thorough consensus process in which it has been subjected to extensive review, and requires the approval of the Professional Council. The medical physics practice guidelines recognize that the safe and effective use of diagnostic and therapeutic radiology requires specific training, skills, and techniques, as described in each document. Reproduction or modification of the published practice guidelines and technical standards by those entities not providing these services is not authorized. The following terms are used in the AAPM practice guidelines:
Must and Must Not: Used to indicate that adherence to the recommendation is considered necessary to conform to this practice guideline. While must is the term to be used in the guidelines, if an entity that adopts the guideline has shall as the preferred term, the AAPM considers that must and shall have the same meaning. Should and Should Not: Used to indicate a prudent practice to which exceptions may occasionally be made in appropriate circumstances.
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Azorín JFP, Saez J, Garcia LIR, Hernandez V. Investigation on the impact of the leaf trailing effect using the Halcyon integrated platform system. Med Phys 2022; 49:6161-6170. [PMID: 35770385 DOI: 10.1002/mp.15833] [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: 12/24/2021] [Revised: 03/25/2022] [Accepted: 06/14/2022] [Indexed: 11/10/2022] Open
Abstract
PURPOSE The double-stacked design of the Halcyon multileaf collimator (MLC) presents new challenges for treatment planning systems (TPSs). The leaf trailing effect has recently been described as the result of the interplay between the fluence transmitted through the leaf tip ends of each MLC layer. This effect makes the dosimetric leaf gap (DLG) dependent on the distance between the leaves of different layers (trailing distance) and is not adequately modeled by the Eclipse TPS. The purpose of our study was to investigate and report the dose discrepancies produced by these limitations in clinical plans and to explore how these discrepancies can be mitigated and avoided. METHODS The integrated platform with the Halcyon v2 system, Eclipse and Aria v15.6, was used. The dose discrepancies were obtained with EPID images and the portal dosimetry software and validated using radiochromic film dosimetry. The results for the AIDA commissioning test and for nine selected clinical beams with the sliding window intensity modulated radiotherapy (dIMRT) technique were thoroughly analyzed and presented. First, the DICOM RT plans were exported and the fluences were computed using different leaf tip models, and then were compared. Second, the detailed characteristics of the corresponding leaf sequences were investigated. Finally, modified DICOM RT plans were created in which the non-collimating (backup) leaves were retracted 2 mm to increase the leaf trailing distance, the modified plans were imported back into the TPS and the measurements were repeated. Dedicated in-house tools were developed in Python to carry out all analyses. RESULTS Dose discrepancies greater than 10% and regions of gamma failure were found in both the AIDA test and clinical beams using static-gantry dIMRT. Fluence analysis highlighted that the discrepancies were due to limitations in the MLC model implemented in the TPS. Analysis of leaf sequences indicated that regions of failure were associated with very low leaf speeds and virtually motionless leaves within the beam aperture. Some of these discrepancies were mitigated by increasing the trailing distance of the non-collimating leaves without affecting the beam aperture, but this strategy was not possible in regions where the leaves from both layers actively defined the beam aperture. CONCLUSIONS Current limitations of the MLC model in Eclipse produced discrepancies between calculated and delivered doses in clinical beams that caused plan-specific quality assurance failures and interruptions in the clinical workflow. Careful evaluation of the clinical plans produced by Eclipse for the Halcyon is recommended, especially for static gantry dIMRT treatments. Some characteristics of leaf sequences are problematic and should be avoided in clinical plans and, in general, a better leaf tip model is needed. This is particularly important in adaptive radiotherapy treatments, where the accuracy and reliability of TPS dose calculations are of the utmost importance.
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Affiliation(s)
- José Fernando Pérez Azorín
- Medical Physics and Radiation Protection Department, Gurutzeta-Cruces University Hospital, Barakaldo, E-48903, Spain.,Biocruces Health Research Institute, Barakaldo, E-48903, Spain
| | - Jordi Saez
- Department of Radiation Oncology, Hospital Clínic de Barcelona, Barcelona, 08036, Spain
| | - Luis Isaac Ramos Garcia
- Department of Oncology, Clínica Universidad de Navarra, University of Navarra, Pamplona, E-31008, Spain
| | - Victor Hernandez
- Department of Medical Physics, Hospital Sant Joan de Reus, IISPV, Tarragona, 43204, Spain.,Universitat Rovira i Virgili, Tarragona, Spain
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14
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Dosimetric advantages of volumetric modulated arc therapy (VMAT) with deep inspiration breath hold (DIBH) technique in Halcyon Linac for left breast cancer treatment. Med Dosim 2022; 47:288-294. [DOI: 10.1016/j.meddos.2022.04.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2022] [Revised: 04/20/2022] [Accepted: 04/24/2022] [Indexed: 11/20/2022]
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15
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Hoisak JD, Kim GYG, Atwood TF, Pawlicki T. Operational Insights From the Longitudinal Analysis of a Linear Accelerator Machine Log. Cureus 2021; 13:e16038. [PMID: 34239800 PMCID: PMC8245652 DOI: 10.7759/cureus.16038] [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] [Accepted: 06/28/2021] [Indexed: 11/06/2022] Open
Abstract
Purpose This study aimed to perform a longitudinal analysis of linear accelerator (linac) technical faults reported with a cloud-based Machine Log system in use in a busy academic clinic and derive operational insights related to linac reliability, clinical utilization, and performance. Methods We queried the Machine Log system for the following parameters: linac type, number of reported technical faults, types of fault, number of faults where the linac was disabled, and estimated clinical downtime. The number of fractions treated and monitor units (MU) delivered were obtained from the record and verify system as metrics of linac utilization and to normalize the number of reported linac faults, facilitating inter-comparison. Two Varian TrueBeam C-arm linacs (Varian Medical Systems, Palo Alto, CA), one Varian 21iX C-arm linac (Varian Medical Systems, Palo Alto, CA), and one newly installed Varian Halcyon ring gantry linac (Varian Medical Systems, Palo Alto, CA) were evaluated. The linacs were studied over a 30-month period from September 2017 to March 2020. Results Over 30 months, comprising 677 clinical days, 1234 faults were reported from all linacs, including 153 “linac down” events requiring rescheduling or cancellation of treatments. The TrueBeam linacs reported nearly twice as many imaging, multileaf collimator (MLC), and beam generation faults per fraction, and MU as the Halcyon. Halcyon experienced fewer beam generation/steering, accessory, and cooling-related faults than the other linacs but reported more computer and networking issues. Although it employs a relatively new MLC design compared to the C-arm linacs and delivers primarily intensity-modulated treatments, Halcyon reported fewer MLC faults than the other linacs. The 21iX linac had the fewest software-related faults but was subject to the most cooling-related faults, which we attributed to extensive use of this linac for treatment techniques with extended beam-on times. Conclusions A longitudinal analysis of a cloud-based Machine Log system yielded operational insights into the utilization, performance, and technical reliability of the linacs in use at our institution. Several trends in linac sub-system reliability were identified and could be attributed to either age, design, clinical use, or operational demands. The results of this analysis will be used as a basis for designing linac quality assurance schedules that reflect actual linac usage and observed sub-system reliability. Such a practice may contribute to a clinic workflow subject to fewer disruptions from linac faults, ultimately improving efficiency and patient safety.
