1
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Kozicki M, Maras P. An Optical Reusable 2D Radiochromic Gel-Based System for Ionising Radiation Measurements in Radiotherapy. Molecules 2024; 29:2558. [PMID: 38893435 PMCID: PMC11173542 DOI: 10.3390/molecules29112558] [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: 04/26/2024] [Revised: 05/25/2024] [Accepted: 05/27/2024] [Indexed: 06/21/2024] Open
Abstract
This work describes the development of a reusable 2D detector based on radiochromic reaction for radiotherapy dosimetric measurements. It consists of a radiochromic gel dosimeter in a cuboidal plastic container, scanning with a flatbed scanner, and data processing using a dedicated software package. This tool is assessed using the example of the application of the coincidence test of radiation and mechanical isocenters for a medical accelerator. The following were examined: scanning repeatability and image homogeneity, the impact of image processing on data processing in coincidence tests, and irradiation conditions-monitor units per radiation beam and irradiation field are selected. Optimal conditions for carrying out the test are chosen: (i) the multi-leaf collimator gap should preferably be 5 mm for 2D star shot irradiation, (ii) it is recommended to apply ≥2500-≤5000 MU per beam to obtain a strong signal enabling easy data processing, (iii) Mean filter can be applied to the images to improve calculations. An approach to dosimeter reuse with the goal of reducing costs is presented; the number of reuses is related to the MUs per beam, which, in this study, is about 5-57 for 30,000-2500 MU per beam (four fields). The proposed reusable system was successfully applied to the coincidence tests, confirming its suitability as a new potential quality assurance tool in radiotherapy.
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Affiliation(s)
- Marek Kozicki
- Department of Mechanical Engineering, Informatics and Chemistry of Polymer Materials, Faculty of Materials Technologies and Textile Design, Lodz University of Technology, Żeromskiego 116, 90-543 Lodz, Poland
- GeVero Co., 90-980 Lodz, Poland
| | - Piotr Maras
- Department of Radiotherapy Planning, Copernicus Hospital, Pabianicka 62, 93-513 Lodz, Poland;
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2
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Piotrowski M, Maras P, Kozicki M. On the Use of the Fricke-Pluronic F-127 Gel Dosimeter for Radiation Isocenter Testing of a Medical Linear Accelerator. MATERIALS (BASEL, SWITZERLAND) 2024; 17:1521. [PMID: 38612035 PMCID: PMC11012804 DOI: 10.3390/ma17071521] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2024] [Revised: 03/19/2024] [Accepted: 03/25/2024] [Indexed: 04/14/2024]
Abstract
This work presents a Fricke-XO-Pluronic F-127 2D radiochromic dosimeter with a flat-bed scanner for 2D reading and a dedicated data processing software package as a tool for performing coincidence testing of the radiation and mechanical isocenter of a medical accelerator. The optimal irradiation parameters were determined as follows: monitor units per beam and multi-leaf collimator gap, which are ≤750-≤2500 MU and 2-5 mm, respectively, for a cuboidal container with dimensions of 12 × 12 × 0.3 cm3. Despite the diffusion of Fe3+ ions occurring during irradiation, 2D reading can be performed at least 3 h after irradiation, without affecting the calculation performance of the coincidence test. The test was successfully performed for various irradiation settings. Overall, the Fricke-XO-Pluronic F-127 dosimeter has proven to be a potential tool for the coincidence testing of medical accelerators.
