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Kirby J, Chester K. Automation to facilitate optimisation of breast radiotherapy treatments using EPID-based in vivodosimetry. Phys Med Biol 2024; 69:095018. [PMID: 38537296 DOI: 10.1088/1361-6560/ad387e] [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: 11/24/2023] [Accepted: 03/26/2024] [Indexed: 04/25/2024]
Abstract
Objective. To use automation to facilitate the monitoring of each treatment fraction using an electronic portal imaging device (EPID) basedin vivodosimetry (IVD) system, allowing optimisation of breast radiotherapy delivery for individual patients and cohorts.Approach. A suite of in-house software was developed to reduce the number of manual interactions with the commercial IVD system, dosimetry check. An EPID specific pixel sensitivity map facilitated use of the EPID panel away from the central axis. Point dose difference and the change in standard deviation in dose were identified as useful dose metrics, with standard deviation used in preference to gamma in the presence of a systematic dose offset. Automated IVD was completed for 3261 fractions across 704 patients receiving breast radiotherapy.Main results. Multiple opportunities for treatment optimisation were identified for individual patients and across patient cohorts as a result of successful implementation of automated IVD. 5.1% of analysed fractions were out of tolerance with 27.1% of these considered true positives. True positive results were obtained on any fraction of treatment and if IVD had only been completed on the first fraction, 84.4% of true positive results would have been missed. This was made possible due to the automation that saved over 800 h of manual intervention and stored data in an accessible database.Significance. An improved EPID calibration to allow off-axis measurement maximises the number of patients eligible for IVD (36.8% of patients in this study). We also demonstrate the importance in selecting context-specific assessment metrics and how these can lead to a managable false positive rate. We have shown that the use of fully automated IVD facilitates use on every fraction of treatment. This leads to identification of areas for treatment improvement for both individuals and across a patient cohort, expanding the uses of IVD from simply gross error detection towards treatment optimisation.
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Affiliation(s)
- Joshua Kirby
- Northern Centre for Cancer Care, Newcastle upon Tyne Hospitals NHS Foundation Trust, Freeman Hospital, United Kingdom
| | - Katherine Chester
- Northern Centre for Cancer Care, Newcastle upon Tyne Hospitals NHS Foundation Trust, Cumberland Infirmary, United Kingdom
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Kido T, Ono T, Nakamura M, Ishihara Y, Itoh H, Matsugi K, Yoshimoto A, Kishigami Y, Mizowaki T. Development and multi-institutional evaluation of a new phantom for verifying beam-positioning errors at off-isocenter positions. Phys Med 2023; 112:102645. [PMID: 37478576 DOI: 10.1016/j.ejmp.2023.102645] [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: 01/04/2023] [Revised: 06/10/2023] [Accepted: 07/13/2023] [Indexed: 07/23/2023] Open
Abstract
PURPOSE Single-isocenter stereotactic radiotherapy for multiple brain metastases requires highly accurate treatment delivery at off-isocenter positions (off-iso). This study aimed to verify the beam-positioning errors at off-iso using a newly developed phantom tested at multiple institutions. METHODS The off-iso phantom comprised five stainless-steel balls with a 3-mm diameter placed at the center and at four peripheral positions on a diagonal line. Each ball was placed 3.5 cm apart along each of the three axes. Two patterns of the phantom setup were defined as 0° and 90° phantom rotations to evaluate the beam-positioning error, which is the distance between the center of the ball and the irradiated field on the electronic portal imaging device. Furthermore, the reproducibility of the beam-positioning errors was verified by evaluating their standard deviation (SD) at a single institution, which included five measurements for two treatment machines. The errors were evaluated at multiple institutions using eight treatment machines. RESULTS The measurement time from setup to image acquisition was approximately 20 min for two patterns. The SD of the beam-positioning errors in the reproducibility tests was 0.41 mm. In the multi-institutional evaluation, the beam-positioning error at the isocenter position was within 1.00 mm of the AAPM-RSS tolerance, with the exception of two linacs. The largest beam-positioning error (1.36 mm) was observed 7.5 cm away from the isocenter in three directions at a gantry angle of 180°. CONCLUSIONS The developed phantom can be applied as a new tool for establishing beam-positioning errors in single-isocenter stereotactic radiotherapy at off-isocenter positions.
