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Richardson SL, Buzurovic IM, Cohen GN, Culberson WS, Dempsey C, Libby B, Melhus CS, Miller RA, Scanderbeg DJ, Simiele SJ. AAPM medical physics practice guideline 13.a: HDR brachytherapy, part A. J Appl Clin Med Phys 2023; 24:e13829. [PMID: 36808798 PMCID: PMC10018677 DOI: 10.1002/acm2.13829] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2022] [Revised: 08/09/2022] [Accepted: 09/22/2022] [Indexed: 02/22/2023] Open
Abstract
The American Association of Physicists in Medicine (AAPM) is a nonprofit professional society whose primary purposes are to advance the science, education, and professional practice of medical physics. The AAPM has more than 8000 members and is the principal organization of medical physicists in the United States. The AAPM will periodically define new practice guidelines for medical physics practice to help advance the science of medical physics and to improve the quality of service to patients throughout the United States. Existing medical physics practice guidelines (MPPGs) will be reviewed for the purpose of revision or renewal, as appropriate, on their fifth anniversary or sooner. Each medical physics practice guideline represents a policy statement by the AAPM, has undergone a thorough consensus process in which it has been subjected to extensive review, and requires the approval of the Professional Council. The medical physics practice guidelines recognize that the safe and effective use of diagnostic and therapeutic radiology requires specific training, skills, and techniques, as described in each document. Reproduction or modification of the published practice guidelines and technical standards by those entities not providing these services is not authorized. The following terms are used in the AAPM practice guidelines: (1) Must and must not: Used to indicate that adherence to the recommendation is considered necessary to conform to this practice guideline. (2) Should and should not: Used to indicate a prudent practice to which exceptions may occasionally be made in appropriate circumstances. Approved by AAPM's Executive Committee April 28, 2022.
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Affiliation(s)
| | - Ivan M Buzurovic
- Brigham & Women's Hospital, Harvard Medical School, Boston, MA, USA
| | - Gil'ad N Cohen
- Memorial Sloan-Kettering Cancer Center, New York, NY, USA
| | | | - Claire Dempsey
- Calvary Mater Newcastle Hospital University of Newcastle, Callaghan, Australia University of Washington, Seattle, USA
| | | | | | - Robin A Miller
- Multicare Regional Cancer Center, Northwest Medical Physics Center, Tacoma, WA, USA
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Walker A, Chlap P, Causer T, Mahmood F, Buckley J, Holloway L. Development of a vendor neutral MRI distortion quality assurance workflow. J Appl Clin Med Phys 2022; 23:e13735. [PMID: 35880651 PMCID: PMC9588272 DOI: 10.1002/acm2.13735] [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: 05/17/2022] [Accepted: 07/07/2022] [Indexed: 12/04/2022] Open
Abstract
With the utilization of magnetic resonance (MR) imaging in radiotherapy increasing, routine quality assurance (QA) of these systems is necessary. The assessment of geometric distortion in images used for radiotherapy treatment planning needs to be quantified and monitored over time. This work presents an adaptable methodology for performing routine QA for systematic MRI geometric distortion. A software tool and compatible protocol (designed to work with any CT and MR compatible phantom on any scanner) were developed to quantify geometric distortion via deformable image registration. The MR image is deformed to the CT, generating a deformation field, which is sampled, quantifying geometric distortion as a function of distance from scanner isocenter. Configurability of the QA tool was tested, and results compared to those provided from commercial solutions. Registration accuracy was investigated by repeating the deformable registration step on the initial deformed MR image to define regions with residual distortions. The geometric distortion of four clinical systems was quantified using the customisable QA method presented. Maximum measured distortions varied from 2.2 to 19.4 mm (image parameter and sampling volume dependent). The workflow was successfully customized for different phantom configurations and volunteer imaging studies. Comparison to a vendor supplied solution showed good agreement in regions where the two procedures were sampling the same imaging volume. On a large field of view phantom across various scanners, the QA tool accurately quantified geometric distortions within 17–22 cm from scanner isocenter. Beyond these regions, the geometric integrity of images in clinical applications should be considered with a higher degree of uncertainty due to increased gradient nonlinearity and B0 inhomogeneity. This tool has been successfully integrated into routine QA of the MRI scanner utilized for radiotherapy within our department. It enables any low susceptibility MR‐CT compatible phantom to quantify the geometric distortion on any MRI scanner with a configurable, user friendly interface for ease of use and consistency in data collection and analysis.