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Affiliation(s)
- Michał Piotrowski
- Department of Mechanical Engineering, Informatics and Chemistry of Polymer Materials, Faculty of Materials Technologies and Textile Design, Lodz University of Technology, 90-543 Lodz, Poland;
| | - Piotr Maras
- Department of Radiotherapy Planning, Copernicus Hospital, 93-513 Lodz, Poland;
| | - Marek Kozicki
- Department of Mechanical Engineering, Informatics and Chemistry of Polymer Materials, Faculty of Materials Technologies and Textile Design, Lodz University of Technology, 90-543 Lodz, Poland;
- GeVero Co., 90-980 Lodz, Poland
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3
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Karger CP, Elter A, Dorsch S, Mann P, Pappas E, Oldham M. Validation of complex radiotherapy techniques using polymer gel dosimetry. Phys Med Biol 2024; 69:06TR01. [PMID: 38330494 DOI: 10.1088/1361-6560/ad278f] [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: 02/06/2023] [Accepted: 02/08/2024] [Indexed: 02/10/2024]
Abstract
Modern radiotherapy delivers highly conformal dose distributions to irregularly shaped target volumes while sparing the surrounding normal tissue. Due to the complex planning and delivery techniques, dose verification and validation of the whole treatment workflow by end-to-end tests became much more important and polymer gel dosimeters are one of the few possibilities to capture the delivered dose distribution in 3D. The basic principles and formulations of gel dosimetry and its evaluation methods are described and the available studies validating device-specific geometrical parameters as well as the dose delivery by advanced radiotherapy techniques, such as 3D-CRT/IMRT and stereotactic radiosurgery treatments, the treatment of moving targets, online-adaptive magnetic resonance-guided radiotherapy as well as proton and ion beam treatments, are reviewed. The present status and limitations as well as future challenges of polymer gel dosimetry for the validation of complex radiotherapy techniques are discussed.
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Affiliation(s)
- Christian P Karger
- Department of Medical Physics in Radiation Oncology, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, D-69120 Heidelberg, Germany
- National Center for Radiation Research in Oncology (NCRO), Heidelberg Institute for Radiation Oncology (HIRO), Heidelberg, Germany
| | - Alina Elter
- Department of Medical Physics in Radiation Oncology, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, D-69120 Heidelberg, Germany
- National Center for Radiation Research in Oncology (NCRO), Heidelberg Institute for Radiation Oncology (HIRO), Heidelberg, Germany
- Department of Radiation Oncology, University Hospital Heidelberg, Im Neuenheimer Feld 400, D-69120 Heidelberg, Germany
| | - Stefan Dorsch
- Department of Medical Physics in Radiation Oncology, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, D-69120 Heidelberg, Germany
- National Center for Radiation Research in Oncology (NCRO), Heidelberg Institute for Radiation Oncology (HIRO), Heidelberg, Germany
| | - Philipp Mann
- Department of Medical Physics in Radiation Oncology, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, D-69120 Heidelberg, Germany
- National Center for Radiation Research in Oncology (NCRO), Heidelberg Institute for Radiation Oncology (HIRO), Heidelberg, Germany
| | - Evangelos Pappas
- Radiology & Radiotherapy Sector, Department of Biomedical Sciences, University of West Attica, Athens, Greece
| | - Mark Oldham
- Department of Radiation Oncology, Duke University Medical Center, Durham, NC, United States of America
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4
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Magugliani G, Marranconi M, Liosi GM, Locatelli F, Gambirasio A, Trombetta L, Hertsyk V, Torri V, Galluccio F, Macerata E, Mossini E, Santi A, Mariani M, Bombardieri E, Vavassori V, Salmoiraghi P. Pilot scale validation campaign of gel dosimetry for pre-treatment quality assurance in stereotactic radiotherapy. Phys Med 2023; 114:103158. [PMID: 37806152 DOI: 10.1016/j.ejmp.2023.103158] [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: 04/19/2023] [Revised: 09/25/2023] [Accepted: 09/28/2023] [Indexed: 10/10/2023] Open
Abstract
PURPOSE Complex stereotactic radiotherapy treatment plans require prior verification. A gel dosimetry system was developed and tested to serve as a high-resolution 3D dosimeter for Quality Assurance (QA) purposes. MATERIALS AND METHODS A modified version of a polyacrylamide polymer gel dosimeter based on chemical response inhibition was employed. Different sample geometries (cuvettes and phantoms) were manufactured for calibration and QA acquisitions. Irradiations were performed with a Varian Trilogy linac, and analyses of irradiated gel dosimeters were performed via MRI with a 1.5 T Philips Achieva at 1 mm3 or 2 mm3 isotropic spatial resolution. To assess reliability of polymer gel data, 54 stereotactic clinical treatment plans were delivered both on dosimetric gel phantoms and on the Delta4 dosimeter. Results from the two devices were evaluated through a global gamma index over a range of acceptance criteria and compared with each other. RESULTS A quantitative and tunable control of dosimetric gel response sensitivity was achieved through chemical inhibition. An optimized MRI analysis protocol allowed to acquire high resolution phantom dose data in timeframes of ≈ 1 h. Conversion of gel dosimeter data into absorbed dose was achieved through internal calibration. Polymer gel dosimeters (2 mm3 resolution) and Delta4 presented an agreement within 4.8 % and 2.7 % at the 3 %/1 mm and 2 %/2 mm gamma criteria, respectively. CONCLUSIONS Gel dosimeters appear as promising tools for high resolution 3D QA. Added complexity of the gel dosimetry protocol may be justifiable in case of small target volumes and steep dose gradients.
