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Hobson MA, Hu Y, Caldwell B, Cohen GN, Glide-Hurst C, Huang L, Jackson PD, Jang S, Langner U, Lee HJ, Levesque IR, Narayanan S, Park JC, Steffen J, Wu QJ, Zhou Y. AAPM Task Group 334: A guidance document to using radiotherapy immobilization devices and accessories in an MR environment. Med Phys 2024; 51:3822-3849. [PMID: 38648857 DOI: 10.1002/mp.17061] [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: 07/10/2023] [Revised: 11/13/2023] [Accepted: 03/28/2024] [Indexed: 04/25/2024] Open
Abstract
Use of magnetic resonance (MR) imaging in radiation therapy has increased substantially in recent years as more radiotherapy centers are having MR simulators installed, requesting more time on clinical diagnostic MR systems, or even treating with combination MR linear accelerator (MR-linac) systems. With this increased use, to ensure the most accurate integration of images into radiotherapy (RT), RT immobilization devices and accessories must be able to be used safely in the MR environment and produce minimal perturbations. The determination of the safety profile and considerations often falls to the medical physicist or other support staff members who at a minimum should be a Level 2 personnel as per the ACR. The purpose of this guidance document will be to help guide the user in making determinations on MR Safety labeling (i.e., MR Safe, Conditional, or Unsafe) including standard testing, and verification of image quality, when using RT immobilization devices and accessories in an MR environment.
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Affiliation(s)
- Maritza A Hobson
- Department of Radiation Oncology, Wake Forest University School of Medicine, Winston-Salem, North Carolina, USA
| | - Yanle Hu
- Department of Radiation Oncology, Mayo Clinic Arizona, Phoenix, Arizona, USA
| | - Barrett Caldwell
- School of Industrial Engineering, Purdue University, West Lafayette, Indiana, USA
- School of Aeronautics and Astronautics, Purdue University, West Lafayette, Indiana, USA
| | - Gil'ad N Cohen
- Department of Medical Physics, Memorial Sloan-Kettering Cancer Center, New York, New York, USA
| | - Carri Glide-Hurst
- Department of Human Oncology, University of Wisconsin--Madison, Madison, Wisconsin, USA
- Department of Medical Physics, University of Wisconsin--Madison, Madison, Wisconsin, USA
| | - Long Huang
- Department of Radiation Oncology, University of Utah, Salt Lake City, Utah, USA
| | - Paul D Jackson
- Department of Radiation Oncology, Henry Ford Health System, Detroit, Michigan, USA
| | - Sunyoung Jang
- Department of Radiation Oncology, Penn State College of Medicine, Hershey, Pennsylvania, USA
| | - Ulrich Langner
- Department of Radiation Oncology, Rhode Island Hospital, Providence, Rhode Island, USA
| | - Hannah J Lee
- Corewell Health William Beaumont University Hospital, Royal Oak, Michigan, USA
| | - Ives R Levesque
- Gerald Bronfman Department of Oncology and Medical Physics Unit, McGill University, Montreal, QC, Canada
- Department of Medical Physics, McGill University Health Centre, Cedars Cancer Centre, Montreal, QC, Canada
| | - Sreeram Narayanan
- Department of Radiation Oncology, Virginia Mason Cancer Institute, Seattle, Washington, USA
| | - Justin C Park
- Division of Medical Physics, Department of Radiation Oncology, Mayo Clinic, Jacksonville, Florida, USA
| | | | - Q Jackie Wu
- Department of Radiation Oncology, Duke University Medical Center, Durham, North Carolina, USA
| | - Yong Zhou
- Department of Radiology Services, Corewell Health, Grand Rapids, Michigan, USA
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Tolpadi AA, Bharadwaj U, Gao KT, Bhattacharjee R, Gassert FG, Luitjens J, Giesler P, Morshuis JN, Fischer P, Hein M, Baumgartner CF, Razumov A, Dylov D, van Lohuizen Q, Fransen SJ, Zhang X, Tibrewala R, de Moura HL, Liu K, Zibetti MVW, Regatte R, Majumdar S, Pedoia V. K2S Challenge: From Undersampled K-Space to Automatic Segmentation. Bioengineering (Basel) 2023; 10:bioengineering10020267. [PMID: 36829761 PMCID: PMC9952400 DOI: 10.3390/bioengineering10020267] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2022] [Revised: 02/01/2023] [Accepted: 02/15/2023] [Indexed: 02/22/2023] Open
Abstract
Magnetic Resonance Imaging (MRI) offers strong soft tissue contrast but suffers from long acquisition times and requires tedious annotation from radiologists. Traditionally, these challenges have been addressed separately with reconstruction and image analysis algorithms. To see if performance could be improved by treating both as end-to-end, we hosted the K2S challenge, in which challenge participants segmented knee bones and cartilage from 8× undersampled k-space. We curated the 300-patient K2S dataset of multicoil raw k-space and radiologist quality-checked segmentations. 87 teams registered for the challenge and there were 12 submissions, varying in methodologies from serial reconstruction and segmentation to end-to-end networks to another that eschewed a reconstruction algorithm altogether. Four teams produced strong submissions, with the winner having a weighted Dice Similarity Coefficient of 0.910 ± 0.021 across knee bones and cartilage. Interestingly, there was no correlation between reconstruction and segmentation metrics. Further analysis showed the top four submissions were suitable for downstream biomarker analysis, largely preserving cartilage thicknesses and key bone shape features with respect to ground truth. K2S thus showed the value in considering reconstruction and image analysis as end-to-end tasks, as this leaves room for optimization while more realistically reflecting the long-term use case of tools being developed by the MR community.