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Affiliation(s)
- Jeremy D Hoisak
- Radiation Medicine and Applied Sciences, University of California San Diego, La Jolla, USA
| | - Gwe-Ya G Kim
- Radiation Medicine and Applied Sciences, University of California San Diego, La Jolla, USA
| | - Todd F Atwood
- Radiation Medicine and Applied Sciences, University of California San Diego, La Jolla, USA
| | - Todd Pawlicki
- Radiation Medicine and Applied Sciences, University of California San Diego, La Jolla, USA
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Yu L, Zhao J, Zhang Z, Wang J, Hu W. Commissioning of and preliminary experience with a new fully integrated computed tomography linac. J Appl Clin Med Phys 2021; 22:208-223. [PMID: 34151504 PMCID: PMC8292712 DOI: 10.1002/acm2.13313] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2020] [Revised: 04/27/2021] [Accepted: 05/13/2021] [Indexed: 12/05/2022] Open
Abstract
Purpose A new medical linear accelerator (linac) platform integrated with helical computed tomography (CT), the uRT‐linac 506c, was introduced into clinical application in 2019 by United Imaging Healthcare (UIH) Co., Ltd. (Shanghai, China). It combines a Carm linac with a diagnostic‐quality 16‐slice CT imager, providing seamless workflow from simulation to treatment. The aim of this report is to assess the technical characteristics, commissioning results and preliminary experiences stemming from clinical usage. Methods The mechanical and imaging test procedures, commissioning data collection and TPS validation were summarized. CTIGRT accuracy was investigated with different loads and couch extensions. A series of end‐to‐end cases for different treatment sites and delivery techniques were tested preclinically to estimate the overall accuracy for the entire treatment scheme. The results of patient‐specific QA and machine stability during a one‐year operation are also reported. Results Gantry/couch/collimator isocentricity was measured as 0.63 mm in radius. The TPS models were in agreement with the beam commissioning data within a deviation of 2%. An overall submillimeter accuracy was demonstrated for the CT‐IGRT process under all conditions. The absolute point dose difference for all the preclinical end‐to‐end tests was within 3%, and the gamma passing rate of the 2D dose distribution measured by EBT3 film was better than 90% (3% DD, 3 mm DTA and 10% threshold). Pretreatment QA of clinical cases resulted with better than 3% point dose difference and more than 99% gamma passing rate (3% DD/2 mm DTA/10% threshold) tested with Delta4. The output of the linac was mostly within 1% of variation in a one‐year operation. Conclusion The commissioning results and clinical QA results show that the uRT‐linac 506c platform exhibits good and stable performance in mechanical and dosimetric accuracy. The integrated CT system provides an efficient workflow for image guidance with submillimeter localization precision, and will be a good starting point to proceed advanced adaptive radiotherapy.
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Affiliation(s)
- Lei Yu
- Department of Radiation Oncology, Fudan University Shanghai Cancer Center, Shanghai, China.,Department of Oncology, Shanghai Medical College, Fudan University, Shanghai, China
| | - Jun Zhao
- Department of Radiation Oncology, Fudan University Shanghai Cancer Center, Shanghai, China.,Department of Oncology, Shanghai Medical College, Fudan University, Shanghai, China
| | - Zhen Zhang
- Department of Radiation Oncology, Fudan University Shanghai Cancer Center, Shanghai, China.,Department of Oncology, Shanghai Medical College, Fudan University, Shanghai, China
| | - Jiazhou Wang
- Department of Radiation Oncology, Fudan University Shanghai Cancer Center, Shanghai, China.,Department of Oncology, Shanghai Medical College, Fudan University, Shanghai, China
| | - Weigang Hu
- Department of Radiation Oncology, Fudan University Shanghai Cancer Center, Shanghai, China.,Department of Oncology, Shanghai Medical College, Fudan University, Shanghai, China
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Pathak PK, Vashisht SK, Baby S, Jithin PK, Jain Y, Mahawar R, Sharan VGGK. Commissioning and quality assurance of Halcyon TM 2.0 linear accelerator. Rep Pract Oncol Radiother 2021; 26:433-444. [PMID: 34277097 PMCID: PMC8281907 DOI: 10.5603/rpor.a2021.0065] [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: 11/20/2020] [Accepted: 02/25/2021] [Indexed: 12/02/2022] Open
Abstract
BACKGROUND Varian Medical Systems has introduced a new medical linear accelerator called HalcyonTM 2.0, which is based on the ring delivery system (RDS). It is a true IGRT machine having 6MV FFF photon energy. In addition to the planar and MV-CBCT imaging techniques it also has an option of ultra-fast kV-iCBCT which enhances the image reconstruction and improves the visualization of soft tissue. The field portals are shaped by a unique dual layer MLC with special stacked and staggered design which enables high modulation with low radiation leakage. Recently, we have commissioned our first Halcyon 2.0 machine. The aim of this work was to systematically investigate various parameters of a newly installed HalcyonTM 2.0 linear accelerator. MATERIALS AND METHODS Detailed measurements were conducted as per various guidelines. Also, the measurements were performed to fulfil the national regulatory requirements. Commissioning data of Halcyon 6 MV-FFF beam was performed in a water tank. For absolute measurements, a 0.6-cc waterproof Farmer chamber and electrometer were used. All relative measurements (PDDs, in-line, cross-line and angular profiles) were performed with 0.0125 cc point chamber. RESULTS All the tests were within the acceptable limit. Measured data were compared with factory data as well as the existing medical linear accelerator of the same category. The obtained results were quite satisfactory. CONCLUSIONS This study summarizes the commissioning experience with Halcyon linear accelerator. Evaluation of mechanical, radiation safety and dosimetric parameters were performed. The obtained parameters were well below the specified tolerance limits.