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Affiliation(s)
- Takahisa Kido
- Department of Advanced Medical Physics, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Tomohiro Ono
- Department of Radiation Oncology and Image-Applied Therapy, Kyoto University, Kyoto, Japan
| | - Mitsuhiro Nakamura
- Department of Advanced Medical Physics, Graduate School of Medicine, Kyoto University, Kyoto, Japan.
| | - Yoshitomo Ishihara
- Department of Radiation Oncology, Division of Medical Physics, Japanese Red Cross Wakayama Medical Center, Japan
| | - Hiroyuki Itoh
- Department of Technology, Division of Medical Technology, Medical Physics Office, Yamatotakada Municipal Hospital, Japan
| | | | | | - Yukako Kishigami
- Department of Advanced Medical Physics, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Takashi Mizowaki
- Department of Radiation Oncology and Image-Applied Therapy, Kyoto University, Kyoto, Japan
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Dogan N, Mijnheer BJ, Padgett K, Nalichowski A, Wu C, Nyflot MJ, Olch AJ, Papanikolaou N, Shi J, Holmes SM, Moran J, Greer PB. AAPM Task Group Report 307: Use of EPIDs for Patient-Specific IMRT and VMAT QA. Med Phys 2023; 50:e865-e903. [PMID: 37384416 PMCID: PMC11230298 DOI: 10.1002/mp.16536] [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: 08/03/2022] [Revised: 04/23/2023] [Accepted: 05/15/2023] [Indexed: 07/01/2023] Open
Abstract
PURPOSE Electronic portal imaging devices (EPIDs) have been widely utilized for patient-specific quality assurance (PSQA) and their use for transit dosimetry applications is emerging. Yet there are no specific guidelines on the potential uses, limitations, and correct utilization of EPIDs for these purposes. The American Association of Physicists in Medicine (AAPM) Task Group 307 (TG-307) provides a comprehensive review of the physics, modeling, algorithms and clinical experience with EPID-based pre-treatment and transit dosimetry techniques. This review also includes the limitations and challenges in the clinical implementation of EPIDs, including recommendations for commissioning, calibration and validation, routine QA, tolerance levels for gamma analysis and risk-based analysis. METHODS Characteristics of the currently available EPID systems and EPID-based PSQA techniques are reviewed. The details of the physics, modeling, and algorithms for both pre-treatment and transit dosimetry methods are discussed, including clinical experience with different EPID dosimetry systems. Commissioning, calibration, and validation, tolerance levels and recommended tests, are reviewed, and analyzed. Risk-based analysis for EPID dosimetry is also addressed. RESULTS Clinical experience, commissioning methods and tolerances for EPID-based PSQA system are described for pre-treatment and transit dosimetry applications. The sensitivity, specificity, and clinical results for EPID dosimetry techniques are presented as well as examples of patient-related and machine-related error detection by these dosimetry solutions. Limitations and challenges in clinical implementation of EPIDs for dosimetric purposes are discussed and acceptance and rejection criteria are outlined. Potential causes of and evaluations of pre-treatment and transit dosimetry failures are discussed. Guidelines and recommendations developed in this report are based on the extensive published data on EPID QA along with the clinical experience of the TG-307 members. CONCLUSION TG-307 focused on the commercially available EPID-based dosimetric tools and provides guidance for medical physicists in the clinical implementation of EPID-based patient-specific pre-treatment and transit dosimetry QA solutions including intensity modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT) treatments.
