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Sun W, Shi Z, Yang X, Huang S, Liao C, Zhang W, Li Y, Huang X. The performance of a new type accelerator uRT-linac 506c evaluated by a quality assurance automation system. J Appl Clin Med Phys 2024; 25:e14226. [PMID: 38009990 PMCID: PMC10795434 DOI: 10.1002/acm2.14226] [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: 09/05/2023] [Revised: 11/01/2023] [Accepted: 11/06/2023] [Indexed: 11/29/2023] Open
Abstract
PURPOSE The purpose of this study was to evaluate the performance of our quality assurance (QA) automation system and to evaluate the machine performance of a new type linear accelerator uRT-linac 506c within 6 months using this system. METHODS This QA automation system consists of a hollow cylindrical phantom with 18 steel balls in the phantom surface and an analysis software to process electronic portal imaging device (EPID) measurement image data and report the results. The performance of the QA automation system was evaluated by the tests of repeatability, archivable precision, detectability of introduced errors, and the impact of set-up errors on QA results. The performance of this linac was evaluated by 31 items using this QA system over 6 months. RESULTS This QA system was able to automatically deliver QA plan, EPID image acquisition, and automatic analysis. All images acquiring and analysis took approximately 4.6 min per energy. The preset error of 0.1 mm in multi-leaf collimator (MLC) leaf were detected as 0.12 ± 0.01 mm for Bank A and 0.10 ± 0.01 mm in Bank B. The 2 mm setup error was detected as -1.95 ± 0.01 mm, -2.02 ± 0.01 mm, 2.01 ± 0.01 mm for X, Y, Z directions, respectively. And data from the tests of repeatability and detectability of introduced errors showed the standard deviation were all within 0.1 mm and 0.1°. and data of the machine performance were all within the tolerance specified by AAPM TG-142. CONCLUSIONS The QA automation system has high precision and good performance, and it can improve the QA efficiency. The performance of the new accelerator has also performed very well during the testing period.
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Affiliation(s)
- WenZhao Sun
- State Key Laboratory of Oncology in South ChinaCollaborative Innovation Center for Cancer MedicineSun Yat‐sen University Cancer CenterGuangzhouChina
- Guangdong Esophageal Cancer InstituteGuangzhouChina
| | - ZhongHua Shi
- Radiotherapy and Imaging R&D departmentShanghai United Imaging Healthcare Co., Ltd.ShanghaiChina
| | - Xin Yang
- State Key Laboratory of Oncology in South ChinaCollaborative Innovation Center for Cancer MedicineSun Yat‐sen University Cancer CenterGuangzhouChina
| | - SiJuan Huang
- State Key Laboratory of Oncology in South ChinaCollaborative Innovation Center for Cancer MedicineSun Yat‐sen University Cancer CenterGuangzhouChina
| | - Can Liao
- Radiotherapy and Imaging R&D departmentShanghai United Imaging Healthcare Co., Ltd.ShanghaiChina
| | - Wei Zhang
- Radiotherapy and Imaging R&D departmentShanghai United Imaging Healthcare Co., Ltd.ShanghaiChina
| | - YongBao Li
- State Key Laboratory of Oncology in South ChinaCollaborative Innovation Center for Cancer MedicineSun Yat‐sen University Cancer CenterGuangzhouChina
| | - XiaoYan Huang
- State Key Laboratory of Oncology in South ChinaCollaborative Innovation Center for Cancer MedicineSun Yat‐sen University Cancer CenterGuangzhouChina
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Pearson M, Barnes MP, Brown KF, Hawthorn K, Stevens SW, Kizhakke Veetil R, Weston S, Whitbourn JR. IPEM topical report: results of a 2022 UK survey on the use of linac manufacturer integrated quality control (MIQC). Phys Med Biol 2023; 68:245018. [PMID: 37988759 DOI: 10.1088/1361-6560/ad0eb3] [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: 07/28/2023] [Accepted: 11/21/2023] [Indexed: 11/23/2023]
Abstract
In recent years Radiotherapy linear accelerator (linac) vendors have developed their own integrated quality control (QC) systems. Such manufacturer-integrated-quality-control (MIQC) has the potential to improve both the quality and efficiency of linac QC but is currently being developed and utilised in the absence of specific best-practice guidance. An Institute of Physics and Engineering in Medicine working party was commissioned with a view to develop guidance for the commissioning and implementation of MIQC. This study is based upon a survey of United Kingdom (UK) radiotherapy departments performed by the working party. The survey was distributed to all heads of radiotherapy physics in the UK and investigated availability and uptake, community beliefs and opinions, utilisation, user experience and associated procedures. The survey achieved a 95% response rate and demonstrated strong support (>95%) for its use and further development. MIQC systems are available in 79% of respondents' centres, and are in clinical use in 66%. The most common MIQC system was Varian MPC, in clinical use in 58% of responding centres, with CyberKnife AQA\E2E in 11%, TomoTherapy TQA in 8% and no users of Elekta Machine QA. A majority of users found their MIQC to be easy to use, reliable, and had five or more years of experience. Most users reported occasions of discrepancy in results between MIQC and conventional testing, but the majority considered this acceptable, indicating a false reporting frequency of quarterly or less. MIQC has shown value in preventative maintenance and early detection of machine deviations. There were inconsistent approaches in the utilisation and commissioning tests performed. Fewer than half of users perform QC of MIQC. 45% of responders have modified their QC processes with the introduction of MIQC, via replacement of conventional tests or reduction in their frequency. Future guidance is recommended to assist in the implementation of MIQC.
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Affiliation(s)
- Michael Pearson
- Medical Physics Department, Guys and St Thomas' Hospital, London, United Kingdom
- School of Biomedical Engineering & Imaging Sciences, King's College London, London, United Kingdom
| | - Michael P Barnes
- Department of Radiation Oncology, Calvary Mater Hospital Newcastle, Waratah, NSW, Australia
| | - Kirstie F Brown
- Edinburgh Cancer Centre, Western General Hospital, Edinburgh, United Kingdom
| | - Karen Hawthorn
- Northern Centre for Cancer Care, Freeman Hospital, Newcastle-upon-Tyne, United Kingdom
| | | | - Rakesh Kizhakke Veetil
- Radiotherapy Department, Southend University Hospital NHS Trust, Westcliff-on-Sea, United Kingdom
| | - Steven Weston
- Medical Physics and Engineering, Leeds Cancer Centre, Leeds Teaching Hospitals NHS Trust, Leeds, United Kingdom
| | - J R Whitbourn
- Department of Medical Physics, The James Cook University Hospital, Middlesbrough, United Kingdom
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Khan AU, Simiele EA, Lotey R, DeWerd LA, Yadav P. An independent Monte Carlo-based IMRT QA tool for a 0.35 T MRI-guided linear accelerator. J Appl Clin Med Phys 2022; 24:e13820. [PMID: 36325743 PMCID: PMC9924112 DOI: 10.1002/acm2.13820] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2022] [Revised: 10/08/2022] [Accepted: 10/11/2022] [Indexed: 11/06/2022] Open
Abstract
PURPOSE To develop an independent log file-based intensity-modulated radiation therapy (IMRT) quality assurance (QA) tool for the 0.35 T magnetic resonance-linac (MR-linac) and investigate the ability of various IMRT plan complexity metrics to predict the QA results. Complexity metrics related to tissue heterogeneity were also introduced. METHODS The tool for particle simulation (TOPAS) Monte Carlo code was utilized with a previously validated linac head model. A cohort of 29 treatment plans was selected for IMRT QA using the developed QA tool and the vendor-supplied adaptive QA (AQA) tool. For 27 independent patient cases, various IMRT plan complexity metrics were calculated to assess the deliverability of these plans. A correlation between the gamma pass rates (GPRs) from the AQA results and calculated IMRT complexity metrics was determined using the Pearson correlation coefficients. Tissue heterogeneity complexity metrics were calculated based on the gradient of the Hounsfield units. RESULTS The median and interquartile range for the TOPAS GPRs (3%/3 mm criteria) were 97.24% and 3.75%, respectively, and were 99.54% and 0.36% for the AQA tool, respectively. The computational time for TOPAS ranged from 4 to 8 h to achieve a statistical uncertainty of <1.5%, whereas the AQA tool had an average calculation time of a few minutes. Of the 23 calculated IMRT plan complexity metrics, the AQA GPRs had correlations with 7 out of 23 of the calculated metrics. Strong correlations (|r| > 0.7) were found between the GPRs and the heterogeneity complexity metrics introduced in this work. CONCLUSIONS An independent MC and log file-based IMRT QA tool was successfully developed and can be clinically deployed for offline QA. The complexity metrics will supplement QA reports and provide information regarding plan complexity.
