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Tani K, Wakita A, Tohyama N, Fujita Y. Dosimetric impact of calibration coefficients determined using linear accelerator photon and electron beams for ionization chamber in an on-site dosimetry audit. JOURNAL OF RADIATION RESEARCH 2024; 65:619-627. [PMID: 39154377 PMCID: PMC11420846 DOI: 10.1093/jrr/rrae054] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2024] [Revised: 06/18/2024] [Indexed: 08/20/2024]
Abstract
This study aimed to clarify the dosimetric impact of calibration beam quality for calibration coefficients of the absorbed dose to water for an ionization chamber in an on-site dosimetry audit. Institution-measured doses of 200 photon and 184 electron beams were compared with the measured dose using one year data before and after the calibration of the ionization chamber used. For photon and electron reference dosimetry, the agreements of the institution-measured dose against two measured doses in this audit were evaluated using the calibration coefficients determined using 60Co (${N}_{D,\mathrm{w},{}^{60}\mathrm{Co}}$) and linear accelerator (linac) (${N}_{D,\mathrm{w},Q}$) beams. For electron reference dosimetry, the agreement of two institution-measured doses against the measured dose was evaluated using${N}_{D,\mathrm{w},Q}$. Institution-measured doses were evaluated using direct- and cross-calibration coefficients. For photon reference dosimetry, the mean differences and standard deviation (SD) of institution-measured dose against the measured dose using ${N}_{D,\mathrm{w},{}^{60}\mathrm{Co}}$ and ${N}_{D,\mathrm{w},Q}$ were -0.1% ± 0.4% and -0.3% ± 0.4%, respectively. For electron reference dosimetry, the mean differences and SD of institution-measured dose using the direct-calibration coefficient against the measured dose using ${N}_{D,\mathrm{w},{}^{60}\mathrm{Co}}$ and ${N}_{D,\mathrm{w},Q}$ were 1.3% ± 0.8% and 0.8% ± 0.8%, respectively. Further, the mean differences and SD of institution-measured dose using the cross-calibration coefficient against the measured dose using ${N}_{D,\mathrm{w},Q}$ were -0.1% ± 0.6%. For photon beams, the dosimetric impact of introducing calibration coefficients determined using linac beams was small. For electron beams, it was larger, and the measured dose using ${N}_{D,\mathrm{w},Q}$ was most consistent with the institution-measured dose, which was evaluated using a cross-calibration coefficient.
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Affiliation(s)
- Kensuke Tani
- Division of Medical Physics, EuroMediTech Co., Ltd, 2-20-4 Higashi-Gotanda, Shinagawa, Tokyo 141-0022, Japan
| | - Akihisa Wakita
- Division of Medical Physics, EuroMediTech Co., Ltd, 2-20-4 Higashi-Gotanda, Shinagawa, Tokyo 141-0022, Japan
| | - Naoki Tohyama
- Department of Health Sciences, Komazawa University, 1-23-1 Komazawa, Setagaya, Tokyo 154-8525, Japan
| | - Yukio Fujita
- Department of Health Sciences, Komazawa University, 1-23-1 Komazawa, Setagaya, Tokyo 154-8525, Japan
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Volz L, Korte J, Martire MC, Zhang Y, Hardcastle N, Durante M, Kron T, Graeff C. Opportunities and challenges of upright patient positioning in radiotherapy. Phys Med Biol 2024; 69:18TR02. [PMID: 39159668 DOI: 10.1088/1361-6560/ad70ee] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2024] [Accepted: 08/19/2024] [Indexed: 08/21/2024]
Abstract
Objective.Upright positioning has seen a surge in interest as a means to reduce radiotherapy (RT) cost, improve patient comfort, and, in selected cases, benefit treatment quality. In particle therapy (PT) in particular, eliminating the need for a gantry can present massive cost and facility footprint reduction. This review discusses the opportunities of upright RT in perspective of the open challenges.Approach.The clinical, technical, and workflow challenges that come with the upright posture have been extracted from an extensive literature review, and the current state of the art was collected in a synergistic perspective from photon and particle therapy. Considerations on future developments and opportunities are provided.Main results.Modern image guidance is paramount to upright RT, but it is not clear which modalities are essential to acquire in upright posture. Using upright MRI or upright CT, anatomical differences between upright/recumbent postures have been observed for nearly all body sites. Patient alignment similar to recumbent positioning was achieved in small patient/volunteer cohorts with prototype upright positioning systems. Possible clinical advantages, such as reduced breathing motion in upright position, have been reported, but limited cohort sizes prevent resilient conclusions on the treatment impact. Redesign of RT equipment for upright positioning, such as immobilization accessories for various body regions, is necessary, where several innovations were recently presented. Few clinical studies in upright PT have already reported promising outcomes for head&neck patients.Significance.With more evidence for benefits of upright RT emerging, several centers worldwide, particularly in PT, are installing upright positioning devices or have commenced upright treatment. Still, many challenges and open questions remain to be addressed to embed upright positioning firmly in the modern RT landscape. Guidelines, professionals trained in upright patient positioning, and large-scale clinical studies are required to bring upright RT to fruition.
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Affiliation(s)
- Lennart Volz
- Biophysics, GSI Helmholtz Center for Heavy Ion Research GmbH, Darmstadt, Germany
| | - James Korte
- Department of Physical Science, Peter MacCallum Cancer Centere, Melbourne, Australia
- Department of Biomedical Engineering, University of Melbourne, Melbourne, Australia
| | - Maria Chiara Martire
- Biophysics, GSI Helmholtz Center for Heavy Ion Research GmbH, Darmstadt, Germany
| | - Ye Zhang
- Center for Proton Therapy, Paul Scherrer Institut, Villigen-PSI, Switzerland
| | - Nicholas Hardcastle
- Department of Physical Science, Peter MacCallum Cancer Centere, Melbourne, Australia
- Sir Peter MacCallum Department of Oncology, University of Melbourne, Melbourne, Australia
- Centre for Medical Radiation Physics, University of Wollongong, Wollongong, Australia
| | - Marco Durante
- Biophysics, GSI Helmholtz Center for Heavy Ion Research GmbH, Darmstadt, Germany
- Institute for Condensed Matter Physics, Technical University Darmstadt, Darmstadt, Germany
| | - Tomas Kron
- Department of Physical Science, Peter MacCallum Cancer Centere, Melbourne, Australia
- Sir Peter MacCallum Department of Oncology, University of Melbourne, Melbourne, Australia
- Centre for Medical Radiation Physics, University of Wollongong, Wollongong, Australia
| | - Christian Graeff
- Biophysics, GSI Helmholtz Center for Heavy Ion Research GmbH, Darmstadt, Germany
- Department for Electronic Engineering and Computer Science, Technical University Darmstadt, Darmstadt, Germany
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McDermott PN. Monte Carlo evaluation of uncertainties in photon and electron TG-51 absorbed dose calibration. J Appl Clin Med Phys 2024; 25:e14339. [PMID: 38608655 PMCID: PMC11244687 DOI: 10.1002/acm2.14339] [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: 06/21/2023] [Revised: 02/09/2024] [Accepted: 03/03/2024] [Indexed: 04/14/2024] Open
Abstract
PURPOSE The accuracy of dose delivery to all patients treated with medical linacs depends on the accuracy of beam calibration. Dose delivery cannot be any more accurate than this. Given the importance of this, it seems worthwhile taking another look at the expected uncertainty in TG-51 photon dose calibration and a first look at electron calibration. This work builds on the 2014 addendum to TG-51 for photons and adds to it by also considering electrons. In that publication, estimates were made of the uncertainty in the dose calibration. In this paper, we take a deeper look at this important issue. METHODS The methodology used here is more rigorous than previous determinations as it is based on Monte Carlo simulation of uncertainties. It is assumed that mechanical QA has been performed following TG-142 prior to beam calibration and that there are no uncertainties that exceed the tolerances specified by TG-142. RESULTS/CONCLUSIONS Despite the different methodology and assumptions, the estimated uncertainty in photon beam calibration is close to that in the addendum. The careful user should be able to easily reach a 95% confidence interval (CI) of ± 2.3% for photon beam calibration with standard instrumentation. For electron beams calibrated with a Farmer chamber, the estimated uncertainties are slightly larger, and the 95% CI is ±2.6% for 6 MeV and slightly smaller than this for 18 MeV. There is no clear energy dependence in these results. It is unlikely that the user will be able to improve on these uncertainties as the dominant factor in the uncertainty resides in the ion chamber dose calibration factorN D , w 60 Co $N_{D,w}^{{}^{60}{\mathrm{Co}}}$ . For both photons and electrons, reduction in the ion chamber depth uncertainty below about 0.5 mm and SSD uncertainty below 1 mm have almost no effect on the total dose uncertainty, as uncertainties beyond the user's control totally dominate under these circumstances.
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Affiliation(s)
- Patrick N McDermott
- Department of Radiation Oncology, William Beaumont University Hospital, Corewell Health, Royal Oak, Michigan, USA
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Taneja S, Barbee DL. Implementation of an ionization chamber array for linear accelerator monthly dosimetry QA. J Appl Clin Med Phys 2024:e14433. [PMID: 38923344 DOI: 10.1002/acm2.14433] [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: 09/27/2023] [Revised: 05/07/2024] [Accepted: 06/02/2024] [Indexed: 06/28/2024] Open
Abstract
PURPOSE The IC Profiler (ICP) manufactured by Sun Nuclear Corporation (SNC) is an ionization chamber (IC) array used for linear accelerator dosimetry measurements. Previous work characterized response of the ICP under various conditions, but there is limited work of its implementation into monthly QA measurement procedures. This work quantifies ICP accuracy and variables that affect accuracy for beam output measurements, and demonstrates feasibility of using the ICP for all recommended monthly dosimetry measurements. METHODS A total of 1985 output measurements on six Varian TrueBeam and Edge linear accelerators were performed using three ICP with quad wedges (QWs) and were compared with conventional IC measurements. The accuracy of the ICP for beam output was characterized as the difference between the ICP and IC. Variables that affect ICP accuracy, including gain settings, calibrations, and template baselining as well as machine or energy-specific bias were investigated. Measurements of profile constancy, energy, dose rate constancy, wedge factors, and gating were performed. RESULTS The initially observed mean output difference between the ICP and IC was 0.16% (0.61%). When gain settings were optimized, the output difference accuracy improved to -0.02% (0.38%). The output accuracy of the ICP was not dependent on array, dose, temperature and pressure calibrations, or template baselining. Statistically, ICP output accuracy was dependent on machine and beam energy, but clinically, all measurements fell within 0.5% of unity. ICP measurements of energy, dose rate constancy, and wedge factors matched passing results with conventional IC in water measurements. Gating and beam profile constancy measurements demonstrated good stability using the ICP. Finally, monthly dosimetry QA using ICP was completed in an average of 33 min compared to 66 min using the IC. CONCLUSION This work demonstrated the feasibility and efficiency of using the ICP, with specific considerations, as a measurement device for dosimetric linear accelerator monthly QA.
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Affiliation(s)
- Sameer Taneja
- Department of Radiation Oncology, New York University Langone Medical Center, New York, New York, USA
| | - David L Barbee
- Department of Radiation Oncology, New York University Langone Medical Center, New York, New York, USA
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Nishioka S, Okamoto H, Chiba T, Kito S, Ishihara Y, Isono M, Ono T, Mizoguchi A, Mizuno N, Tohyama N, Kurooka M, Ota S, Shimizu D. Technical note: A universal worksheet for failure mode and effects analysis-A project of the Japanese College of Medical Physics. Med Phys 2024; 51:3658-3664. [PMID: 38507277 DOI: 10.1002/mp.17033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2023] [Revised: 02/27/2024] [Accepted: 03/04/2024] [Indexed: 03/22/2024] Open
Abstract
BACKGROUND Failure mode and effects analysis (FMEA), which is an effective tool for error prevention, has garnered considerable attention in radiotherapy. FMEA can be performed individually, by a group or committee, and online. PURPOSE To meet the needs of FMEA for various purposes and improve its accessibility, we developed a simple, self-contained, and versatile web-based FMEA risk analysis worksheet. METHODS We developed an FMEA worksheet using Google products, such as Google Sheets, Google Forms, and Google Apps Script. The main sheet was created in Google Sheets and contained elements necessary for performing FMEA by a single person. Automated tasks were implemented using Apps Script to facilitate multiperson FMEA; these functions were built into buttons located on the main sheet. RESULTS The usability of the FMEA worksheet was tested in several situations. The worksheet was feasible for individual, multiperson, seminar, meeting, and online purposes. Simultaneous online editing, automated survey form creation, automatic analysis, and the ability to respond to the form from multiple devices, including mobile phones, were particularly useful for online and multiperson FMEA. Automation enabled through Google Apps Script reduced the FMEA workload. CONCLUSIONS The FMEA worksheet is versatile and has a seamless workflow that promotes collaborative work for safety.
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Affiliation(s)
- Shie Nishioka
- Department of Radiation Oncology, Kyoto Second Red Cross Hospital, Kyoto, Japan
| | - Hiroyuki Okamoto
- Radiation Safety and Quality Assurance Division, National Cancer Center Hospital, Tokyo, Japan
| | - Takahito Chiba
- Radiation Safety and Quality Assurance Division, National Cancer Center Hospital, Tokyo, Japan
| | - Satoshi Kito
- Division of Radiation Oncology, Department of Radiology, Tokyo Metropolitan Cancer and Infectious Diseases Center Komagome Hospital, Tokyo, Japan
| | - Yoshitomo Ishihara
- Department of Radiation Oncology, Division of Medical Physics, Japanese Red Cross Wakayama Medical Center, Wakayama, Japan
| | - Masaru Isono
- Department of Radiation Oncology, Osaka International Cancer Institute, Osaka, Japan
| | - Tomohiro Ono
- Department of Radiation Oncology and Image-Applied Therapy, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Asumi Mizoguchi
- Department of Radiology, Kurume University Hospital, Fukuoka, Japan
| | - Norifumi Mizuno
- Department of Radiation Oncology, Saitama Medical Center, Saitama Medical University, Saitama, Japan
| | - Naoki Tohyama
- Division of Medical Physics, Tokyo Bay Makuhari Clinic for Advanced Imaging, Cancer Screening, and High-Precision Radiotherapy, Chiba, Japan
| | - Masahiko Kurooka
- Department of Radiation Therapy, Tokyo Medical University Hospital, Tokyo, Japan
| | - Seiichi Ota
- Department of Medical Technology, University Hospital, Kyoto Prefectural University of Medicine, Kyoto, Japan
| | - Daisuke Shimizu
- Department of Radiation Oncology, Kyoto Second Red Cross Hospital, Kyoto, Japan
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Dhoundiyal M, Rasal S, Gupte A, Dandekar PR, Jadhav A, Awate O. Validation and Efficiency Evaluation of Automated Quality Assurance Software SunCHECK™ Machine for Mechanical and Dosimetric Quality Assurance. J Med Phys 2024; 49:311-315. [PMID: 39131425 PMCID: PMC11309146 DOI: 10.4103/jmp.jmp_158_23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2023] [Revised: 03/30/2024] [Accepted: 04/15/2024] [Indexed: 08/13/2024] Open
Abstract
Recent decades have witnessed transformative advances in radiation physics and computer technology, revolutionizing the precision of radiation therapy. The adoption of intricate treatment techniques such as three-dimensional conformal radiotherapy, intensity-modulated radiotherapy, volumetric-modulated arc therapy, and image-guided radiotherapy necessitates robust quality assurance (QA) programs. This study introduces the SunCHECK™ Machine (SCM), a web-based QA platform, presenting early results from its integration into a comprehensive QA program. linear accelerators (LINAC) demand QA programs to uphold machine characteristics within accepted tolerances. The increasing treatment complexity underscores the need for streamlined procedures. The selection of QA tools is vital, requiring efficiency, accuracy, and alignment with clinic needs, as per recommendations such as the AAPM task group 142 report. The materials and methods section details SCM implementation in various QA aspects, encompassing daily QA (DQA), imaging QA with Catphan, conventional output assessment with a water phantom, and LINAC isocenter verification through the Winston-Lutz test. Challenges in QA processes, such as manual data transcription and limited device integration, are highlighted. Early results demonstrate SCM's significant reduction in QA time, ensuring accuracy and efficiency. Its automation eliminates interobserver variation and human errors, contributing to time savings and near-immediate result publication. SCM's role in consolidating and storing DQA data within a single platform is emphasized, offering potential in resource optimization, especially in resource-limited settings. In conclusion, SCM shows promise for efficient and accurate mechanical and dosimetric QA in radiation therapy. The study underscores SCM's potential to address contemporary QA challenges, contributing to improved resource utilization without compromising quality and safety standards.