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Affiliation(s)
- Aniket A. Tolpadi
- Department of Bioengineering, University of California, Berkeley, CA 94720, USA
- Department of Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, CA 94158, USA
- Correspondence:
| | - Upasana Bharadwaj
- Department of Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, CA 94158, USA
| | - Kenneth T. Gao
- Department of Bioengineering, University of California, Berkeley, CA 94720, USA
- Department of Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, CA 94158, USA
| | - Rupsa Bhattacharjee
- Department of Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, CA 94158, USA
| | - Felix G. Gassert
- Department of Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, CA 94158, USA
- Department of Radiology, Klinikum Rechts der Isar, School of Medicine, Technical University of Munich, 81675 Munich, Germany
| | - Johanna Luitjens
- Department of Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, CA 94158, USA
- Department of Radiology, Klinikum Großhadern, Ludwig-Maximilians-Universität, 81377 Munich, Germany
| | - Paula Giesler
- Department of Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, CA 94158, USA
| | - Jan Nikolas Morshuis
- Cluster of Excellence Machine Learning, University of Tübingen, 72076 Tübingen, Germany
| | - Paul Fischer
- Cluster of Excellence Machine Learning, University of Tübingen, 72076 Tübingen, Germany
| | - Matthias Hein
- Cluster of Excellence Machine Learning, University of Tübingen, 72076 Tübingen, Germany
| | | | - Artem Razumov
- Center for Computational and Data-Intensive Science and Engineering, Skolkovo Institute of Science and Technology, 121205 Moscow, Russia
| | - Dmitry Dylov
- Center for Computational and Data-Intensive Science and Engineering, Skolkovo Institute of Science and Technology, 121205 Moscow, Russia
| | - Quintin van Lohuizen
- Department of Radiology, University Medical Center Groningen, 9713 GZ Groningen, The Netherlands
| | - Stefan J. Fransen
- Department of Radiology, University Medical Center Groningen, 9713 GZ Groningen, The Netherlands
| | - Xiaoxia Zhang
- Center for Advanced Imaging Innovation and Research, New York University Grossman School of Medicine, New York, NY 10016, USA
| | - Radhika Tibrewala
- Center for Advanced Imaging Innovation and Research, New York University Grossman School of Medicine, New York, NY 10016, USA
| | - Hector Lise de Moura
- Center for Advanced Imaging Innovation and Research, New York University Grossman School of Medicine, New York, NY 10016, USA
| | - Kangning Liu
- Center for Advanced Imaging Innovation and Research, New York University Grossman School of Medicine, New York, NY 10016, USA
| | - Marcelo V. W. Zibetti
- Center for Advanced Imaging Innovation and Research, New York University Grossman School of Medicine, New York, NY 10016, USA
| | - Ravinder Regatte
- Center for Advanced Imaging Innovation and Research, New York University Grossman School of Medicine, New York, NY 10016, USA
| | - Sharmila Majumdar
- Department of Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, CA 94158, USA
| | - Valentina Pedoia
- Department of Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, CA 94158, USA
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Jang JS, Lee HB, Suh CH, Lee MH. Image quality and acquisition time assessments for phase oversampling in compressed sensing sensitivity encoding: Comparison with conventional SENSE. J Appl Clin Med Phys 2021; 23:e13509. [PMID: 34953027 PMCID: PMC8833279 DOI: 10.1002/acm2.13509] [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: 05/26/2021] [Revised: 12/05/2021] [Accepted: 12/06/2021] [Indexed: 11/09/2022] Open
Abstract
This study compared sensitivity encoding (SENSE) and compressed sensing sensitivity encoding (CS-SENSE) for phase oversampling distance and assessed its impact on image quality and image acquisition time. The experiment was performed with a large diameter phantom using 16-channel anterior body coils. All imaging data were divided into three groups according to the parallel imaging technique and oversampling distances: groups A (SENSE with phase oversampling distance of 150 mm), B (CS-SENSE with phase oversampling distance of 100 mm), and C (CS-SENSE with phase oversampling distance of 75 mm). No statistically significant differences were observed among groups A, B, and C regarding both T2 and T1 turbo spin-echo (TSE) sequences using an acceleration factor (AF) of 2 (p = 0.301 and 0.289, respectively). In comparison with AF 2 of group A, the scan time of AF 2 of groups B and C was reduced by 11.2% and 23.5% (T2 TSE) and 15.8% and 22.7% (T1 TSE), respectively, while providing comparable image quality. Significant image noise and aliasing artifact were more evident at AF ≥ 2 in group A compared with groups B and C. CS-SENSE with a less phase oversampling distance can reduce image acquisition time without image quality degradation compared with that of SENSE, despite the increase in aliasing artifact as the AF increased in both CS-SENSE and SENSE.
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Affiliation(s)
- Ji Sung Jang
- Departments of Radiology and Research Institute of Radiology, Asan Medical Center, College of Medicine, University of Ulsan, South Korea
| | - Ho Beom Lee
- Departments of Radiology and Research Institute of Radiology, Asan Medical Center, College of Medicine, University of Ulsan, South Korea
| | - Chong Hyun Suh
- Departments of Radiology and Research Institute of Radiology, Asan Medical Center, College of Medicine, University of Ulsan, South Korea
| | - Min Hee Lee
- Departments of Radiology and Research Institute of Radiology, Asan Medical Center, College of Medicine, University of Ulsan, South Korea
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Torfeh T, Hammoud R, Paloor S, Arunachalam Y, Aouadi S, Al-Hammadi N. Design and construction of a customizable phantom for the characterization of the three-dimensional magnetic resonance imaging geometric distortion. J Appl Clin Med Phys 2021; 22:149-157. [PMID: 34719100 PMCID: PMC8664142 DOI: 10.1002/acm2.13462] [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: 07/04/2021] [Revised: 09/27/2021] [Accepted: 10/17/2021] [Indexed: 11/11/2022] Open
Abstract
One of the main challenges to using magnetic resonance imaging (MRI) in radiotherapy is the existence of system‐related geometric inaccuracies caused mainly by the inhomogeneity in the main magnetic field and the nonlinearities of the gradient coils. Several physical phantoms, with fixed configuration, have been developed and commercialized for the assessment of the MRI geometric distortion. In this study, we propose a new design of a customizable phantom that can fit any type of radio frequency (RF) coil. It is composed of 3D printed plastic blocks containing holes that can hold glass tubes which can be filled with any liquid. The blocks can be assembled to construct phantoms with any dimension. The feasibility of this design has been demonstrated by assembling four phantoms with high robustness allowing the assessment of the geometric distortion for the GE split head coil, the head and neck array coil, the anterior array coil, and the body coil. Phantom reproducibility was evaluated by analyzing the geometric distortion on CT acquisition of five independent assemblages of the phantom. This solution meets all expectations in terms of having a robust, lightweight, modular, and practical tool for measuring distortion in three dimensions. Mean error in the position of the tubes was less than 0.2 mm. For the geometric distortion, our results showed that for all typical MRI sequences used for radiotherapy, the mean geometric distortion was less than 1 mm and less than 2.5 mm over radial distances of 150 mm and 250 mm, respectively. These tools will be part of a quality assurance program aimed at monitoring the image quality of MRI scanners used to guide radiation therapy.
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Affiliation(s)
- Tarraf Torfeh
- Department of Radiation Oncology, National Center for Cancer Care and Research (NCCCR), Hamad Medical Corporation, Doha, Qatar
| | - Rabih Hammoud
- Department of Radiation Oncology, National Center for Cancer Care and Research (NCCCR), Hamad Medical Corporation, Doha, Qatar
| | - Satheesh Paloor
- Department of Radiation Oncology, National Center for Cancer Care and Research (NCCCR), Hamad Medical Corporation, Doha, Qatar
| | - Yoganathan Arunachalam
- Department of Radiation Oncology, National Center for Cancer Care and Research (NCCCR), Hamad Medical Corporation, Doha, Qatar
| | - Souha Aouadi
- Department of Radiation Oncology, National Center for Cancer Care and Research (NCCCR), Hamad Medical Corporation, Doha, Qatar
| | - Noora Al-Hammadi
- Department of Radiation Oncology, National Center for Cancer Care and Research (NCCCR), Hamad Medical Corporation, Doha, Qatar
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Speight R, Dubec M, Eccles CL, George B, Henry A, Herbert T, Johnstone RI, Liney GP, McCallum H, Schmidt MA. IPEM topical report: guidance on the use of MRI for external beam radiotherapy treatment planning . Phys Med Biol 2021; 66:055025. [PMID: 33450742 DOI: 10.1088/1361-6560/abdc30] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Accepted: 01/15/2021] [Indexed: 12/18/2022]
Abstract
This document gives guidance for multidisciplinary teams within institutions setting up and using an MRI-guided radiotherapy (RT) treatment planning service. It has been written by a multidisciplinary working group from the Institute of Physics and Engineering in Medicine (IPEM). Guidance has come from the experience of the institutions represented in the IPEM working group, in consultation with other institutions, and where appropriate references are given for any relevant legislation, other guidance documentation and information in the literature. Guidance is only given for MRI acquired for external beam RT treatment planning in a CT-based workflow, i.e. when MRI is acquired and registered to CT with the purpose of aiding delineation of target or organ at risk volumes. MRI use for treatment response assessment, MRI-only RT and other RT treatment types such as brachytherapy and gamma radiosurgery are not considered within the scope of this document. The aim was to produce guidance that will be useful for institutions who are setting up and using a dedicated MR scanner for RT (referred to as an MR-sim) and those who will have limited time on an MR scanner potentially managed outside of the RT department, often by radiology. Although not specifically covered in this document, there is an increase in the use of hybrid MRI-linac systems worldwide and brief comments are included to highlight any crossover with the early implementation of this technology. In this document, advice is given on introducing a RT workload onto a non-RT-dedicated MR scanner, as well as planning for installation of an MR scanner dedicated for RT. Next, practical guidance is given on the following, in the context of RT planning: training and education for all staff working in and around an MR scanner; RT patient set-up on an MR scanner; MRI sequence optimisation for RT purposes; commissioning and quality assurance (QA) to be performed on an MR scanner; and MRI to CT registration, including commissioning and QA.