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Affiliation(s)
- G Magugliani
- Department of Energy, Nuclear Engineering Division, Politecnico di Milano, Milano, Italy.
| | - M Marranconi
- U. O. Medical Physics, Humanitas Gavazzeni, Bergamo, Italy
| | - G M Liosi
- Department of Energy, Nuclear Engineering Division, Politecnico di Milano, Milano, Italy
| | - F Locatelli
- U. O. Medical Physics, Humanitas Gavazzeni, Bergamo, Italy
| | - A Gambirasio
- U. O. Medical Physics, Humanitas Gavazzeni, Bergamo, Italy
| | - L Trombetta
- U. O. Medical Physics, Humanitas Gavazzeni, Bergamo, Italy
| | - V Hertsyk
- Fondazione Humanitas per la Ricerca, Milano, Italy
| | - V Torri
- Department of Oncologic Research, Istituto di Ricerche Farmacologiche Mario Negri IRCCS, Milano, Italy
| | - F Galluccio
- Department of Energy, Nuclear Engineering Division, Politecnico di Milano, Milano, Italy
| | - E Macerata
- Department of Energy, Nuclear Engineering Division, Politecnico di Milano, Milano, Italy
| | - E Mossini
- Department of Energy, Nuclear Engineering Division, Politecnico di Milano, Milano, Italy
| | - A Santi
- Department of Energy, Nuclear Engineering Division, Politecnico di Milano, Milano, Italy
| | - M Mariani
- Department of Energy, Nuclear Engineering Division, Politecnico di Milano, Milano, Italy
| | - E Bombardieri
- Scientific Direction, Humanitas Gavazzeni, Bergamo, Italy
| | - V Vavassori
- U. O. Radiotherapy, Humanitas Gavazzeni, Bergamo, Italy
| | - P Salmoiraghi
- U. O. Medical Physics, Humanitas Gavazzeni, Bergamo, Italy
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Maras P, Kozicki M. Fast Isocenter Determination Using 3D Polymer Gel Dosimetry with Kilovoltage Cone-Beam CT Reading and the PolyGeVero-CT Software Package for Linac Quality Assurance in Radiotherapy. MATERIALS (BASEL, SWITZERLAND) 2022; 15:6807. [PMID: 36234149 PMCID: PMC9573670 DOI: 10.3390/ma15196807] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/26/2022] [Revised: 09/23/2022] [Accepted: 09/25/2022] [Indexed: 06/16/2023]
Abstract
This work presents an approach to the fast determination of a medical accelerator irradiation isocenter as a quality assurance (QA) procedure in radiotherapy. The isocenter determination tool is the tissue equivalent high-resolution 3D polymer gel dosimeter (PABIGnx) in a dedicated container combined with kilovoltage imaging systems and the polyGeVero-CT software package (v. 1.2, GeVero Co., Poland). Two accelerators were employed: Halcyon and TrueBeam (Varian, USA), both equipped with cone beam computed tomography (CBCT) and iterative reconstruction CBCT (iCBCT) algorithms. The scope of this work includes: (i) the examination of factors influencing image quality (reconstruction algorithms and modes), radiation field parameters (dose and multi-leaf collimator (MLC) gaps), fiducial markers, signal averaging for reconstruction algorithms and the scanning time interval between consecutive scans, (ii) the examination of factors influencing the isocenter determination, image processing (signal averaging, background subtraction, image filtering) and (iii) an isocenter determination report using a 2D and 3D approach. An optimized protocol and isocenter determination conditions were found. The time and effort required to determine the isocenter are discussed.