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Affiliation(s)
- Nesrin Dogan
- Department of Radiation Oncology, University of Miami Miller School of Medicine, Miami, Florida, USA
| | - Ben J Mijnheer
- Department of Radiation Oncology, Netherlands Cancer Institute, Amsterdam, Netherlands
| | - Kyle Padgett
- Department of Radiation Oncology, University of Miami Miller School of Medicine, Miami, Florida, USA
| | - Adrian Nalichowski
- Department of Radiation Oncology, Karmanos Cancer Institute, Detroit, Michigan, USA
| | - Chuan Wu
- Department of Radiation Oncology, Sutter Medical Foundation, Roseville, California, USA
| | - Matthew J Nyflot
- Department of Radiation Oncology, University of Washington, Seattle, Washington, USA
| | - Arthur J Olch
- Department of Radiation Oncology, University of Southern California, and Children's Hospital Los Angeles, Los Angeles, California, USA
| | - Niko Papanikolaou
- Division of Medical Physics, UT Health-MD Anderson, San Antonio, Texas, USA
| | - Jie Shi
- Sun Nuclear Corporation - A Mirion Medical Company, Melbourne, Florida, USA
| | | | - Jean Moran
- Department of Medical Physics, Memorial Sloan Kettering Cancer Center, New York, New York, USA
| | - Peter B Greer
- Department of Radiation Oncology, Calvary Mater Newcastle Hospital, Newcastle, NSW, Australia
- School of Information and Physical Sciences, University of Newcastle, Newcastle, NSW, Australia
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Barnes MP, Sun B, Oborn BM, Lamichhane B, Szwec S, Schmidt M, Cai B, Menk F, Greer P. Determination of the electronic portal imaging device pixel‐sensitivity‐map for quality assurance applications. Part 2: Photon beam dependence. J Appl Clin Med Phys 2022; 23:e13602. [PMID: 35429117 PMCID: PMC9195019 DOI: 10.1002/acm2.13602] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2021] [Revised: 03/08/2022] [Accepted: 03/15/2022] [Indexed: 11/08/2022] Open
Abstract
Purpose Methods Results Conclusion
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Affiliation(s)
- Michael Paul Barnes
- Department of Radiation Oncology Calvary Mater Hospital Newcastle Newcastle NSW Australia
- School of Mathematical and Physical Sciences University of Newcastle Newcastle NSW Australia
| | - Baozhou Sun
- Department of Radiation Oncology Washington University in St Louis St Louis Missouri USA
| | - Brad Michael Oborn
- Centre for Medical Radiation Physics University of Wollongong Wollongong NSW Australia
- Illawarra Cancer Care Centre Wollongong Hospital Wollongong NSW Australia
| | - Bishnu Lamichhane
- School of Mathematical and Physical Sciences University of Newcastle Newcastle NSW Australia
| | - Stuart Szwec
- School of Medicine and Public Health University of Newcastle Newcastle NSW Australia
| | - Matthew Schmidt
- Department of Radiation Oncology Washington University in St Louis St Louis Missouri USA
| | - Bin Cai
- Department of Radiation Oncology Washington University in St Louis St Louis Missouri USA
| | - Frederick Menk
- School of Mathematical and Physical Sciences University of Newcastle Newcastle NSW Australia
| | - Peter Greer
- Department of Radiation Oncology Calvary Mater Hospital Newcastle Newcastle NSW Australia
- School of Mathematical and Physical Sciences University of Newcastle Newcastle NSW Australia
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Barnes MP, Sun B, Oborn BM, Lamichhane B, Szwec S, Schmidt M, Cai B, Menk F, Greer P. Determination of the electronic portal imaging device pixel‐sensitivity‐map for quality assurance applications. Part 1: Comparison of methods. J Appl Clin Med Phys 2022; 23:e13603. [PMID: 35429102 PMCID: PMC9195035 DOI: 10.1002/acm2.13603] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2021] [Revised: 03/08/2022] [Accepted: 03/15/2022] [Indexed: 11/06/2022] Open
Abstract
Purpose Methods Results Conclusion
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Affiliation(s)
- Michael Paul Barnes
- Department of Radiation Oncology Calvary Mater Hospital Newcastle Newcastle New South Wales Australia
- School of Mathematical and Physical Sciences University of Newcastle Newcastle New South Wales Australia
| | - Baozhou Sun
- Department of Radiation Oncology Washington University in St. Louis St. Louis Missouri USA
| | - Brad Michael Oborn