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Affiliation(s)
- Pushpraj K Pathak
- Department of Medical Physics, Jawaharlal Nehru Cancer Hospital and Research Centre, Bhopal, India
| | - S K Vashisht
- Department of Medical Physics, Jawaharlal Nehru Cancer Hospital and Research Centre, Bhopal, India
| | - S Baby
- Department of Medical Physics, Jawaharlal Nehru Cancer Hospital and Research Centre, Bhopal, India
| | - P K Jithin
- Department of Medical Physics, Jawaharlal Nehru Cancer Hospital and Research Centre, Bhopal, India
| | - Y Jain
- Department of Radiation Oncology, Jawaharlal Nehru Cancer Hospital & Research Centre, Bhopal, India
| | - R Mahawar
- Department of Radiation Oncology, Jawaharlal Nehru Cancer Hospital & Research Centre, Bhopal, India
| | - V G G K Sharan
- Department of Radiation Oncology, Jawaharlal Nehru Cancer Hospital & Research Centre, Bhopal, India
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18
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Gao S, Chetvertkov MA, Cai B, Dwivedi A, Mihailidis D, Ray X, Netherton T, Court LE, Simon WE, Balter PA. Beam energy metrics for the acceptance and quality assurance of Halcyon linear accelerator. J Appl Clin Med Phys 2021; 22:121-127. [PMID: 34042271 PMCID: PMC8292713 DOI: 10.1002/acm2.13281] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Revised: 03/25/2021] [Accepted: 04/22/2021] [Indexed: 11/12/2022] Open
Abstract
Purpose Establish and compare two metrics for monitoring beam energy changes in the Halcyon platform and evaluate the accuracy of these metrics across multiple Halcyon linacs. Method The first energy metric is derived from the diagonal normalized flatness (FDN), which is defined as the ratio of the average measurements at a fixed off‐axis equal distance along the open profiles in two diagonals to the measurement at the central axis with an ionization chamber array (ICA). The second energy metric comes from the area ratio (AR) of the quad wedge (QW) profiles measured with the QW on the top of the ICA. Beam energy is changed by adjusting the magnetron current in a non‐clinical Halcyon. With D10cm measured in water at each beam energy, the relationships between FDN or AR energy metrics to D10cm in water is established with linear regression across six energy settings. The coefficients from these regressions allow D10cm(FDN) calculation from FDN using open profiles and D10cm(QW) calculation from AR using QW profiles. Results Five Halcyon linacs from five institutions were used to evaluate the accuracy of the D10cm(FDN) and the D10cm(QW) energy metrics by comparing to the D10cm values computed from the treatment planning system (TPS) and D10cm measured in water. For the five linacs, the D10cm(FDN) reported by the ICA based on FDN from open profiles agreed with that calculated by TPS within –0.29 ± 0.23% and 0.61% maximum discrepancy; the D10cm(QW) reported by the QW profiles agreed with that calculated by TPS within –0.82 ± 1.27% and –2.43% maximum discrepancy. Conclusion The FDN‐based energy metric D10cm(FDN) can be used for acceptance testing of beam energy, and also for the verification of energy in periodic quality assurance (QA) processes.