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Affiliation(s)
- Mayank Dhoundiyal
- Department of Radiation Oncology, Sir H.N Reliance Foundation and Research Centre, Mumbai, Maharashtra, India
| | - Sachin Rasal
- Department of Radiation Oncology, Sir H.N Reliance Foundation and Research Centre, Mumbai, Maharashtra, India
| | - Ajinkya Gupte
- Department of Radiation Oncology, Sir H.N Reliance Foundation and Research Centre, Mumbai, Maharashtra, India
| | - Prasad Raj Dandekar
- Department of Radiation Oncology, Sir H.N Reliance Foundation and Research Centre, Mumbai, Maharashtra, India
| | - Ananda Jadhav
- Department of Radiation Oncology, Sir H.N Reliance Foundation and Research Centre, Mumbai, Maharashtra, India
| | - Omkar Awate
- Department of Radiation Oncology, Sir H.N Reliance Foundation and Research Centre, Mumbai, Maharashtra, India
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Olaciregui-Ruiz I, Simões R, Jan-Jakob S. Deep learning-based tools to distinguish plan-specific from generic deviations in EPID-based in vivo dosimetry. Med Phys 2024; 51:854-869. [PMID: 38112213 DOI: 10.1002/mp.16895] [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: 07/17/2023] [Revised: 11/24/2023] [Accepted: 12/01/2023] [Indexed: 12/21/2023] Open
Abstract
BACKGROUND Dose distributions calculated with electronic portal imaging device (EPID)-based in vivo dosimetry (EIVD) differ from planned dose distributions due to generic and plan-specific deviations. Generic deviations are characteristic to a class of plans. Examples include limitations in EIVD dose reconstruction, inaccuracies in treatment planning system (TPS) calculations and systematic machine deviations. Plan-specific deviations have an unpredictable character. Examples include discrepancies between the patient model used for dose calculation and the patient position or anatomy during delivery, random machine deviations, and data transfer, human or software errors. During the inspection work performed with traditional γ-evaluation statistical methods: (i) generic deviations raise alerts that need to be inspected but that rarely lead to action as their root cause is usually understood and (ii) the detection of relevant plan-specific deviations may be hindered by the presence of generic deviations. PURPOSE To investigate whether deep learning-based tools can help in identifying γ-alerts raised by generic deviations and in improving the detectability of plan-specific deviations. METHODS A 3D U-Net was trained as an autoencoder to reconstruct underlying patterns of generic deviations in γ-distributions. The network was trained for four treatment disease sites differently affected by generic deviations: volumetric modulated arc therapy (VMAT) lung (no known deviations), VMAT prostate (TPS inaccuracies), VMAT head-and-neck (EIVD limitations) and intensity modulated radiation therapy (IMRT) breast (large EIVD limitations). The network was trained with virtual non-transit γ-distributions: 60 train/10 validation for the VMAT sites and 30 train/10 validation for IMRT breast. It was hypothesized that in vivo γ-distributions obtained in the presence of plan-specific deviations would differ from those seen during training. For each disease site, the sensitivity of γ-analysis and the network to detect (synthetically introduced) patient-related deviations was compared by receiver operator characteristic analysis. The investigated deviations were patient positioning errors, weight gain or loss, and tumor volume changes. The clinical relevance was illustrated qualitatively with 793 in vivo clinical cases (141 lung, 136 head-and-neck, 209 prostate and 307 breast). RESULTS Error detectability of patient-related deviations was better with the network than with γ-analysis. The average area under the curve values over all sites were 0.86 ± 0.12(1SD) and 0.69 ± 0.25(1SD), respectively. Regarding in vivo clinical results, the percentage of cases differently classified by γ-analysis and the network was 1%, 19%, 18% and 64% for lung, head-and-neck, prostate, and breast, respectively. In head-and-neck and breast cases, 45 γ-only alerts were examined, of which 43 were attributed to EPID dose reconstruction limitations. For prostate, all 15 investigated γ-only alerts were due to known TPS inaccuracies. All 59 investigated network alerts were explained by either patient-related deviations or EPID acquisition incidents. Some patient-related deviations detected by the network were not detected by γ-analysis. CONCLUSIONS Deep learning-based tools trained to reconstruct underlying patterns of generic deviations in γ-distributions can be used to (i) automatically identify false positives within the set of γ-alerts and (ii) improve the detection of plan-specific deviations, hence minimizing the likelihood of false negatives. The presented method provides clear additional value to the γ-alert management process for large scale EIVD systems.
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Affiliation(s)
- Igor Olaciregui-Ruiz
- Department of Radiation Oncology, Netherlands Cancer Institute, Amsterdam, The Netherlands
| | - Rita Simões
- Department of Radiation Oncology, Netherlands Cancer Institute, Amsterdam, The Netherlands
| | - Sonke Jan-Jakob
- Department of Radiation Oncology, Netherlands Cancer Institute, Amsterdam, The Netherlands
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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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9
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Krauss RF, Balik S, Cirino ET, Hadley A, Hariharan N, Holmes SM, Kielar K, Lavvafi H, McCullough K, Palefsky S, Sawyer JP, Smith K, Tracy J, Winter JD, Wingreen NE. AAPM Medical Physics Practice Guideline 8.b: Linear accelerator performance tests. J Appl Clin Med Phys 2023; 24:e14160. [PMID: 37793084 PMCID: PMC10647991 DOI: 10.1002/acm2.14160] [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: 05/11/2023] [Revised: 06/23/2023] [Accepted: 08/24/2023] [Indexed: 10/06/2023] Open
Abstract
The purpose of this guideline is to provide a list of critical performance tests to assist the Qualified Medical Physicist (QMP) in establishing and maintaining a safe and effective quality assurance (QA) program. The performance tests on a linear accelerator (linac) should be selected to fit the clinical patterns of use of the accelerator and care should be given to perform tests which are relevant to detecting errors related to the specific use of the accelerator. Current recommendations for linac QA were reviewed to determine any changes required to those tests highlighted by the original report as well as considering new components of the treatment process that have become common since its publication. Recommendations are made on the acquisition of reference data, routine establishment of machine isocenter, basing performance tests on clinical use of the linac, working with vendors to establish QA tests and performing tests after maintenance and upgrades. The recommended tests proposed in this guideline were chosen based on consensus of the guideline's committee after assessing necessary changes from the previous report. The tests are grouped together by class of test (e.g., dosimetry, mechanical, etc.) and clinical parameter tested. Implementation notes are included for each test so that the QMP can understand the overall goal of each test. This guideline will assist the QMP in developing a comprehensive QA program for linacs in the external beam radiation therapy setting. The committee sought to prioritize tests by their implication on quality and patient safety. The QMP is ultimately responsible for implementing appropriate tests. In the spirit of the report from American Association of Physicists in Medicine Task Group 100, individual institutions are encouraged to analyze the risks involved in their own clinical practice and determine which performance tests are relevant in their own radiotherapy clinics.
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Affiliation(s)
| | - Salim Balik
- University of Southern CaliforniaLos AngelesCaliforniaUSA
| | | | - Austin Hadley
- Anchorage Radiation Oncology CenterAnchorageAlaskaUSA
| | | | | | | | | | | | | | | | - Koren Smith
- UMass Chan Medical School/IROC Rhode Island QA CenterLincolnRhode IslandUSA
| | | | - Jeff D. Winter
- Department of Medical PhysicsPrincess Margaret Cancer CentreTorontoOntarioCanada
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Marshall H, Selvan T, Ahmad R, Bento M, Veiga C, Sands G, Malone C, King RB, Clark CH, McGarry CK. Evaluation of a novel phantom for the quality assurance of a six-degree-of-freedom couch 3D-printed at multiple centres. Phys Med 2023; 114:103136. [PMID: 37769414 DOI: 10.1016/j.ejmp.2023.103136] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/03/2023] [Revised: 08/18/2023] [Accepted: 09/13/2023] [Indexed: 09/30/2023] Open
Abstract
This study aimed to validate a bespoke 3D-printed phantom for use in quality assurance (QA) of a 6 degrees-of-freedom (6DoF) treatment couch. A novel phantom design comprising a main body with internal cube structures, was fabricated at five centres using Polylactic Acid (PLA) material, with an additional phantom produced incorporating a PLA-stone hybrid material. Correctional setup shifts were determined using image registration by 3D-3D matching of high HU cube structures between obtained cone-beam computer tomography (CBCT) images to reference CTs, containing cubes with fabricated rotational offsets of 3.5°, 1.5° and -2.5° in rotation, pitch, and roll, respectively. Average rotational setup shifts were obtained for each phantom. The reproducibility of 3D-printing was probed by comparing the internal cube size as well as Hounsfield Units between each of the uniquely produced phantoms. For the five PLA phantoms, the average rot, pitch and roll correctional differences from the fabricated offsets were -0.3 ± 0.2°, -0.2 ± 0.5° and 0.2 ± 0.3° respectively, and for the PLA hybrid these differences were -0.09 ± 0.14°, 0.30 ± 0.00° and 0.03 ± 0.10°. There was found to be no statistically significant difference in average cube size between the five PLA printed phantoms, with the significant difference (P < 0.05) in HU of one phantom compared to the others attributed to setup choice and material density. This work demonstrated the capability producing a novel 3D-printed 6DoF couch QA phantom design, at multiple centres, with each unique model capable of sub-degree couch correction.
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Affiliation(s)
- Hannah Marshall
- Patrick G. Johnston Centre for Cancer Research, Queen's University Belfast, Belfast, UK.
| | - Tamil Selvan
- Department of Radiotherapy Physics, Northern Ireland Cancer Centre, Belfast Health and Social Care Trust, Belfast, UK
| | - Reem Ahmad
- Department of Medical Physics and Biomedical Engineering, University College London, London, UK
| | - Mariana Bento
- Department of Medical Physics and Biomedical Engineering, University College London, London, UK
| | - Catarina Veiga
- Department of Medical Physics and Biomedical Engineering, University College London, London, UK
| | - Gordon Sands
- Radiotherapy Physics, UCLH NHS Foundation Trust, London, UK
| | - Ciaran Malone
- Radiotherapy Physics, St. Luke's Radiation Oncology Network, Dublin, Ireland
| | - Raymond B King
- Department of Radiotherapy Physics, Northern Ireland Cancer Centre, Belfast Health and Social Care Trust, Belfast, UK
| | - Catharine H Clark
- Department of Medical Physics and Biomedical Engineering, University College London, London, UK; Radiotherapy Physics, UCLH NHS Foundation Trust, London, UK; Metrology for Medical Physics, National Physical Laboratory, Teddington, UK
| | - Conor K McGarry
- Patrick G. Johnston Centre for Cancer Research, Queen's University Belfast, Belfast, UK; Department of Radiotherapy Physics, Northern Ireland Cancer Centre, Belfast Health and Social Care Trust, Belfast, UK
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11
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Chant T, Ramachandran P. Design and Development of a Low-cost Integrated Dosimeter for External Beam Dosimetry in Radiation Oncology. J Med Phys 2023; 48:392-397. [PMID: 38223802 PMCID: PMC10783195 DOI: 10.4103/jmp.jmp_107_23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2023] [Revised: 10/05/2023] [Accepted: 10/07/2023] [Indexed: 01/16/2024] Open
Abstract
Radiation dosimeters play a crucial role in radiation oncology by accurately measuring radiation dose, ensuring precise and safe radiation therapy. This study presents the design and development of a low-cost printed circuit board (PCB) dosimeter and an integrated electrometer with sensitivity optimized for dose rates intended for use in megavoltage radiation therapy. The PCB dosimeter was designed in KiCad, and it uses a low-cost S5MC-13F general-purpose 1 kV 5A power diode as a radiation detector. The dosimeter is calibrated against a known dose derived from an ionization chamber and tested for dose linearity, dose rate dependence, field size dependence, and detector orientation dependence. The observed average dose differences between the delivered and measured doses for most measurements were found to be < 1.1%; the dose rate linearity between 100 MU/min and 1400 MU/min was found to be within 1.3%. This low-cost architecture could successfully be adapted further for a scalable, cost-effective dosimetry solution through firmware or circuit design.
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Affiliation(s)
- Tim Chant
- Department of Radiation Oncology, Therapeutic Physics, Cancer Services, Princess Alexandra Hospital, Woolloongabba, Queensland, Australia
| | - Prabhakar Ramachandran
- Department of Radiation Oncology, Therapeutic Physics, Cancer Services, Princess Alexandra Hospital, Woolloongabba, Queensland, Australia
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12
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Tsuneda M, Abe K, Fujita Y, Morimoto R, Hashimoto T, Abe Y, Uno T. Delivery accuracy of VMAT on two beam-matched linacs provided by accelerated go live service. J Appl Clin Med Phys 2023:e14071. [PMID: 37327042 DOI: 10.1002/acm2.14071] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2023] [Revised: 05/15/2023] [Accepted: 05/30/2023] [Indexed: 06/17/2023] Open
Abstract
INTRODUCTION Dosimetric accuracy is critical when a patient treated with volumetric modulated arc therapy (VMAT) is transferred to another beam-matched linac. To evaluate the performance of Accelerated Go Live (AGL) service, the measured beam characteristics and patient specific quality assurance (QA) results between two AGL-matched linacs were compared. MATERIALS AND METHODS Two VersaHD linacs were installed using the AGL service. After the installation, the beam data such as percentage depth dose (PDD), lateral profiles and output factors for all photon beams were measured. Relative doses were also measured as a function of the multi-leaf collimator (MLC) leaf gap width. Subsequently, VMAT plans were created for prostate, pelvis, head and neck, liver, lung cancers and multiple brain metastases. Dose distributions and point doses were measured by multi-dimensional detectors and ionization chambers for patient specific quality assurance, and comparisons were made between the two linacs. RESULTS Dose differences in PDDs were all within ± 1% except the entrance region, and the averaged gamma indices of the lateral profiles were within 0.3. The differences in doses as a function of the MLC leaf gap width between the two linacs were within ±0.5%. For all the plans, gamma passing rates were all higher than 95% with criteria of 2%/2 mm. The average and the SD of dose differences on the multi-dimensional detector between both measurements was 0.06 ± 2.12%, and the average of point dose differences was -0.03 ± 0.33%. CONCLUSION We have evaluated the AGL performance in the context of beam characteristics and patient specific QA. It was demonstrated that the AGL service provides an accurate VMAT treatment reproducibility for many tumor sites with gamma pass rates greater than 95% under criteria of 2%/2 mm.