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Affiliation(s)
- Richard Speight
- Leeds Cancer Centre, Leeds Teaching Hospitals NHS Trust, Leeds, United Kingdom
| | - Michael Dubec
- The Christie NHS Foundation Trust and the University of Manchester, Manchester, United Kingdom
| | - Cynthia L Eccles
- The Christie NHS Foundation Trust and the University of Manchester, Manchester, United Kingdom
| | - Ben George
- University of Oxford and GenesisCare, Oxford, United Kingdom
| | - Ann Henry
- Leeds Cancer Centre, Leeds Teaching Hospitals NHS Trust and University of Leeds, Leeds, United Kingdom
| | - Trina Herbert
- Royal Marsden NHS Foundation Trust, London, United Kingdom
| | | | - Gary P Liney
- Ingham Institute for Applied Medical Research and Liverpool Cancer Therapy Centre, Liverpool, Sydney, NSW 2170, Australia
| | - Hazel McCallum
- Translational and Clinical Research Institute, Newcastle University and Northern Centre for Cancer Care, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, United Kingdom
| | - Maria A Schmidt
- Royal Marsden NHS Foundation Trust and Institute of Cancer Research, London, United Kingdom
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Buckley JG, Dong B, Liney GP. Imaging performance of a high-field in-line magnetic resonance imaging linear accelerator with a patient rotation system for fixed-gantry radiotherapy. PHYSICS & IMAGING IN RADIATION ONCOLOGY 2020; 16:130-133. [PMID: 33458355 PMCID: PMC7807630 DOI: 10.1016/j.phro.2020.11.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/10/2020] [Revised: 11/05/2020] [Accepted: 11/05/2020] [Indexed: 02/06/2023]
Abstract
This paper describes the imaging performance of a high-field in-line MRI linear accelerator with a patient rotation system in-situ. Signal quality was quantified using signal-to-noise ratio (SNR) and RF uniformity maps. B0-field inhomogeneity was assessed using magnetic field mapping. SNR was evaluated with various entries into the Faraday cage which were required for extended couch translations. SNR varied between 103 and 87 across PRS rotation angles. Maximum B0-field inhomogeneity corresponded to 0.7 mm of geometric distortion. A 45 × 55 cm2 aperture allowed PRS translation with no reduction in SNR. Imaging performance with the PRS in-situ was found to be acceptable.
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Affiliation(s)
- Jarryd G Buckley
- Centre for Medical Radiation Physics, University of Wollongong, Northfields Avenue, Wollongong, NSW 2522, Australia.,Ingham Institute for Applied Medical Research, 1 Campbell St, Liverpool, NSW 2170, Australia
| | - Bin Dong
- Ingham Institute for Applied Medical Research, 1 Campbell St, Liverpool, NSW 2170, Australia.,Liverpool and Macarthur Cancer Therapy Centre, Liverpool Hospital, 75 Elizabeth St, Liverpool, NSW 2170, Australia
| | - Gary P Liney
- Ingham Institute for Applied Medical Research, 1 Campbell St, Liverpool, NSW 2170, Australia.,Liverpool and Macarthur Cancer Therapy Centre, Liverpool Hospital, 75 Elizabeth St, Liverpool, NSW 2170, Australia
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Implementation of a dedicated 1.5 T MR scanner for radiotherapy treatment planning featuring a novel high-channel coil setup for brain imaging in treatment position. Strahlenther Onkol 2020; 197:246-256. [PMID: 33103231 PMCID: PMC7892740 DOI: 10.1007/s00066-020-01703-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Accepted: 09/29/2020] [Indexed: 12/17/2022]
Abstract
Purpose To share our experiences in implementing a dedicated magnetic resonance (MR) scanner for radiotherapy (RT) treatment planning using a novel coil setup for brain imaging in treatment position as well as to present developed core protocols with sequences specifically tuned for brain and prostate RT treatment planning. Materials and methods Our novel setup consists of two large 18-channel flexible coils and a specifically designed wooden mask holder mounted on a flat tabletop overlay, which allows patients to be measured in treatment position with mask immobilization. The signal-to-noise ratio (SNR) of this setup was compared to the vendor-provided flexible coil RT setup and the standard setup for diagnostic radiology. The occurrence of motion artifacts was quantified. To develop magnetic resonance imaging (MRI) protocols, we formulated site- and disease-specific clinical objectives. Results Our novel setup showed mean SNR of 163 ± 28 anteriorly, 104 ± 23 centrally, and 78 ± 14 posteriorly compared to 84 ± 8 and 102 ± 22 anteriorly, 68 ± 6 and 95 ± 20 centrally, and 56 ± 7 and 119 ± 23 posteriorly for the vendor-provided and diagnostic setup, respectively. All differences were significant (p > 0.05). Image quality of our novel setup was judged suitable for contouring by expert-based assessment. Motion artifacts were found in 8/60 patients in the diagnostic setup, whereas none were found for patients in the RT setup. Site-specific core protocols were designed to minimize distortions while optimizing tissue contrast and 3D resolution according to indication-specific objectives. Conclusion We present a novel setup for high-quality imaging in treatment position that allows use of several immobilization systems enabling MR-only workflows, which could reduce unnecessary dose and registration inaccuracies. Electronic supplementary material The online version of this article (10.1007/s00066-020-01703-y) contains supplementary material, which is available to authorized users.
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Brunnquell CL, Hoff MN, Balu N, Nguyen XV, Oztek MA, Haynor DR. Making Magnets More Attractive: Physics and Engineering Contributions to Patient Comfort in MRI. Top Magn Reson Imaging 2020; 29:167-174. [PMID: 32541257 DOI: 10.1097/rmr.0000000000000246] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Patient comfort is an important factor of a successful magnetic resonance (MR) examination, and improvements in the patient's MR scanning experience can contribute to improved image quality, diagnostic accuracy, and efficiency in the radiology department, and therefore reduced cost. Magnet designs that are more open and accessible, reduced auditory noise of MR examinations, light and flexible radiofrequency (RF) coils, and faster motion-insensitive imaging techniques can all significantly improve the patient experience in MR imaging. In this work, we review the design, development, and implementation of these physics and engineering approaches to improve patient comfort.