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Affiliation(s)
- Ahtesham Ullah Khan
- Department of Medical PhysicsSchool of Medicine and Public HealthUniversity of Wisconsin‐MadisonMadisonWisconsinUSA
| | - Eric A. Simiele
- Department of Radiation OncologyRutgers Cancer Institute of New Jersey, Rutgers Robert Wood Johnson Medical SchoolNew BrunswickNew JerseyUSA
| | | | - Larry A. DeWerd
- Department of Medical PhysicsSchool of Medicine and Public HealthUniversity of Wisconsin‐MadisonMadisonWisconsinUSA
| | - Poonam Yadav
- Department of Radiation OncologyNorthwestern Memorial HospitalNorthwestern University Feinberg School of MedicineChicagoIllinoisUSA
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Automating QA analysis for a six-degree-of-freedom (6DOF) couch using image displacement and an accelerometer sensor. Phys Med 2022; 101:129-136. [PMID: 35998433 DOI: 10.1016/j.ejmp.2022.08.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/03/2022] [Revised: 06/13/2022] [Accepted: 08/04/2022] [Indexed: 11/23/2022] Open
Abstract
The purpose of this study is to develop an approach for automating quality assurance (QA) analysis for a six-degree-of-freedom (6DOF) couch using image displacement and an accelerometer sensor. A cubic phantom was fabricated using 3D printing and the accelerometer sensor was embedded in the phantom to measure the couch in the pitch and roll directions. The accuracy and reliability of image displacement and the accelerometer sensor were investigated prior to their practical use for 6DOF couch QA. Image displacement performance had an accuracy and reliability of 0.026 ± 0.026 mm for the translation direction and 0.021 ± 0.016° for the rotation direction. Accelerometer sensor performance had an accuracy and reliability of 0.023 ± 0.018° for pitch rotation and 0.051 ± 0.024° for roll rotation. Automating QA analysis was used to perform 6DOF couch QA, and the couch position errors measured using image displacement were less than 0.99 mm, 0.91 mm, 0.82 mm for the vertical, longitudinal, lateral translation in range between ±20 mm, and 0.07°, 0.23°, and 0.2° for pitch, roll, and yaw rotation in range between ±3° whereas the couch position errors measured using the accelerometer sensor were less than 0.1° and 0.19° for the pitch and roll rotation in range between ±3°.
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Renaud J, Muir B. Assessing the accuracy of electronic portal imaging device (EPID)-based dosimetry: I. Quantities influencing long-term stability. Med Phys 2021; 49:1231-1237. [PMID: 34964136 DOI: 10.1002/mp.15434] [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: 03/09/2021] [Revised: 12/08/2021] [Accepted: 12/12/2021] [Indexed: 11/07/2022] Open
Abstract
PURPOSE The aim of this study is to reduce the uncertainty associated with determining dose-to-water using an amorphous silicon electronic portal imaging detector (EPID) under reference conditions by identifying and accounting for operational and environmental factors influencing long-term stability of EPID response. METHODS Measurements of the EPID relative response, corrected for variations in linear accelerator (linac) output, were performed regularly over a period of 12 months. For every acquired image set, measurements of detector supply voltages, internal operating temperature, and ambient environmental conditions were obtained. Pearson r correlation coefficients were then calculated for each pair of variables, a subset of which were fitted using multiple linear regression to develop a predictive model of EPID response. Principal component analysis was performed on the dataset to reveal the internal structure of the data in a way that best accounts for the observed variations. RESULTS The +5.5 V power supply voltage, internal operating temperature, and the accumulated dose absorbed in EPID were identified as having the greatest influence on the long-term stability of EPID response. By correcting for the combined effect of these variables, the mean difference in linac output as measured by the EPID relative to a reference-class chamber improved from -0.46 % to 0.23 % over the period of the study. CONCLUSIONS This work suggests that the stability of an EPID over a period of a year can be improved by a factor of two by monitoring and accounting for the effects of variations in power supply voltage, internal temperature of the detector, and accumulated absorbed dose. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- James Renaud
- Metrology Research Centre, National Research Council Canada, Ottawa, Ontario, Canada
| | - Bryan Muir
- Metrology Research Centre, National Research Council Canada, Ottawa, Ontario, Canada
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Renaud J, Muir B. Assessing the accuracy of electronic portal imaging device (EPID)-based dosimetry: II. Evaluation of a dosimetric uncertainty budget and development of a new film-in-EPID absorbed dose calibration methodology. Med Phys 2021; 49:1238-1247. [PMID: 34954834 DOI: 10.1002/mp.15425] [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: 11/22/2021] [Accepted: 12/12/2021] [Indexed: 11/08/2022] Open
Abstract
PURPOSE The aim of this study is to reduce the uncertainty associated with determining dose-to-water using an amorphous silicon electronic portal imaging detector (EPID) under reference conditions by developing a direct calibration formalism based on radiochromic film measurements made within the EPID panel and detailed Monte Carlo simulations. To our knowledge, this is the first EPID-based dosimetry study reporting an uncertainty budget . METHODS Pixel sensitivity and relative off-axis response was mapped by simultaneously irradiating film contained within the imager panel and acquiring an EPID image set. The detector panel was disassembled for the purpose of modeling the EPID in detail using the EGSnrc DOSXYZnrc usercode, which was in turn used to calculate dose-to-film in EPID to dose-to-water in water conversion factors . RESULTS A direct comparison of the two correction methodologies investigated in this work, the previously established empirical method and the proposed simultaneous measurement approach involving in-EPID film dosimetry, produced an agreement with an RMS deviation of 1.4 % overall. A combined standard relative uncertainty of 3.3 % (k = 1) was estimated for the determination of absorbed dose to water at the position of the EPID using the proposed calibration methodology . CONCLUSIONS This work describes a direct method of calibrating EPID response in terms of absorbed dose to water requiring fewer measurements than other empirical approaches, and without 2D spatial interpolation of correction factors. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- James Renaud
- Metrology Research Centre, National Research Council Canada, Ottawa, Ontario, Canada
| | - Bryan Muir
- Metrology Research Centre, National Research Council Canada, Ottawa, Ontario, Canada
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Improving the Quality of Care in Radiation Oncology using Artificial Intelligence. Clin Oncol (R Coll Radiol) 2021; 34:89-98. [PMID: 34887152 DOI: 10.1016/j.clon.2021.11.011] [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: 09/23/2021] [Revised: 10/20/2021] [Accepted: 11/12/2021] [Indexed: 12/13/2022]
Abstract
Radiation therapy is a complex process involving multiple professionals and steps from simulation to treatment planning to delivery, and these procedures are prone to error. Additionally, the imaging and treatment delivery equipment in radiotherapy is highly complex and interconnected and represents another risk point in the quality of care. Numerous quality assurance tasks are carried out to ensure quality and to detect and prevent potential errors in the process of care. Recent developments in artificial intelligence provide potential tools to the radiation oncology community to improve the efficiency and performance of quality assurance efforts. Targets for artificial intelligence enhancement include the quality assurance of treatment plans, target and tissue structure delineation used in the plans, delivery of the plans and the radiotherapy delivery equipment itself. Here we review recent developments of artificial intelligence applications that aim to improve quality assurance processes in radiation therapy and discuss some of the challenges and limitations that require further development work to realise the potential of artificial intelligence for quality assurance.