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Affiliation(s)
- Masato Tsuneda
- Department of Radiation Oncology, MR Linac ART Division, Graduate School of Medicine, Chiba University, Chuo-ku, Chiba, Japan
| | - Kota Abe
- Department of Radiation Oncology, MR Linac ART Division, Graduate School of Medicine, Chiba University, Chuo-ku, Chiba, Japan
| | - Yukio Fujita
- Department of Radiation Oncology, MR Linac ART Division, Graduate School of Medicine, Chiba University, Chuo-ku, Chiba, Japan
- Department of Radiation Sciences, Komazawa University, Setagaya-ku, Tokyo, Japan
| | - Ryo Morimoto
- Department of Radiology, Chiba University Hospital, Chuo-ku, Chiba, Japan
| | - Takuma Hashimoto
- Department of Radiology, Chiba University Hospital, Chuo-ku, Chiba, Japan
| | - Yukinao Abe
- Department of Radiology, Chiba University Hospital, Chuo-ku, Chiba, Japan
| | - Takashi Uno
- Diagnostic Radiology and Radiation Oncology, Graduate School of Medicine, Chiba University, Chuo-ku, Chiba, Japan
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13
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Stambaugh C, Yancey J, Shukla U, Melhus C, Stambaugh N. Daily Quality Assurance Efficiency Evaluation Using SunCHECK Machine and Machine Performance Check. Cureus 2023; 15:e35695. [PMID: 37012967 PMCID: PMC10066746 DOI: 10.7759/cureus.35695] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/25/2023] [Indexed: 03/06/2023] Open
Abstract
Purpose To investigate time efficiency, applicability, and accuracy of using a web-based, independent quality assurance (QA) platform and vendor-dependent based system check for daily linear accelerator (LINAC) QA. Methods Time needed to perform daily QA on a single (n=1) LINAC was collected for three months. Task Group report 142 (TG-142) compliant daily QA included dosimetry checks (four photon, four electron beams); imaging checks (planar kilovolt (kV) & megavolt (MV), kV cone-beam computed tomography (CBCT)); and mechanical and safety checks using SunCHECK Machine (SCM) (Sun Nuclear Inc., Melbourne, FL, USA). Additionally, Machine Performance Check (MPC) (Varian Medical Systems, Inc., Palo Alto, CA, USA) was performed for all energies. Four trained radiation therapists performed daily QA on both platforms. Data were collected to identify the time required to complete both SCM and MPC. Additionally, the two platforms were evaluated on usability and features. Output results were compared to our monthly standard to assess accuracy. Results On average, SCM took 22 minutes with a standard deviation of six minutes and MPC took 15 minutes with a standard deviation of three minutes. MPC output results were impacted due to the beam output being coupled to the beam profile changes. As a result, the two systems on average disagreed by -1.41% after three months despite being baselined at the same time point and output agreeing well initially (average difference of -0.1% across all energies). While there was overlap in the tests performed, SCM tests were more relevant to TG-142 while MPC tests were beneficial to machine service and, with a clear understanding of the limitations of the system, found suitable as a secondary backup to SCM for daily output verification. Conclusions This work demonstrates that a comprehensive TG-142 daily QA can be designed using SCM and MPC can be added as a beneficial tool and backup for output verification while still maintaining an efficient daily QA process.
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14
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Baltz GC, Manigold R, Seier R, Kirsner SM. A hybrid method to improve efficiency of patient specific SRS and SBRT QA using 3D secondary dose verification. J Appl Clin Med Phys 2023; 24:e13858. [PMID: 36583305 PMCID: PMC10018667 DOI: 10.1002/acm2.13858] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2022] [Revised: 10/25/2022] [Accepted: 11/20/2022] [Indexed: 12/31/2022] Open
Abstract
PURPOSE Patient Specific QA (PSQA) by direct phantom measurement for all intensity modulated radiation therapy (IMRT) cases is labor intensive and an inefficient use of the Medical Physicist's time. The purpose of this work was to develop a hybrid quality assurance (QA) technique utilizing 3D dose verification as a screening tool to determine if a measurement is necessary. METHODS This study utilized Sun Nuclear DoseCHECK (DC), a 3D secondary verification software, and Fraction 0, a trajectory log IMRT QA software. Twenty-two Lung stereotactic body radiation therapy (SBRT) and thirty single isocentre multi-lesion SRS (MLSRS) plans were retrospectively analysed in DC. Agreement of DC and the TPS dose for selected dosimetric criteria was recorded. Calculated 95% confidence limits (CL) were used to establish action limits. All cases were delivered and measured using the Sun Nuclear stereotactic radiosurgery (SRS) MapCheck. Trajectory logs of the delivery were used to calculate Fraction 0 results for the same criteria calculated by DC. Correlation of DC and Fraction 0 results were calculated. Phantom measured QA was compared to Fraction 0 QA results for the cases which had DC criteria action limits exceeded. RESULTS Correlation of DC and Fraction 0 results were excellent, demonstrating the same action limits could be used for both and DC can predict Fraction 0 results. Based on the calculated action limits, zero lung SBRT cases and six MLSRS cases were identified as requiring a measurement. All plans that passed the DC screening had a passing measurement based PSQA and agreed with Fraction 0 results. CONCLUSION Using 95% CL action limits of dosimetric criteria, a 3D secondary dose verification can be used to determine if a measurement is required for PSQA. This method is efficient for it is part of the normal clinical workflow when verifying any clinical treatment. In addition, it can drastically reduce the number of measurements needed for PSQA.
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Affiliation(s)
- Garrett C Baltz
- Scripps MD Anderson Cancer Center, San Diego, California, USA
| | - Remy Manigold
- Scripps MD Anderson Cancer Center, San Diego, California, USA
| | - Richard Seier
- Scripps MD Anderson Cancer Center, San Diego, California, USA
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15
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Moran JM, Bazan JG, Dawes SL, Kujundzic K, Napolitano B, Redmond KJ, Xiao Y, Yamada Y, Burmeister J. Quality and Safety Considerations in Intensity Modulated Radiation Therapy: An ASTRO Safety White Paper Update. Pract Radiat Oncol 2022; 13:203-216. [PMID: 36710210 DOI: 10.1016/j.prro.2022.11.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2022] [Accepted: 11/11/2022] [Indexed: 12/14/2022]
Abstract
PURPOSE This updated report on intensity modulated radiation therapy (IMRT) is part of a series of consensus-based white papers previously published by the American Society for Radiation Oncology (ASTRO) addressing patient safety. Since the first white papers were published, IMRT went from widespread use to now being the main delivery technique for many treatment sites. IMRT enables higher radiation doses to be delivered to more precise targets while minimizing the dose to uninvolved normal tissue. Due to the associated complexity, IMRT requires additional planning and safety checks before treatment begins and, therefore, quality and safety considerations for this technique remain important areas of focus. METHODS AND MATERIALS ASTRO convened an interdisciplinary task force to assess the original IMRT white paper and update content where appropriate. Recommendations were created using a consensus-building methodology, and task force members indicated their level of agreement based on a 5-point Likert scale, from "strongly agree" to "strongly disagree." A prespecified threshold of ≥75% of raters who select "strongly agree" or "agree" indicated consensus. CONCLUSIONS This IMRT white paper primarily focuses on quality and safety processes in planning and delivery. Building on the prior version, this consensus paper incorporates revised and new guidance documents and technology updates. IMRT requires an interdisciplinary team-based approach, staffed by appropriately trained individuals as well as significant personnel resources, specialized technology, and implementation time. A comprehensive quality assurance program must be developed, using established guidance, to ensure IMRT is performed in a safe and effective manner. Patient safety in the delivery of IMRT is everyone's responsibility, and professional organizations, regulators, vendors, and end-users must work together to ensure the highest levels of safety.
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Affiliation(s)
- Jean M Moran
- Department of Medical Physics, Memorial Sloan Kettering Cancer Center, New York, New York
| | - Jose G Bazan
- Department of Radiation Oncology, Ohio State University, James Cancer Hospital and Solove Research Institute, Columbus, Ohio
| | | | | | - Brian Napolitano
- Department of Radiation Oncology, Massachusetts General Hospital, Boston, Massachusetts
| | - Kristin J Redmond
- Department of Radiation Oncology and Molecular Radiation Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Ying Xiao
- Department of Radiation Oncology, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Yoshiya Yamada
- Department of Radiation Oncology, Memorial Sloan Kettering Cancer Center, New York, New York
| | - Jay Burmeister
- Department of Oncology, Wayne State University School of Medicine, Karmanos Cancer Center, Detroit, Michigan
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16
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Pearson M, Butterworth V, Misson‐Yates S, Naeem M, Gonzalez Vaz R, Eaton D, Greener T. Application of failure mode and effects analysis to validate a novel hybrid Linac QC program that integrates automated and conventional QC testing. J Appl Clin Med Phys 2022; 23:e13798. [PMID: 36453139 PMCID: PMC9797170 DOI: 10.1002/acm2.13798] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2022] [Revised: 09/01/2022] [Accepted: 09/09/2022] [Indexed: 12/05/2022] Open
Abstract
A hybrid quality control (QC) program was developed that integrates automated and conventional Linac QC, realizing the benefits of both automated and conventional QC, increasing efficiency and maintaining independent measurement methods. Failure mode and effects analysis (FMEA) was then applied in order to validate the program prior to clinical implementation. The hybrid QC program consists of automated QC with machine performance check and DailyQA3 array on the TrueBeam Linac, and Delta4 volumetric modulated arc therapy (VMAT) standard plan measurements, alongside conventional monthly QC at a reduced frequency. The FMEA followed the method outlined in TG-100. Process maps were created for each treatment type at our center: VMAT, stereotactic body radiotherapy (SBRT), conformal, and palliative. Possible failure modes were established by evaluating each stage in the process map. The FMEA followed semiquantitative methods, using data from our QC records from eight Linacs over 3 years for the occurrence estimates, and simulation of failure modes in the treatment planning system, with scoring surveys for severity and detectability. The risk priority number (RPN) was calculated from the product of the occurrence, severity, and detectability scores and then normalized to the maximum and ranked to determine the most critical failure modes. The highest normalized RPN values (100, 90) were found to be for MLC position dynamic for both VMAT and SBRT treatments. The next highest score was 35 for beam position for SBRT, and the majority of scores were less than 20. Overall, these RPN scores for the hybrid Linac QC program indicated that it would be acceptable, but the high RPN score associated with the dynamic MLC failure mode indicates that it would be valuable to perform more rigorous testing of the MLC. The FMEA proved to be a useful tool in validating hybrid QC.
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Affiliation(s)
- Michael Pearson
- Medical Physics DepartmentGuy's and St Thomas' HospitalLondonUK
| | | | - Sarah Misson‐Yates
- Medical Physics DepartmentGuy's and St Thomas' HospitalLondonUK,School of Biomedical Engineering & Imaging SciencesKing's College LondonLondonUK
| | - Marium Naeem
- Medical Physics DepartmentGuy's and St Thomas' HospitalLondonUK
| | | | - David Eaton
- Medical Physics DepartmentGuy's and St Thomas' HospitalLondonUK,School of Biomedical Engineering & Imaging SciencesKing's College LondonLondonUK
| | - Tony Greener
- Medical Physics DepartmentGuy's and St Thomas' HospitalLondonUK
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17
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Time-resolved radiation dosimetry using a cerium and terbium Co-doped YAG crystal scintillator. Radiat Phys Chem Oxf Engl 1993 2022. [DOI: 10.1016/j.radphyschem.2022.110625] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Kisling K, Keiper TD, Branco D, Kim GG, Moore KL, Ray X. Clinical commissioning of an adaptive radiotherapy platform: Results and recommendations. J Appl Clin Med Phys 2022; 23:e13801. [PMID: 36316805 PMCID: PMC9797177 DOI: 10.1002/acm2.13801] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2022] [Revised: 08/31/2022] [Accepted: 09/09/2022] [Indexed: 12/29/2022] Open
Abstract
Online adaptive radiotherapy platforms present a unique challenge for commissioning as guidance is lacking and specialized adaptive equipment, such as deformable phantoms, are rare. We designed a novel adaptive commissioning process consisting of end-to-end tests using standard clinical resources. These tests were designed to simulate anatomical changes regularly observed at patient treatments. The test results will inform users of the magnitude of uncertainty from on-treatment changes during the adaptive workflow and the limitations of their systems. We implemented these tests for the cone-beam computed tomography (CT)-based Varian Ethos online adaptive platform. Many adaptive platforms perform online dose calculation on a synthetic CT (synCT). To assess the impact of the synCT generation and online dose calculation on dosimetric accuracy, we conducted end-to-end tests using commonly available equipment: a CIRS IMRT Thorax phantom, PinPoint ionization chamber, Gafchromic film, and bolus. Four clinical scenarios were evaluated: weight gain and weight loss were simulated by adding and removing bolus, internal target shifts were simulated by editing the CTV during the adaptive workflow to displace it, and changes in gas were simulated by removing and reinserting rods in varying phantom locations. The effect of overriding gas pockets during planning was also assessed. All point dose measurements agreed within 2.7% of the calculated dose, with one exception: a scenario simulating gas present in the planning CT, not overridden during planning, and dissipating at treatment. Relative film measurements passed gamma analysis (3%/3 mm criteria) for all scenarios. Our process validated the Ethos dose calculation for online adapted treatment plans. Based on our results, we made several recommendations for our clinical adaptive workflow. This commissioning process used commonly available equipment and, therefore, can be applied in other clinics for their respective online adaptive platforms.
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Affiliation(s)
- Kelly Kisling
- Department of Radiation Medicine and Applied SciencesUniversity of California San DiegoSan DiegoCaliforniaUSA
| | - Timothy D. Keiper
- Department of Radiation Medicine and Applied SciencesUniversity of California San DiegoSan DiegoCaliforniaUSA
| | - Daniela Branco
- Department of Radiation Medicine and Applied SciencesUniversity of California San DiegoSan DiegoCaliforniaUSA
| | - Grace Gwe‐Ya Kim
- Department of Radiation Medicine and Applied SciencesUniversity of California San DiegoSan DiegoCaliforniaUSA
| | - Kevin L Moore
- Department of Radiation Medicine and Applied SciencesUniversity of California San DiegoSan DiegoCaliforniaUSA
| | - Xenia Ray
- Department of Radiation Medicine and Applied SciencesUniversity of California San DiegoSan DiegoCaliforniaUSA
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19
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Tang G, LoSasso T, Chan M, Hunt M. Impact of a Centralized Database System on Radiation Therapy Quality Assurance Management at a Large Health Care Network: 5 Years' Experience. Pract Radiat Oncol 2022; 12:e434-e441. [PMID: 35431152 PMCID: PMC9452445 DOI: 10.1016/j.prro.2022.03.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2021] [Revised: 01/27/2022] [Accepted: 03/02/2022] [Indexed: 11/20/2022]
Abstract
PURPOSE This study reports the impact of using a centralized database system for major equipment quality assurance (QA) at a large institution. METHODS AND MATERIALS A centralized database system has been implemented for radiation therapy machine QA in our institution at 6 campuses with 11 computed tomographies and 22 linear accelerators (LINACs). The database system was customized to manage monthly and annual computed tomography and LINAC QA. This includes providing the same set of QA procedures across the enterprise, digitally storing all measurement records, and generating trend analyses. Compared with conventional methods (ie, paper forms), the effectiveness of the database system was quantified by changes in the compliance of QA tests and perceptions of staff to the efficiency of data retrieval and analyses. An anonymized questionnaire was provided to physicists enterprise-wide to assess workflow changes. RESULTS With the implementation of the database system, the compliance of QA test completion improved from 80% to >99% for the entire institution. This resonates with the 56% of physicists who found the database system helpful in guiding them through QA, and 25% of physicists found the contrary, and 19% reported no difference (n = 16). Meanwhile, 40% of physicists reported longer times needed to record data using the database system compared with conventional methods, and another 40% suggested otherwise. In addition, 87% and 80% found the database more efficient to analyze and retrieve previous data, respectively. This was also reflected by the shorter time taken to generate year-end QA statistics using the software (5 vs 30 min per LINAC). Overall, 94% of physicists preferred the centralized database system over conventional methods and endorsed continued use of the system. CONCLUSIONS A centralized database system is useful and can improve the effectiveness and efficiency of QA management in a large institution. With consistent data collection and proper data storage using a database, high-quality data can be obtained for failure modes and effects analyses as per TG 100.