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Affiliation(s)
- Christina L Brunnquell
- Department of Radiology, University of Washington, Seattle, WA Department of Radiology, The Ohio State University Wexler Medical Center, Columbus, OH
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Ahmadian S, Jabbari I, Bagherimofidi SM, Saligheh Rad H. Characterization of hardware-related spatial distortions for IR-PETRA pulse sequence using a brain specific phantom. MAGNETIC RESONANCE MATERIALS IN PHYSICS BIOLOGY AND MEDICINE 2020; 34:213-228. [PMID: 32632747 DOI: 10.1007/s10334-020-00863-3] [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: 12/31/2019] [Revised: 06/22/2020] [Accepted: 06/24/2020] [Indexed: 11/26/2022]
Abstract
OBJECTIVE Inversion recovery-pointwise encoding time reduction with radial acquisition (IR-PETRA) is an effective magnetic resonance (MR) pulse sequence in generating pseudo-CTs. The hardware-related spatial-distortion (HRSD) in MR images potentially deteriorates the accuracy of pseudo-CTs. Thus, we aimed at characterizing HRSD for IR-PETRA. MATERIALS AND METHODS gross-HRSDoverall (Euclidean-sum of gross-HRSDi (i = x, y, z)) for IR-PETRA was assessed using a brain-specific phantom for two MR scanners (1.5 T-Aera and 3.0 T-Prisma). Moreover, hardware imperfections were analyzed by determining gradient-nonlinearity spatial-distortion (GNSD) and B0-inhomogeneity spatial-distortion (B0ISD) for magnetization-prepared rapid acquisition gradient-echo (MP-RAGE) which has well-known distortion characteristics. RESULTS In 3.0 T, maximum of gross-GNSDoverall (Euclidean-sum of gross-GNSDi) and gross-B0ISD for MP-RAGE was 2.77 mm and 0.57 mm, respectively. For this scanner, the mean and maximum of gross-HRSDoverall for IR-PETRA were 0.63 ± 0.38 mm and 1.91 mm, respectively. In 1.5 T, maximum of gross-GNSDoverall and gross-B0ISD for MP-RAGE was 3.41 mm and 0.78 mm, respectively. The mean and maximum of gross-HRSDoverall for IR-PETRA were 1.02 ± 0.50 mm and 3.12 mm, respectively. DISCUSSION The spatial accuracy of MR images, besides being impacted by hardware performance, scanner capabilities, and imaging parameters, is mainly affected by its imaging strategy and data acquisition scheme. In 3.0 T, even without applying vendor correction algorithms, spatial accuracy of IR-PETRA image is sufficient for generating pseudo-CTs. In 1.5 T, distortion-correction is required to provide this accuracy.
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Affiliation(s)
- Sima Ahmadian
- Faculty of Advanced Sciences and Technologies, University of Isfahan, Isfahan, Iran
| | - Iraj Jabbari
- Faculty of Advanced Sciences and Technologies, University of Isfahan, Isfahan, Iran.
| | - Seyed Mehdi Bagherimofidi
- Department of Biomedical Engineering, Aliabad Katoul Branch, Islamic Azad University, Aliabad-e-Katoul, Iran
| | - Hamidreza Saligheh Rad
- Quantitative MR Imaging and Spectroscopy Group, Research Center for Molecular and Cellular Imaging, Tehran University of Medical Sciences, Tehran, Iran
- Department of Medical Physics and Biomedical Engineering, Tehran University of Medical Sciences, Tehran, Iran
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Head-and-Neck MRI-only radiotherapy treatment planning: From acquisition in treatment position to pseudo-CT generation. Cancer Radiother 2020; 24:288-297. [DOI: 10.1016/j.canrad.2020.01.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2019] [Revised: 01/08/2020] [Accepted: 01/15/2020] [Indexed: 12/25/2022]
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Chin S, Eccles CL, McWilliam A, Chuter R, Walker E, Whitehurst P, Berresford J, Van Herk M, Hoskin PJ, Choudhury A. Magnetic resonance-guided radiation therapy: A review. J Med Imaging Radiat Oncol 2020; 64:163-177. [PMID: 31646742 DOI: 10.1111/1754-9485.12968] [Citation(s) in RCA: 88] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2019] [Accepted: 09/24/2019] [Indexed: 12/11/2022]
Abstract
Magnetic resonance-guided radiation therapy (MRgRT) is a promising approach to improving clinical outcomes for patients treated with radiation therapy. The roles of image guidance, adaptive planning and magnetic resonance imaging in radiation therapy have been increasing over the last two decades. Technical advances have led to the feasible combination of magnetic resonance imaging and radiation therapy technologies, leading to improved soft-tissue visualisation, assessment of inter- and intrafraction motion, motion management, online adaptive radiation therapy and the incorporation of functional information into treatment. MRgRT can potentially transform radiation oncology by improving tumour control and quality of life after radiation therapy and increasing convenience of treatment by shortening treatment courses for patients. Multiple groups have developed clinical implementations of MRgRT predominantly in the abdomen and pelvis, with patients having been treated since 2014. While studies of MRgRT have primarily been dosimetric so far, an increasing number of trials are underway examining the potential clinical benefits of MRgRT, with coordinated efforts to rigorously evaluate the benefits of the promising technology. This review discusses the current implementations, studies, potential benefits and challenges of MRgRT.