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Affiliation(s)
- Amy Walker
- Liverpool and Macarthur Cancer Therapy Centres, Sydney, Australia.,Ingham Institute of Applied Medical Research, Sydney, Australia.,Centre for Medical Radiation Physics, University of Wollongong, Wollongong, Australia.,South Western Clinical School, University of New South Wales, Sydney, Australia
| | - Phillip Chlap
- Liverpool and Macarthur Cancer Therapy Centres, Sydney, Australia.,Ingham Institute of Applied Medical Research, Sydney, Australia.,South Western Clinical School, University of New South Wales, Sydney, Australia
| | - Trent Causer
- Centre for Medical Radiation Physics, University of Wollongong, Wollongong, Australia.,Illawarra Cancer Care Centre, Wollongong, Australia
| | - Faisal Mahmood
- Laboratory of Radiation Physics, Department of Oncology, Odense University Hospital, Odense, Denmark.,Department of Clinical Research, University of Southern Denmark, Odense, Denmark
| | - Jarryd Buckley
- Liverpool and Macarthur Cancer Therapy Centres, Sydney, Australia.,Ingham Institute of Applied Medical Research, Sydney, Australia.,Centre for Medical Radiation Physics, University of Wollongong, Wollongong, Australia.,Illawarra Cancer Care Centre, Wollongong, Australia
| | - Lois Holloway
- Liverpool and Macarthur Cancer Therapy Centres, Sydney, Australia.,Ingham Institute of Applied Medical Research, Sydney, Australia.,Centre for Medical Radiation Physics, University of Wollongong, Wollongong, Australia.,South Western Clinical School, University of New South Wales, Sydney, Australia.,Institute of Medical Physics, University of Sydney, Sydney, Australia
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Wyatt JJ, McCallum HM, Maxwell RJ. Developing quality assurance tests for simultaneous Positron Emission Tomography – Magnetic Resonance imaging for radiotherapy planning. Phys Imaging Radiat Oncol 2022; 22:28-35. [PMID: 35493852 PMCID: PMC9048159 DOI: 10.1016/j.phro.2022.03.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Revised: 03/02/2022] [Accepted: 03/18/2022] [Indexed: 12/05/2022] Open
Abstract
Background and purpose Simultaneous Positron Emission Tomography – Magnetic Resonance (PET-MR) imaging can potentially improve radiotherapy by enabling more accurate tumour delineation and dose painting. The use of PET-MR imaging for radiotherapy planning requires a comprehensive Quality Assurance (QA) programme to be developed. This study aimed to develop the QA tests required and assess their repeatability and stability. Materials and methods QA tests were developed for: MR image quality, MR geometric accuracy, electromechanical accuracy, PET-MR alignment accuracy, Diffusion Weighted (DW)-MR Apparent Diffusion Coefficient (ADC) accuracy and PET Standard Uptake Value (SUV) accuracy. Each test used a dedicated phantom and was analysed automatically or semi-automatically, with in–house software. Repeatability was evaluated by three same-day measurements with independent phantom positions. Stability was assessed through 12 monthly measurements. Results The repeatability Standard Deviations (SDs) of distortion for the MR geometric accuracy test were ⩽0.7mm. The repeatability SDs in ADC difference from reference were ⩽3% for the DW-MR accuracy test. The PET SUV difference from reference repeatability SD was 0.3%. The stability SDs agreed within 0.6mm, 1 percentage point and 1.4 percentage points of the repeatability SDs for the geometric, ADC and SUV accuracy tests respectively. There were no monthly trends apparent. These results were representative of the other tests. Conclusions QA Tests for radiotherapy planning PET-MR have been developed. The tests appeared repeatable and stable over a 12-month period. The developed QA tests could form the basis of a QA programme that enables high-quality, robust PET-MR imaging for radiotherapy planning.