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Affiliation(s)
- Grace Tang
- Department of Medical Physics, Memorial Sloan Kettering Cancer Center, New York, New York.
| | - Thomas LoSasso
- Department of Medical Physics, Memorial Sloan Kettering Cancer Center, New York, New York
| | - Maria Chan
- Department of Medical Physics, Memorial Sloan Kettering Cancer Center, New York, New York
| | - Margie Hunt
- Department of Medical Physics, Memorial Sloan Kettering Cancer Center, New York, New York
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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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21
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Kalavagunta C, Xu H, Zhang B, Mossahebi S, MacFarlane M, Jiang K, Lee SW, Chen S, Sawant A, Gopal A, Yi B. Is a weekly qualitative picket fence test sufficient? A proposed alternate EPID-based weekly MLC QA program. J Appl Clin Med Phys 2022; 23:e13699. [PMID: 35856943 PMCID: PMC9359020 DOI: 10.1002/acm2.13699] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2021] [Revised: 05/18/2022] [Accepted: 05/30/2022] [Indexed: 11/05/2022] Open
Abstract
PURPOSE Well-designed routine multileaf collimator (MLC) quality assurance (QA) is important to assure external-beam radiation treatment delivery accuracy. This study evaluates the clinical necessity of a comprehensive weekly (C-Weekly) MLC QA program compared to the American Association of Physics in Medicinerecommended weekly picket fence test (PF-Weekly), based on our seven-year experience with weekly MLC QA. METHODS The C-Weekly MLC QA program used in this study includes 5 tests to analyze: (1) absolute MLC leaf position; (2) interdigitation MLC leaf position; (3) picket fence MLC leaf positions at static gantry angle; (4) minimum leaf-gap setting; and (5) volumetric-modulated arc therapy delivery. A total of 20,226 QA images from 16,855 tests (3,371 tests × 5) for 11 linacs at 5 photon clinical sites from May 2014 to June 2021 were analyzed. Failure mode and effects analysis was performed with 5 failure modes related to the 5 tests. For each failure mode, a risk probability number (RPN) was calculated for a C-Weekly and a PF-Weekly MLC QA program. The probability of occurrence was evaluated from statistical analyses of the C-Weekly MLC QA. RESULTS The total number of failures for these 16,855 tests was 143 (0.9%): 39 (27.3%) for absolute MLC leaf position, 13 (9.1%) for interdigitation position, 9 (6.3%) for static gantry picket fence, 2 (1.4%) for minimum leaf-gap setting, and 80 (55.9%) for VMAT delivery. RPN scores for PF-Weekly MLC QA ranged from 60 to 192 and from 48 to 96 for C-Weekly MLC QA. CONCLUSION RPNs for the 5 failure modes of MLC QA tests were quantitatively determined and analyzed. A comprehensive weekly MLC QA is imperative to lower the RPNs of the 5 failure modes to the desired level (<125); those from the PF-Weekly MLC QA program were found to be higher (>125). This supports the clinical necessity for comprehensive weekly MLC QA.
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Affiliation(s)
- Chaitanya Kalavagunta
- Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Huijun Xu
- Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Baoshe Zhang
- Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Sina Mossahebi
- Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Michael MacFarlane
- Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Kai Jiang
- Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Sung-Woo Lee
- Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Shifeng Chen
- Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Amit Sawant
- Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Arun Gopal
- Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - ByongYong Yi
- Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, Maryland, USA
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22
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Goodall SK, Norvill C. Variation in Elekta iView electronic portal imager pixel scale factor with gantry angle, and impact on multi-leaf collimator quality assurance. J Appl Clin Med Phys 2022; 23:e13661. [PMID: 35666629 PMCID: PMC9278680 DOI: 10.1002/acm2.13661] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Revised: 05/01/2022] [Accepted: 05/10/2022] [Indexed: 12/31/2022] Open
Abstract
For Elekta Agility linear accelerators, the iViewGT electronic portal imaging device (EPID) is positioned at a nominal X‐Ray source‐to‐panel distance of 1600 mm. For display, image registration, and data processing purposes, the image pixels are scaled to spatial units at the treatment isocenter plane. This is achieved by applying a pixel scaling factor (PSF). During this investigation, the dependence of the PSF at cardinal gantry angles was determined along with the resulting effects on the multi‐leaf collimator (MLC) quality assurance (QA) results for three linear accelerators (linacs). The PSF was found to vary by 0.0018–0.0022 mm/pixel during gantry rotation, which resulted in variations in the mean MLC reported error of up to 0.8 mm at 100 mm off‐axis with the gantry rotated to 180°. Measurement and application of a gantry angle–specific PSF is a simple process that can be implemented to improve the accuracy of EPID‐based MLC QA at cardinal gantry angles.
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Affiliation(s)
- Simon K Goodall
- GenesisCare, Wembley, Western Australia, Australia.,School of Physics, Mathematics, and Computing, Faculty of Engineering and Mathematical Sciences, University of Western Australia, Crawley, Western Australia, Australia
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Azorín JFP, Saez J, Garcia LIR, Hernandez V. Investigation on the impact of the leaf trailing effect using the Halcyon integrated platform system. Med Phys 2022; 49:6161-6170. [PMID: 35770385 DOI: 10.1002/mp.15833] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2021] [Revised: 03/25/2022] [Accepted: 06/14/2022] [Indexed: 11/10/2022] Open
Abstract
PURPOSE The double-stacked design of the Halcyon multileaf collimator (MLC) presents new challenges for treatment planning systems (TPSs). The leaf trailing effect has recently been described as the result of the interplay between the fluence transmitted through the leaf tip ends of each MLC layer. This effect makes the dosimetric leaf gap (DLG) dependent on the distance between the leaves of different layers (trailing distance) and is not adequately modeled by the Eclipse TPS. The purpose of our study was to investigate and report the dose discrepancies produced by these limitations in clinical plans and to explore how these discrepancies can be mitigated and avoided. METHODS The integrated platform with the Halcyon v2 system, Eclipse and Aria v15.6, was used. The dose discrepancies were obtained with EPID images and the portal dosimetry software and validated using radiochromic film dosimetry. The results for the AIDA commissioning test and for nine selected clinical beams with the sliding window intensity modulated radiotherapy (dIMRT) technique were thoroughly analyzed and presented. First, the DICOM RT plans were exported and the fluences were computed using different leaf tip models, and then were compared. Second, the detailed characteristics of the corresponding leaf sequences were investigated. Finally, modified DICOM RT plans were created in which the non-collimating (backup) leaves were retracted 2 mm to increase the leaf trailing distance, the modified plans were imported back into the TPS and the measurements were repeated. Dedicated in-house tools were developed in Python to carry out all analyses. RESULTS Dose discrepancies greater than 10% and regions of gamma failure were found in both the AIDA test and clinical beams using static-gantry dIMRT. Fluence analysis highlighted that the discrepancies were due to limitations in the MLC model implemented in the TPS. Analysis of leaf sequences indicated that regions of failure were associated with very low leaf speeds and virtually motionless leaves within the beam aperture. Some of these discrepancies were mitigated by increasing the trailing distance of the non-collimating leaves without affecting the beam aperture, but this strategy was not possible in regions where the leaves from both layers actively defined the beam aperture. CONCLUSIONS Current limitations of the MLC model in Eclipse produced discrepancies between calculated and delivered doses in clinical beams that caused plan-specific quality assurance failures and interruptions in the clinical workflow. Careful evaluation of the clinical plans produced by Eclipse for the Halcyon is recommended, especially for static gantry dIMRT treatments. Some characteristics of leaf sequences are problematic and should be avoided in clinical plans and, in general, a better leaf tip model is needed. This is particularly important in adaptive radiotherapy treatments, where the accuracy and reliability of TPS dose calculations are of the utmost importance.
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Affiliation(s)
- José Fernando Pérez Azorín
- Medical Physics and Radiation Protection Department, Gurutzeta-Cruces University Hospital, Barakaldo, E-48903, Spain.,Biocruces Health Research Institute, Barakaldo, E-48903, Spain
| | - Jordi Saez
- Department of Radiation Oncology, Hospital Clínic de Barcelona, Barcelona, 08036, Spain
| | - Luis Isaac Ramos Garcia
- Department of Oncology, Clínica Universidad de Navarra, University of Navarra, Pamplona, E-31008, Spain
| | - Victor Hernandez
- Department of Medical Physics, Hospital Sant Joan de Reus, IISPV, Tarragona, 43204, Spain.,Universitat Rovira i Virgili, Tarragona, Spain
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Barnes M, Pomare D, Doebrich M, Standen TS, Wolf J, Greer P, Simpson J. Insensitivity of machine log files to MLC leaf backlash and effect of MLC backlash on clinical dynamic MLC motion: An experimental investigation. J Appl Clin Med Phys 2022; 23:e13660. [PMID: 35678793 PMCID: PMC9512360 DOI: 10.1002/acm2.13660] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Revised: 05/09/2022] [Accepted: 05/11/2022] [Indexed: 12/02/2022] Open
Abstract
Purpose Multi‐leaf‐collimator (MLC) leaf position accuracy is important for accurate dynamic radiotherapy treatment plan delivery. Machine log files have become widely utilized for quality assurance (QA) of such dynamic treatments. The primary aim is to test the sensitivity of machine log files in comparison to electronic portal imaging device (EPID)‐based measurements to MLC position errors caused by leaf backlash. The secondary aim is to investigate the effect of MLC leaf backlash on MLC leaf motion during clinical dynamic plan delivery. Methods The sensitivity of machine log files and two EPID‐based measurements were assessed via a controlled experiment, whereby the length of the “T” section of a series of 12 MLC leaf T‐nuts in a Varian Millennium MLC for a Trilogy C‐series type linac was reduced by sandpapering the top of the “T” to introduce backlash. The built‐in machine MLC leaf backlash test as well as measurements for two EPID‐based dynamic MLC positional tests along with log files were recorded pre‐ and post‐T‐nut modification. All methods were investigated for sensitivity to the T‐nut change by assessing the effect on measured MLC leaf positions. A reduced version of the experiment was repeated on a TrueBeam type linac with Millennium MLC. Results No significant differences before and after T‐nut modification were detected in any of the log file data. Both EPID methods demonstrated sensitivity to the introduced change at approximately the expected magnitude with a strong dependence observed with gantry angle. EPID‐based data showed MLC positional error in agreement with the micrometer measured T‐nut length change to 0.07 ± 0.05 mm (1 SD) using the departmental routine QA test. Backlash results were consistent between linac types. Conclusion Machine log files appear insensitive to MLC position errors caused by MLC leaf backlash introduced via the T‐nut. The effect of backlash on clinical MLC motions is heavily gantry angle dependent.
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Affiliation(s)
- Michael 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
| | - Dennis Pomare
- Department of Radiation Oncology, Calvary Mater Hospital Newcastle, Newcastle, New South Wales, Australia
| | - Marcus Doebrich
- Department of Radiation Oncology, Calvary Mater Hospital Newcastle, Newcastle, New South Wales, Australia
| | - Therese S Standen
- Department of Radiation Oncology, Calvary Mater Hospital Newcastle, Newcastle, New South Wales, Australia
| | - Joshua Wolf
- Department of Radiation Oncology, Calvary Mater Hospital Newcastle, Newcastle, New South Wales, Australia.,Icon Cancer Centre Maitland, Maitland Private Hospital, Maitland, 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
| | - John Simpson
- 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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Wall PDH, Hirata E, Morin O, Valdes G, Witztum A. Prospective clinical validation of virtual patient-specific quality assurance of VMAT radiation therapy plans. Int J Radiat Oncol Biol Phys 2022; 113:1091-1102. [PMID: 35533908 DOI: 10.1016/j.ijrobp.2022.04.040] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2021] [Revised: 04/05/2022] [Accepted: 04/27/2022] [Indexed: 10/18/2022]
Abstract
PURPOSE Performing measurement-based patient-specific quality assurance (PSQA) is recognized as a resource-intensive and time inefficient task in the radiotherapy treatment workflow. Paired with technological refinements in modern radiotherapy, research towards measurement-free PSQA has seen increased interest over the last five years. However, these efforts have not been clinically implemented or prospectively validated in the U.S. We propose a virtual QA (VQA) system and workflow to assess the safety and workload reduction of measurement-free PSQA. METHODS An XGBoost machine learning model was designed to predict PSQA outcomes of VMAT plans, represented as percent differences between the measured ion chamber point dose in a phantom and the corresponding planned dose. The final model was deployed within a web application to predict PSQA outcomes of clinical plans within an existing clinical workflow. The application also displays relevant feature importance and plan-specific distribution analyses relative to database plans for documentation and to aid physicist interpretation and evaluation. VQA predictions were prospectively validated over three months of measurements at our clinic to assess safety and efficiency gains. RESULTS Over three months, VQA predictions for 445 VMAT plans were prospectively validated at our institution. VQA predictions for these plans had a mean absolute error of 1.08 +/- 0.77%, with a maximum absolute error of 2.98%. Employing a 1% prediction threshold (i.e. plans predicted to have an absolute error of less than 1% would not require a measurement) would yield a 69.2% reduction in QA workload - saving 32.5 hours per month on average - with 81.5%/72.4%/0.81 sensitivity/specificity/AUC at a 3% clinical threshold and 100%/70%/0.93 sensitivity/specificity/AUC at a 4% clinical threshold. CONCLUSION This is the first prospective clinical implementation and validation of VQA in the U.S., which we observed to be efficient. Using a conservative threshold, VQA can substantially reduce the number of required measurements for PSQA, leading to more effective allocation of clinical resources.