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Ayan AS, Kim G, Whitaker M, Al-Hallaq H, Hsu SH, Woollard J, Roberts DA, Shtraus N, Gao S, Gupta N, Moran JM. A framework for automated and streamlined kV cone beam computed tomography image quality assurance: a multi-institutional study. Biomed Phys Eng Express 2021; 7. [PMID: 34544065 DOI: 10.1088/2057-1976/ac2876] [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: 06/11/2021] [Accepted: 09/20/2021] [Indexed: 11/12/2022]
Abstract
The purpose of this study was to develop and evaluate a framework to support automated standardized testing and analysis of Cone Beam Computed Tomography (CBCT) image quality QA across multiple institutions. A survey was conducted among the participating institutions to understand the variability of the CBCT QA practices. A commercial, automated software platform was validated by seven institutions participating in a consortium dedicated to automated quality assurance. The CBCT image analysis framework was used to compare periodic QA results among 23 linear accelerators (linacs) from seven institutions. The CBCT image quality metrics (geometric distortion, spatial resolution, contrast, HU constancy, uniformity and noise) data are plotted as a function of means with the upper and lower control limits compared to the linac acceptance criteria and AAPM recommendations. For example, mean geometric distortion and HU constancy metrics were found to be 0.13 mm (TG142 recommendation: ≤2 mm) and 13.4 respectively (manufacturer acceptance specification: ≤±50).Image upload and analysis process was fully automated using a MATLAB-based platform. This analysis enabled a quantitative, longitudinal assessment of the performance of quality metrics which were also compared across 23 linacs. For key CBCT parameters such as uniformity, contrast, and HU constancy, all seven institutions used stricter goals than what would be recommended based on the analysis of the upper and lower control limits. These institutional goals were also found to be stricter than that found in AAPM published guidance. This work provides a reference that could be used to machine-specific optimized tolerance of CBCT image maintenance via control charts to monitor performance we well as the sensitivity of different tests in support of a broader quality assurance program. To ensure the daily image quality needed for patient care, the optimized statistical QA metrics recommended to using along with risk-based QA.
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Affiliation(s)
- Ahmet S Ayan
- Ohio State University, OH, United States of America
| | - Grace Kim
- UC-San Diego, CA, United States of America
| | | | | | | | | | | | | | - Song Gao
- MD Anderson Cancer CenterCenter, TX,United States of America
| | | | - Jean M Moran
- University of Michigan, MI, United States of America
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Lim SB, Zwan BJ, Lee D, Greer PB, Lovelock DM. A novel quality assurance procedure for trajectory log validation using phantom-less real-time latency corrected EPID images. J Appl Clin Med Phys 2021; 22:176-185. [PMID: 33634952 PMCID: PMC7984475 DOI: 10.1002/acm2.13202] [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: 11/30/2020] [Revised: 01/09/2021] [Accepted: 01/24/2021] [Indexed: 11/13/2022] Open
Abstract
The use of trajectory log files for routine patient quality assurance is gaining acceptance. Such use requires the validation of the trajectory log itself. However, the accurate localization of a multileaf collimator (MLC) leaf while it is in motion remains a challenging task. We propose an efficient phantom‐less technique using the EPID to verify the dynamic MLC positions with high accuracy. Measurements were made on four Varian TrueBeams equipped with M120 MLCs. Two machines were equipped with the S1000 EPID; two were equipped with the S1200 EPID. All EPIDs were geometrically corrected prior to measurements. Dosimetry mode EPID measurements were captured by a frame grabber card directly linked to the linac. All leaf position measurements were corrected both temporally and geometrically. The readout latency of each panel, as a function of pixel row, was determined using a 40 × 1.0 cm2 sliding window (SW) field moving at 2.5 cm/s orthogonal to the row readout direction. The latency of each panel type was determined by averaging the results of two panels of the same type. Geometric correction was achieved by computing leaf positions with respect to the projected isocenter position as a function of gantry angle. This was determined by averaging the central axis position of fields at two collimator positions of 90° and 270°. The radiological to physical leaf end position was determined by comparison of the measured gap with that determined using a feeler gauge. The radiological to physical leaf position difference was found to be 0.1 mm. With geometric and latency correction, the proposed method was found to be improve the ability to detect dynamic MLC positions from 1.0 to 0.2 mm for all leaves. Latency and panel residual geometric error correction improve EPID‐based MLC position measurement. These improvements provide for the first time a trajectory log QA procedure.
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Affiliation(s)
- Seng Boh Lim
- Department of Medical Physics, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Benjamin J Zwan
- School of Mathematical and Physical Sciences, University of Newcastle, Newcastle, NSW, Australia.,Central Coast Cancer Centre, Gosford Hospital, Gosford, NSW, Australia
| | - Danny Lee
- School of Mathematical and Physical Sciences, University of Newcastle, Newcastle, NSW, Australia.,Department of Radiation Oncology, Allegheny Health Network, Pittsburgh, PA, USA
| | - Peter B Greer
- School of Mathematical and Physical Sciences, University of Newcastle, Newcastle, NSW, Australia.,Department of Radiation Oncology, Calvary Mater Hospital Newcastle, Waratah, NSW, Australia
| | - Dale Michael Lovelock
- Department of Medical Physics, Memorial Sloan Kettering Cancer Center, New York, NY, USA
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Pearson M, Eaton D, Greener T. Long-term experience of MPC across multiple TrueBeam linacs: MPC concordance with conventional QC and sensitivity to real-world faults. J Appl Clin Med Phys 2020; 21:224-235. [PMID: 32790139 PMCID: PMC7484877 DOI: 10.1002/acm2.12950] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2020] [Revised: 05/11/2020] [Accepted: 05/16/2020] [Indexed: 11/12/2022] Open
Abstract
Machine Performance Check (MPC) is an automated Quality Control (QC) tool that is integrated into the TrueBeam and Halcyon linear accelerators (Linacs), utilizing the imaging systems to verify the Linac beam and geometry. This work compares the concordance of daily MPC results with conventional QC tests over a 3-year period for eight Linacs in order to assess the sensitivity of MPC in detecting faults. The MPC output measurements were compared with the monthly ionization chamber measurements for 6 and 10 MV photon beams and 6, 9, 12, 16, and 18 MeV electron beams. All 6 MV Beam and Geometry (6MVBG) MPC test failures were analyzed to determine the failure rate and the number of true and false negative results, using the conventional QC record as the reference. The concordance between conventional QC test failures and MPC test failures was investigated. The mean agreement across 1933 MPC output and monthly comparison chamber measurements for all beam energies was 0.2%, with 97.8% within 1.5%, and a maximum difference of 2.9%. Of the 5000-6000 MPC individual test parameter results for the 6MVBG test, the highest failure rate was BeamOutputChange (0.5%), then BeamCenterShift (0.3%), and was ≤ 0.1% for the remaining parameters. There were 50 true negative and 27 false negative out of tolerance MPC results, with false negatives resolved by repeating MPC or by independent measurement. The analysis of conventional QC failures demonstrated that MPC detected all failures, except occasions when MPC reported output within tolerance, a result of the MPC-chamber response variation. The variation in MPC output versus chamber measurement indicates MPC is appropriate for daily output constancy but not for the measurement of absolute output. The comparison of the 6MVBG results and conventional records provides evidence that MPC is a sensitive method of performing beam and mechanical checks in a clinical setting.
