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Tsuneda M, Nishio T, Ezura T, Karasawa K. Plastic scintillation dosimeter with a conical mirror for measuring 3D dose distribution. Med Phys 2021; 48:5639-5650. [PMID: 34389992 DOI: 10.1002/mp.15164] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Revised: 03/22/2021] [Accepted: 08/01/2021] [Indexed: 11/11/2022] Open
Abstract
PURPOSE To test the measurement technique of the three-dimensional (3D) dose distribution measured image by capturing the scintillation light generated using a plastic scintillator and a scintillating screen. METHODS Our imaging system constituted a column shaped plastic scintillator covered by a Gd2 O2 S:Tb scintillating screen, a conical mirror and a cooled CCD camera. The scintillator was irradiated with 6 MV photon beams. Meanwhile, the irradiated plan was prepared for the static field plans, two-field plan (2F plan) and the conformal arc plan (CA plan). The 2F plan contained 16 mm2 and 10 mm2 fields irradiated from gantry angles of 0° and 25°, respectively. The gantry was rotated counterclockwise from 45° to 315° for the CA plan. The field size was then obtained as 10 mm2 . A Monte Carlo simulation was performed in the experimental geometry to obtain the calculated 3D dose distribution as the reference data. Dose response was acquired by comparing between the reference and the measurement. The dose rate dependence was verified by irradiating the same MU value at different dose rates ranging from 100 to 600 MU/min. Deconvolution processing was applied to the measured images for the correction of light blurring. The measured 3D dose distribution was reconstructed from each measured image. Gamma analysis was performed to these 3D dose distributions. The gamma criteria were 3% for the dose difference, 2 mm for the distance-to-agreement and 10% for the threshold. RESULTS Dose response for the scintillation light was linear. The variation in the light intensity for the dose rate ranging from 100 to 600 MU/min was less than 0.5%, while our system presents dose rate independence. For the 3D dose measurement, blurring of light through deconvolution processing worked well. The 3D gamma passing rate (3D GPR) for the 10 × 10 mm2 , 16 × 16 mm2 , and 20 × 20 mm2 fields were observed to be 99.3%, 98.8%, and 97.8%, respectively. Reproducibility of measurement was verified. The 3D GPR results for the 2F plan and the CA plan were 99.7% and 100%, respectively. CONCLUSIONS We developed a plastic scintillation dosimeter and demonstrated that our system concept can act as a suitable technique for measuring the 3D dose distribution from the gamma results. In the future, we will attempt to measure the 4D dose distribution for clinical volumetric modulated arc radiation therapy (VMAT)-SBRTplans.
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Affiliation(s)
- Masato Tsuneda
- Department of Radiation Oncology, Tokyo Women's Medical University, Shinjuku-ku, Tokyo, Japan
| | - Teiji Nishio
- Department of Medical Physics, Tokyo Women's Medical University, Shinjuku-ku, Tokyo, Japan
| | - Takatomo Ezura
- Division of Radiation Medical Physics, Kanagawa Cancer Center, Yokohama, Kanagawa, Japan
| | - Kumiko Karasawa
- Department of Radiation Oncology, Tokyo Women's Medical University, Shinjuku-ku, Tokyo, Japan
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Das IJ, Francescon P, Moran JM, Ahnesjö A, Aspradakis MM, Cheng CW, Ding GX, Fenwick JD, Saiful Huq M, Oldham M, Reft CS, Sauer OA. Report of AAPM Task Group 155: Megavoltage photon beam dosimetry in small fields and non-equilibrium conditions. Med Phys 2021; 48:e886-e921. [PMID: 34101836 DOI: 10.1002/mp.15030] [Citation(s) in RCA: 51] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2021] [Revised: 05/06/2021] [Accepted: 06/02/2021] [Indexed: 12/14/2022] Open
Abstract
Small-field dosimetry used in advance treatment technologies poses challenges due to loss of lateral charged particle equilibrium (LCPE), occlusion of the primary photon source, and the limited choice of suitable radiation detectors. These challenges greatly influence dosimetric accuracy. Many high-profile radiation incidents have demonstrated a poor understanding of appropriate methodology for small-field dosimetry. These incidents are a cause for concern because the use of small fields in various specialized radiation treatment techniques continues to grow rapidly. Reference and relative dosimetry in small and composite fields are the subject of the International Atomic Energy Agency (IAEA) dosimetry code of practice that has been published as TRS-483 and an AAPM summary publication (IAEA TRS 483; Dosimetry of small static fields used in external beam radiotherapy: An IAEA/AAPM International Code of Practice for reference and relative dose determination, Technical Report Series No. 483; Palmans et al., Med Phys 45(11):e1123, 2018). The charge of AAPM task group 155 (TG-155) is to summarize current knowledge on small-field dosimetry and to provide recommendations of best practices for relative dose determination in small megavoltage photon beams. An overview of the issue of LCPE and the changes in photon beam perturbations with decreasing field size is provided. Recommendations are included on