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Affiliation(s)
- Piotr Maras
- Department of Radiotherapy Planning, Copernicus Hospital, 93-513 Lodz, Poland
- GeVero Co., Tansmana 2/11, 92-548 Lodz, Poland
| | - Marek Kozicki
- GeVero Co., Tansmana 2/11, 92-548 Lodz, Poland
- Department of Mechanical Engineering, Informatics and Chemistry of Polymer Materials, Faculty of Materials Technologies and Textile Design, Lodz University of Technology, 90-543 Lodz, Poland
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6
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Kim JH, Kim B, Shin W, Son J, Choi CH, Park JM, Hwang U, Kim J, Jung S. 3D star shot analysis using MAGAT gel dosimeter for integrated imaging and radiation isocenter verification of MR-Linac system. J Appl Clin Med Phys 2022; 23:e13615. [PMID: 35436031 PMCID: PMC9195025 DOI: 10.1002/acm2.13615] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Revised: 02/24/2022] [Accepted: 03/28/2022] [Indexed: 01/08/2023] Open
Abstract
Purpose This study aims to investigate a star shot analysis using a three‐dimensional (3D) gel dosimeter for the imaging and radiation isocenter verification of a magnetic resonance linear accelerator (MR‐Linac). Methods A mixture of methacrylic acid, gelatin, and tetrakis (hydroxymethyl) phosphonium chloride, called MAGAT gel, was fabricated. One MAGAT gel for each Linac and MR‐Linac was irradiated under six gantry angles. A 6 MV photon beam of Linac and a 6 MV flattening filter free beam of MR‐Linac were delivered to two MAGAT gels and EBT3 films. MR images were acquired by MR‐Linac with a clinical sequence (i.e., TrueFISP). The 3D star shot analysis for seven consecutive slices of the MR images with TrueFISP was performed. The 2D star shot analysis for the central plane of the gel was compared to the results from the EBT3 films. The radius of isocircle (ICr) and the distance between the center of the circle and the center marked on the image (ICd) were evaluated. Results For MR‐Linac with MAGAT gel measurements, ICd at the central plane was 0.46 mm for TrueFISP. Compared to EBT3 film measurements, the differences in ICd and ICr for both Linac and MR‐Linac were within 0.11 and 0.13 mm, respectively. For the 3D analysis, seven consecutive slices of TrueFISP images were analyzed and the maximum radii of isocircles (ICr_max) were 0.18 mm for Linac and 0.73 mm for MR‐Linac. The tilting angles of radiation axis were 0.31° for Linac and 0.10° for MR‐Linac. Conclusion The accuracy of 3D star shot analysis using MAGAT gel was comparable to that of EBT3 film, having a capability for integrated analysis for imaging isocenter and radiation isocenter. 3D star shot analysis using MAGAT gel can provide 3D information of radiation isocenter, suggesting a quantitative extent of gantry‐tilting.
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Affiliation(s)
- Jeong Ho Kim
- Department of Radiation OncologySamsung Changwon HospitalSungkyunkwan University School of MedicineChangwonRepublic of Korea
| | - Bitbyeol Kim
- Department of Radiation OncologySeoul National University HospitalSeoulRepublic of Korea
| | - Wook‐Geun Shin
- Department of Radiation OncologySeoul National University HospitalSeoulRepublic of Korea
| | - Jaeman Son
- Department of Radiation OncologySeoul National University HospitalSeoulRepublic of Korea
- Institute of Radiation MedicineSeoul National University Medical Research CenterSeoulRepublic of Korea
- Biomedical Research InstituteSeoul National University HospitalSeoulRepublic of Korea
| | - Chang Heon Choi
- Department of Radiation OncologySeoul National University HospitalSeoulRepublic of Korea
- Institute of Radiation MedicineSeoul National University Medical Research CenterSeoulRepublic of Korea
- Biomedical Research InstituteSeoul National University HospitalSeoulRepublic of Korea
| | - Jong Min Park
- Department of Radiation OncologySeoul National University HospitalSeoulRepublic of Korea
- Institute of Radiation MedicineSeoul National University Medical Research CenterSeoulRepublic of Korea
- Biomedical Research InstituteSeoul National University HospitalSeoulRepublic of Korea
- Department of Radiation OncologySeoul National University College of MedicineSeoulRepublic of Korea
- Robotics Research Laboratory for Extreme EnvironmentsAdvanced Institute of Convergence TechnologySuwonRepublic of Korea
| | - Ui‐Jung Hwang
- Department of Radiation OncologyChungnam National University Sejong HospitalSejongRepublic of Korea
| | - Jung‐in Kim
- Department of Radiation OncologySeoul National University HospitalSeoulRepublic of Korea
- Institute of Radiation MedicineSeoul National University Medical Research CenterSeoulRepublic of Korea