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Affiliation(s)
- Michael Pearson
- Medical Physics Department, Guys and St Thomas' Hospital, London, SE1 9RT, United Kingdom
| | - David Eaton
- Medical Physics Department, Guys and St Thomas' Hospital, London, SE1 9RT, United Kingdom
| | - Tony Greener
- Medical Physics Department, Guys and St Thomas' Hospital, London, SE1 9RT, United Kingdom
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11
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Skinner LB, Yang Y, Hsu A, Xing L, Yu AS, Niedermayr T. Factor 10 Expedience of Monthly Linac Quality Assurance via an Ion Chamber Array and Automation Scripts. Technol Cancer Res Treat 2020; 18:1533033819876897. [PMID: 31707931 PMCID: PMC6843702 DOI: 10.1177/1533033819876897] [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] [Indexed: 11/22/2022] Open
Abstract
Purpose: While critical for safe and accurate radiotherapy, monthly quality assurance of medical linear accelerators is time-consuming and takes physics resources away from other valuable tasks. The previous methods at our institution required 5 hours to perform the mechanical and dosimetric monthly linear accelerator quality assurance tests. An improved workflow was developed to perform these tests with higher accuracy, with fewer error pathways, in significantly less time. Methods: A commercial ion chamber array (IC profiler, Sun Nuclear, Melbourne, Florida) is combined with automation scripts to consolidate monthly linear accelerator QA. The array was used to measure output, flatness, symmetry, jaw positions, gated dose constancy, energy constancy, collimator walkout, crosshair centering, and dosimetric leaf gap constancy. Treatment plans were combined with automation scripts that interface with Sun Nuclear’s graphical user interface. This workflow was implemented on a standard Varian clinac, with no special adaptations, and can be easily applied to other C-arm linear accelerators. Results: These methods enable, in 30 minutes, measurement and analysis of 20 of the 26 dosimetric and mechanical monthly tests recommended by TG-142. This method also reduces uncertainties in the measured beam profile constancy, beam energy constancy, field size, and jaw position tests, compared to our previous methods. One drawback is the increased uncertainty associated with output constancy. Output differences between IC profiler and farmer chamber in plastic water measurements over a 6-month period, across 4 machines, were found to have a 0.3% standard deviation for photons and a 0.5% standard deviation for electrons, which is sufficient for verifying output accuracy according to TG-142 guidelines. To minimize error pathways, automation scripts which apply the required settings, as well as check the exported data file integrity were employed. Conclusions: The equipment, procedure, and scripts used here reduce the time burden of routine quality assurance tests and in most instances improve precision over our previous methods.
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Affiliation(s)
- Lawrie B Skinner
- Department of Radiation Oncology, Stanford University, Palo Alto, CA, USA
| | - Yong Yang
- Department of Radiation Oncology, Stanford University, Palo Alto, CA, USA
| | - Annie Hsu
- Department of Radiation Oncology, Stanford University, Palo Alto, CA, USA
| | - Lei Xing
- Department of Radiation Oncology, Stanford University, Palo Alto, CA, USA
| | - Amy S Yu
- Department of Radiation Oncology, Stanford University, Palo Alto, CA, USA
| | - Thomas Niedermayr
- Department of Radiation Oncology, Stanford University, Palo Alto, CA, USA
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Simiele SJ, Chen X, Lee C, Rosen BS, Mikell JK, Moran JM, Prisciandaro JI. Development and comprehensive commissioning of an automated brachytherapy plan checker. Brachytherapy 2020; 19:355-361. [DOI: 10.1016/j.brachy.2020.02.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2019] [Revised: 02/13/2020] [Accepted: 02/13/2020] [Indexed: 11/26/2022]
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13
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Chojnowski JM, Taylor LM, Sykes JR, Thwaites DI. Assessing the dependency of the uncertainties in the Elekta Agility MLC calibration procedure on the focal spot position. AUSTRALASIAN PHYSICAL & ENGINEERING SCIENCES IN MEDICINE 2019; 43:10.1007/s13246-019-00821-x. [PMID: 31792725 DOI: 10.1007/s13246-019-00821-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/05/2019] [Accepted: 11/17/2019] [Indexed: 11/30/2022]
Abstract
The effectiveness of radiotherapy treatments depends on the accuracy of the dose delivery process. The majority of radiotherapy courses are delivered on linear accelerators with a Multi Leaf Collimator (MLC) in 3D conformal Radiation Therapy, Intensity Modulated Radiation Therapy (IMRT) or Volumetric Modulated Arc Therapy (VMAT) modes that require accurate MLC positioning. This study investigates the MLC calibration accuracy, following manufacturer procedures for an Elekta Synergy linac with the Agility head, against the radiation focal spot offset (alignment with the collimator axis of rotation). If the radiation focal spot is not aligned ideally with the collimator axis of rotation then a systematic error can be introduced into the calibration procedure affecting absolute MLC leaf positions. Calibration of diaphrams is equally affected; however they are not investigated here. The results indicate that an estimated 0.15 mm MLC uncertainty in all MLC leaves positions can be introduced due to uncertainty of the radiation focal spot position of 0.21 mm.
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Affiliation(s)
- Jacek M Chojnowski
- Mid North Coast Cancer Institute, Coffs Harbour Health Campus, 345 Pacific Highway, Coffs Harbour, NSW, 2450, Australia.