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Affiliation(s)
- Song Gao
- Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | | | - Bin Cai
- Radiation Oncology, Washington University School of Medicine, St. Louis, MO, USA
| | - Abhishek Dwivedi
- Radiation Oncology, Rutgers CINJ/Robert Wood, Johnson University Hospital, New Brunswick, NJ, USA
| | | | - Xenia Ray
- Radiation Medicine and Applied Science, University of California San Diego, Moores Cancer Center, La Jolla, CA, USA
| | - Tucker Netherton
- Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Laurence E Court
- Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | | | - Peter A Balter
- Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
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Hernandez V, Saez J, Angerud A, Cayez R, Khamphan C, Nguyen D, Vieillevigne L, Feygelman V. Dosimetric leaf gap and leaf trailing effect in a double-stacked multileaf collimator. Med Phys 2021; 48:3413-3424. [PMID: 33932237 DOI: 10.1002/mp.14914] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2021] [Revised: 04/02/2021] [Accepted: 04/23/2021] [Indexed: 01/21/2023] Open
Abstract
PURPOSE To investigate (i) the dosimetric leaf gap (DLG) and the effect of the "trailing distance" between leaves from different multileaf collimator (MLC) layers in Halcyon systems and (ii) the ability of the currently available treatment planning systems (TPSs) to approximate this effect. METHODS DICOM plans with transmission beams and sweeping gap tests were created in Python for measuring the DLG for each MLC layer independently and for both layers combined. In clinical Halcyon plans both MLC layers are interchangeably used and leaves from different layers are offset, thus forming a trailing pattern. To characterize the impact of such configuration, new tests called "trailing sweeping gaps" were designed and created where the leaves from one layer follow the leaves from the other layer at a fixed "trailing distance" t between the tips. Measurements were carried out on five Halcyons SX2 from different institutions and calculations from both the Eclipse and RayStation TPSs were compared with measurements. RESULTS The dose accumulated during a sweeping gap delivery progressively increased with the trailing distance t . We call this "the trailing effect." It is most pronounced for t between 0 and 5 mm, although some changes were obtained up to 20 mm. The dose variation was independent of the gap size. The measured DLG values also increased with t up to 20 mm, again with the steepest variation between 0 and 5 mm. Measured DLG values were negative at t = 0 (the leaves from both layers at the same position) but changed sign for t ≥ 1 mm, in line with the positive DLG sign usually observed with single-layer rounded-end MLCs. The Eclipse TPS does not explicitly model the leaf tip and, as a consequence, could not predict the dose reduction due to the trailing effect. This resulted in dose discrepancies up to +10% and -8% for the 5 mm sweeping gap and up to ±5% for the 10 mm one depending on the distance t . RayStation implements a simple model of the leaf tip that was able to approximate the trailing effect and improved the agreement with measured doses. In particular, with a prototype version of RayStation that assigned a higher transmission at the leaf tip the agreement with measured doses was within ±3% even for the 5 mm gap. The five Halcyon systems behaved very similarly but differences in the DLG around 0.2 mm were found across different treatment units and between MLC layers from the same system. The DLG for the proximal layer was consistently higher than for the distal layer, with differences ranging between 0.10 mm and 0.24 mm. CONCLUSIONS The trailing distance between the leaves from different layers substantially affected the doses delivered by sweeping gaps and the measured DLG values. Stacked MLCs introduce a new level of complexity in TPSs, which ideally need to implement an explicit model of the leaf tip in order to reproduce the trailing effect. Dynamic tests called "trailing sweeping gaps" were designed that are useful for characterizing and commissioning dual-layer MLC systems.
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Affiliation(s)
- Victor Hernandez
- Department of Medical Physics, Hospital Sant Joan de Reus, IISPV, 43204, Tarragona, Spain
| | - Jordi Saez
- Department of Radiation Oncology, Hospital Clínic de Barcelona, 08036, Barcelona, Spain
| | | | - Romain Cayez
- Department of Medical Physics, Oscar Lambret Center, 59000, Lille, France
| | - Catherine Khamphan
- Medical Physics Department, Institut Sainte-Catherine, 84000, Avignon, France
| | - Daniel Nguyen
- Centre de Radiothérapie de Mâcon, 71000, Mâcon, France
| | - Laure Vieillevigne
- Department of Medical Physics, Institut Claudius Regaud-Institut Universitaire du Cancer de Toulouse, 31059, Toulouse, France.,Centre de Recherche en Cancérologie de Toulouse UMR1037 INSERM, Université Toulouse 3-ERL5294 CNRS, Oncopole, 31037, Toulouse, France
| | - Vladimir Feygelman
- Department of Radiation Oncology, Moffitt Cancer Center, Tampa, 12902, Florida, USA
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Cai B, Laugeman E, Hsu H, Green O, Knutson N, Goddu SM, Mutic S, Du S, Henke L, Kim H, Hugo GD. Technical Note: Self-shielding evaluation and radiation leakage measurement of a jawless ring gantry linac with a beam stopper. Med Phys 2021; 48:3143-3150. [PMID: 33763897 DOI: 10.1002/mp.14858] [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: 08/19/2020] [Revised: 02/22/2021] [Accepted: 02/22/2021] [Indexed: 11/11/2022] Open
Abstract
PURPOSE To characterize the shielding design and leakage radiation from a newly released ring gantry linac (Halcyon, Varian Medical Systems). METHODS To assess the radiation leakage surrounding headshield and the radiation level after the beam stopper, measurements were made with GafChromic films. To evaluate the in-room radiation levels, the radiation leakage in the isocenter plane was measured with a large volume spherical ionization chamber (Exradin A6, Standard Imaging). A lead enclosure was constructed to shield the chamber from the low energy scatter radiation from the room. The radiation level at multiple locations was measured with the MLC fully closed and gantry at 0, 45, 90, 135, 180, 225, 270, and 315 degrees. The leakage radiation passing through multiple concrete slabs with various thickness was recorded in a narrow beam geometry to determine the tenth value layer (TVL). RESULTS A uniform leakage (<0.05%) at 1 m from electron beam line was measured surrounding the linac head with the maximum leakage measured at the top of the head enclosure. The highest radiation level (<0.08%) was measured near the edge of the beam stopper when projected to the measurement plane. The maximum radiation levels due to the head leakage at 15 locations inside the treatment room were recorded and a radiation map was plotted. The maximum leakage was measured at points that along the electron beam line while the gantry at 90 or 270 degree and at the end of head enclosure (0.314%, 0.4 m from electron beamline). The leakage TVL value is found to be 226 mm in a narrow beam geometry with the concrete density of 2.16 g/cm3 or 134.6 lb/cu.ft. CONCLUSION An overall uniform leakage was measured surrounding linac head. The beam stopper shields the primary radiation with the highest valued measured near the edge of beam stopper. The leakage TVL values are derived and less than the values reported for conventional C-arm linac.