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Affiliation(s)
- Phillip D H Wall
- Department of Radiation Oncology, University of California, San Francisco, USA.
| | - Emily Hirata
- Department of Radiation Oncology, University of California, San Francisco, USA
| | - Olivier Morin
- Department of Radiation Oncology, University of California, San Francisco, USA
| | - Gilmer Valdes
- Department of Radiation Oncology, University of California, San Francisco, USA
| | - Alon Witztum
- Department of Radiation Oncology, University of California, San Francisco, USA
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Eder MM, Reiner M, Heinz C, Garny S, Freislederer P, Landry G, Niyazi M, Belka C, Riboldi M. Single-isocenter stereotactic radiosurgery for multiple brain metastases: Impact of patient misalignments on target coverage in non-coplanar treatments. Z Med Phys 2022; 32:296-311. [PMID: 35504799 PMCID: PMC9948862 DOI: 10.1016/j.zemedi.2022.02.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2021] [Revised: 02/10/2022] [Accepted: 02/14/2022] [Indexed: 10/18/2022]
Abstract
Frameless single-isocenter non-coplanar stereotactic radiosurgery (SRS) for patients with multiple brain metastases is a treatment at high geometrical complexity. The goal of this study is to analyze the dosimetric impact of non-coplanar image guidance with stereoscopic X-ray imaging. Such an analysis is meant to provide insights on the adequacy of safety margins, and to evaluate the benefit of imaging at non-coplanar configurations. The ExacTrac® (ET) system (Brainlab AG, Munich, Germany) was used for stereoscopic X-ray imaging in frameless single-isocenter non-coplanar SRS for multiple brain metastases. Sub-millimeter precision was found for the ET-based pre-treatment setup, whereas a degradation was noted for non-coplanar treatment angles. Misalignments without intra-fractional positioning corrections were reconstructed in 6 degrees of freedom (DoF) to resemble the situation without non-coplanar image guidance. Dose recalculation in 20 SRS patients with applied positioning corrections did not reveal any significant differences in D98% for 75 planning target volumes (PTVs) and gross tumor volumes (GTVs). For recalculation without applied positioning corrections, significant differences (p<0.05) were reported in D98% for both PTVs and GTVs, with stronger effects for small PTV volumes. A worst-case analysis at increasing translational and rotational misalignment revealed that dosimetric changes are a complex function of the combination thereof. This study highlighted the important role of positioning correction with ET at non-coplanar configurations in frameless single-isocenter non-coplanar SRS for patients with multiple brain metastases. Uncorrected patient misalignments at non-coplanar couch angles were linked to a significant loss of PTV coverage, with effects varying according to the combination of single DoF and PTV geometrical properties.
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Affiliation(s)
- Michael Martin Eder
- Department of Radiation Oncology, University Hospital, LMU Munich, Munich, Germany; Department of Medical Physics, Ludwig-Maximilians University, Garching, Germany.
| | - Michael Reiner
- Department of Radiation Oncology, University Hospital, LMU Munich, Munich, Germany.
| | - Christian Heinz
- Department of Radiation Oncology, University Hospital, LMU Munich, Munich, Germany.
| | - Sylvia Garny
- Department of Radiation Oncology, University Hospital, LMU Munich, Munich, Germany.
| | - Philipp Freislederer
- Department of Radiation Oncology, University Hospital, LMU Munich, Munich, Germany.
| | - Guillaume Landry
- Department of Radiation Oncology, University Hospital, LMU Munich, Munich, Germany; Department of Medical Physics, Ludwig-Maximilians University, Garching, Germany.
| | - Maximilian Niyazi
- Department of Radiation Oncology, University Hospital, LMU Munich, Munich, Germany; German Cancer Consortium (DKTK), Partner Site Munich, Munich, Germany.
| | - Claus Belka
- Department of Radiation Oncology, University Hospital, LMU Munich, Munich, Germany; German Cancer Consortium (DKTK), Partner Site Munich, Munich, Germany.
| | - Marco Riboldi
- Department of Radiation Oncology, University Hospital, LMU Munich, Munich, Germany.
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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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Time-Resolved Radioluminescence Dosimetry Applications and the Influence of Ge Dopants In Silica Optical Fiber Scintillators. QUANTUM BEAM SCIENCE 2022. [DOI: 10.3390/qubs6020015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The quality of treatment delivery as prescribed in radiotherapy is exceptionally important. One element that helps provide quality assurance is the ability to carry out time-resolved radiotherapy dose measurements. Reports on doped silica optical fibers scintillators using radioluminescence (RL) based radiotherapy dosimetry have indicated merits, especially regarding robustness, versatility, wide dynamic range, and high spatial resolution. Topping the list is the ability to provide time-resolved measurements, alluding to pulse-by-pulse dosimetry. For effective time-resolved dose measurements, high temporal resolution is enabled by high-speed electronics and scintillator material offering sufficiently fast rise and decay time. In the present work, we examine the influence of Ge doping on the RL response of Ge-doped silica optical fiber scintillators. We particularly look at the size of the Ge-doped core relative to the fiber diameter, and its associated effects as it is adjusted from single-mode fiber geometry to a large core-to-cladding ratio structure. The primary objective is to produce a structure that facilitates short decay times with a sufficiently large yield for time-resolved dosimetry. RL characterization was carried out using a high-energy clinical X-ray beam (6 MV), delivered by an Elekta Synergy linear accelerator located at the Advanced Medical and Dental Institute, Universiti Sains Malaysia (USM). The Ge-doped silica optical fiber scintillator samples, fabricated using chemical vapor deposition methods, comprised of large core and small core optical fiber scintillators with high and low core-to-cladding ratios, respectively. Accordingly, these samples having different Ge-dopant contents offer distinct numbers of defects in the amorphous silica network. Responses were recorded for six dose-rates (between 35 MU/min and 590 MU/min), using a photomultiplier tube setup with the photon-counting circuit capable of gating time as small as 1 μs. The samples showed linear RL response, with differing memory and afterglow effects depending on its geometry. Samples with a large core-to-cladding ratio showed a relatively short decay time (<1 ms). The results suggest a contribution of Ge-doping in affecting the triplet states of the SiO2 matrix, thereby reducing phosphorescence effects. This is a desirable feature of scintillating glass materials that enables avoiding the pulse pile-up effect, especially in high dose-rate applications. These results demonstrate the potential of Ge-doped optical-fiber scintillators, with a large core-to-cladding ratio for use in time-resolved radiation dosimetry.
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Kron T, Fox C, Ebert MA, Thwaites D. Quality management in radiotherapy treatment delivery. J Med Imaging Radiat Oncol 2022; 66:279-290. [PMID: 35243785 DOI: 10.1111/1754-9485.13348] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Accepted: 10/29/2021] [Indexed: 12/17/2022]
Abstract
Radiation Oncology continues to rely on accurate delivery of radiation, in particular where patients can benefit from more modulated and hypofractioned treatments that can deliver higher dose to the target while optimising dose to normal structures. These deliveries are more complex, and the treatment units are more computerised, leading to a re-evaluation of quality assurance (QA) to test a larger range of options with more stringent criteria without becoming too time and resource consuming. This review explores how modern approaches of risk management and automation can be used to develop and maintain an effective and efficient QA programme. It considers various tools to control and guide radiation delivery including image guidance and motion management. Links with typical maintenance and repair activities are discussed, as well as patient-specific quality control activities. It is demonstrated that a quality management programme applied to treatment delivery can have an impact on individual patients but also on the quality of treatment techniques and future planning. Developing and customising a QA programme for treatment delivery is an important part of radiotherapy. Using modern multidisciplinary approaches can make this also a useful tool for department management.
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Affiliation(s)
- Tomas Kron
- Department of Physical Sciences, Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia.,Sir Peter MacCallum Institute of Oncology, Melbourne University, Melbourne, Victoria, Australia.,Centre for Medical Radiation Physics, University of Wollongong, Wollongong, New South Wales, Australia
| | - Chris Fox
- Department of Physical Sciences, Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia
| | - Martin A Ebert
- Centre for Medical Radiation Physics, University of Wollongong, Wollongong, New South Wales, Australia.,Department of Radiation Oncology, Sir Charles Gairdner Hospital, Perth, Western Australia, Australia.,School of Physics, Mathematics and Computing, University of Western Australia, Perth, Western Australia, Australia.,5D Clinics, Perth, Western Australia, Australia
| | - David Thwaites
- Institute of Medical Physics, School of Physics, University of Sydney, Sydney, New South Wales, Australia.,Medical Physics Group, Leeds Institute of Cardiovascular and Metabolic Medicine and Leeds Institute of Medical Research, University of Leeds, Leeds, UK
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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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Gondré M, Marsolat F, Bourhis J, Bochud F, Moeckli R. Validation of Monte Carlo dose calculation algorithm for CyberKnife multileaf collimator. J Appl Clin Med Phys 2021; 23:e13481. [PMID: 34851007 PMCID: PMC8833269 DOI: 10.1002/acm2.13481] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2021] [Revised: 10/17/2021] [Accepted: 11/01/2021] [Indexed: 11/08/2022] Open
Abstract
PURPOSE To commission and evaluate the Monte Carlo (MC) dose calculation algorithm for the CyberKnife equipped with a multileaf collimator (MLC). METHODS We created a MC model for the MLC using an integrated module of the CyberKnife treatment planning software (TPS). Two parameters could be optimized: the maximum energy and the source full width at half-maximum (FWHM). The optimization was performed by minimizing the differences between the measured and the MC calculated tissue phantom ratios and profiles. MLC plans were calculated in the TPS with the MC algorithm and irradiated on different phantoms. The dose was measured using an A1SL ionization chamber and EBT3 Gafchromic films, and then compared to the TPS dose to obtain dose differences (ΔD). Finally, patient-specific quality assurances (QA) were performed with global gamma index criteria of 3%/1 mm. RESULTS The maximum energy and source FWHM showing the best agreement with measurements were 6.4 MeV and 1.8 mm. The output factors calculated with these parameters gave an agreement within ±1% with measurements. The ΔD showed that MC model systematically underestimated the dose with an average of -1.5% over all configurations tested. For depths deeper than 12 cm, the ΔD increased, up to -3.0% (maximum at 15.5 cm depth). CONCLUSIONS The MC model for MLC of CyberKnife is clinically acceptable but underestimates the delivered dose by an average of -1.5%. Therefore, we recommend using the MC algorithm with the MLC only in heterogeneous regions and for shallow-seated tumors.
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Affiliation(s)
- Maude Gondré
- Institute of Radiation Physics, Lausanne University Hospital and Lausanne University, Lausanne, Switzerland
| | - Fanny Marsolat
- Institute of Radiation Physics, Lausanne University Hospital and Lausanne University, Lausanne, Switzerland
| | - Jean Bourhis
- Radio-Oncology Department, Lausanne University Hospital and Lausanne University, Lausanne, Switzerland
| | - François Bochud
- Institute of Radiation Physics, Lausanne University Hospital and Lausanne University, Lausanne, Switzerland
| | - Raphaël Moeckli
- Institute of Radiation Physics, Lausanne University Hospital and Lausanne University, Lausanne, Switzerland
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Xia P, Sintay BJ, Colussi VC, Chuang C, Lo YC, Schofield D, Wells M, Zhou S. Medical Physics Practice Guideline (MPPG) 11.a: Plan and chart review in external beam radiotherapy and brachytherapy. J Appl Clin Med Phys 2021; 22:4-19. [PMID: 34342124 PMCID: PMC8425907 DOI: 10.1002/acm2.13366] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Revised: 07/01/2021] [Accepted: 07/05/2021] [Indexed: 01/12/2023] Open
Abstract
A therapeutic medical physicist is responsible for reviewing radiation therapy treatment plans and patient charts, including initial treatment plans and new chart review, on treatment chart (weekly) review, and end of treatment chart review for both external beam radiation and brachytherapy. Task group report TG 275 examined this topic using a risk‐based approach to provide a thorough analysis and guidance for best practice. Considering differences in resources and workflows of various clinical practice settings, the Professional Council of the American Association of Physicists in Medicine assembled this task group to develop a practice guideline on the same topic to provide a minimum standard that balances an appropriate level of safety and resource utilization. This medical physics practice guidelines (MPPG) thus provides a concise set of recommendations for medical physicists and other clinical staff regarding the review of treatment plans and patient charts while providing specific recommendations about who to be involved, and when/what to check in the chart review process. The recommendations, particularly those related to the initial plan review process, are critical for preventing errors and ensuring smooth clinical workflow. We believe that an effective review process for high‐risk items should include multiple layers with collective efforts across the department. Therefore, in this report, we make specific recommendations for various roles beyond medical physicists. The recommendations of this MPPG have been reviewed and endorsed by the American Society of Radiologic Technologists and the American Association of Medical Dosimetrists.
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Affiliation(s)
- Ping Xia
- Department of Radiation Oncology, Cleveland Clinic, Cleveland, Ohio, USA
| | - Benjamin J Sintay
- Department of Radiation Oncology, Cone Health, Greensboro, North Carolina, USA
| | - Valdir C Colussi
- Department of Radiation Oncology, University Hospitals Cleveland Medical Center, Cleveland, Ohio, USA
| | - Cynthia Chuang
- Department of Radiation Oncology, Stanford University, Stanford, California, USA
| | - Yeh-Chi Lo
- Department of Radiation Oncology, Mount Sinai Hospital- New York, New York, New York, USA
| | - Deborah Schofield
- Department of Radiation Oncology, AdventHealth Orlando, Orlando, Florida, USA
| | - Michelle Wells
- Department of Radiation Oncology, Piedmont Healthcare, Atlanta, Georgia, USA
| | - Sumin Zhou
- Department of Radiation Oncology, University of Nebraska Medical Center, Omaha, Nebraska, USA
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Lim SB, LoSasso T, Chan M, Cervino L, Lovelock DM. Risk Management of Clinical Reference Dosimetry of a Large Hospital Network Using Statistical Process Control. ACTA ACUST UNITED AC 2021; 10:119-131. [PMID: 34395105 PMCID: PMC8360384 DOI: 10.4236/ijmpcero.2021.103011] [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: 12/04/2022]
Abstract
Managing TG-51 reference dosimetry in a large hospital network can be a challenging task. The objectives of this study are to investigate the effectiveness of using Statistical Process Control (SPC) to manage TG-51 workflow in such a network. All the sites in the network performed the annual reference dosimetry in water according to TG-51. These data were used to cross-calibrate the same ion chambers in plastic phantoms for monthly QA output measurements. An energy-specific dimensionless beam quality cross-calibration factor, kqnSW, was derived to monitor the process across multiple sites. The SPC analysis was then performed to obtain the mean, 〈kqnSW〉, standard deviation, σk, the Upper Control Limit (UCL) and Lower Control Limit (LCL) in each beam. This process was first applied to 15 years of historical data at the main campus to assess the effectiveness of the process. A two-year prospective study including all 30 linear accelerators spread over the main campus and seven satellites in the network followed. The ranges of the control limits (±3σ) were found to be in the range of 1.7% – 2.6% and 3.3% – 4.2% for the main campus and the satellite sites respectively. The wider range in the satellite sites was attributed to variations in the workflow. Standardization of workflow was also found to be effective in narrowing the control limits. The SPC is effective in identifying variations in the workflow and was shown to be an effective tool in managing large network reference dosimetry.