- Biomedical Research InstituteSeoul National University HospitalSeoulRepublic of Korea
| | - Seongmoon Jung
- Department of Radiation OncologySeoul National University HospitalSeoulRepublic of Korea
- Institute of Radiation MedicineSeoul National University Medical Research CenterSeoulRepublic of Korea
- Biomedical Research InstituteSeoul National University HospitalSeoulRepublic of Korea
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7
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Elter A, Dorsch S, Thomas S, Hentschke CM, Floca RO, Runz A, Karger CP, Mann P. PAGAT gel dosimetry for everyone: gel production, measurement and evaluation. Biomed Phys Eng Express 2021; 7. [PMID: 34237712 DOI: 10.1088/2057-1976/ac12a5] [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: 05/28/2021] [Accepted: 07/08/2021] [Indexed: 11/12/2022]
Abstract
Polymer gel (PG) dosimetry is a valuable tool to measure complex dose distributions in 3D with a high spatial resolution. However, due to complex protocols that need to be followed for in-house produced PGs and the high costs of commercially available gels, PG gels are only rarely applied in quality assurance procedures worldwide. In this work, we provide an introduction to perform highly standardized dosimetric PG experiments using PAGAT (PolyAcrylamide Gelatine gel fabricated at ATmospheric conditions) dosimetry gel. PAGAT gel can be produced at atmospheric conditions, at low costs and is evaluated using magnetic resonance imaging (MRI). The conduction of PG experiments is described in great detail including the gel production, treatment planning, irradiation, MRI evaluation and post-processing procedure. Furthermore, a plugin in an open source image processing tool for post-processing is provided free of charge that allows a standardized and reproducible analysis of PG experiments.
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Affiliation(s)
- A Elter
- Division of Medical Physics in Radiation Oncology, German Cancer Research Center (DKFZ), Heidelberg, Germany.,Faculty of Physics and Astronomy, University of Heidelberg, Heidelberg, Germany.,National Center for Radiation Research in Oncology (NCRO), Heidelberg Institute for Radiation Oncology (HIRO), Heidelberg, Germany
| | - S Dorsch
- Division of Medical Physics in Radiation Oncology, German Cancer Research Center (DKFZ), Heidelberg, Germany.,National Center for Radiation Research in Oncology (NCRO), Heidelberg Institute for Radiation Oncology (HIRO), Heidelberg, Germany
| | - S Thomas
- Division of Medical Image Computing, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - C M Hentschke
- Division of Medical Image Computing, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - R O Floca
- National Center for Radiation Research in Oncology (NCRO), Heidelberg Institute for Radiation Oncology (HIRO), Heidelberg, Germany.,Division of Medical Image Computing, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - A Runz
- Division of Medical Physics in Radiation Oncology, German Cancer Research Center (DKFZ), Heidelberg, Germany.,National Center for Radiation Research in Oncology (NCRO), Heidelberg Institute for Radiation Oncology (HIRO), Heidelberg, Germany
| | - C P Karger
- Division of Medical Physics in Radiation Oncology, German Cancer Research Center (DKFZ), Heidelberg, Germany.,National Center for Radiation Research in Oncology (NCRO), Heidelberg Institute for Radiation Oncology (HIRO), Heidelberg, Germany
| | - P Mann
- Division of Medical Physics in Radiation Oncology, German Cancer Research Center (DKFZ), Heidelberg, Germany.,National Center for Radiation Research in Oncology (NCRO), Heidelberg Institute for Radiation Oncology (HIRO), Heidelberg, Germany
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Marrale M, d’Errico F. Hydrogels for Three-Dimensional Ionizing-Radiation Dosimetry. Gels 2021; 7:74. [PMID: 34205640 PMCID: PMC8293215 DOI: 10.3390/gels7020074] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Revised: 06/15/2021] [Accepted: 06/16/2021] [Indexed: 11/28/2022] Open
Abstract