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Affiliation(s)
- Bin Cai
- Department of Radiation Oncology, Washington University, St. Louis, MO, 63110, USA
| | - Eric Laugeman
- Department of Radiation Oncology, Washington University, St. Louis, MO, 63110, USA
| | - HsinLu Hsu
- Varian Medical Systems, 3100 Hansen Way, Palo Alto, CA, 94304, USA
| | - Olga Green
- Department of Radiation Oncology, Washington University, St. Louis, MO, 63110, USA
| | - Nels Knutson
- Department of Radiation Oncology, Washington University, St. Louis, MO, 63110, USA
| | - S Murty Goddu
- Department of Radiation Oncology, Washington University, St. Louis, MO, 63110, USA
| | - Sasa Mutic
- Varian Medical Systems, 3100 Hansen Way, Palo Alto, CA, 94304, USA
| | - Shuhua Du
- Department of Radiation Oncology, Washington University, St. Louis, MO, 63110, USA
| | - Lauren Henke
- Department of Radiation Oncology, Washington University, St. Louis, MO, 63110, USA
| | - Hyun Kim
- Department of Radiation Oncology, Washington University, St. Louis, MO, 63110, USA
| | - Geoffrey D Hugo
- Department of Radiation Oncology, Washington University, St. Louis, MO, 63110, USA
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21
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Saini A, Tichacek C, Johansson W, Redler G, Zhang G, Moros EG, Qayyum M, Feygelman V. Unlocking a closed system: dosimetric commissioning of a ring gantry linear accelerator in a multivendor environment. J Appl Clin Med Phys 2021; 22:21-34. [PMID: 33452738 PMCID: PMC7882119 DOI: 10.1002/acm2.13116] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2020] [Revised: 10/10/2020] [Accepted: 11/16/2020] [Indexed: 01/08/2023] Open
Abstract
The Halcyon™ platform is self‐contained, combining a treatment planning (Eclipse) system TPS) with information management and radiation delivery components. The standard TPS beam model is configured and locked down by the vendor. A portal dosimetry‐based system for patient‐specific QA (PSQA) is also included. While ensuring consistency across the user base, this closed model may not be optimal for every department. We set out to commission independent TPS (RayStation 9B, RaySearch Laboratories) and PSQA (PerFraction, Sun Nuclear Corp.) systems for use with the Halcyon linac. The output factors and PDDs for very small fields (0.5 × 0.5 cm2) were collected to augment the standard Varian dataset. The MLC leaf‐end parameters were estimated based on the various static and dynamic tests with simple model fields and honed by minimizing the mean and standard deviation of dose difference between the ion chamber measurements and RayStation Monte Carlo calculations for 15 VMAT and IMRT test plans. Two chamber measurements were taken per plan, in the high (isocenter) and lower dose regions. The ratio of low to high doses ranged from 0.4 to 0.8. All percent dose differences were expressed relative to the local dose. The mean error was 0.0 ± 1.1% (TG119‐style confidence limit ± 2%). Gamma analysis with the helical diode array using the standard 3%Global/2mm criteria resulted in the average passing rate of 99.3 ± 0.5% (confidence limit 98.3%–100%). The average local dose error for all detectors across all plans was 0.2% ± 5.3%. The ion chamber results compared favorably with our recalculation with Eclipse and PerFraction, as well as with several published Eclipse reports. Dose distribution gamma analysis comparisons between RayStation and PerFraction with 2%Local/2mm criteria yielded an average passing rate of 98.5% ± 0.8% (confidence limit 96.9%–100%). It is feasible to use the Halcyon accelerator with independent planning and verification systems without sacrificing dosimetric accuracy.
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Affiliation(s)
- Amarjit Saini
- Department of Radiation Oncology, Moffitt Cancer Center, Tampa, FL, USA
| | - Chris Tichacek
- Department of Radiation Oncology, Moffitt Cancer Center, Tampa, FL, USA
| | - William Johansson
- Department of Radiation Oncology, Moffitt Cancer Center, Tampa, FL, USA
| | - Gage Redler
- Department of Radiation Oncology, Moffitt Cancer Center, Tampa, FL, USA
| | - Geoffrey Zhang
- Department of Radiation Oncology, Moffitt Cancer Center, Tampa, FL, USA
| | - Eduardo G Moros
- Department of Radiation Oncology, Moffitt Cancer Center, Tampa, FL, USA
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22
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Choi MG, Law M, Yoon DK, Tamura M, Matsumoto K, Otsuka M, Kim MS, Djeng SK, Monzen H, Suh TS. Simplified sigmoidal curve fitting for a 6 MV FFF photon beam of the Halcyon to determine the field size for beam commissioning and quality assurance. Radiat Oncol 2020; 15:273. [PMID: 33287828 PMCID: PMC7720380 DOI: 10.1186/s13014-020-01709-x] [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: 04/07/2020] [Accepted: 11/06/2020] [Indexed: 11/22/2022] Open
Abstract
Background An O-ring gantry-type linear accelerator (LINAC) with a 6-MV flattening filter-free (FFF) photon beam, Halcyon, includes a reference beam that contains representative information such as the percent depth dose, profile and output factor for commissioning and quality assurance. However, because it does not provide information about the field size, we proposed a method to determine all field sizes according to all depths for radiation therapy using simplified sigmoidal curve fitting (SCF). Methods After mathematical definition of the SCF using four coefficients, the defined curves were fitted to both the reference data (RD) and the measured data (MD). For good agreement between the fitting curve and the profiles in each data set, the field sizes were determined by identifying the maximum point along the third derivative of the fitting curve. The curve fitting included the field sizes for beam profiles of 2 × 2, 4 × 4, 6 × 6, 8 × 8, 10 × 10, 20 × 20 and 28 × 28 cm2 as a function of depth (at 1.3, 5, 10 and 20 cm). The field size results from the RD were compared with the results from the MD using the same condition. Results All fitting curves show goodness of fit, R2, values that are greater than 0.99. The differences in field size between the RD and the MD were within the range of 0 to 0.2 cm. The smallest difference in the field sizes at a depth of 10 cm, which is a surface-to-axis distance, was reported. Conclusion Application of the SCF method has been proven to accurately capture the field size of the preconfigured RD and the measured FFF photon beam data for the Halcyon system. The current work can be useful for beam commissioning as a countercheck methodology to determine the field size from RD in the treatment planning system of a newly installed Halcyon system and for routine quality assurance to ascertain the correctness of field sizes for clinical use of the Halcyon system.