appropriate detector systems and measurement methodologies. Existing published data on dosimetric parameters in small photon fields (e.g., percentage depth dose, tissue phantom ratio/tissue maximum ratio, off-axis ratios, and field output factors) together with the necessary perturbation corrections for various detectors are reviewed. A discussion on errors and an uncertainty analysis in measurements is provided. The design of beam models in treatment planning systems to simulate small fields necessitates special attention on the influence of the primary beam source and collimating devices in the computation of energy fluence and dose. The general requirements for fluence and dose calculation engines suitable for modeling dose in small fields are reviewed. Implementations in commercial treatment planning systems vary widely, and the aims of this report are to provide insight for the medical physicist and guidance to developers of beams models for radiotherapy treatment planning systems.
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Affiliation(s)
- Indra J Das
- Department of Radiation Oncology, Northwestern Memorial Hospital, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - Paolo Francescon
- Department of Radiation Oncology, Ospedale Di Vicenza, Vicenza, Italy
| | - Jean M Moran
- Department of Medical Physics, Memorial Sloan-Kettering Cancer Center, New York, NY, USA
| | - Anders Ahnesjö
- Medical Radiation Sciences, Department of Immunology, Genetics and Pathology, Uppsala University, Uppsala, Sweden
| | - Maria M Aspradakis
- Institute of Radiation Oncology, Cantonal Hospital of Graubünden, Chur, Switzerland
| | - Chee-Wai Cheng
- Department of Radiation Oncology, University Hospitals Cleveland Medical Center, Cleveland, OH, USA
| | - George X Ding
- Department of Radiation Oncology, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - John D Fenwick
- Molecular and Clinical Cancer Medicine, Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Liverpool, UK
| | - M Saiful Huq
- Department of Radiation Oncology, University of Pittsburgh, School of Medicine and UPMC Hillman Cancer Center, Pittsburgh, PA, USA
| | - Mark Oldham
- Department of Radiation Oncology, Duke University Medical Center, Durham, NC, USA
| | - Chester S Reft
- Department of Radiation Oncology, University of Chicago, Chicago, IL, USA
| | - Otto A Sauer
- Department of Radiation Oncology, Klinik fur Strahlentherapie, University of Würzburg, Würzburg, Germany
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Lis M, Newhauser W, Donetti M, Wolf M, Steinsberger T, Paz A, Durante M, Graeff C. A Modular System for Treating Moving Anatomical Targets With Scanned Ion Beams at Multiple Facilities: Pre-Clinical Testing for Quality and Safety of Beam Delivery. Front Oncol 2021; 11:620388. [PMID: 33816251 PMCID: PMC8018284 DOI: 10.3389/fonc.2021.620388] [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: 10/22/2020] [Accepted: 01/25/2021] [Indexed: 12/26/2022] Open
Abstract
Background Quality management and safety are integral to modern radiotherapy. New radiotherapy technologies require new consensus guidelines on quality and safety. Established analysis strategies, such as the failure modes and effects analysis (FMEA) and incident learning systems have been developed as tools to assess the safety of several types of radiation therapies. An extensive literature documents the widespread application of risk analysis methods to photon radiation therapy. Relatively little attention has been paid to performing risk analyses of nascent radiation therapy systems to treat moving tumors with scanned heavy ion beams. The purpose of this study was to apply a comprehensive safety analysis strategy to a motion-synchronized dose delivery system (M-DDS) for ion therapy. Methods We applied a risk analysis method to new treatment planning and treatment delivery processes with scanned heavy ion beams. The processes utilize a prototype, modular dose delivery system, currently undergoing preclinical testing, that provides new capabilities for treating moving anatomy. Each step in the treatment process was listed in a process map, potential errors for each step were identified and scored using the risk probability number in an FMEA, and the possible causes of each error were described in a fault tree analysis. Solutions were identified to mitigate the risk of these errors, including permanent corrective actions, periodic quality assurance (QA) tests, and patient specific QA (PSQA) tests. Each solution was tested experimentally. Results The analysis revealed 58 potential errors that could compromise beam delivery quality or safety. Each of the 14 binary (pass-or-fail) tests passed. Each of the nine QA and four PSQA tests were within anticipated clinical specifications. The modular M-DDS was modified accordingly, and was found to function at two centers. Conclusion We have applied a comprehensive risk analysis strategy to the M-DDS and shown that it is a clinically viable motion mitigation strategy. The described strategy can be utilized at any ion therapy center that operates with the modular M-DDS. The approach can also be adapted for use at other facilities and can be combined with existing safety analysis systems.
