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Abstract
Magnetic resonance imaging-guided radiation therapy (MRIgRT) has improved soft tissue contrast over computed tomography (CT) based image-guided RT. Superior visualization of the target and surrounding radiosensitive structures has the potential to improve oncological outcomes partly due to safer dose-escalation and adaptive planning. In this review, we highlight the workflow of adaptive MRIgRT planning, which includes simulation imaging, daily MRI, identifying isocenter shifts, contouring, plan optimization, quality control, and delivery. Increased utilization of MRIgRT will depend on addressing technical limitations of this technology, while addressing treatment efficacy, cost-effectiveness, and workflow training.
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Affiliation(s)
- Cecil M Benitez
- Department of Radiation Oncology, UCLA Medical Center, Los Angeles, CA
| | - Michael D Chuong
- Department of Radiation Oncology, Miami Cancer Institute, Baptist Health South Florida; Miami, FL
| | - Luise A Künzel
- National Center for Tumor Diseases (NCT), Dresden; German Cancer Research Center (DKFZ), Heidelberg; Faculty of Medicine and University Hospital Carl Gustav Carus, Technische Universität Dresden, Dresden; Helmholtz-Zentrum Dresden - Rossendorf (HZDR), Dresden, Germany; Department of Radiotherapy and Radiation Oncology, Faculty of Medicine and University Hospital Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany.; OncoRay-National Center for Radiation Research in Oncology, Faculty of Medicine and University Hospital Carl Gustav Carus, Technische Universität Dresden, Helmholtz-Zentrum Dresden Rossendorf, Dresden, Germany
| | - Daniela Thorwarth
- Department of Radiation Oncology, Section for Biomedical Physics, University of Tübingen, Tübingen, Germany..
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Riis HL, Chick J, Dunlop A, Tilly D. The Quality Assurance of a 1.5 T MR-Linac. Semin Radiat Oncol 2024; 34:120-128. [PMID: 38105086 DOI: 10.1016/j.semradonc.2023.10.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2023]
Abstract
The recent introduction of a commercial 1.5 T MR-linac system has considerably improved the image quality of the patient acquired in the treatment unit as well as enabling online adaptive radiation therapy (oART) treatment strategies. Quality Assurance (QA) of this new technology requires new methodology that allows for the high field MR in a linac environment. The presence of the magnetic field requires special attention to the phantoms, detectors, and tools to perform QA. Due to the design of the system, the integrated megavoltage imager (MVI) is essential for radiation beam calibrations and QA. Additionally, the alignment between the MR image system and the radiation isocenter must be checked. The MR-linac system has vendor-supplied phantoms for calibration and QA tests. However, users have developed their own routine QA systems to independently check that the machine is performing as required, as to ensure we are able to deliver the intended dose with sufficient certainty. The aim of this work is therefore to review the MR-linac specific QA procedures reported in the literature.
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Affiliation(s)
- Hans Lynggaard Riis
- Department of Oncology, Odense University Hospital, Odense, Denmark; Department of Clinical Research, University of Southern Denmark, Odense, Denmark.
| | - Joan Chick
- The Joint Department of Physics, The Royal Marsden Hospital and the Institute of Cancer Research, London, UK
| | - Alex Dunlop
- The Joint Department of Physics, The Royal Marsden Hospital and the Institute of Cancer Research, London, UK
| | - David Tilly
- Department of Immunology, Genetics and Pathology, Medical Radiation Physics, Uppsala University, Uppsala, Sweden; Medical Physics, Uppsala University Hospital, Uppsala, Sweden
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3
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Stevens S, Moloney S, Blackmore A, Hart C, Rixham P, Bangiri A, Pooler A, Doolan P. IPEM topical report: guidance for the clinical implementation of online treatment monitoring solutions for IMRT/VMAT. Phys Med Biol 2023; 68:18TR02. [PMID: 37531959 DOI: 10.1088/1361-6560/acecd0] [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: 03/24/2023] [Accepted: 08/02/2023] [Indexed: 08/04/2023]
Abstract
This report provides guidance for the implementation of online treatment monitoring (OTM) solutions in radiotherapy (RT), with a focus on modulated treatments. Support is provided covering the implementation process, from identification of an OTM solution to local implementation strategy. Guidance has been developed by a RT special interest group (RTSIG) working party (WP) on behalf of the Institute of Physics and Engineering in Medicine (IPEM). Recommendations within the report are derived from the experience of the WP members (in consultation with manufacturers, vendors and user groups), existing guidance or legislation and a UK survey conducted in 2020 (Stevenset al2021). OTM is an inclusive term representing any system capable of providing a direct or inferred measurement of the delivered dose to a RT patient. Information on each type of OTM is provided but, commensurate with UK demand, guidance is largely influenced byin vivodosimetry methods utilising the electronic portal imager device (EPID). Sections are included on the choice of OTM solutions, acceptance and commissioning methods with recommendations on routine quality control, analytical methods and tolerance setting, clinical introduction and staffing/resource requirements. The guidance aims to give a practical solution to sensitivity and specificity testing. Functionality is provided for the user to introduce known errors into treatment plans for local testing. Receiver operating characteristic analysis is discussed as a tool to performance assess OTM systems. OTM solutions can help verify the correct delivery of radiotherapy treatment. Furthermore, modern systems are increasingly capable of providing clinical decision-making information which can impact the course of a patient's treatment. However, technical limitations persist. It is not within the scope of this guidance to critique each available solution, but the user is encouraged to carefully consider workflow and engage with manufacturers in resolving compatibility issues.