Radiation-sensitive gels are among the most recent and promising developments for radiation therapy (RT) dosimetry. RT dosimetry has the twofold goal of ensuring the quality of the treatment and the radiation protection of the patient. Benchmark dosimetry for acceptance testing and commissioning of RT systems is still based on ionization chambers. However, even the smallest chambers cannot resolve the steep dose gradients of up to 30-50% per mm generated with the most advanced techniques. While a multitude of systems based, e.g., on luminescence, silicon diodes and radiochromic materials have been developed, they do not allow the truly continuous 3D dose measurements offered by radiation-sensitive gels. The gels are tissue equivalent, so they also serve as phantoms, and their response is largely independent of radiation quality and dose rate. Some of them are infused with ferrous sulfate and rely on the radiation-induced oxidation of ferrous ions to ferric ions (Fricke-gels). Other formulations consist of monomers dispersed in a gelatinous medium (Polyacrylamide gels) and rely on radiation-induced polymerization, which creates a stable polymer structure. In both gel types, irradiation causes changes in proton relaxation rates that are proportional to locally absorbed dose and can be imaged using magnetic resonance imaging (MRI). Changes in color and/or opacification of the gels also occur upon irradiation, allowing the use of optical tomography techniques. In this work, we review both Fricke and polyacrylamide gels with emphasis on their chemical and physical properties and on their applications for radiation dosimetry.
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Affiliation(s)
- Maurizio Marrale
- Department of Physics and Chemistry, “Emilio Segrè” ATeN Center, University of Palermo, 90128 Palermo, Italy
- Istituto Nazionale di Fisica Nucleare (INFN), Sezione di Catania, 95123 Catania, Italy
| | - Francesco d’Errico
- Scuola di Ingegneria, Università degli Studi di Pisa, 56126 Pisa, Italy;
- Istituto Nazionale di Fisica Nucleare (INFN), Sezione di Pisa, 56127 Pisa, Italy
- School of Medicine, Yale University New Haven, CT 06510, USA
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9
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Schwahofer A, Mann P, Spindeldreier CK, Karger CP. On the feasibility of absolute 3D dosimetry using LiF thermoluminescence detectors and polymer gels on a 0.35T MR-LINAC. ACTA ACUST UNITED AC 2020; 65:215002. [DOI: 10.1088/1361-6560/aba6d7] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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10
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Kurz C, Buizza G, Landry G, Kamp F, Rabe M, Paganelli C, Baroni G, Reiner M, Keall PJ, van den Berg CAT, Riboldi M. Medical physics challenges in clinical MR-guided radiotherapy. Radiat Oncol 2020; 15:93. [PMID: 32370788 PMCID: PMC7201982 DOI: 10.1186/s13014-020-01524-4] [Citation(s) in RCA: 79] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Accepted: 03/24/2020] [Indexed: 12/18/2022] Open
Abstract
The integration of magnetic resonance imaging (MRI) for guidance in external beam radiotherapy has faced significant research and development efforts in recent years. The current availability of linear accelerators with an embedded MRI unit, providing volumetric imaging at excellent soft tissue contrast, is expected to provide novel possibilities in the implementation of image-guided adaptive radiotherapy (IGART) protocols. This study reviews open medical physics issues in MR-guided radiotherapy (MRgRT) implementation, with a focus on current approaches and on the potential for innovation in IGART.Daily imaging in MRgRT provides the ability to visualize the static anatomy, to capture internal tumor motion and to extract quantitative image features for treatment verification and monitoring. Those capabilities enable the use of treatment adaptation, with potential benefits in terms of personalized medicine. The use of online MRI requires dedicated efforts to perform accurate dose measurements and calculations, due to the presence of magnetic fields. Likewise, MRgRT requires dedicated quality assurance (QA) protocols for safe clinical implementation.Reaction to anatomical changes in MRgRT, as visualized on daily images, demands for treatment adaptation concepts, with stringent requirements in terms of fast and accurate validation before the treatment fraction can be delivered. This entails specific challenges in terms of treatment workflow optimization, QA, and verification of the expected delivered dose while the patient is in treatment position. Those challenges require specialized medical physics developments towards the aim of fully exploiting MRI capabilities. Conversely, the use of MRgRT allows for higher confidence in tumor targeting and organs-at-risk (OAR) sparing.The systematic use of MRgRT brings the possibility of leveraging IGART methods for the optimization of tumor targeting and quantitative treatment verification. Although several challenges exist, the intrinsic benefits of MRgRT will provide a deeper understanding of dose delivery effects on an individual basis, with the potential for further treatment personalization.