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Lui JCF, Tang AM, Law CC, Lee JCY, Lee FKH, Chiu J, Wong KH. A practical methodology to improve the dosimetric accuracy of MR-based radiotherapy simulation for brain tumors. Phys Med 2021; 91:1-12. [PMID: 34678686 DOI: 10.1016/j.ejmp.2021.10.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Revised: 10/04/2021] [Accepted: 10/05/2021] [Indexed: 11/25/2022] Open
Abstract
PURPOSE To investigate the dosimetric accuracy of synthetic computed tomography (sCT) images generated by a clinically-ready voxel-based MRI simulation package, and to develop a simple and feasible method to improve the accuracy. METHODS 20 patients with brain tumor were selected to undergo CT and MRI simulation. sCT images were generated by a clinical MRI simulation package. The discrepancy between planning CT and sCT in CT number and body contour were evaluated. To resolve the discrepancies, an sCT specific CT-relative electron density (RED) calibration curve was used, and a layer of pseudo-skin was created on the sCT. The dosimetric impact of these discrepancies, and the improvement brought about by the modifications, were evaluated by a planning study. Volumetric modulated arc therapy (VMAT) treatment plans for each patient were created and optimized on the planning CT, which were then transferred to the original sCT and the modified-sCT for dose re-calculation. Dosimetric comparisons and gamma analysis between the calculated doses in different images were performed. RESULTS The average gamma passing rate with 1%/1 mm criteria was only 70.8% for the comparison of dose distribution between planning CT and original sCT. The mean dose difference between the planning CT and the original sCT were -1.2% for PTV D95 and -1.7% for PTV Dmax, while the mean dose difference was within 0.7 Gy for all relevant OARs. After applying the modifications on the sCT, the average gamma passing rate was increased to 92.2%. Mean dose difference in PTV D95 and Dmax were reduced to -0.1% and -0.3% respectively. The mean dose difference was within 0.2 Gy for all OAR structures and no statistically significant difference were found. CONCLUSIONS The modified-sCT demonstrated improved dosimetric agreement with the planning CT. These results indicated the overall dosimetric accuracy and practicality of this improved MR-based treatment planning method.
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Affiliation(s)
- Jeffrey C F Lui
- Department of Clinical Oncology, Queen Elizabeth Hospital, Hong Kong.
| | - Annie M Tang
- Department of Clinical Oncology, Queen Elizabeth Hospital, Hong Kong
| | - C C Law
- Department of Clinical Oncology, Queen Elizabeth Hospital, Hong Kong
| | - Jonan C Y Lee
- Department of Radiology, Queen Elizabeth Hospital, Hong Kong
| | - Francis K H Lee
- Department of Clinical Oncology, Queen Elizabeth Hospital, Hong Kong
| | - Jeffrey Chiu
- Department of Radiology, Queen Elizabeth Hospital, Hong Kong
| | - Kam-Hung Wong
- Department of Clinical Oncology, Queen Elizabeth Hospital, Hong Kong
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Keyriläinen J, Sjöblom O, Turnbull-Smith S, Hovirinta T, Minn H. Clinical experience and cost evaluation of magnetic resonance imaging -only workflow in radiation therapy planning of prostate cancer. PHYSICS & IMAGING IN RADIATION ONCOLOGY 2021; 19:66-71. [PMID: 34307921 PMCID: PMC8295845 DOI: 10.1016/j.phro.2021.07.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Revised: 05/31/2021] [Accepted: 07/01/2021] [Indexed: 12/24/2022]
Abstract
Using MRI-only for prostate cancer radiation therapy planning (RTP) can reduce costs. An MRI-only workflow is particularly suitable for medium-sized and large departments. Omitting CT in the RTP workflow saves scanner, staff, and patient time.