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Affiliation(s)
| | - Stephen Moloney
- University Hospitals Dorset NHS Foundation Trust, Poole, United Kingdom
| | | | - Clare Hart
- Cambridge University Hospitals NHS Foundation Trust, Cambridge, United Kingdom
| | - Philip Rixham
- Leeds Cancer Centre, Leeds Teaching Hospitals NHS Trust, Leeds, United Kingdom
| | - Anna Bangiri
- Nottingham University Hospitals NHS Trust, Nottingham, United Kingdom
| | - Alistair Pooler
- Christie Medical Physics and Engineering, The Christie NHS Foundation Trust, Manchester, United Kingdom
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Azzi A, Heilemann G, Georg D, Ardjo Pawiro S, Mart T, Lechner W. Impact of log file source and data frequency on accuracy of log file-based patient specific quality assurance. Z Med Phys 2023:S0939-3889(23)00075-2. [PMID: 37365087 DOI: 10.1016/j.zemedi.2023.05.006] [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: 10/22/2022] [Revised: 05/04/2023] [Accepted: 05/20/2023] [Indexed: 06/28/2023]
Abstract
Performing phantom measurements for patient-specific quality assurance (PSQA) adds a significant amount of time to the adaptive radiotherapy procedure. Log file based PSQA can be used to increase the efficiency of this process. This study compared the dosimetric accuracy of high-frequency linear accelerator (Linac) log files and low-frequency log data stored in the oncology information system (OIS). Thirty patients were included, that were recently treated in the head and neck (HN), brain, and prostate region with volumetric modulated arc therapy (VMAT) and an additional ten patients treated using stereotactic body radiation therapy (SBRT) with 3D-conformal radiotherapy (3D-CRT) technique. Log data containing a single fraction were used to calculate the dose distributions. The dosimetric differences between Linac log files and OIS logs were evaluated with a gamma analysis with 2%/2 mm criterion and dose threshold of 30%. The original treatment plan was used as a reference. Moreover, DVH parameters of D98%, D50%, and D2% of the planning-target volume (PTV) and dose to several organs at risk (OARs) were reported. Significant differences in dose distributions between the two log types and the original dose were observed for PTV D98% and D2% (r < 0.001) for HN cases, PTV D98% (r = 0.005) for brain cases, and PTV D50% (r = 0.015) for prostate cases. No significant differences were found between the two log types with respect to D50%. The root mean square (RMS) error of the leaf positions of the OIS log was approximately twice the RMS error of the Linac log file for VMAT plans, but identical for 3D-CRT plans. The relationship between the gamma pass rate and the RMS error showed a moderate correlation for the Linac log files (r = -0.58, p < 0.001) and strong correlation for OIS logs (r = -0.71, p < 0.001). Furthermore, all doses calculated using Linac log files and OIS log data had a GPR >90% for an RMS error < 3.3 mm. Based on these findings, a tolerance limit of RMS error of 3.3 mm for considering OIS log based PSQA was established. Nevertheless, the OIS log data quality should be improved to achieve adequate PSQA.