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Affiliation(s)
- Christopher Kurz
- Department of Radiation Oncology, University Hospital, LMU Munich, Marchioninistraße 15, 81377, Munich, Germany
- Department of Medical Physics, Ludwig-Maximilians-Universität München, Am Coulombwall 1, 85748, Garching, Germany
| | - Giulia Buizza
- Department of Electronics, Information and Bioengineering, Politecnico di Milano, P.za Leonardo da Vinci 32, 20133, Milano, Italy
| | - Guillaume Landry
- Department of Radiation Oncology, University Hospital, LMU Munich, Marchioninistraße 15, 81377, Munich, Germany
- Department of Medical Physics, Ludwig-Maximilians-Universität München, Am Coulombwall 1, 85748, Garching, Germany
- German Cancer Consortium (DKTK), 81377, Munich, Germany
| | - Florian Kamp
- Department of Radiation Oncology, University Hospital, LMU Munich, Marchioninistraße 15, 81377, Munich, Germany
| | - Moritz Rabe
- Department of Radiation Oncology, University Hospital, LMU Munich, Marchioninistraße 15, 81377, Munich, Germany
| | - Chiara Paganelli
- Department of Electronics, Information and Bioengineering, Politecnico di Milano, P.za Leonardo da Vinci 32, 20133, Milano, Italy
| | - Guido Baroni
- Department of Electronics, Information and Bioengineering, Politecnico di Milano, P.za Leonardo da Vinci 32, 20133, Milano, Italy
- Bioengineering Unit, National Center of Oncological Hadrontherapy (CNAO), Strada Privata Campeggi 53, 27100, Pavia, Italy
| | - Michael Reiner
- Department of Radiation Oncology, University Hospital, LMU Munich, Marchioninistraße 15, 81377, Munich, Germany
| | - Paul J Keall
- ACRF Image X Institute, University of Sydney, Sydney, NSW, 2006, Australia
| | - Cornelis A T van den Berg
- Department of Radiotherapy, University Medical Centre Utrecht, PO box 85500, 3508 GA, Utrecht, The Netherlands
| | - Marco Riboldi
- Department of Medical Physics, Ludwig-Maximilians-Universität München, Am Coulombwall 1, 85748, Garching, Germany.
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11
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Kim T, Gu B, Maraghechi B, Green O, Lewis B, Mutic S, Gach HM. Characterizing MR Imaging isocenter variation in MRgRT. Biomed Phys Eng Express 2020; 6:035009. [PMID: 33438654 DOI: 10.1088/2057-1976/ab7bc6] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
We characterized MRI isocenter variation at various gantry positions in two 0.35 T MRgRT systems using two independent methods. First, image center-based quantification was employed on 3D volumetric and 2D cine images of a 24 cm diameter spherical phantom at various gantry positions in the MRI QA mode. The center of the phantom images was identified to quantify the variation of the imaging center at each gantry position. Second, image registration-based quantification was used in radiotherapy mode. 3D volumetric MRIs of a cylindrical phantom were acquired and corresponding image registration from MRI to planning CT was performed. The shifts of the couch were identified to quantify the variation of the imaging center. For verification of noticeable MRI isocenter variation, star-shot pattern measurements with five beams were delivered on the radio-chromic film inserted into the phantom after the couch was shifted. The center of the star-shot pattern was identified to quantify the variation of the imaging center. The proposed methods for measuring MRI isocenter variation were demonstrated with MR-LINAC and MR-60Co systems. Both of the MRgRT systems had field inhomogeneities <5 ppm over a 24 cm diameter spherical volume (DSV) and spatial integrity distortion: <1 mm within 100 mm radius and <2 mm within 175 mm radius. The MRI isocenter of the MR-LINAC system showed noticeable 3D variation (max magnitude: 1.8 mm) compared to that of MR-60Co system (max magnitude: 0.9 mm) relative to the reference gantry positions. In addition, 2D variations (max magnitude) of the MRI isocenter from sagittal cine images were 0.9 mm for the MR-LINAC system and 0.5 mm for the MR-60Co system. Two proposed methods quantified the MRI isocenter variation for various gantry positions in two 0.35 T MRgRT systems. The results of significant isocenter variation in the MR-LINAC system requires further investigation to determine the cause.