Background and purpose In radiation therapy (RT), significant improvements have been made recently particularly in the practices of planning imaging. This study aimed to conduct a cost evaluation between magnetic resonance imaging (MRI) -only and combined computed tomography (CT) and MRI workflows. Materials and methods The time-driven activity-based costing (TDABC) model was used to conduct a cost evaluation between the two workflows in those steps, where cost differences were expected. Costs were divided into capital costs and operational costs. The former consisted of fixed, one-time expenses, e.g. the purchase of a scanner, whereas the latter were partially based on the amount of activity consumed i.e. time required for image acquisition, image registration and structure contouring. Results In a review over a period of 10 years for 300 annual prostate cancer patients, the total cost of the workflow steps included in the study for an individual patient applying the MRI-only workflow was 903 € (100%), comprised of 537 € (59%) capital costs and 366 € (41%) operational costs. The corresponding total cost for an individual patient applying the CT + MRI workflow was 922 € (100%), comprised of 197 € (21%) capital costs and 726 € (79%) operational costs. In 10 years for 3000 patients, a total saving of 58,544 € (2%) was achieved with the MRI-only workflow compared with the dual imaging workflow. Conclusions MRI-only workflow is a feasible and economic way to perform clinical RT for localized prostate cancer, in particular for medium- and large-sized departments treating a sufficient number of patients.
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Affiliation(s)
- Jani Keyriläinen
- Department of Medical Physics, Turku University Hospital, Hämeentie 11, FI-20521 Turku, Finland
- Department of Oncology and Radiotherapy, Turku University Hospital, Hämeentie 11, FI-20521 Turku, Finland
- Corresponding author at: Hämeentie 11, FIN-20521 Turku, Finland.
| | - Olli Sjöblom
- Turku University School of Economics, Information Systems Science, Rehtorinpellonkatu 3, FI-20500 Turku, Finland
| | - Sonja Turnbull-Smith
- Philips Oy, Philips Medical Systems MR Finland, Radiation Oncology Helsinki, Äyritie 4, FI-01510 Vantaa, Finland
| | - Taru Hovirinta
- Department of Finance, The Hospital District of Southwest Finland, Kiinamyllynkatu 4-8, FI-20521 Turku, Finland
| | - Heikki Minn
- Department of Oncology and Radiotherapy, Turku University Hospital, Hämeentie 11, FI-20521 Turku, Finland
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Kavaluus H, Nousiainen K, Kaijaluoto S, Seppälä T, Saarilahti K, Tenhunen M. Determination of acceptance criteria for geometric accuracy of magnetic resonance imaging scanners used in radiotherapy planning. PHYSICS & IMAGING IN RADIATION ONCOLOGY 2021; 17:58-64. [PMID: 33898780 PMCID: PMC8058029 DOI: 10.1016/j.phro.2021.01.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Revised: 01/14/2021] [Accepted: 01/14/2021] [Indexed: 12/23/2022]
Abstract
Geometric accuracy of MRI-scanners in radiotherapy planning must be evaluated. Phantom acquisitions with standard and clinical sequences were performed. Geometric distortions were determined in several volumes of interest. We recommend acceptance criteria for MRI-scanners in radiotherapy planning. Explicit and simple acceptance criteria enable effective regulatory inspections.