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Affiliation(s)
- Akbar Azzi
- Department of Physics, Faculty of Mathematics and Natural Sciences, Universitas Indonesia, 16424 Depok, Indonesia
| | - Gerd Heilemann
- Department of Radiation Oncology, Division of Medical Physics, Medical University of Vienna, 1090 Vienna, Austria
| | - Dietmar Georg
- Department of Radiation Oncology, Division of Medical Physics, Medical University of Vienna, 1090 Vienna, Austria
| | - Supriyanto Ardjo Pawiro
- Department of Physics, Faculty of Mathematics and Natural Sciences, Universitas Indonesia, 16424 Depok, Indonesia.
| | - Terry Mart
- Department of Physics, Faculty of Mathematics and Natural Sciences, Universitas Indonesia, 16424 Depok, Indonesia
| | - Wolfgang Lechner
- Department of Radiation Oncology, Division of Medical Physics, Medical University of Vienna, 1090 Vienna, Austria
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Yang J, Zhang P, Tyagi N, Scripes PG, Subashi E, Liang J, Lovelock D, Mechalakos J, Li A, Lim SB. Integration of an Independent Monitor Unit Check for High-Magnetic-Field MR-Guided Radiation Therapy System. Front Oncol 2022; 12:747825. [PMID: 35359395 PMCID: PMC8963466 DOI: 10.3389/fonc.2022.747825] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2021] [Accepted: 02/16/2022] [Indexed: 11/13/2022] Open
Abstract
Purpose Commercial independent monitor unit (IMU) check systems for high-magnetic-field MR-guided radiation therapy (RT) systems are lacking. We investigated the feasibility of adopting an existing treatment planning system (TPS) as an IMU check for online adaptive radiotherapy using 1.5-Tesla MR-Linac. Methods The 7-MV flattening filter free (FFF) beam and multi-leaf collimator (MLC) models of a 1.5-T Elekta Unity MR-Linac within Monte Carlo-based Monaco TPS were used to generate an optimized beam model in Eclipse TPS. The MLC dosimetric leaf gap of the beam in Eclipse was determined by matching the dose distribution of Eclipse-generated intensity-modulated radiation therapy (IMRT) plans using the Analytical Anisotropic Algorithm (AAA) algorithm to Monaco plans. The plans were automatically adjusted for different source-to-axis distances (SADs) between the two systems. For IMU check, the treatment plans developed in Monaco were transferred to Eclipse to recalculate the dose using AAA. A plug-in within Eclipse was created to perform a 2D gamma analysis of the AAA and Monte Carlo dose distribution on a beam’s eye view parallel plane. Monaco dose distribution was shifted laterally by 2 mm during gamma analysis to account for the impact of magnetic field on electron trajectories. Eclipse doses for posterior beams were corrected for both the Unity couch and the posterior MR coil attenuation. Thirteen patients, each with 4–5 fractions for a variety of tumor sites (pancreas, rectum, and prostate), were tested. Results After thorough commissioning, the method was implemented as part of the standard clinical workflow. A total of 62 online plans, each with approximately 15 beams, were evaluated. The average per-beam gamma (3%/3 mm) pass rate for plans was 97.9% (range, 95.9% to 98.8%). The average pass rate per beam for all 932 beams used in these plans was 97.9% ± 1.9%, with the lowest per-beam gamma pass rate at 88.4%. The time for the process was within 3.2 ± 0.9 min. Conclusion The use of a second planning system provides an efficient way to perform IMU checks with clinically acceptable accuracy for online adaptive plans on Unity MR-Linac. This is essential for meeting the safety requirements for second checks as outlined in American Association of Physicists in Medicine Task Group (AAPM TG) reports 114 and 219.
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Powers M, Baines J, Crane R, Fisher C, Gibson S, Marsh L, Oar B, Shoobridge A, Simpson-Page E, Van der Walt M, de Vine G. Commissioning measurements on an Elekta Unity MR-Linac. Phys Eng Sci Med 2022; 45:457-473. [PMID: 35235188 PMCID: PMC9239956 DOI: 10.1007/s13246-022-01113-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2021] [Accepted: 02/18/2022] [Indexed: 11/03/2022]
Abstract
Magnetic resonance-guided radiotherapy technology is relatively new and commissioning publications, quality assurance (QA) protocols and commercial products are limited. This work provides guidance for implementation measurements that may be performed on the Elekta Unity MR-Linac (Elekta, Stockholm, Sweden). Adaptations of vendor supplied phantoms facilitated determination of gantry angle accuracy and linac isocentre, whereas in-house developed phantoms were used for end-to-end testing and anterior coil attenuation measurements. Third-party devices were used for measuring beam quality, reference dosimetry and during treatment plan commissioning; however, due to several challenges, variations on standard techniques were required. Gantry angle accuracy was within 0.1°, confirmed with pixel intensity profiles, and MV isocentre diameter was < 0.5 mm. Anterior coil attenuation was approximately 0.6%. Beam quality as determined by TPR20,10 was 0.705 ± 0.001, in agreement with treatment planning system (TPS) calculations, and gamma comparison against the TPS for a 22.0 × 22.0 cm2 field was above 95.0% (2.0%, 2.0 mm). Machine output was 1.000 ± 0.002 Gy per 100 MU, depth 5.0 cm. During treatment plan commissioning, sub-standard results indicated issues with machine behaviour. Once rectified, gamma comparisons were above 95.0% (2.0%, 2.0 mm). Centres which may not have access to specialized equipment can use in-house developed phantoms, or adapt those supplied by the vendor, to perform commissioning work and confirm operation of the MRL within published tolerances. The plan QA techniques used in this work can highlight issues with machine behaviour when appropriate gamma criteria are set.