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Affiliation(s)
- Michelle Lis
- Biophysics, GSI Helmholtzzentrum für Schwerionenforschung GmbH, Darmstadt, Germany.,Department of Physics and Astronomy, Louisiana State University, Baton Rouge, LA, United States
| | - Wayne Newhauser
- Department of Physics and Astronomy, Louisiana State University, Baton Rouge, LA, United States.,Department of Radiation Physics, Mary Bird Perkins Cancer Center, Baton Rouge, LA, United States
| | - Marco Donetti
- Research and Development Department, Centro Nazionale di Androterapia Oncologia, Pavia, Italy
| | - Moritz Wolf
- Biophysics, GSI Helmholtzzentrum für Schwerionenforschung GmbH, Darmstadt, Germany
| | - Timo Steinsberger
- Biophysics, GSI Helmholtzzentrum für Schwerionenforschung GmbH, Darmstadt, Germany.,Institute of Condensed Matter Physics, Technical University of Darmstadt, Darmstadt, Germany
| | - Athena Paz
- Biophysics, GSI Helmholtzzentrum für Schwerionenforschung GmbH, Darmstadt, Germany
| | - Marco Durante
- Biophysics, GSI Helmholtzzentrum für Schwerionenforschung GmbH, Darmstadt, Germany.,Institute of Condensed Matter Physics, Technical University of Darmstadt, Darmstadt, Germany
| | - Christian Graeff
- Biophysics, GSI Helmholtzzentrum für Schwerionenforschung GmbH, Darmstadt, Germany
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Liu K, Wang YF, Dona Lemus OM, Adamovics J, Wuu CS. Temperature dependence and temporal stability of stacked radiochromic sheets for three-dimensional dose verification. Med Phys 2020; 47:5906-5918. [PMID: 32996168 DOI: 10.1002/mp.14506] [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: 06/14/2020] [Revised: 09/12/2020] [Accepted: 09/21/2020] [Indexed: 11/07/2022] Open
Abstract
PURPOSE Recently a novel radiochromic sheet dosimeter, termed as PRESAGE sheets, consisting of leuco crystal violet dye and radical initiator had been developed and characterized. This study examines the dosimeter's temporal stability and storage temperature dependence postirradiation, and its applicability for dose verification in three dimensions (3D) as a stack dosimeter. METHODS PRESAGE sheets were irradiated using 6 MV photons at a dose range of 0-20 Gy with the change in optical density measured using a flatbed scanner. Following their irradiation, PRESAGE sheets were stored in different temperature environments (-18 °C, 4 °C, and 22 °C) and scanned at different time points, ranging from 1 to 168 h postirradiation, to track changes in measured signal and linearity of dose response. Multiple PRESAGE sheets were bound together to create a 12 × 13 × 8.7 cm3 film stack, with EBT3 film inserted between the sheets in the central region of the stack, that was treated using a clinical VMAT plan. Based on the results from the time and storage temperature study, two-dimensional (2D) relative dose distribution measurements in PRESAGE were acquired promptly following irradiation at selected planes in the coronal, sagittal, and axial orientation of the film stack and compared to the treatment planning system calculations in their respective axes. Dose distribution measurements on the coronal axis of the stack dosimeter were also independently verified using EBT3 film. RESULTS The dose response was observed to be linear (R2 > 0.995) with sheets stored in colder temperatures retaining their signal and dose response sensitivity for extended periods postirradiation. Sheets stored in 22 °C environment should be measured within an hour postirradiation. Sheets stored in a 4 °C and -18 °C environment can be scanned up to 20- and 72 h postirradiation, respectively, while preserving the integrity of their dose response sensitivity and linearity of dose response within a mean absolute percent error of 2.0%. For instance, at 20 h postirradiation the dose response sensitivity