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Affiliation(s)
- Seng-Boh Lim
- Department of Medical Physics, Memorial Sloan Kettering Cancer Center, New York, USA
| | - Thomas LoSasso
- Department of Medical Physics, Memorial Sloan Kettering Cancer Center, New York, USA
| | - Maria Chan
- Department of Medical Physics, Memorial Sloan Kettering Cancer Center, New York, USA
| | - Laura Cervino
- Department of Medical Physics, Memorial Sloan Kettering Cancer Center, New York, USA
| | - Dale Michael Lovelock
- Department of Medical Physics, Memorial Sloan Kettering Cancer Center, New York, USA
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Omi Y, Yasui K, Shimomura A, Muramatsu R, Iwata H, Ogino H, Furukawa A, Hayashi N. Dosimetric effects of quality assurance-related setup errors in passive proton therapy for prostate cancer with and without a hydrogel spacer. Radiol Phys Technol 2021; 14:328-335. [PMID: 34313911 DOI: 10.1007/s12194-021-00632-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Revised: 07/20/2021] [Accepted: 07/21/2021] [Indexed: 11/30/2022]
Abstract
The purpose of this study was to evaluate the effect of quality assurance (QA)-related setup errors in passive proton therapy for prostate cancer with and without a hydrogel spacer. We used 20 typical computed tomography (CT) images of prostate cancer: 10 patients with and 10 patients without spacers. The following 12 model errors were assumed: output error ± 2%, range error ± 1 mm, setup error ± 1 mm for three directions, and multileaf collimator (MLC) position error ± 1 mm. We created verification plans with model errors and compared the prostate-rectal (PR) distance and dose indices with and without the spacer. The mean PR distance at the isocenter was 1.1 ± 1.3 mm without the spacer and 12.9 ± 2.9 mm with the spacer (P < 0.001). The mean rectum V53.5 GyE, V50 GyE, and V34.5 GyE in the original plan were 2.3%, 4.1%, and 12.1% without the spacer and 0.1%, 0.4%, and 3.3% with the spacer (P = 0.0011, < 0.001, and < 0.001). The effects of the range and lateral setup errors were small; however, the effects of the vertical/long setup and MLC error were significant in the cases without the spacer. The means of the maximum absolute change from original plans across all scenarios in the rectum V53.5 GyE, V50 GyE, and V34.5 GyE were 1.3%, 1.5%, and 2.3% without the spacer, and 0.2%, 0.4%, and 1.3% with the spacer (P < 0.001, < 0.001, and = 0.0019). This study indicated that spacer injections were also effective in reducing the change in the rectal dose due to setup errors.
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Affiliation(s)
- Yuta Omi
- Anjo Kosei Hospital, 28 Higashi-Hirokute, Anjo-cho, Anjo, Aichi, 446-8602, Japan
| | - Keisuke Yasui
- Faculty of Radiological Technology, School of Health Sciences, Fujita Health University, 1-98 Dengakugakubo, Kutsukake-cho, Toyoake, Aichi, 470-1192, Japan.
| | - Akira Shimomura
- Nagoya Proton Therapy Center, Nagoya City West Medical Center, 1-1-1, Hirate-cho, Kita-ku, Nagoya, Aichi, 462-8508, Japan
| | - Rie Muramatsu
- Nagoya Proton Therapy Center, Nagoya City West Medical Center, 1-1-1, Hirate-cho, Kita-ku, Nagoya, Aichi, 462-8508, Japan
| | - Hiromitsu Iwata
- Nagoya Proton Therapy Center, Nagoya City West Medical Center, 1-1-1, Hirate-cho, Kita-ku, Nagoya, Aichi, 462-8508, Japan
| | - Hiroyuki Ogino
- Nagoya Proton Therapy Center, Nagoya City West Medical Center, 1-1-1, Hirate-cho, Kita-ku, Nagoya, Aichi, 462-8508, Japan
| | - Akari Furukawa
- Faculty of Radiological Technology, School of Health Sciences, Fujita Health University, 1-98 Dengakugakubo, Kutsukake-cho, Toyoake, Aichi, 470-1192, Japan
| | - Naoki Hayashi
- Faculty of Radiological Technology, School of Health Sciences, Fujita Health University, 1-98 Dengakugakubo, Kutsukake-cho, Toyoake, Aichi, 470-1192, Japan
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Lee YS, Kim S, Kim GJ, Lee JH, Kim IS, Kim JI, Shin KY, Seol Y, Oh T, An NY, Lee J, Hwang J, Oh Y, Kang YN. Medical X-band linear accelerator for high-precision radiotherapy. Med Phys 2021; 48:5327-5342. [PMID: 34224166 DOI: 10.1002/mp.15077] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2020] [Revised: 05/27/2021] [Accepted: 06/14/2021] [Indexed: 11/07/2022] Open
Abstract
PURPOSE Recently, high-precision radiotherapy systems have been developed by integrating computerized tomography or magnetic resonance imaging to enhance the precision of radiotherapy. For integration with additional imaging systems in a limited space, miniaturization and weight reduction of the linear accelerator (linac) system have become important. The aim of this work is to develop a compact medical linac based on 9.3 GHz X-band RF technology instead of the S-band RF technology typically used in the radiotherapy field. METHODS The accelerating tube was designed by 3D finite-difference time-domain and particle-in-cell simulations because the frequency variation resulting from the structural parameters and processing errors is relatively sensitive to the operating performance of the X-band linac. Through the 3D simulation of the electric field distribution and beam dynamics process, we designed an accelerating tube to efficiently accelerate the electron beam and used a magnetron as the RF source to miniaturize the entire linac. In addition, a side-coupled structure was adopted to design a compact linac to reduce the RF power loss. To verify the performance of the linac, we developed a beam diagnostic system to analyze the electron beam characteristics and a quality assurance (QA) experimental environment including 3D lateral water phantoms to analyze the primary performance parameters (energy, dose rate, flatness, symmetry, and penumbra) The QA process was based on the standard protocols AAPM TG-51, 106, 142 and IAEA TRS-398. RESULTS The X-band linac has high shunt impedance and electric field strength. Therefore, even though the length of the accelerating tube is 37 cm, the linac could accelerate an electron beam to more than 6 MeV and produce a beam current of more than 90 mA. The transmission ratio is measured to be approximately 30% ~ 40% when the electron gun operates in the constant emission region. The percent depth dose ratio at the measured depths of 10 and 20 cm was approximately 0.572, so we verified that the photon beam energy was matched to approximately 6 MV. The maximum dose rate was measured as 820 cGy/min when the source-to-skin distance was 80 cm. The symmetry was smaller than the QA standard and the flatness had a higher than standard value due to the flattening filter-free beam characteristics. In the case of the penumbra, it was not sufficiently steep compared to commercial equipment, but it could be compensated by improving additional devices such as multileaf collimator and jaw. CONCLUSIONS A 9.3 GHz X-band medical linac was developed for high-precision radiotherapy. Since a more precise design and machining process are required for X-band RF technology, this linac was developed by performing a 3D simulation and ultraprecision machining. The X-band linac has a short length and a compact volume, but it can generate a validated therapeutic beam. Therefore, it has more flexibility to be coupled with imaging systems such as CT or MRI and can reduce the bore size of the gantry. In addition, the weight reduction can improve the mechanical stiffness of the unit and reduce the mechanical load.
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Affiliation(s)
- Yong-Seok Lee
- Electro-Medical Device Research Center, Korea Electrotechnology Research Institute, Ansan, Republic of Korea.,PLS-II Accelerator Division, Pohang Accelerator Laboratory, Pohang, Republic of Korea
| | - Sanghoon Kim
- Electro-Medical Device Research Center, Korea Electrotechnology Research Institute, Ansan, Republic of Korea
| | - Geun-Ju Kim
- Electro-Medical Device Research Center, Korea Electrotechnology Research Institute, Ansan, Republic of Korea
| | - Jeong-Hun Lee
- Electro-Medical Device Research Center, Korea Electrotechnology Research Institute, Ansan, Republic of Korea
| | - Insoo S Kim
- Electro-Medical Device Research Center, Korea Electrotechnology Research Institute, Ansan, Republic of Korea
| | - Jung-Il Kim
- Electro-Medical Device Research Center, Korea Electrotechnology Research Institute, Ansan, Republic of Korea
| | - Ki Young Shin
- Russia Science Seoul Center, Korea Electrotechnology Research Institute, Ansan, Republic of Korea
| | - Yunji Seol
- Department of Biomedicine & Health Sciences, The Catholic University of Korea, Seoul, Republic of Korea.,Advanced Institute for Radiation Fusion Medical Technology, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea
| | - Taegeon Oh
- Department of Biomedicine & Health Sciences, The Catholic University of Korea, Seoul, Republic of Korea.,Advanced Institute for Radiation Fusion Medical Technology, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea
| | - Na-Young An
- Department of Biomedicine & Health Sciences, The Catholic University of Korea, Seoul, Republic of Korea.,Advanced Institute for Radiation Fusion Medical Technology, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea
| | - Jaehyeon Lee
- Department of Biomedicine & Health Sciences, The Catholic University of Korea, Seoul, Republic of Korea.,Advanced Institute for Radiation Fusion Medical Technology, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea
| | - Jinho Hwang
- Department of Radiation Oncology, Incheon St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Incheon, Republic of Korea
| | - Youngah Oh
- Advanced Institute for Radiation Fusion Medical Technology, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea
| | - Young-Nam Kang
- Advanced Institute for Radiation Fusion Medical Technology, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea.,Department of Radiation Oncology, Seoul St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea
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Oresegun A, Tarif ZH, Ghassan L, Zin H, Abdul-Rashid HA, Bradley DA. Radioluminescence of cylindrical and flat Ge-doped silica optical fibers for real-time dosimetry applications. Appl Radiat Isot 2021; 176:109812. [PMID: 34166948 DOI: 10.1016/j.apradiso.2021.109812] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Revised: 05/31/2021] [Accepted: 06/01/2021] [Indexed: 11/19/2022]
Abstract
Investigation has been made of the radioluminescence dose response of Ge-doped silica flat and cylindrical fibers subjected to 6 and 10 MV photon beams. The fibers have been custom fabricated, obtaining Ge dopant concentrations of 6 and 10 mol%, subsequently cut into 20 mm lengths. Each sample has been exposed under a set of similar conditions, with use made of a fixed field size and source to surface distance (SSD). Investigation of dosimetric performance has involved radioluminescence linearity, dose-rate dependence, energy dependence, and reproducibility. Mass for mass, the 6 mol% Ge-doped samples provided the greater radioluminescence yield, with both flat and cylindrical fibers responding linearly to the absorbed dose. Further found has been that the cylindrical fibers provided a yield some 38% greater than that of the flat fibers. At 6 MV, the cylindrical fibers were also found to exhibit repeatability variation of <1%, superior to that of the flat fibers, offering strong potential for use in real-time dosimetry applications.
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Affiliation(s)
- Adebiyi Oresegun
- Fibre Optics Research Centre, Faculty of Engineering, Multimedia University, Jalan Multimedia, 63100, Cyberjaya, Malaysia
| | - Zubair H Tarif
- Fibre Optics Research Centre, Faculty of Engineering, Multimedia University, Jalan Multimedia, 63100, Cyberjaya, Malaysia; Lumisysns Technology Sdn Bhd, Cyberjaya, 63100, Selangor, Malaysia
| | - Louay Ghassan
- Fibre Optics Research Centre, Faculty of Engineering, Multimedia University, Jalan Multimedia, 63100, Cyberjaya, Malaysia
| | - Hafiz Zin
- Advanced Medical and Dental Institute, Universiti Sains Malaysia (USM), Bertam, 13200, Kepala Batas Penang, Malaysia
| | - Hairul Azhar Abdul-Rashid
- Fibre Optics Research Centre, Faculty of Engineering, Multimedia University, Jalan Multimedia, 63100, Cyberjaya, Malaysia.
| | - D A Bradley
- Centre for Applied Physics and Radiation Technologies, Sunway University, 46150, PJ, Malaysia; Department of Physics, University of Surrey, Guildford, GU2 7XH, UK
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Chan GH, Chin LCL, Abdellatif A, Bissonnette JP, Buckley L, Comsa D, Granville D, King J, Rapley PL, Vandermeer A. Survey of patient-specific quality assurance practice for IMRT and VMAT. J Appl Clin Med Phys 2021; 22:155-164. [PMID: 34145732 PMCID: PMC8292698 DOI: 10.1002/acm2.13294] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2021] [Revised: 04/03/2021] [Accepted: 05/06/2021] [Indexed: 12/03/2022] Open
Abstract
A first‐time survey across 15 cancer centers in Ontario, Canada, on the current practice of patient‐specific quality assurance (PSQA) for intensity modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT) delivery was conducted. The objectives were to assess the current state of PSQA practice, identify areas for potential improvement, and facilitate the continued improvement in standardization, consistency, efficacy, and efficiency of PSQA regionally. The survey asked 40 questions related to PSQA practice for IMRT/VMAT delivery. The questions addressed PSQA policy and procedure, delivery log evaluation, instrumentation, measurement setup and methodology, data analysis and interpretation, documentation, process, failure modes, and feedback. The focus of this survey was on PSQA activities related to routine IMRT/VMAT treatments on conventional linacs, including stereotactic body radiation therapy but excluding stereotactic radiosurgery. The participating centers were instructed to submit answers that reflected the collective view or opinion of their department and represented the most typical process practiced. The results of the survey provided a snapshot of the current state of PSQA practice in Ontario and demonstrated considerable variations in the practice. A large majority (80%) of centers performed PSQA measurements on all VMAT plans. Most employed pseudo‐3D array detectors with a true composite (TC) geometry. No standard approach was found for stopping or reducing frequency of measurements. The sole use of delivery log evaluation was not widely implemented, though most centers expressed interest in adopting this technology. All used the Gamma evaluation method for analyzing PSQA measurements; however, no universal approach was reported on how Gamma evaluation and pass determination criteria were determined. All or some PSQA results were reviewed regularly in two‐thirds of the centers. Planning related issues were considered the most frequent source for PSQA failures (40%), whereas the most frequent course of action for a failed PSQA was to review the result and decide whether to proceed to treatment.
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Affiliation(s)
- Gordon H Chan
- Department of Medical Physics, Juravinski Cancer Centre, Hamilton, Ontario, Canada
| | - Lee C L Chin
- Department of Medical Physics, Odette Cancer Centre, Toronto, Ontario, Canada
| | - Ady Abdellatif
- Department of Medical Physics, R.S. McLaughlin Durham Regional Cancer Centre, Oshawa, Ontario, Canada
| | - Jean-Pierre Bissonnette
- Department of Medical Physics, Princess Margaret Cancer Centre-UHN, Toronto, Ontario, Canada
| | - Lesley Buckley
- Department of Medical Physics, The Ottawa Hospital, Ottawa, Ontario, Canada
| | - Daria Comsa
- Radiation Physics Department, Southlake Regional Cancer Centre, Newmarket, Ontario, Canada
| | - Dal Granville
- Department of Medical Physics, The Ottawa Hospital, Ottawa, Ontario, Canada
| | - Jenna King
- Radiation Oncology Physics, Simcoe Muskoka Regional Cancer Centre, Barrie, Ontario, Canada
| | - Patrick L Rapley
- Medical Physics Department, Thunder Bay Regional Health Sciences Centre, Thunder Bay, Ontario, Canada
| | - Aaron Vandermeer
- Department of Medical Physics, R.S. McLaughlin Durham Regional Cancer Centre, Oshawa, Ontario, Canada
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Chojnowski JM, Sykes JR, Thwaites DI. A novel method to determine linac mechanical isocenter position and size and examples of specific QA applications. J Appl Clin Med Phys 2021; 22:44-55. [PMID: 34056850 PMCID: PMC8292690 DOI: 10.1002/acm2.13257] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Revised: 02/07/2021] [Accepted: 03/27/2021] [Indexed: 11/08/2022] Open
Abstract
The most important geometric characteristic of stereotactic treatment is the accuracy of positioning the target at the treatment isocenter and the accuracy of directing the radiation beam at the treatment isocenter. Commonly, the radiation isocenter is used as the reference for the treatment isocenter, but its method of localization is not strictly defined, and it depends on the linac-specific beam steering parameters. A novel method is presented for determining the linac mechanical isocenter position and size based on the localization of the collimator axis of rotation at arbitrary gantry angle. The collimator axis of rotation position is determined from the radiation beam center position corrected for the focal spot offset. The focal spot offset is determined using the image center shift method with a custom-design rigid phantom with two sets of ball-bearings. Three specific quality assurance (QA) applications and assessment methods are also presented to demonstrate the functionality of linac mechanical isocenter position and size determination in clinical practice. The first is a mechanical and radiation isocenters coincidence test suitable for quick congruence assessment of these two isocenters for a selected energy, usually required after a nonroutine linac repair and/or energy adjustment. The second is a stereotactic beam isocentricity assessment suitable for pretreatment stereotactic QA. The third is a comprehensive linac geometrical performance test suitable for routine linac QA. The uncertainties of the method for determining mechanical isocenter position and size were measured to be 0.05 mm and 0.04 mm, respectively, using four available photon energies, and were significantly smaller than those of determining the radiation isocenter position and size, which were 0.36 mm and 0.12 mm respectively. It is therefore recommended that the mechanical isocenter position and size be used as the reference linac treatment isocenter and a linac mechanical characteristic parameter respectively.