- Institute of Medical Physics, School of Physics, University of Sydney, Sydney, NSW, Australia.
| | - Lee M Taylor
- Mid North Coast Cancer Institute, Coffs Harbour Health Campus, 345 Pacific Highway, Coffs Harbour, NSW, 2450, Australia
| | - Jonathan R Sykes
- Institute of Medical Physics, School of Physics, University of Sydney, Sydney, NSW, Australia
- Department of Radiation Oncology, Blacktown Cancer & Haematology Centre, Blacktown, NSW, Australia
| | - David I Thwaites
- Institute of Medical Physics, School of Physics, University of Sydney, Sydney, NSW, Australia
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14
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Kang H, Patel R, Roeske JC. Efficient quality assurance method with automated data acquisition of a single phantom setup to determine radiation and imaging isocenter congruence. J Appl Clin Med Phys 2019; 20:127-133. [PMID: 31535781 PMCID: PMC6806465 DOI: 10.1002/acm2.12723] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2018] [Revised: 07/22/2019] [Accepted: 08/27/2019] [Indexed: 12/31/2022] Open
Abstract
We developed a quality assurance (QA) method to determine the isocenter congruence of Optical Surface Monitoring System (OSMS, Varian, CA, USA), kilovoltage (kV), and megavoltage (MV) imaging, and the radiation isocenter using a single setup of the OSMS phantom for frameless Stereotactic Radiosurgery (SRS) treatment. After aligning the phantom to the OSMS isocenter, a cone‐beam computed tomography (CBCT) of the phantom was acquired and registered to a computed tomography (CT) scan of the phantom to determine the CBCT isocenter. Without moving the phantom, MV and kV images were simultaneously acquired at four gantry angles to localize MV and kV isocenters. Then, Winston‐Lutz (W‐L) test images of the central BB in the phantom were acquired to analyze the radiation isocenter. The gantry and couch were automatically controlled using the TrueBeam Developer Mode during MV, kV, and W‐L image acquisition. All the images were acquired weekly for 17 weeks to track the congruence of all the imaging modalities' isocenter in six‐dimensional (6D) translations and rotations, and the radiation isocenter in three‐dimensional (3D) translations. The shifts of isocenters of all imaging modalities and the radiation isocenter from the OSMS isocenter were within 0.2 mm and 0.2° on average over 17 weeks. The maximum discrepancy between OSMS and other imaging modalities or radiation isocenters was 0.8 mm and 0.3°. However, systematic shifts of radiation isocenter anteriorly and laterally relative to the OSMS isocenter were observed. The measured discrepancies were consistent from week‐to‐week except for two weeks when the isocenter discrepancies of 0.8 mm were noted due to drifts of the OSMS isocenter. Once recalibration was performed on OSMS, the discrepancy was reduced to 0.3 mm and 0.2°.By performing the proposed QA on a weekly basis, the isocenter congruencies of multiple imaging systems and radiation isocenter were validated for a linear accelerator.
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Affiliation(s)
- Hyejoo Kang
- Department of Radiation Oncology, Loyola Medicine, Maywood, IL, USA
| | - Rakesh Patel
- Department of Radiation Oncology, Loyola Medicine, Maywood, IL, USA
| | - John C Roeske
- Department of Radiation Oncology, Loyola Medicine, Maywood, IL, USA
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15
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Smyth G, Evans PM, Bamber JC, Mandeville HC, Rollo Moore A, Welsh LC, Saran FH, Bedford JL. Dosimetric accuracy of dynamic couch rotation during volumetric modulated arc therapy (DCR-VMAT) for primary brain tumours. Phys Med Biol 2019; 64:08NT01. [PMID: 30808011 PMCID: PMC6877349 DOI: 10.1088/1361-6560/ab0a8e] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Radiotherapy treatment plans using dynamic couch rotation during volumetric modulated arc therapy (DCR-VMAT) reduce the dose to organs at risk (OARs) compared to coplanar VMAT, while maintaining the dose to the planning target volume (PTV). This paper seeks to validate this finding with measurements. DCR-VMAT treatment plans were produced for five patients with primary brain tumours and delivered using a commercial linear accelerator (linac). Dosimetric accuracy was assessed using point dose and radiochromic film measurements. Linac-recorded mechanical errors were assessed by extracting deviations from log files for multi-leaf collimator (MLC), couch, and gantry positions every 20 ms. Dose distributions, reconstructed from every fifth log file sample, were calculated and used to determine deviations from the treatment plans. Median (range) treatment delivery times were 125 s (123-133 s) for DCR-VMAT, compared to 78 s (64-130 s) for coplanar VMAT. Absolute point doses were 0.8% (0.6%-1.7%) higher than prediction. For coronal and sagittal films, respectively, 99.2% (96.7%-100%) and 98.1% (92.9%-99.0%) of pixels above a 20% low dose threshold reported gamma <1 for 3% and 3 mm criteria. Log file analysis showed similar gantry rotation root-mean-square error (RMSE) for VMAT and DCR-VMAT. Couch rotation RMSE for DCR-VMAT was 0.091° (0.086-0.102°). For delivered dose reconstructions, 100% of pixels above a 5% low dose threshold reported gamma <1 for 2% and 2 mm criteria in all cases. DCR-VMAT, for the primary brain tumour cases studied, can be delivered accurately using a commercial linac.
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Affiliation(s)
- Gregory Smyth
- Joint Department of Physics at The Institute of Cancer Research and The Royal Marsden NHS Foundation Trust, London, United Kingdom. Author to whom any correspondence should be addressed
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16
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El Naqa I, Irrer J, Ritter TA, DeMarco J, Al‐Hallaq H, Booth J, Kim G, Alkhatib A, Popple R, Perez M, Farrey K, Moran JM. Machine learning for automated quality assurance in radiotherapy: A proof of principle using
EPID
data description. Med Phys 2019; 46:1914-1921. [DOI: 10.1002/mp.13433] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2018] [Revised: 01/02/2019] [Accepted: 01/30/2019] [Indexed: 11/07/2022] Open
Affiliation(s)
- Issam El Naqa
- Department of Radiation Oncology University of Michigan Ann Arbor MI 48103 USA
| | - Jim Irrer
- Department of Radiation Oncology University of Michigan Ann Arbor MI 48103 USA
| | - Tim A. Ritter
- Department of Radiation Oncology Virginia Commonwealth University Richmond VA 23298 USA
| | - John DeMarco
- Department of Radiation Oncology Cedars‐Sinai Medical Center Los Angeles California 90048 USA
| | - Hania Al‐Hallaq
- University of Chicago Radiation and Cellular Oncology Chicago IL 60637 USA
| | - Jeremy Booth
- Royal North Shore Hospital St Leonards New South Wales 2065 Australia
| | - Grace Kim
- University of California at San Diego San Diego CA 92093 USA
| | - Ahmad Alkhatib
- Karmanos Cancer Institute McLaren‐Flint Flint MI 48532 USA
| | - Richard Popple
- University of Alabama at Birmingham Birmingham AL 35249 USA
| | - Mario Perez
- Royal North Shore Hospital St Leonards New South Wales 2065 Australia
| | - Karl Farrey
- University of Chicago Radiation and Cellular Oncology Chicago IL 60637 USA
| | - Jean M. Moran
- Department of Radiation Oncology University of Michigan Ann Arbor MI 48103 USA
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17
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Borzov E, Nevelsky A, Bar-Deroma R, Orion I. Dosimetric evaluation of the gantry sag effect in clinical SRS plans. BJR Open 2019; 1:20180026. [PMID: 33178920 PMCID: PMC7592487 DOI: 10.1259/bjro.20180026] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2018] [Revised: 01/29/2019] [Accepted: 01/31/2019] [Indexed: 12/25/2022] Open
Abstract
Objectives The gantry sag introduces a largely reproducible variation of the radiation field center around the radiation isocenter. The purpose of this work is to assess the change of the dose distribution caused by the gantry sag in clinical stereotactic plans. Methods Brain stereotactic radio surgery treatment plans were evaluated and grouped according to radiation therapy planning technique. Group 1 was planned with volumetric arc therapy technique using coplanar arcs while Group 2-non-coplanar arcs. To simulate the gantry sag effect in the treatment planning system, the original plan segments were divided into four groups according to corresponding gantry angles: upper, lower, left and right quadrants. Then, isocenter of the upper quadrant was shifted towards "Gun", isocenter of the lower quadrant was shifted towards "Target" and isocenter of the left and right quadrants was left at its original positions. The magnitude of the shift was 0.5, 1 and 1.5 mm in each direction, corresponding to 1, 2 and 3 mm of gantry isocenter diameter. To estimate the changes in dose distribution between the original and modified plans, the following dose-volume metrics were tracked: planning target volume (PTV) coverage (V99;PTV), hotspot dose in PTV (DPTV;0.015cc)), coldspot doses in PTV (DPTV;(V-0.015cc)), conformity and gradient indexes, maximum point doses in organs at risk (OAR, DOAR;0.015cc) and outside PTV (DoutsidePTV;0,015cc). For the second group of patients volume of brain receiving 12 Gy (V12Gy) was analyzed. Results The mean relative change of all metrics was within -2%/+2.5% range for both techniques for isocenter diameter up to 2 mm. Isocenter diameter of 3 mm causes significant changes in V99;PTV, conformity and gradient indexes for coplanar, and additionally in DPTV;(V-0.015cc) for non-coplanar plans. The largest increase of maximum point dose in OAR was 1.1, 2.1 and 3.2% for ±0.5, ±1 and ±1.5 mm shift, respectively. Conclusion The results demonstrate dosimetric effect of gantry sag depending on its value. By itself, the gantry sag effect does not produce clinically perceptible dose changes neither for PTV nor for OARs for shift ranges up to ±1 mm, both for coplanar and non-coplanar delivery techniques. For the larger gantry sag magnitude dosimetric changes can become significant, especially for non-coplanar plans. It indicates that 2 mm diameter tolerance of gantry isocenter postulated in TG-142 is reasonable, as variations in excess of this value start to affect the overall dosimetric and spatial uncertainty. Advances in knowledge Dosimetric evaluation of the gantry sag effect in clinical stereotactic radio surgery plans is presented for the first time.