for sheets stored in a -18 °C, 4 °C, and 22 °C temperature environment was measured to be 97%, 91%, and 77% of their original values measured within an hour postirradiation, respectively. The 2D gamma pass rate for central slices exceed 95% for PRESAGE film stack compared with treatment planning system on selected planes in the axial, coronal, and sagittal orientation and EBT3 film in the coronal orientation using a 2D gamma index of 2%/2mm. The gamma pass rate in comparing the calculated dose distribution with the measured dose distribution from PRESAGE-LCV was observed to decrease in sheets scanned at later elapsed times postirradiation. In one example, the gamma pass rate for 2%/2mm criteria in the coronal plane was observed to decrease from 97.7% pass rate when scanned within an hour postirradiation to 92.1% pass rate when scanned at 20 h postirradiation under room temperature conditions. CONCLUSIONS This is the first study to demonstrate that the temporal stability of PRESAGE sheets can be enhanced through its storage in colder temperature environments postirradiation and that sheets as a film stack dosimeter hold promise for precise relative dose distribution measurements in 3D where advanced optical CT is unavailable.
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Affiliation(s)
- Kevin Liu
- Department of Radiation Oncology, Columbia University, New York, NY, 10032, USA
| | - Yi-Fang Wang
- Department of Radiation Oncology, Columbia University, New York, NY, 10032, USA
| | - Olga M Dona Lemus
- Department of Radiation Oncology, Columbia University, New York, NY, 10032, USA
| | - John Adamovics
- Department of Chemistry, Biochemistry & Physics, Rider University, Lawrenceville, NJ, 08648, USA
| | - Cheng-Shie Wuu
- Department of Radiation Oncology, Columbia University, New York, NY, 10032, USA
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Arab-Bafrani Z, Mahani L, Khoshbin-Khoshnazar A, Kermani MZ. Three dimensional film dosimetry of photon beam in small field sizes and beyond the heterogeneous regions using a GAFchromic films array. Radiat Phys Chem Oxf Engl 1993 2020. [DOI: 10.1016/j.radphyschem.2019.108467] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Hanušová T, Horáková I, Koniarová I. PSEUDO-3D IMRT VERIFICATION WITH EBT3 RADIOCHROMIC FILM. RADIATION PROTECTION DOSIMETRY 2019; 186:362-366. [PMID: 31943097 DOI: 10.1093/rpd/ncz232] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2018] [Revised: 02/01/2019] [Accepted: 07/18/2019] [Indexed: 06/10/2023]
Abstract
This work proposes a new method for pseudo-3D verification of intensity-modulated radiation therapy (IMRT) dose distributions. Unlike commercial solutions, it uses measured doses only for gamma evaluation. Its resolution is far better than with electronic detectors within the measured plane and comparable in other directions. It is readily available at clinics because it uses existing resources-a slab phantom and EBT3 films. The method was tested on six IMRT clinical cases. An in-house code for 2D and pseudo-3D gamma analysis was written in MATLAB and compared to OmniPro I'mRT.
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Affiliation(s)
- Tereza Hanušová
- Department of Dosimetry and Application of Ionizing Radiation, Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University in Prague, Břehová 7, 115 19 Praha 1, Czech Republic
| | - Ivana Horáková
- National Radiation Protection Institute, Bartoškova 28, 140 00 Praha 4, Czech Republic
| | - Irena Koniarová
- Department of Dosimetry and Application of Ionizing Radiation, Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University in Prague, Břehová 7, 115 19 Praha 1, Czech Republic
- National Radiation Protection Institute, Bartoškova 28, 140 00 Praha 4, Czech Republic
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