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Affiliation(s)
- Stephen Chin
- Department of Clinical Oncology, The Christie NHS Foundation Trust, Manchester, UK
- Westmead Clinical School, University of Sydney, Sydney, New South Wales, Australia
| | - Cynthia L Eccles
- Department of Radiotherapy, The Christie NHS Foundation Trust, Manchester, UK
- Division of Cancer Sciences, The University of Manchester, Manchester, UK
| | - Alan McWilliam
- Division of Cancer Sciences, The University of Manchester, Manchester, UK
- Christie Medical Physics and Engineering, The Christie NHS Foundation Trust, Manchester, UK
| | - Robert Chuter
- Division of Cancer Sciences, The University of Manchester, Manchester, UK
- Christie Medical Physics and Engineering, The Christie NHS Foundation Trust, Manchester, UK
| | - Emma Walker
- Christie Medical Physics and Engineering, The Christie NHS Foundation Trust, Manchester, UK
| | - Philip Whitehurst
- Christie Medical Physics and Engineering, The Christie NHS Foundation Trust, Manchester, UK
| | - Joseph Berresford
- Christie Medical Physics and Engineering, The Christie NHS Foundation Trust, Manchester, UK
| | - Marcel Van Herk
- Division of Cancer Sciences, The University of Manchester, Manchester, UK
- Christie Medical Physics and Engineering, The Christie NHS Foundation Trust, Manchester, UK
| | - Peter J Hoskin
- Department of Clinical Oncology, The Christie NHS Foundation Trust, Manchester, UK
- Division of Cancer Sciences, The University of Manchester, Manchester, UK
| | - Ananya Choudhury
- Department of Clinical Oncology, The Christie NHS Foundation Trust, Manchester, UK
- Division of Cancer Sciences, The University of Manchester, Manchester, UK
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Hinault P, Gardin I, Wiesinger F, Cozzini C, Gouel P, Poujol J, Vera P, Gensanne D. 60 Characterization of radiotherapy dedicated head and neck coils. Phys Med 2019. [DOI: 10.1016/j.ejmp.2019.09.141] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
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Speight R, Schmidt MA, Liney GP, Johnstone RI, Eccles CL, Dubec M, George B, Henry A, McCallum H. IPEM Topical Report: A 2018 IPEM survey of MRI use for external beam radiotherapy treatment planning in the UK. Phys Med Biol 2019; 64:175021. [PMID: 31239419 DOI: 10.1088/1361-6560/ab2c7c] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The benefits of integrating MRI into the radiotherapy pathway are well published, however there is little consensus in guidance on how to commission or implement its use. With a view to developing consensus guidelines for the use of MRI in external beam radiotherapy (EBRT) treatment planning in the UK, a survey was undertaken by an Institute of Physics and Engineering in Medicine (IPEM) working-party to assess the current landscape of MRI use in EBRT in the UK. A multi-disciplinary working-party developed a survey to understand current practice using MRI for EBRT treatment planning; investigate how MRI is currently used and managed; and identify knowledge gaps. The survey was distributed electronically to radiotherapy service managers and physics leads in 71 UK radiotherapy (RT) departments (all NHS and private groups). The survey response rate was 87% overall, with 89% of NHS and 75% of private centres responding. All responding centres include EBRT in some RT pathways: 94% using Picture Archiving and Communication System (PACS) images potentially acquired without any input from RT departments, and 69% had some form of MRI access for planning EBRT. Most centres reporting direct access use a radiology scanner within the same hospital in dedicated (26%) or non-dedicated (52%) RT scanning sessions. Only two centres reported having dedicated RT MRI scanners in the UK, lower than reported in other countries. Six percent of radiotherapy patients in England (data not publically available outside of England) have MRI as part of their treatment, which again is lower than reported elsewhere. Although a substantial number of centres acquire MRI scans for treatment planning purposes, most centres acquire less than five patient scans per month for each treatment site. Commissioning and quality assurance of both image registration and MRI scanners was found to be variable across the UK. In addition, staffing models and training given to different staff groups varied considerably across the UK, reflecting the current lack of national guidelines. The primary barriers reported to MRI implementation in EBRT planning included costs (e.g. lack of a national tariff for planning MRI), lack of MRI access and/or capacity within hospitals. Despite these challenges, significant interest remains in increasing MRI-assisted EBRT planning over the next five years.
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Affiliation(s)
- Richard Speight
- Leeds Cancer Centre, Leeds Teaching Hospitals NHS Trust, Leeds, United Kingdom. Author to whom correspondence should be addressed
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14
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Buckley JG, Rai R, Liney GP, Dowling JA, Holloway LC, Metcalfe PE, Keall PJ. Anatomical deformation due to horizontal rotation: towards gantry-free radiation therapy. ACTA ACUST UNITED AC 2019; 64:175014. [DOI: 10.1088/1361-6560/ab324c] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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15
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Mandija S, D'Agata F, Navest RJM, Sbrizzi A, Tijssen RHN, Philippens MEP, Raaijmakers CPJ, Seravalli E, Verhoeff JJC, Lagendijk JJW, van den Berg CAT. Brain and Head-and-Neck MRI in Immobilization Mask: A Practical Solution for MR-Only Radiotherapy. Front Oncol 2019; 9:647. [PMID: 31380283 PMCID: PMC6650525 DOI: 10.3389/fonc.2019.00647] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2019] [Accepted: 07/02/2019] [Indexed: 01/08/2023] Open
Abstract
In brain/head-and-neck radiotherapy (RT), thermoplastic immobilization masks guarantee reproducible patient positioning in treatment position between MRI, CT, and irradiation. Since immobilization masks do not fit in the diagnostic MR head/head-and-neck coils, flexible surface coils are used for MRI imaging in clinical practice. These coils are placed around the head/neck, in contact with the immobilization masks. However, the positioning of these flexible coils is technician dependent, thus leading to poor image reproducibility. Additionally, flexible surface coils have an inferior signal-to-noise-ratio (SNR) compared to diagnostic coils. The aim of this work was to create a new immobilization setup which fits into the diagnostic MR coils in order to enhance MR image quality and reproducibility. For this purpose, a practical immobilization setup was constructed. The performances of the standard clinical and the proposed setups were compared with four tests: SNR, image quality, motion restriction, and reproducibility of inter-fraction subject positioning. The new immobilization setup resulted in 3.4 times higher SNR values on average than the standard setup, except directly below the flexible surface coils where similar SNR was observed. Overall, the image quality was superior for brain/head-and-neck images acquired with the proposed RT setup. Comparable motion restriction in feet-head/left-right directions (maximum motion ≈1 mm) and comparable inter-fraction repositioning accuracy (mean inter-fraction movement 1 ± 0.5 mm) were observed for the standard and the new setup.
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Affiliation(s)
- Stefano Mandija
- Computational Imaging Group for MRI Diagnostics and Therapy, Center for Image Sciences, University Medical Center Utrecht, Utrecht, Netherlands.,Department of Radiotherapy, University Medical Center Utrecht, Utrecht, Netherlands
| | - Federico D'Agata
- Computational Imaging Group for MRI Diagnostics and Therapy, Center for Image Sciences, University Medical Center Utrecht, Utrecht, Netherlands.,Department of Radiotherapy, University Medical Center Utrecht, Utrecht, Netherlands.,Department of Neurosciences, University of Turin, Turin, Italy
| | - Robin J M Navest
- Computational Imaging Group for MRI Diagnostics and Therapy, Center for Image Sciences, University Medical Center Utrecht, Utrecht, Netherlands.,Department of Radiotherapy, University Medical Center Utrecht, Utrecht, Netherlands
| | - Alessandro Sbrizzi
- Computational Imaging Group for MRI Diagnostics and Therapy, Center for Image Sciences, University Medical Center Utrecht, Utrecht, Netherlands.,Department of Radiotherapy, University Medical Center Utrecht, Utrecht, Netherlands
| | - Rob H N Tijssen
- Department of Radiotherapy, University Medical Center Utrecht, Utrecht, Netherlands
| | | | | | - Enrica Seravalli
- Department of Radiotherapy, University Medical Center Utrecht, Utrecht, Netherlands
| | - Joost J C Verhoeff
- Department of Radiotherapy, University Medical Center Utrecht, Utrecht, Netherlands
| | - Jan J W Lagendijk
- Department of Radiotherapy, University Medical Center Utrecht, Utrecht, Netherlands
| | - Cornelis A T van den Berg
- Computational Imaging Group for MRI Diagnostics and Therapy, Center for Image Sciences, University Medical Center Utrecht, Utrecht, Netherlands.,Department of Radiotherapy, University Medical Center Utrecht, Utrecht, Netherlands
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Jackson S, Glitzner M, Tijssen RHN, Raaymakers BW. MRI B 0 homogeneity and geometric distortion with continuous linac gantry rotation on an Elekta Unity MR-linac. ACTA ACUST UNITED AC 2019; 64:12NT01. [DOI: 10.1088/1361-6560/ab231a] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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17
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Tijssen RHN, Philippens MEP, Paulson ES, Glitzner M, Chugh B, Wetscherek A, Dubec M, Wang J, van der Heide UA. MRI commissioning of 1.5T MR-linac systems - a multi-institutional study. Radiother Oncol 2018; 132:114-120. [PMID: 30825959 DOI: 10.1016/j.radonc.2018.12.011] [Citation(s) in RCA: 92] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2018] [Revised: 11/14/2018] [Accepted: 12/11/2018] [Indexed: 10/27/2022]
Abstract
BACKGROUND Magnetic Resonance linear accelerator (MR-linac) systems represent a new type of technology that allows for online MR-guidance for high precision radiotherapy (RT). Currently, the first MR-linac installations are being introduced clinically. Since the imaging performance of these integrated MR-linac systems is critical for their application, a thorough commissioning of the MRI performance is essential. However, guidelines on the commissioning of MR-guided RT systems are not yet defined and data on the performance of MR-linacs are not yet available. MATERIALS & METHODS Here we describe a comprehensive commissioning protocol, which contains standard MRI performance measurements as well as dedicated hybrid tests that specifically assess the interactions between the Linac and the MRI system. The commissioning results of four MR-linac systems are presented in a multi-center study. RESULTS Although the four systems showed similar performance in all the standard MRI performance tests, some differences were observed relating to the hybrid character of the systems. Field homogeneity measurements identified differences in the gantry shim configuration, which was later confirmed by the vendor. CONCLUSION Our results highlight the importance of dedicated hybrid commissioning tests and the ability to compare the machines between institutes at this very early stage of clinical introduction. Until formal guidelines and tolerances are defined the tests described in this study may be used as a practical guideline. Moreover, the multi-center results provide initial bench mark data for future MR-linac installations.