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Affiliation(s)
- Jacek M Chojnowski
- Mid North Coast Cancer Institute, Coffs Harbour Health Campus, Coffs Harbour, NSW, Australia.,Institute of Medical Physics, School of Physics, University of Sydney, Sydney, NSW, 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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Hanley J, Dresser S, Simon W, Flynn R, Klein EE, Letourneau D, Liu C, Yin FF, Arjomandy B, Ma L, Aguirre F, Jones J, Bayouth J, Holmes T. AAPM Task Group 198 Report: An implementation guide for TG 142 quality assurance of medical accelerators. Med Phys 2021; 48:e830-e885. [PMID: 34036590 DOI: 10.1002/mp.14992] [Citation(s) in RCA: 47] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Revised: 03/16/2021] [Accepted: 04/28/2021] [Indexed: 11/11/2022] Open
Abstract
The charges on this task group (TG) were as follows: (a) provide specific procedural guidelines for performing the tests recommended in TG 142; (b) provide estimate of the range of time, appropriate personnel, and qualifications necessary to complete the tests in TG 142; and (c) provide sample daily, weekly, monthly, or annual quality assurance (QA) forms. Many of the guidelines in this report are drawn from the literature and are included in the references. When literature was not available, specific test methods reflect the experiences of the TG members (e.g., a test method for door interlock is self-evident with no literature necessary). In other cases, the technology is so new that no literature for test methods was available. Given broad clinical adaptation of volumetric modulated arc therapy (VMAT), which is not a specific topic of TG 142, several tests and criteria specific to VMAT were added.
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Affiliation(s)
- Joseph Hanley
- Princeton Radiation Oncology, Monroe, New Jersey, 08831, USA
| | - Sean Dresser
- Winship Cancer Institute, Radiation Oncology, Emory University, Atlanta, Georgia, 30322, USA
| | | | - Ryan Flynn
- Department of Radiation Oncology, University of Iowa, Iowa City, Iowa, 52242, USA
| | - Eric E Klein
- Brown university, Rhode Island Hospital, Providence, Rhode Island, 02905, USA
| | | | - Chihray Liu
- University of Florida, Gainesville, Florida, 32610-0385, USA
| | - Fang-Fang Yin
- Department of Radiation Oncology, Duke University Medical Center, Durham, North Carolina, 27710, USA
| | - Bijan Arjomandy
- Karmanos Cancer Institute at McLaren-Flint, Flint, Michigan, 48532, USA
| | - Lijun Ma
- Department of Radiation Oncology, University of California San Francisco, San Francisco, 94143-0226, USA
| | | | - Jimmy Jones
- Department of Radiation Oncology, The University of Colorado Health-Poudre Valley, Fort Collins, Colorado, 80525, USA
| | - John Bayouth
- Department of Human Oncology, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, Wisconsin, 53792-0600, USA
| | - Todd Holmes
- Varian Medical Systems, Palo Alto, California, 94304, USA
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Hernandez V, Saez J, Angerud A, Cayez R, Khamphan C, Nguyen D, Vieillevigne L, Feygelman V. Dosimetric leaf gap and leaf trailing effect in a double-stacked multileaf collimator. Med Phys 2021; 48:3413-3424. [PMID: 33932237 DOI: 10.1002/mp.14914] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2021] [Revised: 04/02/2021] [Accepted: 04/23/2021] [Indexed: 01/21/2023] Open
Abstract
PURPOSE To investigate (i) the dosimetric leaf gap (DLG) and the effect of the "trailing distance" between leaves from different multileaf collimator (MLC) layers in Halcyon systems and (ii) the ability of the currently available treatment planning systems (TPSs) to approximate this effect. METHODS DICOM plans with transmission beams and sweeping gap tests were created in Python for measuring the DLG for each MLC layer independently and for both layers combined. In clinical Halcyon plans both MLC layers are interchangeably used and leaves from different layers are offset, thus forming a trailing pattern. To characterize the impact of such configuration, new tests called "trailing sweeping gaps" were designed and created where the leaves from one layer follow the leaves from the other layer at a fixed "trailing distance" t between the tips. Measurements were carried out on five Halcyons SX2 from different institutions and calculations from both the Eclipse and RayStation TPSs were compared with measurements. RESULTS The dose accumulated during a sweeping gap delivery progressively increased with the trailing distance t . We call this "the trailing effect." It is most pronounced for t between 0 and 5 mm, although some changes were obtained up to 20 mm. The dose variation was independent of the gap size. The measured DLG values also increased with t up to 20 mm, again with the steepest variation between 0 and 5 mm. Measured DLG values were negative at t = 0 (the leaves from both layers at the same position) but changed sign for t ≥ 1 mm, in line with the positive DLG sign usually observed with single-layer rounded-end MLCs. The Eclipse TPS does not explicitly model the leaf tip and, as a consequence, could not predict the dose reduction due to the trailing effect. This resulted in dose discrepancies up to +10% and -8% for the 5 mm sweeping gap and up to ±5% for the 10 mm one depending on the distance t . RayStation implements a simple model of the leaf tip that was able to approximate the trailing effect and improved the agreement with measured doses. In particular, with a prototype version of RayStation that assigned a higher transmission at the leaf tip the agreement with measured doses was within ±3% even for the 5 mm gap. The five Halcyon systems behaved very similarly but differences in the DLG around 0.2 mm were found across different treatment units and between MLC layers from the same system. The DLG for the proximal layer was consistently higher than for the distal layer, with differences ranging between 0.10 mm and 0.24 mm. CONCLUSIONS The trailing distance between the leaves from different layers substantially affected the doses delivered by sweeping gaps and the measured DLG values. Stacked MLCs introduce a new level of complexity in TPSs, which ideally need to implement an explicit model of the leaf tip in order to reproduce the trailing effect. Dynamic tests called "trailing sweeping gaps" were designed that are useful for characterizing and commissioning dual-layer MLC systems.
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Affiliation(s)
- Victor Hernandez
- Department of Medical Physics, Hospital Sant Joan de Reus, IISPV, 43204, Tarragona, Spain
| | - Jordi Saez
- Department of Radiation Oncology, Hospital Clínic de Barcelona, 08036, Barcelona, Spain
| | | | - Romain Cayez
- Department of Medical Physics, Oscar Lambret Center, 59000, Lille, France
| | - Catherine Khamphan
- Medical Physics Department, Institut Sainte-Catherine, 84000, Avignon, France
| | - Daniel Nguyen
- Centre de Radiothérapie de Mâcon, 71000, Mâcon, France
| | - Laure Vieillevigne
- Department of Medical Physics, Institut Claudius Regaud-Institut Universitaire du Cancer de Toulouse, 31059, Toulouse, France.,Centre de Recherche en Cancérologie de Toulouse UMR1037 INSERM, Université Toulouse 3-ERL5294 CNRS, Oncopole, 31037, Toulouse, France
| | - Vladimir Feygelman
- Department of Radiation Oncology, Moffitt Cancer Center, Tampa, 12902, Florida, USA
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Alexander DA, Bruza P, Rassias AG, Andreozzi JM, Pogue BW, Zhang R, Gladstone DJ. Visual Isocenter Position Enhanced Review (VIPER): a Cherenkov imaging-based solution for MR-linac daily QA. Med Phys 2021; 48:2750-2759. [PMID: 33887796 DOI: 10.1002/mp.14892] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2020] [Revised: 02/28/2021] [Accepted: 04/05/2021] [Indexed: 11/07/2022] Open
Abstract
PURPOSE This study demonstrates a robust Cherenkov imaging-based solution to MR-Linac daily QA, including mechanical-imaging-radiation isocenter coincidence verification. METHODS A fully enclosed acrylic cylindrical phantom was designed to be mountable to the existing jig, indexable to the treatment couch. An ABS plastic conical structure was fixed inside the phantom, held in place with 3D-printed spacers, and filled with water allowing for high edge contrast on MR imaging scans. Both a star shot plan and a four-angle sheet beam plan were delivered to the phantom; the former allowed for radiation isocenter localization in the x-z plane (A/P and L/R directions) relative to physical landmarks on the phantom, and the latter allowed for the longitudinal position of the sheet beam to be encoded as a ring of Cherenkov radiation emitted from the phantom, allowing for isocenter localization on the y-axis (S/I directions). A custom software application was developed to perform near-real-time analysis of the data by any clinical user. RESULTS Calibration procedures show that linearity between longitudinal position and optical ring diameter is high (R2 > 0.99), and that RMSE is low (0.184 mm). The star shot analysis showed a minimum circle radius of 0.34 mm. The final isocenter coincidence measurements in the lateral, longitudinal, and vertical directions were -0.61 mm, 0.55 mm, and -0.14 mm, respectively, and the total 3D distance coincidence was 0.83 mm, with each of these being below 2 mm tolerance. CONCLUSION This novel system provided an efficient, MR safe, all-in-one method for acquisition and near-real-time analysis of isocenter coincidence data. This represents a direct measurement of the 3D isocentricity. The combination of this phantom and the custom analysis application makes this solution readily clinically deployable after the longitudinal analysis of performance consistency.
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Affiliation(s)
| | - Petr Bruza
- Thayer School of Engineering, Dartmouth College, Hanover, NH, USA
| | - Aris G Rassias
- Thayer School of Engineering, Dartmouth College, Hanover, NH, USA
| | | | - Brian W Pogue
- Thayer School of Engineering, Dartmouth College, Hanover, NH, USA
- Geisel School of Medicine, Dartmouth College, Hanover, NH, USA
- Norris Cotton Cancer Center, Dartmouth-Hitchcock Medical Center, Lebanon, NH, USA
| | - Rongxiao Zhang
- Thayer School of Engineering, Dartmouth College, Hanover, NH, USA
- Geisel School of Medicine, Dartmouth College, Hanover, NH, USA
- Norris Cotton Cancer Center, Dartmouth-Hitchcock Medical Center, Lebanon, NH, USA
| | - David J Gladstone
- Thayer School of Engineering, Dartmouth College, Hanover, NH, USA
- Geisel School of Medicine, Dartmouth College, Hanover, NH, USA
- Norris Cotton Cancer Center, Dartmouth-Hitchcock Medical Center, Lebanon, NH, USA
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43
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Alharthi T, Vial P, Holloway L, Thwaites D. Intrinsic detector sensitivity analysis as a tool to characterize ArcCHECK and EPID sensitivity to variations in delivery for lung SBRT VMAT plans. J Appl Clin Med Phys 2021; 22:229-240. [PMID: 33949087 PMCID: PMC8200424 DOI: 10.1002/acm2.13221] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2020] [Revised: 02/08/2021] [Accepted: 02/12/2021] [Indexed: 12/16/2022] Open
Abstract
PURPOSE To investigate intrinsic sensitivity of an electronic portal imaging device (EPID) and the ArcCHECK detector and to use this in assessing their performance in detecting delivery variations for lung SBRT VMAT. The effect of detector spatial resolution and dose matrix interpolation on the gamma pass rate was also considered. MATERIALS AND METHODS Fifteen patients' lung SBRT VMAT plans were used. Delivery variations (errors) were introduced by modifying collimator angles, multi-leaf collimator (MLC) field sizes and MLC field shifts by ±5, ±2, and ±1 degrees or mm (investigating 103 plans in total). EPID and ArcCHECK measured signals with introduced variations were compared to measured signals without variations (baseline), using OmniPro-I'mRT software and gamma criteria of 3%/3 mm, 2%/2 mm, 2%/1 mm, and 1%/1 mm, to test each system's basic performance. The measurement sampling resolution for each was also changed to 1 mm and results compared to those with the default detector system resolution. RESULTS Intrinsic detector sensitivity analysis, that is, comparing measurement to baseline measurement, rather than measurement to plan, demonstrated the intrinsic constraints of each detector and indicated the limiting performance that users might expect. Changes in the gamma pass rates for ArcCHECK, for a given introduced error, were affected only by dose difference (DD %) criteria. However, the EPID showed only slight changes when changing DD%, but greater effects when changing distance-to-agreement criteria. This is pertinent for lung SBRT where the minimum dose to the target will drop dramatically with geometric errors. Detector resolution and dose matrix interpolation have an impact on the gamma results for these SBRT plans and can lead to false positives or negatives in error detection if not understood. CONCLUSION The intrinsic sensitivity approach may help in the selection of more meaningful gamma criteria and the choice of optimal QA device for site-specific dose verification.
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Affiliation(s)
- Thahabah Alharthi
- Institute of Medical Physics, School of Physics, The University of Sydney, Sydney, NSW, Australia.,School of Medicine, Taif University, Taif, Saudi Arabia.,Liverpool and Macarthur Cancer Therapy Centers, Liverpool, NSW, Australia.,Ingham Institute for Applied Medical Research, Sydney, NSW, Australia
| | - Phil Vial
- Liverpool and Macarthur Cancer Therapy Centers, Liverpool, NSW, Australia.,Ingham Institute for Applied Medical Research, Sydney, NSW, Australia.,South Western Sydney Clinical School, University of New South Wales, Sydney, NSW, Australia
| | - Lois Holloway
- Institute of Medical Physics, School of Physics, The University of Sydney, Sydney, NSW, Australia.,Liverpool and Macarthur Cancer Therapy Centers, Liverpool, NSW, Australia.,Ingham Institute for Applied Medical Research, Sydney, NSW, Australia.,South Western Sydney Clinical School, University of New South Wales, Sydney, NSW, Australia.,Centre for Medical Radiation Physics, University of Wollongong, Wollongong, NSW, Australia
| | - David Thwaites
- Institute of Medical Physics, School of Physics, The University of Sydney, Sydney, NSW, Australia
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Hao Y, Cai B, Green O, Knutson N, Yaddanapudi S, Zhao T, Rodriguez V, Schmidt M, Mutic S, Sun B. Technical Note: An alternative approach to verify 6FFF beam dosimetry for Ethos and MR Linac without using a 3D water tank. Med Phys 2021; 48:1533-1539. [PMID: 33547684 DOI: 10.1002/mp.14757] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2020] [Revised: 12/17/2020] [Accepted: 01/29/2021] [Indexed: 12/24/2022] Open
Abstract
PURPOSE The current approach to Linac beam dosimetry verification is typically performed utilizing a three-dimensional (3D) water tank system. The 3D beam scanning process is cumbersome, labor intensive, error-prone, and costly. This is especially challenging for the new Ethos system and MR Linacs with a ring gantry. This work proposes an alternative approach to verify 6FFF beam dosimetry for Ethos, ViewRay MRIdian® Linac, and other Linacs with 6FFF beam quality using two-dimensional (2D) ion chamber arrays. METHODS Percentage depth dose (PDD) and profiles of an Ethos, an MRIdian® Linac, and several Linacs with 6FFF beams were measured at the nominal beam current. The beam energy was detuned by changing the bending magnet current on one TrueBeam. PDDs and profiles were measured for detuned beam energies. The peak shape of the 6FFF profile was defined by a "slope" parameter and unflatness. Correlations between peak slope and unflatness metrics vs PDDs were used to evaluate the sensitivity of beam energy to beam profile changes at different field sizes and depths. RESULTS Strong correlations were found between peak slope and PDDs for all Linacs with 6FFF beam. The R-squared values in the linear regression fitting between PDD and peak slope and unflatness were 0.99 and 0.84, respectively. Both profile slope and unflatness were proportional to PDD at the 10 cm depth and the peak slope was 4.3 times more sensitive than PDD. We have identified that measurements with a shallow depth are preferred to quantify the beam energy consistency. CONCLUSIONS Our work shows the feasibility of verifying 6FFF beam quality of Ethos, MR Linac, and other Linacs by defining a profile slope measured from 2D ionization chambers array devices. This new approach provides a simplified method for performing a routine beam quality check without using a 3D water tank system while maximizing cost effectiveness and efficiency.