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Affiliation(s)
- Min-Geon Choi
- Department of Biomedical Engineering and Research Institute of Biomedical Engineering, College of Medicine, The Catholic University of Korea, Seoul, 06591, Republic of Korea
| | - Martin Law
- Proton Therapy Pte Ltd., 1 Biopolis Drive, Singapore, 138622, Singapore
| | - Do-Kun Yoon
- Department of Biomedical Engineering and Research Institute of Biomedical Engineering, College of Medicine, The Catholic University of Korea, Seoul, 06591, Republic of Korea
| | - Mikoto Tamura
- Department of Medical Physics, Graduate School of Medical Sciences, Kindai University, Osaka-Sayama-Shi, 377-2, Ohno-Higashi, Osaka-Sayama-Shi, Osaka, 589-8511, Japan
| | - Kenji Matsumoto
- Department of Radiology, Kindai University Hospital, Osaka-Sayama-Shi, 377-2, Ono-Higashi, Osaka-Sayama-Shi, Osaka, 589-8511, Japan
| | - Masakazu Otsuka
- Department of Medical Physics, Graduate School of Medical Sciences, Kindai University, Osaka-Sayama-Shi, 377-2, Ohno-Higashi, Osaka-Sayama-Shi, Osaka, 589-8511, Japan
| | - Moo-Sub Kim
- Department of Biomedical Engineering and Research Institute of Biomedical Engineering, College of Medicine, The Catholic University of Korea, Seoul, 06591, Republic of Korea
| | - Shih-Kien Djeng
- Proton Therapy Pte Ltd., 1 Biopolis Drive, Singapore, 138622, Singapore
| | - Hajime Monzen
- Department of Medical Physics, Graduate School of Medical Sciences, Kindai University, Osaka-Sayama-Shi, 377-2, Ohno-Higashi, Osaka-Sayama-Shi, Osaka, 589-8511, Japan.
| | - Tae Suk Suh
- Department of Biomedical Engineering and Research Institute of Biomedical Engineering, College of Medicine, The Catholic University of Korea, Seoul, 06591, Republic of Korea.
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23
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Hu Y, Byrne M, Archibald-Heeren B, Collett N, Liu G, Aland T. Validation of the preconfigured Varian Ethos Acuros XB Beam Model for treatment planning dose calculations: A dosimetric study. J Appl Clin Med Phys 2020; 21:27-42. [PMID: 33068070 PMCID: PMC7769396 DOI: 10.1002/acm2.13056] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2020] [Revised: 08/26/2020] [Accepted: 09/18/2020] [Indexed: 12/29/2022] Open
Abstract
Varian (Palo Alto, California, United States) recently released an online adaptation treatment platform, Ethos, which has introduced a new Dose Preview and Automated Plan Generation module despite sharing identical beam data with the existing Halcyon linac. The module incorporates a preconfigured beam model and the Acuros XB algorithm (Ethos AXB model) to generate final dose calculations from an initial fluence optimization. In this study, we comprehensively validated the accuracy of the Ethos AXB model by comparing it against the Halcyon AXB model, the Halcyon Anisotropic Analytical Algorithm (AAA) model, and measurements acquired on an Ethos linac. Results indicated that the Ethos AXB model demonstrated a comparable if not superior dosimetric accuracy to the Halcyon AXB model in basic and complex calculations, and at the same time its dosimetric accuracy in modulated and heterogeneous plans was better than that of the Halcyon AAA model. Despite the fact that the same algorithm was utilized, the Ethos AXB model and the Halcyon AXB model still exhibited variations across a range of tests, although these variations were predominantly insignificant in the clinical environment. The accuracy of the Ethos AXB model has been successfully verified in this study and is considered appropriate for the current clinical scope. On the basis of this study, clinical physicists can perform a data validation instead of a full data commissioning when implementing the Ethos system, thereby adopting a more efficient approach for Ethos installation.
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Affiliation(s)
- Yunfei Hu
- Icon Cancer Center Gosford, Gosford, NSW, Australia
| | - Mikel Byrne
- Icon Cancer Centre Wahroonga, Wahroonga, NSW, Australia
| | | | - Nick Collett
- Icon Cancer Centre Wahroonga, Wahroonga, NSW, Australia
| | - Guilin Liu
- Icon Cancer Centre Wahroonga, Wahroonga, NSW, Australia
| | - Trent Aland
- Icon Core Office, South Brisbane, QLD, Australia
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24
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Zhao W, Patil I, Han B, Yang Y, Xing L, Schüler E. Beam data modeling of linear accelerators (linacs) through machine learning and its potential applications in fast and robust linac commissioning and quality assurance. Radiother Oncol 2020; 153:122-129. [PMID: 33039427 DOI: 10.1016/j.radonc.2020.09.057] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2020] [Revised: 09/28/2020] [Accepted: 09/29/2020] [Indexed: 12/20/2022]
Abstract
BACKGROUND AND PURPOSE To propose a novel machine learning-based method for reliable and accurate modeling of linac beam data applicable to the processes of linac commissioning and QA. MATERIALS AND METHODS We hypothesize that the beam data is a function of inherent linac features and percentage depth doses (PDDs) and profiles of different field sizes are correlated with each other. The correlation is formulated as a multivariable regression problem using a machine learning framework. Varian TrueBeam beam data sets (n = 43) acquired from multiple institutions were used to evaluate the framework. The data sets included PDDs and profiles across different energies and field sizes. A multivariate regression model was trained for prediction of beam specific PDDs and profiles of different field sizes using a 10 × 10 cm2 field as input. RESULTS Predictions of PDDs were achieved with a mean absolute percent relative error (%RE) of 0.19-0.35% across the different beam energies investigated. The maximum mean absolute %RE was 0.93%. For profile prediction, the mean absolute %RE was 0.66-0.93% with a maximum absolute %RE of 3.76%. The largest uncertainties in the PDD and profile predictions were found at the build-up region and at the field penumbra, respectively. The prediction accuracy increased with the number of training sets up to around 20 training sets. CONCLUSIONS Through this novel machine learning-based method we have shown accurate and reproducible generation of beam data for linac commissioning for routine radiation therapy. This method has the potential to simplify the linac commissioning procedure, save time and manpower while increasing the accuracy of the commissioning process.