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Affiliation(s)
- Rob H N Tijssen
- Department of Radiotherapy, University Medical Center Utrecht, the Netherlands.
| | | | - Eric S Paulson
- Department of Radiation Oncology, Medical College of Wisconsin, Milwaukee, United States
| | - Markus Glitzner
- Department of Radiotherapy, University Medical Center Utrecht, the Netherlands
| | - Brige Chugh
- Department of Radiation Oncology, Sunnybrook Health Sciences Centre, Toronto, Canada
| | - Andreas Wetscherek
- Joint Department of Physics, the Institute of Cancer Research and the Royal Marsden Hospital NHS Foundation Trust, London, UK
| | - Michael Dubec
- The Christie NHS Foundation Trust and the University of Manchester, UK
| | - Jihong Wang
- Department of Radiation Physics, the University of Texas MD Anderson Cancer Center, Houston, United States
| | - Uulke A van der Heide
- Department of Radiation Oncology, the Netherlands Cancer Institute, Amsterdam, the Netherlands
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Assessment of electron density effects on dose calculation and optimisation accuracy for nasopharynx, for MRI only treatment planning. AUSTRALASIAN PHYSICAL & ENGINEERING SCIENCES IN MEDICINE 2018; 41:811-820. [DOI: 10.1007/s13246-018-0675-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2018] [Accepted: 08/14/2018] [Indexed: 12/25/2022]
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Chen X, Dai J. Quantitative analysis of image quality for acceptance and commissioning of an MRI simulator with a semiautomatic method. J Appl Clin Med Phys 2018; 19:326-335. [PMID: 29573140 PMCID: PMC5978956 DOI: 10.1002/acm2.12311] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2017] [Revised: 01/09/2018] [Accepted: 02/06/2018] [Indexed: 11/28/2022] Open
Abstract
Magnetic Resonance Imaging (MRI) simulation differs from diagnostic MRI in purpose, technical requirements, and implementation. We propose a semiautomatic method for image acceptance and commissioning for the scanner, the radiofrequency (RF) coils, and pulse sequences for an MRI simulator. The ACR MRI accreditation large phantom was used for image quality analysis with seven parameters. Standard ACR sequences with a split head coil were adopted to examine the scanner's basic performance. The performance of simulation RF coils were measured and compared using the standard sequence with different clinical diagnostic coils. We used simulation sequences with simulation coils to test the quality of image and advanced performance of the scanner. Codes and procedures were developed for semiautomatic image quality analysis. When using standard ACR sequences with a split head coil, image quality passed all ACR recommended criteria. The image intensity uniformity with a simulation RF coil decreased about 34% compared with the eight‐channel diagnostic head coil, while the other six image quality parameters were acceptable. Those two image quality parameters could be improved to more than 85% by built‐in intensity calibration methods. In the simulation sequences test, the contrast resolution was sensitive to the FOV and matrix settings. The geometric distortion of simulation sequences such as T1‐weighted and T2‐weighted images was well‐controlled in the isocenter and 10 cm off‐center within a range of ±1% (2 mm). We developed a semiautomatic image quality analysis method for quantitative evaluation of images and commissioning of an MRI simulator. The baseline performances of simulation RF coils and pulse sequences have been established for routine QA.
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Affiliation(s)
- Xinyuan Chen
- Department of Radiation Oncology, National Cancer Center/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Jianrong Dai
- Department of Radiation Oncology, National Cancer Center/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
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Torfeh T, Hammoud R, El Kaissi T, McGarry M, Aouadi S, Fayad H, Al-Hammadi N. Geometric accuracy of the MR imaging techniques in the presence of motion. J Appl Clin Med Phys 2018; 19:168-175. [PMID: 29388320 PMCID: PMC5849831 DOI: 10.1002/acm2.12274] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2017] [Revised: 11/23/2017] [Accepted: 12/23/2017] [Indexed: 11/10/2022] Open
Abstract
Magnetic Resonance Imaging (MRI) is increasingly being used for improving tumor delineation and tumor tracking in the presence of respiratory motion. The purpose of this work is to design and build an MR compatible motion platform and to use it for evaluating the geometric accuracy of MR imaging techniques during respiratory motion. The motion platform presented in this work is composed of a mobile base made up of a flat plate and four wheels. The mobile base is attached from one end and through a rigid rod to a synchrony motion table by Accuray® placed at the end of the MRI table and from the other end to an elastic rod. The geometric accuracy was measured by placing a control point‐based phantom on top of the mobile base. In‐house software module was used to automatically assess the geometric distortion. The blurring artifact was also assessed by measuring the Full Width Half Maximum (FWHM) of each control point. Our results were assessed for 50, 100, and 150 mm radial distances, with a mean geometric distortion during the superior–inferior motion of 0.27, 0.41, and 0.55 mm, respectively. Adding the anterior–posterior motion, the mean geometric distortions increased to 0.4, 0.6, and 0.8 mm. Blurring was observed during motion causing an increase in the FWHM of ≈30%. The platform presented in this work provides a valuable tool for the assessment of the geometric accuracy and blurring artifact for MR during motion. Although the main objective was to test the spatial accuracy of an MR system during motion, the modular aspect of the presented platform enables the use of any commercially available phantom for a full quality control of the MR system during motion.