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Affiliation(s)
- Yao Hao
- Department of Radiation Oncology, Washington University School of Medicine, 660 S. Euclid Ave, St. Louis, MO, 63110, USA
| | - Bin Cai
- Department of Radiation Oncology, Washington University School of Medicine, 660 S. Euclid Ave, St. Louis, MO, 63110, USA
| | - Olga Green
- Department of Radiation Oncology, Washington University School of Medicine, 660 S. Euclid Ave, St. Louis, MO, 63110, USA
| | - Nels Knutson
- Department of Radiation Oncology, Washington University School of Medicine, 660 S. Euclid Ave, St. Louis, MO, 63110, USA
| | - Sridhar Yaddanapudi
- Department of Radiation Oncology, University of Iowa, 200 Hawkins Drive, LL-W Pomerantz Family Pavilion, Iowa City, IA, 52242-1089, USA
| | - Tianyu Zhao
- Department of Radiation Oncology, Washington University School of Medicine, 660 S. Euclid Ave, St. Louis, MO, 63110, USA
| | - Vivian Rodriguez
- Department of Radiation Oncology, Washington University School of Medicine, 660 S. Euclid Ave, St. Louis, MO, 63110, USA
| | - Matthew Schmidt
- Department of Radiation Oncology, Washington University School of Medicine, 660 S. Euclid Ave, St. Louis, MO, 63110, USA
| | - Sasa Mutic
- Department of Radiation Oncology, Washington University School of Medicine, 660 S. Euclid Ave, St. Louis, MO, 63110, USA
| | - Baozhou Sun
- Department of Radiation Oncology, Washington University School of Medicine, 660 S. Euclid Ave, St. Louis, MO, 63110, USA
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45
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Han SC, Kim J, Han MC, Chang KH, Park K, Kim HJ, Kim DW, Kim JS. Monitoring beam-quality constancy considering uncertainties associated with ionization chambers in Daily QA3 device. PLoS One 2021; 16:e0246845. [PMID: 33596210 PMCID: PMC7888663 DOI: 10.1371/journal.pone.0246845] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2020] [Accepted: 01/26/2021] [Indexed: 11/21/2022] Open
Abstract
This study evaluates the changes occurring in the X-ray energy of a linear accelerator (LINAC) using a Daily QA3 detector system. This is accomplished by comparing the Daily QA3 results against those obtained using a water phantom. The X-energy levels of a LINAC were monitored over a duration of 1 month using the Daily QA3 system. Moreover, to account for the uncertainty, the reproducibility of the Daily QA3 ionization-chamber results was assessed by performing repeated measurements (12 per day). Subsequently, the energy-monitoring results were compared with the energy-change results calculated using the water-phantom percentage depth dose (PDD) ratio. As observed, the 6- and 10-MV beams experienced average daily energy-level changes of (-0.30 ± 0.32)% and (0.05 ± 0.38)%, respectively, during repeated measurements. The corresponding energy changes equaled (-0.30 ± 0.55)% and (-0.05 ± 0.48)%, respectively, when considering the measurement uncertainty. The Daily QA3 measurements performed at 6 MV demonstrated a variation of (2.15 ± 0.81)% (i.e., up to 3%). Meanwhile, the corresponding measurements performed using a water phantom demonstrated an increase in the PDD ratio from 0.577 to 0.580 (i.e., approximately 0.5%). At 10 MV, the energy variation in the Daily QA3 measurements equaled (-0.41 ± 0.82)% (i.e., within 1.5%), whereas the corresponding water phantom PDD ratio remained constant at 0.626. These results reveal that the Daily QA3 system can be used to monitor small energy changes occurring within radiotherapy machines. This demonstrates its potential for use as a secondary system for monitoring energy changes as part of the daily quality-assurance workflow.
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Affiliation(s)
- Su Chul Han
- Department of Radiation Oncology, Yonsei University College of Medicine, Seoul, Republic of Korea
| | - Jihun Kim
- Department of Radiation Oncology, Yonsei University College of Medicine, Seoul, Republic of Korea
| | - Min Cheol Han
- Department of Radiation Oncology, Yonsei University College of Medicine, Seoul, Republic of Korea
| | - Kyung Hwan Chang
- Department of Healthcare Solution, Douzone Bizon, Seoul, Republic of Korea
| | - Kwangwoo Park
- Department of Radiation Oncology, Yonsei University College of Medicine, Seoul, Republic of Korea
| | - Ho Jin Kim
- Department of Radiation Oncology, Yonsei University College of Medicine, Seoul, Republic of Korea
| | - Dong Wook Kim
- Department of Radiation Oncology, Yonsei University College of Medicine, Seoul, Republic of Korea
- * E-mail: (DWK); (JSK)
| | - Jin Sung Kim
- Department of Radiation Oncology, Yonsei University College of Medicine, Seoul, Republic of Korea
- * E-mail: (DWK); (JSK)
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46
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Wright B, Hassan GM, Mukwada G, Ebert M, Goodall S, Sabet M, Rowshanfarzad P. Comprehensive investigation into the stability of Varian and Elekta kV imaging systems during arc delivery. Biomed Phys Eng Express 2020; 6. [DOI: 10.1088/2057-1976/abbabd] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Accepted: 09/22/2020] [Indexed: 01/05/2023]
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47
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Taylor M, Williams J, Gleason JF. Effects of Multileaf Collimator Design and Function When Using an Optimized Dynamic Conformal Arc Approach for Stereotactic Radiosurgery Treatment of Multiple Brain Metastases With a Single Isocenter: A Planning Study. Cureus 2020; 12:e9833. [PMID: 32832305 PMCID: PMC7437117 DOI: 10.7759/cureus.9833] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2020] [Accepted: 08/17/2020] [Indexed: 12/11/2022] Open
Abstract
Background Stereotactic radiosurgery (SRS) or fractionated SRS (fSRS) are effective options for the treatment of brain metastases. When treating multiple metastases with a linear accelerator-based approach, a single isocenter allows for efficient treatment delivery. In this study, we present our findings comparing dosimetric parameters of Brainlab (Munich, Germany) Elements™ Multiple Brain Mets SRS (MME) software (version 1.5 versus version 2.0) for a variety of scenarios and patients. The impact of multileaf collimator design and function on plan quality within the software was also evaluated. Materials and methods Twenty previously treated patients with a total of 58 lesions (from one to seven lesions each) were replanned with an updated version of the multiple brain Mets software solution. For each plan, the mean conformity index (CI), mean gradient index (GI), the volume of normal brain receiving 12 Gy (V12), and mean brain dose were evaluated. Additionally, all v2.0 plans were further evaluated with jaw tracking for by Elekta (Stockholm, Sweden) and HD120™ multileaf collimator by Varian Medical Systems (Palo Alto, USA). Results The new software version demonstrated improvements for CI, GI and V12 (p <0.01). For the Elekta Agility™ multileaf collimator, jaw tracking improved all dosimetric parameters except for CI (p =0.178) and mean brain dose (p =0.93). For the Varian with HD120 multileaf collimator, all parameters improved. Conclusions The software enhancements in v2.0 of the software provided improvements in planning efficiency and dosimetric parameters. Differences in multileaf collimator design may provide an additional incremental benefit in a subset of clinical scenarios.
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Affiliation(s)
| | | | - John F Gleason
- Radiation Oncology, Alliance Cancer Care, Huntsville, USA
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48
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Alexander DA, Zhang R, Brůža P, Pogue BW, Gladstone DJ. Scintillation imaging as a high‐resolution, remote, versatile 2D detection system for MR‐linac quality assurance. Med Phys 2020; 47:3861-3869. [PMID: 32583484 PMCID: PMC10363284 DOI: 10.1002/mp.14353] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2020] [Revised: 05/31/2020] [Accepted: 06/11/2020] [Indexed: 02/04/2023] Open
Abstract
PURPOSE To demonstrate the potential benefits of remote camera-based scintillation imaging for routine quality assurance (QA) measurements for magnetic resonance guided radiotherapy (MRgRT) linear accelerators. METHODS A wall-mounted CMOS camera with a time-synchronized intensifier was used to image photons produced from a scintillation screen in response to dose deposition from a 6 MV FFF x-ray beam produced by a 0.35 T MR-linac. The oblique angle of the field of view was corrected using a projective transform from a checkerboard calibration target. Output sensitivity and constancy was measured using the scintillator and benchmarked against an A28 ion chamber. Field cross-plane and in-plane profiles were measured for field sizes ranging from 1.68 × 1.66 cm2 to 20.02 × 19.92 cm2 with both scintillation imaging and using an IC profiler. Multileaf collimator (MLC) shifts were introduced to test sensitivity of the scintillation imaging system to small spatial deviations. A picket fence test and star-shot were delivered to both the scintillator and EBT3 film to compare accuracy in measuring MLC positions and isocenter size. RESULTS The scintillation imaging system showed comparable sensitivity and linearity to the ion chamber in response to changes in machine output down to 0.5 MU (R2 = 0.99). Cross-plane profiles show strong agreement with defined field sizes using full width half maximum (FWHM) measurement of <2 mm for field sizes below 15 cm, but the oblique viewing angle was the limiting factor in accuracy of in-plane profile widths. However, the system provided high-resolution profiles in both directions for constancy measurements. Small shifts in the field position down to 0.5 mm were detectable with <0.1 mm accuracy. Multileaf collimator positions as measured with both scintillation imaging and EBT3 film were measured within ± 1 mm tolerance and both detection systems produced similar isocenter sizes from the star-shot analysis (0.81 and 0.83 mm radii). CONCLUSIONS Remote scintillation imaging of a two-dimensional screen provided a rapid, versatile, MR-compatible solution to many routine quality assurance procedures including output constancy, profile flatness and symmetry constancy, MLC position verification and isocenter size. This method is high-resolution, does not require post-irradiation readout, and provides simple, instantaneous data acquisition. Full automation of the readout and processing could make this a very simple but effective QA tool, and is adaptable to all medical accelerators.
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Affiliation(s)
| | - Rongxiao Zhang
- Thayer School of Engineering and Geisel School of Medicine Dartmouth College Hanover NH03755USA
- Norris Cotton Cancer Center Dartmouth‐Hitchcock Medical Center Lebanon NH03756USA
| | - Petr Brůža
- Thayer School of Engineering Dartmouth College Hanover NH03755USA
| | - Brian W. Pogue
- Thayer School of Engineering and Geisel School of Medicine Dartmouth College Hanover NH03755USA
- Norris Cotton Cancer Center Dartmouth‐Hitchcock Medical Center Lebanon NH03756USA
| | - David J. Gladstone
- Thayer School of Engineering and Geisel School of Medicine Dartmouth College Hanover NH03755USA
- Norris Cotton Cancer Center Dartmouth‐Hitchcock Medical Center Lebanon NH03756USA
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49
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Puyati W, Khawne A, Barnes M, Zwan B, Greer P, Fuangrod T. Predictive quality assurance of a linear accelerator based on the machine performance check application using statistical process control and ARIMA forecast modeling. J Appl Clin Med Phys 2020; 21:73-82. [PMID: 32543097 PMCID: PMC7484849 DOI: 10.1002/acm2.12917] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2019] [Revised: 12/04/2019] [Accepted: 04/21/2020] [Indexed: 12/16/2022] Open
Abstract
Purpose A predictive linac quality assurance system based on the output of the Machine Performance Check (MPC) application was developed using statistical process control and autoregressive integrated moving average forecast modeling. The aim of this study is to demonstrate the feasibility of predictive quality assurance based on MPC tests that allow proactive preventative maintenance procedures to be carried out to better ensure optimal linac performance and minimize downtime. Method and Materials Daily MPC data were acquired for a total of 490 measurements. The initial 85% of data were used in prediction model learning with the autoregressive integrated moving average technique and in calculating upper and lower control limits for statistical process control analysis. The remaining 15% of data were used in testing the accuracy of the predictions of the proposed system. Two types of prediction were studied, namely, one‐step‐ahead values for predicting the next day's quality assurance results and six‐step‐ahead values for predicting up to a week ahead. Results that fall within the upper and lower control limits indicate a normal stage of machine performance, while the tolerance, determined from AAPM TG‐142, is the clinically required performance. The gap between the control limits and the clinical tolerances (as the warning stage) provides a window of opportunity for rectifying linac performance issues before they become clinically significant. The accuracy of the predictive model was tested using the root‐mean‐square error, absolute error, and average accuracy rate for all MPC test parameters. Results The accuracy of the predictive model is considered high (average root‐mean‐square error and absolute error for all parameters of less than 0.05). The average accuracy rate for indicating the normal/warning stages was higher than 85.00%. Conclusion Predictive quality assurance with the MPC will allow preventative maintenance, which could lead to improved linac performance and a reduction in unscheduled linac downtime.
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Affiliation(s)
- Wayo Puyati
- Department of Computer Engineering, Faculty of Engineering, King Mongkut's Institute of Technology Ladkrabang, Bangkok, 10520, Thailand.,Department of Mathematics Statistics and Computer, Faculty of Science, Ubon Ratchathani University, Ubon Ratchathani, 34190, Thailand
| | - Amnach Khawne
- Department of Computer Engineering, Faculty of Engineering, King Mongkut's Institute of Technology Ladkrabang, Bangkok, 10520, Thailand
| | - Michael Barnes
- Department of Radiation Oncology, Calvary Mater Hospital Newcastle, NSW, 2298, Australia.,School of Mathematical and Physical Sciences, University of Newcastle, Newcastle, NSW, 2308, Australia
| | - Benjamin Zwan
- School of Mathematical and Physical Sciences, University of Newcastle, Newcastle, NSW, 2308, Australia.,Central Coast Cancer Centre, Gosford Hospital, Gosford, NSW, 2250, Australia
| | - Peter Greer
- Department of Radiation Oncology, Calvary Mater Hospital Newcastle, NSW, 2298, Australia.,School of Mathematical and Physical Sciences, University of Newcastle, Newcastle, NSW, 2308, Australia
| | - Todsaporn Fuangrod
- Faculty of Medicine and Public Health, HRH Princess Chulabhorn College of Medical Science, Chulabhorn Royal Academy, Bangkok, 10210, Thailand
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50
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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: 2] [Impact Index Per Article: 0.5] [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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