- Centre for Medical Radiation Physics University of Wollongong Wollongong New South Wales Australia
- Illawarra Cancer Care Centre Wollongong Hospital Wollongong New South Wales Australia
| | - Bishnu Lamichhane
- School of Mathematical and Physical Sciences University of Newcastle Newcastle New South Wales Australia
| | - Stuart Szwec
- School of Medicine and Public Health University of Newcastle Newcastle New South Wales Australia
| | - Matthew Schmidt
- Department of Radiation Oncology Washington University in St. Louis St. Louis Missouri USA
| | - Bin Cai
- Department of Radiation Oncology Washington University in St. Louis St. Louis Missouri USA
| | - Frederick Menk
- School of Mathematical and Physical Sciences University of Newcastle Newcastle New South Wales Australia
| | - Peter Greer
- Department of Radiation Oncology Calvary Mater Hospital Newcastle Newcastle New South Wales Australia
- School of Mathematical and Physical Sciences University of Newcastle Newcastle New South Wales Australia
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Development of an Electronic Portal Imaging Device Dosimetry Method. Diagnostics (Basel) 2021; 11:diagnostics11091654. [PMID: 34573994 PMCID: PMC8464714 DOI: 10.3390/diagnostics11091654] [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: 07/26/2021] [Revised: 08/31/2021] [Accepted: 09/06/2021] [Indexed: 12/03/2022] Open
Abstract
Support arm backscatter and off-axis effects of an electronic portal imaging device (EPID) are challenging for radiotherapy quality assurance. Aiming at the issue, we proposed a simple yet effective method with correction matrices to rectify backscatter and off-axis responses for EPID images. First, we measured the square fields with ionization chamber array (ICA) and EPID simultaneously. Second, we calculated the dose-to-pixel value ratio and used it as the correction matrix of the corresponding field. Third, the correction value of the large field was replaced with that of the same point in the small field to generate a correction matrix suitable for different EPID images. Finally, we rectified the EPID image with the correction matrix, and then the processed EPID images were converted into the absolute dose. The calculated dose was compared with the measured dose via ICA. The gamma pass rates of 3%/3 mm and 2%/2 mm (5% threshold) were 99.6% ± 0.94% and 95.48% ± 1.03%, and the average gamma values were 0.28 ± 0.04 and 0.42 ± 0.05, respectively. Experimental results verified our method accurately corrected EPID images and converted pixel values into absolute dose values such that EPID was an efficient radiotherapy dosimetry tool.
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Ahmad M, Nourzadeh H, Siebers J. A regression-based approach to compute the pixels sensitivity map of linear accelerator portal imaging devices. Med Phys 2021; 48:4598-4609. [PMID: 33774827 DOI: 10.1002/mp.14862] [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: 09/17/2020] [Revised: 02/03/2021] [Accepted: 03/10/2021] [Indexed: 11/06/2022] Open
Abstract
PURPOSE To determine the pixel sensitivity map (PSM) for amorphous silicon electronic portal imaging devices (EPIDs) using a single flood field signal. METHOD AND MATERIALS A raw EPID signal results from the incident particle energy fluence, the inherent pixels response, and the background signal. In large open fields, particle energy fluence is a slow-varying signal that is locally considered spatially constant. Pixels response is a fast and abrupt varying behavior. The background signal is due to the EPID panel electronics, which is determined during radiation absence. To determine the PSM, after correcting for the background signal, we apply a model that captures the underlying smooth particle energy fluence-induced signal. This fluence signal-fitted model is then used to determine the PSM. Here, we use a polynomial-based regression surface model in both x and y dimensions. To validate the generated PSM, we measure beams and compute PSMs for multiple beam energies with and without flattening filters and for multiple source-to-imager distances. Since the PSM is a detector characteristic, it should be independent of those variables. We also intercompare measurements of fixed slit fields with the EPID being shifted between