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Affiliation(s)
- Tarraf Torfeh
- Department of Radiation Oncology, National Center for Cancer Care & Research (NCCCR), Hamad Medical Corporation, Doha, Qatar
| | - Rabih Hammoud
- Department of Radiation Oncology, National Center for Cancer Care & Research (NCCCR), Hamad Medical Corporation, Doha, Qatar
| | - Tarek El Kaissi
- Department of Radiation Oncology, National Center for Cancer Care & Research (NCCCR), Hamad Medical Corporation, Doha, Qatar
| | - Maeve McGarry
- Department of Radiation Oncology, National Center for Cancer Care & Research (NCCCR), Hamad Medical Corporation, Doha, Qatar
| | - Souha Aouadi
- Department of Radiation Oncology, National Center for Cancer Care & Research (NCCCR), Hamad Medical Corporation, Doha, Qatar
| | - Hadi Fayad
- Occupational Health & Safety, Hamad Medical Corporation, Doha, Qatar
| | - Noora Al-Hammadi
- Department of Radiation Oncology, National Center for Cancer Care & Research (NCCCR), Hamad Medical Corporation, Doha, Qatar
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Paulson ES, Crijns SPM, Keller BM, Wang J, Schmidt MA, Coutts G, van der Heide UA. Consensus opinion on MRI simulation for external beam radiation treatment planning. Radiother Oncol 2016; 121:187-192. [PMID: 27838146 DOI: 10.1016/j.radonc.2016.09.018] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2016] [Revised: 09/08/2016] [Accepted: 09/09/2016] [Indexed: 11/26/2022]
Abstract
AIM To determine the levels at which consensus could be reached regarding general and site-specific principles of MRI simulation for offline MRI-aided external beam radiation treatment planning. METHODS A process inspired by the Delphi method was employed to determine levels of consensus using a series of questionnaires interspersed with controlled opinion feedback. RESULTS In general, full consensus was reached regarding general principles of MRI simulation. However, the level of consensus decreased when site-specific principles of MRI simulation were considered. CONCLUSIONS These results indicate variability in MRI simulation approaches that are largely explained by the use of MRI in combination with CT.
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Affiliation(s)
| | | | | | - Jihong Wang
- MD Anderson Cancer Center, Houston, United States
| | - Maria A Schmidt
- The Royal Marsden NHS Foundation Trust and Institute of Cancer Research, Sutton, United Kingdom
| | - Glyn Coutts
- The Christie NHS Foundation Trust, Manchester, United Kingdom
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22
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Maingon P. Argumentaire clinique pour la radiothérapie guidée par imagerie par résonance magnétique. Cancer Radiother 2016; 20:558-63. [DOI: 10.1016/j.canrad.2016.07.070] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2016] [Revised: 07/12/2016] [Accepted: 07/13/2016] [Indexed: 11/24/2022]
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23
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Ogasawara G, Inoue Y, Matsunaga K, Fujii K, Hata H, Takato Y. Image Non-Uniformity Correction for 3-T Gd-EOB-DTPA-Enhanced MR Imaging of the Liver. Magn Reson Med Sci 2016; 16:115-122. [PMID: 27385553 PMCID: PMC5600070 DOI: 10.2463/mrms.mp.2016-0012] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Purpose: Image non-uniformity may cause substantial problems in magnetic resonance (MR) imaging especially when a 3-T scanner is used. We evaluated the effect of image non-uniformity correction in gadolinium ethoxybenzyl-diethylenetriamine pentaacetic acid (Gd-EOB-DTPA)-enhanced MR imaging using a 3-T scanner. Methods: Two commercially available methods for image non-uniformity correction, surface coil intensity correction (SCIC), and phased-array uniformity enhancement (PURE), were applied to Gd-EOB-DTPA-enhanced images acquired at 3-T in 20 patients. The calibration images were used for PURE and not for SCIC. Uniformity in the liver signal was evaluated visually and using histogram analysis. The liver-to-muscle signal ratio (LMR) and liver-to-spleen signal ratio (LSR) were estimated, and the contrast enhancement ratio (CER) was calculated from the liver signal, LMR, and LSR. Results: Without non-uniformity correction, hyperintensity was consistently observed near the liver surface. Both SCIC and PURE improved uniformity in the liver signal; however, the superficial hyperintensity remained after the application of SCIC, especially in the hepatobiliary-phase images, and focal hyperintensity was shown in the lateral segment of the left hepatic lobe after the application of PURE. PURE increased LMR dramatically and LSR mildly, with no changes in CERs. SCIC depressed temporal changes in LMR and LSR and obscured contrast effects, regardless of the method used for calculation of CER. Conclusion: SCIC improves uniformity in the liver signal; however, it is not suitable for a quantitative assessment of contrast effects. PURE is indicated to be a useful method for non-uniformity correction in Gd-EOB-DTPA-enhanced MR imaging using a 3-T scanner.
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Affiliation(s)
- Gou Ogasawara
- Department of Diagnostic Radiology, Kitasato University School of Medicine
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Xing A, Holloway L, Arumugam S. Commissioning and quality control of a dedicated wide bore 3T MRI simulator for radiotherapy planning. INTERNATIONAL JOURNAL OF CANCER THERAPY AND ONCOLOGY 2016. [DOI: 10.14319/ijcto.42.1] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
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Characterization of 3D geometric distortion of magnetic resonance imaging scanners commissioned for radiation therapy planning. Magn Reson Imaging 2016; 34:645-53. [PMID: 26795695 DOI: 10.1016/j.mri.2016.01.001] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2015] [Revised: 12/15/2015] [Accepted: 01/07/2016] [Indexed: 01/16/2023]
Abstract
OBJECTIVE To develop a method for the assessment and characterization of 3D geometric distortion as part of routine quality assurance for MRI scanners commissioned for Radiation Therapy planning. MATERIALS AND METHODS In this study, the in-plane and through-plane geometric distortions on a 1.5T GE MRI-SIM unit are characterized and the 2D and 3D correction algorithms provided by the vendor are evaluated. We used a phantom developed by GE Healthcare that covers a large field of view of 500mm, and consists of layers of foam embedded with a matrix of ellipsoidal markers. An in-house Java-based software module was developed to automatically assess the geometric distortion by calculating the center of each marker using the center of mass method, correcting of gross rotation errors and comparing the corrected positions with a CT gold standard data set. Spatial accuracy of typical pulse sequences used in RT planning was assessed (2D T1/T2 FSE, 3D CUBE, T1 SPGR) using the software. The accuracy of vendor specific geometric distortion correction (GDC) algorithms was quantified by measuring distortions before and after the application of the 2D and 3D correction algorithms. RESULTS Our algorithm was able to accurately calculate geometric distortion with sub-pixel precision. For all typical MR sequences used in Radiotherapy, the vendor's GDC was able to substantially reduce the distortions. Our results showed also that the impact of the acquisition produced a maximum variation of 0.2mm over a radial distance of 200mm. It has been shown that while the 2D correction algorithm remarkably reduces the in-plane geometric distortion, 3D geometric distortion further reduced the geometric distortion by correcting both in-plane and through-plane distortions in all acquisitions. CONCLUSION The presented methods represent a valuable tool for routine quality assurance of MR applications that require stringent spatial accuracy assessment such as radiotherapy. The phantom used in this study provides three dimensional arrays of control points. These tools and the detailed results can be also used for developing new geometric distortion correction algorithms or improving the existing ones.