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Affiliation(s)
- Taeho Kim
- Department of Radiation Oncology, Washington University School of Medicine, St Louis, MO 63110, United States of America
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Velten C, Wang YF, Adamovics J, Wuu CS. 3D isocentricity analysis for clinical linear accelerators. Med Phys 2020; 47:1460-1467. [PMID: 31970794 DOI: 10.1002/mp.14039] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2019] [Revised: 01/02/2020] [Accepted: 01/09/2020] [Indexed: 11/05/2022] Open
Abstract
PURPOSE To perform a three-dimensional (3D) concurrent isocentricity measurement of a clinical linear accelerator's (linac) using a single 3D dosimeter, PRESAGE. METHODS A 3D dosimeter, PRESAGE, set up on the treatment couch of a Varian TrueBeam LINAC using the setup lasers, was irradiated under gantry angles of 0 ∘ , 50 ∘ , 160 ∘ , and 270 ∘ with the couch fixed at 0 ∘ and subsequently, under couch angles of 10 ∘ , 330 ∘ , 300 ∘ , and 265 ∘ with the gantry fixed at 270 ∘ . The 1 cm 2 (at 100 cm SAD) square fields were delivered at 6 MV with 800 MU/field. After irradiation, the dosimeter was scanned using a single-beam optical scanner and images were reconstructed with submillimeter resolution using filtered back-projection. Postprocessing was used to extract views parallel to the star-shot planes from which beam trajectories and the smallest circles enclosing these were drawn and extracted. These circles and information from the view orthogonal to both star-shots were used to represent the rotational centers as spheroids. The linac isocenter was defined by the distribution of midpoints between any, randomly selected, points lying inside the center spheroids defined by the table and gantry rotations; isocenter location and size were defined by the average midpoint and the distribution's semi-axes. Collimator rotations were not included in this study. RESULTS Relative to the setup center defined by lasers, the table and gantry rotation center coordinates (lat., long., vert.) were measured in units of millimeters, to be (-0.24, 0.18, -0.52) and (0.10, 0.53, -0.52), respectively. Displacements from the setup center were 0.60 and 0.75 mm for the table and gantry centers, while the distance between them measured 0.49 mm. The linac's radiation isocenter was calculated to be at (-0.07, -0.17, 0.51) relative to the setup lasers and its size was found to be most easily described by a spheroid prolate in vertical direction with semi-axis lengths of 0.13 and 0.23 mm for the lateral-longitudinal and vertical directions, respectively. CONCLUSIONS This study demonstrates how to measure the location and sizes of rotational centers in 3D with one setup. The proposed method provides a more comprehensive view on the isocentricity of LINAC than the conventional two-dimensional film measurements. Additionally, a new definition of isocenter and its size was proposed.
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Affiliation(s)
- Christian Velten
- Department of Radiation Oncology, Columbia University, New York, NY, USA.,Department of Radiation Oncology, Montefiore Medical Center, Bronx, NY, USA
| | - Yi-Fang Wang
- Department of Radiation Oncology, Columbia University, New York, NY, USA
| | - John Adamovics
- Department of Chemistry, Biochemistry, and Physics, Rider University, Lawrenceville, NJ, USA
| | - Cheng-Shie Wuu
- Department of Radiation Oncology, Columbia University, New York, NY, USA
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Dorsch S, Mann P, Elter A, Runz A, Spindeldreier CK, Klüter S, Karger CP. Measurement of isocenter alignment accuracy and image distortion of an 0.35 T MR-Linac system. ACTA ACUST UNITED AC 2019; 64:205011. [DOI: 10.1088/1361-6560/ab4540] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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