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Affiliation(s)
- Egor Borzov
- Department of Radiotherapy, Division of Oncology, Rambam Health Care Campus, Haifa, Israel
| | - Alex Nevelsky
- Department of Radiotherapy, Division of Oncology, Rambam Health Care Campus, Haifa, Israel
| | - Rachel Bar-Deroma
- Department of Radiotherapy, Division of Oncology, Rambam Health Care Campus, Haifa, Israel
| | - Itzhak Orion
- Department of Nuclear Engineering, Ben-Gurion University of the Negev, Beer Sheva, Israel
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18
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Teo PT, Hwang MS, Shields WG, Kosterin P, Jang SY, Heron DE, Lalonde RJ, Huq MS. Application of TG-100 risk analysis methods to the acceptance testing and commissioning process of a Halcyon linear accelerator. Med Phys 2019; 46:1341-1354. [PMID: 30620406 DOI: 10.1002/mp.13378] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2018] [Revised: 11/25/2018] [Accepted: 12/17/2018] [Indexed: 11/08/2022] Open
Abstract
PURPOSE A new type of linear accelerator (linac) was recently introduced into the market by a major manufacturer. Our institution is one of the early users of this preassembled and preconfigured dual-layer multileaf collimator (MLC), ring-gantry linac - Halcyon™ (1st version). We performed a set of full acceptance testing and commissioning (ATC) measurements for three Halcyon machines and compared the measured data with the standard beam model provided by the manufacturer. The ATC measurements were performed following the guidelines given in different AAPM protocols as well as guidelines provided by the manufacturer. The purpose of the present work was to perform a risk assessment of the ATC process for this new type of linac and investigate whether the results obtained from this analysis could potentially be used as a guideline for improving the design features of this type of linac. METHODS AAPM's TG100 risk assessment methodology was applied to the ATC process. The acceptance testing process relied heavily on the use of a manufacturer-supplied phantom and the automated analysis of electronic portal imaging device (EPID) images. For the commissioning process, a conventional measurement setup and process (e.g., use of water tank for scanning) was largely used. ATC was performed using guidelines recommended in various AAPM protocols (e.g., TG-106, TG-51) as well as guidelines provided by the manufacturer. Six medical physicists were involved in this study. Process maps, process steps, and failure modes (FMs) were generated for the ATC procedures. Failure modes and effects analysis (FMEA) were performed following the guidelines given in AAPM TG-100 protocol. The top 5 and top 10 highest-ranked FMs were identified for the acceptance and commissioning procedures, respectively. Quality control measures were suggested to mitigate these FMs. RESULTS A total of 38 steps and 88 FMs were identified for the entire ATC process. Fourteen steps and 34 FMs arose from acceptance testing. The top 5 FMs that were identified could potentially be mitigated by the manufacturer. For commissioning, a total of 24 steps and 54 potential FMs were identified. The use of separate measurement tools that are not machine-integrated has been identified as a cause for the higher number of steps and FMs generated from the conventional ATC approach. More than half of the quality control measures recommended for both acceptance and commissioning could potentially be incorporated by the manufacturer in the design of the Halcyon machine. CONCLUSION This paper presents the results of FMEA and quality control measures to mitigate the FMs for the ATC process for Halcyon machine. Unique FMs that result from the differences in the ATC guidelines provided by the vendor and current conventional protocols, and the challenges of performing the ATC due to the new linac features and ring-gantry design were highlighted for the first time. The FMs identified in the present work along with the suggested quality control measures, could potentially be used to improve the design features of future ring-gantry type of linacs that are likely to be preassembled, preconfigured, and heavily reliant on automation and image guidance.