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Affiliation(s)
- Wei Zhao
- Stanford University, Department of Radiation Oncology, Stanford, CA 94305, USA.
| | - Ishan Patil
- Stanford University, Department of Radiation Oncology, Stanford, CA 94305, USA
| | - Bin Han
- Stanford University, Department of Radiation Oncology, Stanford, CA 94305, USA.
| | - Yong Yang
- Stanford University, Department of Radiation Oncology, Stanford, CA 94305, USA.
| | - Lei Xing
- Stanford University, Department of Radiation Oncology, Stanford, CA 94305, USA.
| | - Emil Schüler
- Stanford University, Department of Radiation Oncology, Stanford, CA 94305, USA; The University of Texas MD Anderson Cancer Center, Department of Radiation Physics, Houston, TX 77030, USA.
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25
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Tamura M, Monzen H, Matsumoto K, Otsuka M, Nishimura Y, Okumura M. Design of commissioning process for Halcyon™ linac with a new rigid board: A clinical experience. Phys Med 2020; 77:121-126. [DOI: 10.1016/j.ejmp.2020.08.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Revised: 06/15/2020] [Accepted: 08/05/2020] [Indexed: 10/23/2022] Open
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26
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Velarde A, Najera KD, Gay H, Powderly WG, Mutic S, Green J, Michalski JM, Henke L, de Falla V, Laugeman E, Catu M, Hugo GD, Cai B, van Rheenen J. Taking Guatemala From Cobalt to IMRT: A Tale of US Agency Collaboration With Academic Institutions and Industry. Int J Radiat Oncol Biol Phys 2020; 107:867-872. [PMID: 32698977 DOI: 10.1016/j.ijrobp.2020.04.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2020] [Revised: 03/31/2020] [Accepted: 04/01/2020] [Indexed: 11/29/2022]
Abstract
The not-for-profit organization La LIGA Nacional Contra el Cáncer, with its hospital Instituto de Cancerología (INCAN), is responsible for cancer treatment of much of the indigent population in Guatemala, a country with a population of 16 million. Annually, approximately 70% of patients at INCAN are seen in late stages of cancer, which places a great strain on the hospital's limited resources. Private clinics account for 75% of radiation therapy centers in Guatemala and have considerable resources. However, private facilities are fee-based, which creates a barrier for low-income patients; this is an especially significant problem in Guatemala, which has the highest income inequalities and poverty rates in Latin America. This article describes a project on the transition from cobalt to a Halcyon radiation therapy system at INCAN through a partnership with the US Agency for International Development's Office of American Schools and Hospitals Abroad (USAID/ASHA), Washington University in St. Louis (WUSTL), industry partner Varian Medical Systems, and the US National Nuclear Security Administration to provide access to state-of-the-art radiation therapy technology while increasing the overall treatment capacity for the underserved population of Guatemala.
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Affiliation(s)
- Angel Velarde
- Liga Nacional Contra El Cáncer e Instituto de Cancerología-INCAN, Guatemala City, Guatemala
| | - Kirk Douglas Najera
- Liga Nacional Contra El Cáncer e Instituto de Cancerología-INCAN, Guatemala City, Guatemala
| | - Hiram Gay
- Department of Radiation Oncology, Washington University in St Louis, St Louis, Missouri
| | - William G Powderly
- Division of Infectious Diseases and Institute for Public Health, Washington University in St Louis, St Louis, Missouri
| | - Sasa Mutic
- Department of Radiation Oncology, Washington University in St Louis, St Louis, Missouri
| | - Jonathan Green
- Office of Human Subjects Research Protections, National Institutes of Health: Intramural Research Program, Bethesda, Maryland
| | - Jeff M Michalski
- Department of Radiation Oncology, Washington University in St Louis, St Louis, Missouri
| | - Lauren Henke
- Department of Radiation Oncology, Washington University in St Louis, St Louis, Missouri
| | - Vicky de Falla
- Liga Nacional Contra El Cáncer e Instituto de Cancerología-INCAN, Guatemala City, Guatemala
| | - Eric Laugeman
- Department of Radiation Oncology, Washington University in St Louis, St Louis, Missouri
| | - Marcos Catu
- Liga Nacional Contra El Cáncer e Instituto de Cancerología-INCAN, Guatemala City, Guatemala
| | - Geoffrey D Hugo
- Department of Radiation Oncology, Washington University in St Louis, St Louis, Missouri
| | - Bin Cai
- Department of Radiation Oncology, Washington University in St Louis, St Louis, Missouri
| | - Jacaranda van Rheenen
- Global Health Center, Institute for Public Health, Washington University in St Louis, St Louis, Missouri.