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Affiliation(s)
- Marcus Powers
- Townsville Cancer Centre, Townsville Hospital and Health Service, Townsville, QLD, Australia. .,College of Science and Engineering, James Cook University, Townsville, QLD, Australia.
| | - John Baines
- Townsville Cancer Centre, Townsville Hospital and Health Service, Townsville, QLD, Australia.
| | - Robert Crane
- Townsville Cancer Centre, Townsville Hospital and Health Service, Townsville, QLD, Australia
| | - Chantelle Fisher
- Townsville Cancer Centre, Townsville Hospital and Health Service, Townsville, QLD, Australia
| | - Stephen Gibson
- Townsville Cancer Centre, Townsville Hospital and Health Service, Townsville, QLD, Australia
| | - Linda Marsh
- Townsville Cancer Centre, Townsville Hospital and Health Service, Townsville, QLD, Australia
| | - Bronwyn Oar
- Townsville Cancer Centre, Townsville Hospital and Health Service, Townsville, QLD, Australia
| | - Ariadne Shoobridge
- Townsville Cancer Centre, Townsville Hospital and Health Service, Townsville, QLD, Australia.,College of Science and Engineering, James Cook University, Townsville, QLD, Australia
| | - Emily Simpson-Page
- Cancer Care Services, Royal Brisbane and Women's Hospital, Herston, QLD, Australia
| | - Marchant Van der Walt
- Townsville Cancer Centre, Townsville Hospital and Health Service, Townsville, QLD, Australia
| | - Glenn de Vine
- Townsville Cancer Centre, Townsville Hospital and Health Service, Townsville, QLD, Australia
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Lim SB, Godoy Scripes P, Napolitano M, Subashi E, Tyagi N, Cervino Arriba L, Lovelock DM. An investigation of using log-file analysis for automated patient-specific quality assurance in MRgRT. J Appl Clin Med Phys 2021; 22:183-188. [PMID: 34278711 PMCID: PMC8425925 DOI: 10.1002/acm2.13361] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2020] [Revised: 05/28/2021] [Accepted: 07/01/2021] [Indexed: 11/22/2022] Open
Abstract
Objective Adaptive radiation therapy (ART) is an integral part of MR‐guided RT (MRgRT), requiring a new RT plan for each treatment fraction and resulting in a significant increase in patient‐specific quality assurance (PSQA). This study investigates the possibility of using treatment log‐file for automated PSQA. Method All treatment plans were delivered in 1.5T Unity MR‐Linac (Elekta). A Unity compatible version of LinacView (Standard Imaging) was commissioned to automatically monitor and analyze the log‐files. A total of 220 fields were delivered and measured by ArcCheck®‐MR (Sun Nuclear) and LinacView. Thirty incorrectly matched fields were also delivered to check for error detection sensitivity. The gamma analysis, γ, with 3%, 3 mm criteria was used in both ArcCheck®‐MR and LinacView. Additionally, the gantry angle, jaws, and multileaf collimators (MLC) positions reported in the log‐file were compared with plan positions using TG‐142 criteria. Result The γ (3%, 3 mm) for the 190 plans were found to be between the range of 72.5%–100.0% and 95.4%–100.0% for ArcCheck®‐MR and LinacVeiw, respectively. All the delivered gantry angle and jaws were found to be within 0.2° and 2 mm. MLCs that were outside the guard leaves or under the diaphragms were found to have more than 1.0 mm discrepancy. This was attributed to the linac internal override for these MLCs and had no dosimetric impact. Excluding these discrepancies, all MLC positions were found to be within 1.0 mm. The γ (3%, 3 mm) for the 30 incorrectly matched fields were found to be 3.9%–84.8% and 0.1%–64.4% for ArcCheck®‐MR and LinacVeiw, respectively. Conclusion Significant ranked correlation demonstrates the automated log‐file analysis can be used for PSQA and expedite the ART workflow. Ongoing PSQA will be compared with log‐file analysis to investigate the longer term reproducibility and correlation.
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Affiliation(s)
- Seng Boh Lim
- Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | | | | | - Ergys Subashi
- Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Neelam Tyagi
- Memorial Sloan Kettering Cancer Center, New York, NY, USA
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