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Affiliation(s)
- P Troy Teo
- Division of Medical Physics, Department of Radiation Oncology, University of Pittsburgh School of Medicine and UPMC Hillman Cancer Center, Pittsburgh, PA, USA
| | - Min-Sig Hwang
- Division of Medical Physics, Department of Radiation Oncology, University of Pittsburgh School of Medicine and UPMC Hillman Cancer Center, Pittsburgh, PA, USA
| | | | - Pavel Kosterin
- Division of Medical Physics, Department of Radiation Oncology, University of Pittsburgh School of Medicine and UPMC Hillman Cancer Center, Pittsburgh, PA, USA
| | - Si Young Jang
- Division of Medical Physics, Department of Radiation Oncology, University of Pittsburgh School of Medicine and UPMC Hillman Cancer Center, Pittsburgh, PA, USA
| | - Dwight E Heron
- Division of Medical Physics, Department of Radiation Oncology, University of Pittsburgh School of Medicine and UPMC Hillman Cancer Center, Pittsburgh, PA, USA
| | - Ronald J Lalonde
- Division of Medical Physics, Department of Radiation Oncology, University of Pittsburgh School of Medicine and UPMC Hillman Cancer Center, Pittsburgh, PA, USA
| | - M Saiful Huq
- Division of Medical Physics, Department of Radiation Oncology, University of Pittsburgh School of Medicine and UPMC Hillman Cancer Center, Pittsburgh, PA, USA
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19
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Wu B, Zhang P, Tsirakis B, Kanchaveli D, LoSasso T. Utilizing historical
MLC
performance data from trajectory logs and service reports to establish a proactive maintenance model for minimizing treatment disruptions. Med Phys 2019; 46:475-483. [DOI: 10.1002/mp.13363] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2018] [Revised: 12/13/2018] [Accepted: 12/13/2018] [Indexed: 11/08/2022] Open
Affiliation(s)
- Binbin Wu
- Department of Medical Physics Memorial Sloan Kettering Cancer Center (MSKCC) New York NY USA
| | - Pengpeng Zhang
- Department of Medical Physics Memorial Sloan Kettering Cancer Center (MSKCC) New York NY USA
| | - Bill Tsirakis
- Department of Medical Physics Memorial Sloan Kettering Cancer Center (MSKCC) New York NY USA
| | - David Kanchaveli
- Department of Medical Physics Memorial Sloan Kettering Cancer Center (MSKCC) New York NY USA
| | - Thomas LoSasso
- Department of Medical Physics Memorial Sloan Kettering Cancer Center (MSKCC) New York NY USA
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20
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Cai B, He Y, Bollinger D, Li H, Goddu SM, Mutic S, Sun B. Three year experience of electronic portal imaging device based daily QA for photon radiation beams. Biomed Phys Eng Express 2018. [DOI: 10.1088/2057-1976/aae419] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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21
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Hirashima H, Miyabe Y, Nakamura M, Mukumoto N, Mizowaki T, Hiraoka M. Quality assurance of geometric accuracy based on an electronic portal imaging device and log data analysis for Dynamic WaveArc irradiation. J Appl Clin Med Phys 2018; 19:234-242. [PMID: 29633542 PMCID: PMC5978977 DOI: 10.1002/acm2.12324] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2017] [Revised: 12/28/2017] [Accepted: 03/02/2018] [Indexed: 11/26/2022] Open
Abstract
The purpose of this study was to develop a simple verification method for the routine quality assurance (QA) of Dynamic WaveArc (DWA) irradiation using electronic portal imaging device (EPID) images and log data analysis. First, an automatic calibration method utilizing the outermost multileaf collimator (MLC) slits was developed to correct the misalignment between the center of the EPID and the beam axis. Moreover, to verify the detection accuracy of the MLC position according to the EPID images, various positions of the MLC with intentional errors in the range 0.1–1 mm were assessed. Second, to validate the geometric accuracy during DWA irradiation, tests were designed in consideration of three indices. Test 1 evaluated the accuracy of the MLC position. Test 2 assessed dose output consistency with variable dose rate (160–400 MU/min), gantry speed (2.2–6°/s), and ring speed (0.5–2.7°/s). Test 3 validated dose output consistency with variable values of the above parameters plus MLC speed (1.6–4.2 cm/s). All tests were delivered to the EPID and compared with those obtained using a stationary radiation beam with a 0° gantry angle. Irradiation log data were recorded simultaneously. The 0.1‐mm intentional error on the MLC position could be detected by the EPID, which is smaller than the EPID pixel size. In Test 1, the MLC slit widths agreed within 0.20 mm of their exposed values. The averaged root‐mean‐square error (RMSE) of the dose outputs was less than 0.8% in Test 2 and Test 3. Using log data analysis in Test 3, the RMSE between the planned and recorded data was 0.1 mm, 0.12°, and 0.07° for the MLC position, gantry angle, and ring angle, respectively. The proposed method is useful for routine QA of the accuracy of DWA.
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Affiliation(s)
- Hideaki Hirashima
- Department of Radiation Oncology and Image-applied therapy, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Yuki Miyabe
- Department of Radiation Oncology and Image-applied therapy, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Mitsuhiro Nakamura
- Department of Radiation Oncology and Image-applied therapy, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Nobutaka Mukumoto
- Department of Radiation Oncology and Image-applied therapy, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Takashi Mizowaki
- Department of Radiation Oncology and Image-applied therapy, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Masahiro Hiraoka
- Department of Radiation Oncology and Image-applied therapy, Graduate School of Medicine, Kyoto University, Kyoto, Japan
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22
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Ritter TA, Schultz B, Barnes M, Popple R, Perez M, Farrey K, Kim G, Moran JM. Automated EPID-based measurement of MLC leaf offset as a quality control tool. Biomed Phys Eng Express 2018. [DOI: 10.1088/2057-1976/aa9f76] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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23
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Pasler M, Hernandez V, Jornet N, Clark CH. Novel methodologies for dosimetry audits: Adapting to advanced radiotherapy techniques. Phys Imaging Radiat Oncol 2018; 5:76-84. [PMID: 33458373 PMCID: PMC7807589 DOI: 10.1016/j.phro.2018.03.002] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2017] [Revised: 03/08/2018] [Accepted: 03/08/2018] [Indexed: 11/25/2022] Open
Abstract
With new radiotherapy techniques, treatment delivery is becoming more complex and accordingly, these treatment techniques require dosimetry audits to test advanced aspects of the delivery to ensure best practice and safe patient treatment. This review of novel methodologies for dosimetry audits for advanced radiotherapy techniques includes recent developments and future techniques to be applied in dosimetry audits. Phantom-based methods (i.e. phantom-detector combinations) including independent audit equipment and local measurement equipment as well as phantom-less methods (i.e. portal dosimetry, transmission detectors and log files) are presented and discussed. Methodologies for both conventional linear accelerator (linacs) and new types of delivery units, i.e. Tomotherapy, stereotactic devices and MR-linacs, are reviewed. Novel dosimetry audit techniques such as portal dosimetry or log file evaluation have the potential to allow parallel auditing (i.e. performing an audit at multiple institutions at the same time), automation of data analysis and evaluation of multiple steps of the radiotherapy treatment chain. These methods could also significantly reduce the time needed for audit and increase the information gained. However, to maximise the potential, further development and harmonisation of dosimetry audit techniques are required before these novel methodologies can be applied.
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Affiliation(s)
- Marlies Pasler
- Lake Constance Radiation Oncology Center Singen-Friedrichshafen, Germany
| | - Victor Hernandez
- Department of Medical Physics, Hospital Sant Joan de Reus, IISPV, Tarragona, Spain
| | - Núria Jornet
- Servei de RadiofísicaiRadioprotecció, Hospital de la Santa CreuiSant Pau, Spain
| | - Catharine H. Clark
- Department of Medical Physics, Royal Surrey County Hospital, Guildford, Surrey, UK
- Metrology for Medical Physics (MEMPHYS), National Physical Laboratory, Teddington, Middlesex, UK
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24
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Yaddanapudi S, Cai B, Harry T, Dolly S, Sun B, Li H, Stinson K, Noel C, Santanam L, Pawlicki T, Mutic S, Goddu SM. Rapid acceptance testing of modern linac using on-board MV and kV imaging systems. Med Phys 2017; 44:3393-3406. [PMID: 28432806 DOI: 10.1002/mp.12294] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2016] [Revised: 04/11/2017] [Accepted: 04/11/2017] [Indexed: 11/07/2022] Open
Abstract
PURPOSE The purpose of this study was to develop a novel process for using on-board MV and kV Electronic Portal Imaging Devices (EPIDs) to perform linac acceptance testing (AT) for two reasons: (a) to standardize the assessment of new equipment performance, and (b) to reduce the time to clinical use while reducing physicist workload. METHODS AND MATERIALS In this study, Varian TrueBeam linacs equipped with amorphous silicon-based EPID (aS1000) were used. The conventional set of AT tests and tolerances were used as a baseline guide. A novel methodology was developed or adopted from published literature to perform as many tests as possible using the MV and kV EPIDs. The developer mode on Varian TrueBeam linacs was used to automate the process. In the EPID-based approach, most of mechanical tests were conducted by acquiring images through a custom phantom and software tools were developed for quantitative analysis to extract different performance parameters. The embedded steel-spheres in a custom phantom provided both visual and radiographic guidance for beam geometry testing. For photon beams, open field EPID images were used to extract inline/crossline profiles to verify the beam energy, flatness and symmetry. EPID images through a double wedge phantom were used for evaluating electron beam properties via diagonal profile. Testing was augmented with a commercial automated application (Machine Performance Check) which was used to perform several geometric accuracy tests such as gantry, collimator rotations, and couch rotations/translations. RESULTS The developed process demonstrated that the tests, which required customer demonstration, were efficiently performed using EPIDs. The AT tests that were performed using EPIDs were fully automated using the developer mode on the Varian TrueBeam system, while some tests, such as the light field versus radiation field congruence, and collision interlock checks required user interaction. CONCLUSIONS On-board imagers are quite suitable for both geometric and dosimetric testing of linac system involved in AT. Electronic format of the acquired data lends itself to benchmarking, transparency, as well as longitudinal use of AT data. While the tests were performed on a specific model of a linear accelerator, the proposed approach can be extended to other linacs.