measurements. RESULTS The fluence signal of the flattening filter-free (FFF) beams was optimally modeled as a 12th degree polynomial surfaces, which had ≤ 0.1% residuals near the central axis. The 6 and 10 MV FFF PSMs were within ˜0.1%, and independent of the EPID SID, suggesting that the PSM is energy independent. The 6, 10, and 15 MV flattened-beam PSMs were well modeled as 12th degree polynomial surfaces, which were equivalent within ˜0.24% but differed from the FFF PSM by up to 0.5% near the beam central axis. Applying the FFF PSMs to the flattened-beam measurements reduced the central-axis deviation between the raw and corrected signal to < 0.1%, confirming the PSM energy independence hypothesis. When the FFF PSM is utilized, output verification with shifted slit deliveries agreed within ˜0.5% for all beam energies, which is within the radiation delivery uncertainty of ˜0.57%. CONCLUSION PSM for MV EPIDs can be determined by separating out the slowly varying, well-behaved fluence signal from the pixel-to-pixel sensitivity variations. The quality of the PSM is found to be dependent on the quality of the surface fit, which is best for the 6 MV FFF beam measured at SID equal to 180 cm. Within fitting errors, the PSM is independent of beam energy for 6, 10, and 15 MV beams with and without flattening filters. The PSM generation does not require shifting the EPID panel nor multiple EPID panel irradiations and should be usable for linacs with fixed geometry EPIDs.
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Affiliation(s)
- Mahmoud Ahmad
- Vanderbilt University Medical Center, Nashville, TN, 37212, USA.,Radiation Oncology Department, University of Virginia, Charlottesville, VA, 22908, USA
| | - Hamidreza Nourzadeh
- Radiation Oncology Department, Sidney Kimmel Medical College and Cancer Center at Thomas Jefferson University, Philadelphia, PA, 19107, USA
| | - Jeffrey Siebers
- Radiation Oncology Department, University of Virginia, Charlottesville, VA, 22908, USA
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Barnes MP, Menk FW, Lamichhane BP, Greer PB. A proposed method for linear accelerator photon beam steering using EPID. J Appl Clin Med Phys 2018; 19:591-597. [PMID: 30047209 PMCID: PMC6123104 DOI: 10.1002/acm2.12419] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2018] [Revised: 05/11/2018] [Accepted: 06/29/2018] [Indexed: 11/30/2022] Open
Abstract
Beam steering is the process of calibrating the angle and translational position with which a linear accelerator's (linac's) electron beam strikes the x‐ray target with respect to the collimator rotation axis. The shape of the dose profile is highly dependent on accurate beam steering and is essential for ensuring correct delivery of the radiotherapy treatment plan. Traditional methods of beam steering utilize a scanning water tank phantom that makes the process user‐dependent. This study is the first to provide a methodology for both beam angle steering and beam translational position steering based on EPID imaging of the beam and does not require a phantom. Both the EPID‐based beam angle steering and beam translational steering methods described have been validated against IC Profiler measurement. Wide field symmetry agreement was found between the EPID and IC Profiler to within 0.06 ± 0.14% (1 SD) and 0.32 ± 0.11% (1 SD) for flattened and flattening‐filter‐free (FFF) beams, respectively. For a 1.1% change in symmetry measured by IC Profiler the EPID method agreed to within 0.23%. For beam translational position steering, the EPID method agreed with IC Profiler method to within 0.03 ± 0.05 mm (1 SD) at isocenter. The EPID‐based methods presented are quick to perform, simple, accurate and could easily be integrated with the linac, potentially via the MPC application. The methods have the potential to remove user variability and to standardize the process of beam steering throughout the radiotherapy community.
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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
| | - Frederick W Menk
- School of Mathematical and Physical Sciences, University of Newcastle, Newcastle, NSW, Australia
| | - Bishnu P Lamichhane
- 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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