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27
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Fogliata A, Cayez R, Garcia R, Khamphan C, Reggiori G, Scorsetti M, Cozzi L. Technical Note: Flattening filter free beam from Halcyon linac: Evaluation of the profile parameters for quality assurance. Med Phys 2020; 47:3669-3674. [PMID: 32367534 DOI: 10.1002/mp.14217] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2020] [Revised: 04/21/2020] [Accepted: 04/22/2020] [Indexed: 01/15/2023] Open
Abstract
INTRODUCTION The use of flattening filter free (FFF) beams generated by standard linear accelerators is increasing in the clinical practice. The radiation intensity peaked toward the beam central axis is properly managed in the optimization process of treatment planning through intensity modulation. Specific FFF parameters for profile analysis, as unflatness and slope for FFF beams, based on the renormalization factor concept has been introduced for quality assurance purposes. Recently, Halcyon, an O-ring based linear accelerator equipped with a 6 MV FFF beam only has been introduced by Varian. METHODS Renormalization factors and related fit parameters according to Fogliata et al. ["Definition of parameters for quality assurance of FFF photon beams in radiation therapy," Med. Phys. 39, 6455-6464 (2012)] have been evaluated for the 6 MV FFF beam generated by Halcyon units. The Halcyon representative beam data provided by Varian were used. Dose fall-off at the field edges was matched with an unflattened beam generated by a 6 MV from a TrueBeam linac. Consistency of the results was evaluated against measurements on a clinical Halcyon unit, as well as a TrueBeam 6 MV FFF for comparison. RESULTS The five parameters in the analytical equation for estimating the renormalization factor were determined with an R2 of 0.997. The comparison of the unflatness parameters between the Halcyon representative and hospital beam data was consistent within a range of 0.6%. Consistently with the computed parameters, the Halcyon profiles resulted in a less pronounced peak than TrueBeam. CONCLUSION Renormalization factors and related fit parameters from the 6 MV FFF beam generated by the Varian Halcyon unit are provided.
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Affiliation(s)
- A Fogliata
- Humanitas Clinical and Research Center - IRCCS, Radiotherapy Dept, via Manzoni 56, 20089, Milan, Rozzano, Italy
| | - R Cayez
- Oscar Lambret Center, rue Frédéric Combemale, Radiotherapy, 59000, Lille, France
| | - R Garcia
- Medical Physics Department, Institut Sainte-Catherine, 250 Chemin de Baigne Pieds, 84000, Avignon, France
| | - C Khamphan
- Medical Physics Department, Institut Sainte-Catherine, 250 Chemin de Baigne Pieds, 84000, Avignon, France
| | - G Reggiori
- Humanitas Clinical and Research Center - IRCCS, Radiotherapy Dept, via Manzoni 56, 20089, Milan, Rozzano, Italy
| | - M Scorsetti
- Humanitas Clinical and Research Center - IRCCS, Radiotherapy Dept, via Manzoni 56, 20089, Milan, Rozzano, Italy.,Department of Biomedical Science, Humanitas University, via Rita Levi Montalcini 4, 20090, Milan, Pieve Emanuele, Italy
| | - L Cozzi
- Humanitas Clinical and Research Center - IRCCS, Radiotherapy Dept, via Manzoni 56, 20089, Milan, Rozzano, Italy.,Department of Biomedical Science, Humanitas University, via Rita Levi Montalcini 4, 20090, Milan, Pieve Emanuele, Italy
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28
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Gao S, Netherton T, Chetvertkov MA, Li Y, Court LE, Simon WE, Shi J, Balter PA. Acceptance and verification of the Halcyon-Eclipse linear accelerator-treatment planning system without 3D water scanning system. J Appl Clin Med Phys 2019; 20:111-117. [PMID: 31553525 PMCID: PMC6806699 DOI: 10.1002/acm2.12719] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2019] [Revised: 08/01/2019] [Accepted: 08/26/2019] [Indexed: 11/10/2022] Open
Abstract
We tested whether an ionization chamber array (ICA) and a one-dimensional water scanner (1DS) could be used instead of a three-dimensional water scanning system (3DWS) for acceptance testing and commissioning verification of the Varian Halcyon-Eclipse Treatment Planning System (TPS). The Halcyon linear accelerator has a single 6-MV flattening-filter-free beam and a nonadjustable beam model for the TPS. Beam data were measured with a 1DS, ICA, ionization chambers, and electrometer. Acceptance testing and commissioning were done simultaneously by comparing the measured data with TPS-calculated percent-depth-dose (PDD) and profiles. The ICA was used to measure profiles of various field sizes (10-, 20-, and 28 cm2 ) at depths of dmax (1.3 cm), 5-, 10-, and 20 cm. The 1DS was used for output factors (OFs) and PDDs. OFs were measured with 1DS for various fields (2-28 cm2 ) at a source-to-surface distance of 90 cm. All measured data were compared with TPS-calculations. Profiles, off-axis ratios (OAR), PDDs and OFs were also measured with a 3DWS as a secondary check. Profiles between the ICA and TPS (ICA and 3DWS) at various depths across the fields indicated that the maximum discrepancies in high-dose and low-dose tail were within 2% and 3%, respectively, and the maximum distance-to-agreement in the penumbra region was <3 mm. The largest OAR differences between ICA and TPS (ICA and 3DWS) values were 0.23% (-0.25%) for a 28 × 28 cm2 field, and the largest point-by-point PDD differences between 1DS and TPS (1DS and 3DWS) were -0.41% ± 0.12% (-0.32% ± 0.17%) across the fields. Both OAR and PDD showed the beam energy is well matched to the TPS model. The average ratios of 1DS-measured OFs to the TPS (1DS to 3DWS) values were 1.000 ± 0.002 (0.999 ± 0.003). The Halcyon-Eclipse system can be accepted and commissioned without the need for a 3DWS.
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Affiliation(s)
- Song Gao
- Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Tucker Netherton
- Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Mikhail A Chetvertkov
- Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Yuting Li
- Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Laurence E Court
- Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - William E Simon
- Sun Nuclear Corporation, 3275 Suntree Boulevard, Melbourne, FL, 32940, USA
| | - Jie Shi
- Sun Nuclear Corporation, 3275 Suntree Boulevard, Melbourne, FL, 32940, USA
| | - Peter A Balter
- Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
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