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Affiliation(s)
- Sridhar Yaddanapudi
- Department of Radiation Oncology, Washington University School of Medicine, 4921 Parkview Place, St. Louis, MO, 63110, USA
| | - Bin Cai
- Department of Radiation Oncology, Washington University School of Medicine, 4921 Parkview Place, St. Louis, MO, 63110, USA
| | - Taylor Harry
- Department of Radiation Medicine and Applied Sciences, University of California San Diego, Moores Cancer Center, 3855 Health Sciences Dr., La Jolla, CA, 92093, USA
| | - Steven Dolly
- Department of Radiation Oncology, Washington University School of Medicine, 4921 Parkview Place, St. Louis, MO, 63110, USA
| | - Baozhou Sun
- Department of Radiation Oncology, Washington University School of Medicine, 4921 Parkview Place, St. Louis, MO, 63110, USA
| | - Hua Li
- Department of Radiation Oncology, Washington University School of Medicine, 4921 Parkview Place, St. Louis, MO, 63110, USA
| | - Keith Stinson
- Varian Medical Systems, 3100 Hansen Way, Palo Alto, CA, 94304, USA
| | - Camille Noel
- Varian Medical Systems, 3100 Hansen Way, Palo Alto, CA, 94304, USA
| | - Lakshmi Santanam
- Department of Radiation Oncology, Washington University School of Medicine, 4921 Parkview Place, St. Louis, MO, 63110, USA
| | - Todd Pawlicki
- Department of Radiation Medicine and Applied Sciences, University of California San Diego, Moores Cancer Center, 3855 Health Sciences Dr., La Jolla, CA, 92093, USA
| | - Sasa Mutic
- Department of Radiation Oncology, Washington University School of Medicine, 4921 Parkview Place, St. Louis, MO, 63110, USA
| | - S Murty Goddu
- Department of Radiation Oncology, Washington University School of Medicine, 4921 Parkview Place, St. Louis, MO, 63110, USA
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25
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Mutic S, Pawlicki T, Orton CG. EPID-based daily quality assurance of linear accelerators will likely replace other methods within the next ten years. Med Phys 2017; 43:2691-2693. [PMID: 27277015 DOI: 10.1118/1.4944423] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Affiliation(s)
- Sasa Mutic
- Radiation Oncology, Washington University School of Medicine, St. Louis, Missouri 63110 (Tel: 314-362-2634; E-mail: )
| | - Todd Pawlicki
- Radiation Medicine and Applied Sciences, University of California San Diego, La Jolla, California 92093-0843 (Tel: 858-822-6058; E-mail: )
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26
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Barnes MP, Greer PB. Evaluation of the TrueBeam machine performance check (MPC) beam constancy checks for flattened and flattening filter-free (FFF) photon beams. J Appl Clin Med Phys 2016; 18:139-150. [PMID: 28291921 PMCID: PMC5689878 DOI: 10.1002/acm2.12016] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2016] [Accepted: 10/27/2016] [Indexed: 11/12/2022] Open
Abstract
Machine Performance Check (MPC) is an automated and integrated image‐based tool for verification of beam and geometric performance of the TrueBeam linac. The aims of the study were to evaluate the MPC beam performance tests against current daily quality assurance (QA) methods, to compare MPC performance against more accurate monthly QA tests and to test the sensitivity of MPC to changes in beam performance. The MPC beam constancy checks test the beam output, uniformity, and beam center against the user defined baseline. MPC was run daily over a period of 5 months (n = 115) in parallel with the Daily QA3 device. Additionally, IC Profiler, in‐house EPID tests, and ion chamber measurements were performed biweekly and results presented in a form directly comparable to MPC. The sensitivity of MPC was investigated using controlled adjustments of output, beam angle, and beam position steering. Over the period, MPC output agreed with ion chamber to within 0.6%. For an output adjustment of 1.2%, MPC was found to agree with ion chamber to within 0.17%. MPC beam center was found to agree with the in‐house EPID method within 0.1 mm. A focal spot position adjustment of 0.4 mm (at isocenter) was measured with MPC beam center to within 0.01 mm. An average systematic offset of 0.5% was measured in the MPC uniformity and agreement of MPC uniformity with symmetry measurements was found to be within 0.9% for all beams. MPC uniformity detected a change in beam symmetry of 1.5% to within 0.3% and 0.9% of IC Profiler for flattened and FFF beams, respectively.
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Affiliation(s)
- Michael P Barnes
- Department of Radiation Oncology, Calvary Mater Hospital Newcastle, NSW, Australia.,School of Medical Radiation Sciences, University of Newcastle, Newcastle, NSW, Australia.,School of Mathematical and Physical Sciences, University of Newcastle, Newcastle, NSW, Australia
| | - Peter B Greer
- Department of Radiation Oncology, Calvary Mater Hospital Newcastle, NSW, Australia.,School of Mathematical and Physical Sciences, University of Newcastle, Newcastle, NSW, Australia
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Christophides D, Davies A, Fleckney M. Automatic detection of MLC relative position errors for VMAT using the EPID-based picket fence test. Phys Med Biol 2016; 61:8340-8359. [PMID: 27811392 DOI: 10.1088/0031-9155/61/23/8340] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Multi-leaf collimators (MLCs) ensure the accurate delivery of treatments requiring complex beam fluences like intensity modulated radiotherapy and volumetric modulated arc therapy. The purpose of this work is to automate the detection of MLC relative position errors ⩾0.5 mm using electronic portal imaging device-based picket fence tests and compare the results to the qualitative assessment currently in use. Picket fence tests with and without intentional MLC errors were measured weekly on three Varian linacs. The picket fence images analysed covered a time period ranging between 14-20 months depending on the linac. An algorithm was developed that calculated the MLC error for each leaf-pair present in the picket fence images. The baseline error distributions of each linac were characterised for an initial period of 6 months and compared with the intentional MLC errors using statistical metrics. The distributions of median and one-sample Kolmogorov-Smirnov test p-value exhibited no overlap between baseline and intentional errors and were used retrospectively to automatically detect MLC errors in routine clinical practice. Agreement was found between the MLC errors detected by the automatic method and the fault reports during clinical use, as well as interventions for MLC repair and calibration. In conclusion the method presented provides for full automation of MLC quality assurance, based on individual linac performance characteristics. The use of the automatic method has been shown to provide early warning for MLC errors that resulted in clinical downtime.
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Affiliation(s)
- Damianos Christophides
- Radiotherapy Physics, Level 1 Bexley Wing, St. James's Institute of Oncology, Beckett Street, Leeds LS9 7TF, UK. University of Leeds, Leeds Institute of Cancer and Pathology, Leeds, UK
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