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Walker A, Liney G, Holloway L, Dowling J, Rivest-Henault D, Metcalfe P. Continuous table acquisition MRI for radiotherapy treatment planning: distortion assessment with a new extended 3D volumetric phantom. Med Phys 2015; 42:1982-91. [PMID: 25832089 DOI: 10.1118/1.4915920] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE Accurate geometry is required for radiotherapy treatment planning (RTP). When considering the use of magnetic resonance imaging (MRI) for RTP, geometric distortions observed in the acquired images should be considered. While scanner technology and vendor supplied correction algorithms provide some correction, large distortions are still present in images, even when considering considerably smaller scan lengths than those typically acquired with CT in conventional RTP. This study investigates MRI acquisition with a moving table compared with static scans for potential geometric benefits for RTP. METHODS A full field of view (FOV) phantom (diameter 500 mm; length 513 mm) was developed for measuring geometric distortions in MR images over volumes pertinent to RTP. The phantom consisted of layers of refined plastic within which vitamin E capsules were inserted. The phantom was scanned on CT to provide the geometric gold standard and on MRI, with differences in capsule location determining the distortion. MRI images were acquired with two techniques. For the first method, standard static table acquisitions were considered. Both 2D and 3D acquisition techniques were investigated. With the second technique, images were acquired with a moving table. The same sequence was acquired with a static table and then with table speeds of 1.1 mm/s and 2 mm/s. All of the MR images acquired were registered to the CT dataset using a deformable B-spline registration with the resulting deformation fields providing the distortion information for each acquisition. RESULTS MR images acquired with the moving table enabled imaging of the whole phantom length while images acquired with a static table were only able to image 50%-70% of the phantom length of 513 mm. Maximum distortion values were reduced across a larger volume when imaging with a moving table. Increased table speed resulted in a larger contribution of distortion from gradient nonlinearities in the through-plane direction and an increased blurring of capsule images, resulting in an apparent capsule volume increase by up to 170% in extreme axial FOV regions. Blurring increased with table speed and in the central regions of the phantom, geometric distortion was less for static table acquisitions compared to a table speed of 2 mm/s over the same volume. Overall, the best geometric accuracy was achieved with a table speed of 1.1 mm/s. CONCLUSIONS The phantom designed enables full FOV imaging for distortion assessment for the purposes of RTP. MRI acquisition with a moving table extends the imaging volume in the z direction with reduced distortions which could be useful particularly if considering MR-only planning. If utilizing MR images to provide additional soft tissue information to the planning CT, standard acquisition sequences over a smaller volume would avoid introducing additional blurring or distortions from the through-plane table movement.
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Affiliation(s)
- Amy Walker
- Centre for Medical Radiation Physics, University of Wollongong, Wollongong, NSW 2522, Australia and Liverpool and Macarthur Cancer Therapy Centres and Ingham Institute for Applied Medical Research, Liverpool, NSW 2170, Australia
| | - Gary Liney
- Centre for Medical Radiation Physics, University of Wollongong, Wollongong, NSW 2522, Australia; Liverpool and Macarthur Cancer Therapy Centres and Ingham Institute for Applied Medical Research, Liverpool, NSW 2170, Australia; and South West Clinical School, University of New South Wales, Sydney, NSW 2170, Australia
| | - Lois Holloway
- Centre for Medical Radiation Physics, University of Wollongong, Wollongong, NSW 2522, Australia; Liverpool and Macarthur Cancer Therapy Centres and Ingham Institute for Applied Medical Research, Liverpool, NSW 2170, Australia; South West Clinical School, University of New South Wales, Sydney, NSW 2170, Australia; and Institute of Medical Physics, School of Physics, University of Sydney, Sydney, NSW 2006, Australia
| | - Jason Dowling
- Commonwealth Scientific and Industrial Research Organisation, Australian E-Health Research Centre, Herston, QLD 4029, Australia
| | - David Rivest-Henault
- Commonwealth Scientific and Industrial Research Organisation, Australian E-Health Research Centre, Herston, QLD 4029, Australia
| | - Peter Metcalfe
- Centre for Medical Radiation Physics, University of Wollongong, Wollongong, NSW 2522, Australia and Liverpool and Macarthur Cancer Therapy Centres and Ingham Institute for Applied Medical Research, Liverpool, NSW 2170, Australia
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Torfeh T, Hammoud R, McGarry M, Al-Hammadi N, Perkins G. Development and validation of a novel large field of view phantom and a software module for the quality assurance of geometric distortion in magnetic resonance imaging. Magn Reson Imaging 2015; 33:939-49. [DOI: 10.1016/j.mri.2015.04.003] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2014] [Revised: 04/01/2015] [Accepted: 04/08/2015] [Indexed: 11/26/2022]
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Liney GP, Moerland MA. Magnetic resonance imaging acquisition techniques for radiotherapy planning. Semin Radiat Oncol 2015; 24:160-8. [PMID: 24931086 DOI: 10.1016/j.semradonc.2014.02.014] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Magnetic resonance imaging (MRI) has a number of benefits for the planning of radiotherapy (RT), but its uptake into clinical practice has often been restricted to specialist research sites. There is often a lack of detailed MRI knowledge within the RT community and an apprehension of geometric distortions, both of which prevent its best utilization and merit the introduction of a standardized approach and common guidelines. This review sets out to address some of the issues involved in acquiring MRI scans for RT planning in the context of a number of clinical sites of interest and concludes with recommendations for its best practice in terms of imaging protocol and quality assurance. The article is of particular interest to the growing number of cancer therapy centers that are embarking on MRI simulation on either existing systems or their own dedicated scanners.
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Affiliation(s)
- Gary P Liney
- Ingham Institute for Applied Medical Research, Liverpool, Sydney, New South Wales, Australia; Department of Medical Physics, University of Wollongong, Wollongong, New South Wales, Australia.
| | - Marinus A Moerland
- Department of Radiation Oncology, University Medical Center Utrecht, Utrecht, The Netherlands
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Nakazawa H, Komori M, Shibamoto Y, Takikawa Y, Mori Y, Tsugawa T. Geometric accuracy in three-dimensional coordinates of Leksell stereotactic skull frame with wide-bore 1.5-T MRI compared with conventional 1.5-T MRI. J Med Imaging Radiat Oncol 2014; 58:595-600. [DOI: 10.1111/1754-9485.12225] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2014] [Accepted: 07/12/2014] [Indexed: 11/26/2022]
Affiliation(s)
- Hisato Nakazawa
- Department of Radiological Sciences; Nagoya University Graduate School of Medicine; Nagoya Aichi Japan
- Nagoya Radiosurgery Center; Nagoya Kyoritsu Hospital; Nagoya Aichi Japan
| | - Masataka Komori
- Department of Radiological Sciences; Nagoya University Graduate School of Medicine; Nagoya Aichi Japan
| | - Yuta Shibamoto
- Department of Radiology; Nagoya City University Graduate School of Medical Sciences; Nagoya Aichi Japan
| | - Yukinori Takikawa
- Nagoya Radiosurgery Center; Nagoya Kyoritsu Hospital; Nagoya Aichi Japan
| | - Yoshimasa Mori
- Department of Radiology and Radiation Oncology; Aichi Medical University; Nagakute Aichi Japan
| | - Takahiko Tsugawa
- Nagoya Radiosurgery Center; Nagoya Kyoritsu Hospital; Nagoya Aichi Japan
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