Background and Purpose Magnetic resonance imaging is increasingly used in radiotherapy planning; yet, the performance of the utilized scanners is rarely regulated by any authority. The aim of this study was to determine the geometric accuracy of several magnetic resonance imaging scanners used for radiotherapy planning, and to establish acceptance criteria for such scanners. Materials and Methods The geometric accuracy of five different scanners was measured with three sequences using a commercial large-field-of-view phantom. The distortion magnitudes were determined in spherical volumes around the scanner isocenter and in cylindrical volumes along scanner z-axis. The repeatability of the measurements was determined on a single scanner with two quality assurance sequences with three single-setup and seven repeated-setup measurements. Results For all scanners and sequences except one, the mean and median distortion magnitude was <1 mm and <2 mm in spherical volumes with diameters of 400 mm and 500 mm, respectively. For all sequences maximum distortion was <2 mm in spherical volume with diameter of 300 mm. The mean standard deviation of marker-by-marker distortion magnitudes over repeated acquisitions was ≤0.6 mm with both tested sequences. Conclusions All tested scanners were geometrically accurate for their current use in radiotherapy planning. The acceptance criteria of geometric accuracy for regulatory inspections of a supervising authority could be set according to these results.
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Affiliation(s)
- Henna Kavaluus
- Radiation and Nuclear Safety Authority, STUK, Laippatie 4, FI-00880 Helsinki, Finland.,HUS Cancer Center, Helsinki University Hospital and University of Helsinki, P.O. Box 180, FI-00029 Helsinki, Finland.,Department of Physics, University of Helsinki, P.O. Box 64, FI-00014 Helsinki, Finland
| | - Katri Nousiainen
- Radiation and Nuclear Safety Authority, STUK, Laippatie 4, FI-00880 Helsinki, Finland.,HUS Cancer Center, Helsinki University Hospital and University of Helsinki, P.O. Box 180, FI-00029 Helsinki, Finland.,Department of Physics, University of Helsinki, P.O. Box 64, FI-00014 Helsinki, Finland.,HUS Medical Imaging Center, Helsinki University Hospital and University of Helsinki, B.O. Box 340, FI-00029 Helsinki, Finland
| | - Sampsa Kaijaluoto
- Radiation and Nuclear Safety Authority, STUK, Laippatie 4, FI-00880 Helsinki, Finland
| | - Tiina Seppälä
- HUS Cancer Center, Helsinki University Hospital and University of Helsinki, P.O. Box 180, FI-00029 Helsinki, Finland
| | - Kauko Saarilahti
- HUS Cancer Center, Helsinki University Hospital and University of Helsinki, P.O. Box 180, FI-00029 Helsinki, Finland
| | - Mikko Tenhunen
- HUS Cancer Center, Helsinki University Hospital and University of Helsinki, P.O. Box 180, FI-00029 Helsinki, Finland
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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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van den Ende RPJ, Ercan E, Keesman R, Kerkhof EM, Marijnen CAM, van der Heide UA. Applicator visualization using ultrashort echo time MRI for high-dose-rate endorectal brachytherapy. Brachytherapy 2020; 19:618-623. [PMID: 32747144 DOI: 10.1016/j.brachy.2020.06.010] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2020] [Revised: 06/08/2020] [Accepted: 06/09/2020] [Indexed: 11/18/2022]
Abstract
PURPOSE The individual channels in an endorectal applicator for high-dose-rate endorectal brachytherapy are not visible on standard MRI sequences. The aim of this study was to test whether an ultrashort echo time (UTE) MRI sequence could be used to visualize the individual channels to enable MR-only treatment planning for rectal cancer. METHODS AND MATERIALS We used a radial three-dimensional (3D) UTE pulse sequence and acquired images of phantoms and two patients with rectal cancer. We rigidly registered a UTE image and CT scan of an applicator phantom, based on the outline of the applicator. One observer compared channel positions on the UTE image and CT scan in five slices spaced 25 mm apart. To quantify geometric distortions, we scanned a commercial 3D geometric quality assurance phantom and calculated the difference between detected marker positions on the UTE image and corresponding marker positions on two 3D T1-weighted images with opposing readout directions. RESULTS On the UTE images, there is sufficient contrast to discern the individual channels. The difference in channel positions on the UTE image compared with the CT was on average -0.1 ± 0.1 mm (left-right) and 0.1 ± 0.3 mm (anteroposterior). After rigid registration to the 3D T1-weighted sequences, the residual 95th percentile of the geometric distortion inside a 550-mm-diameter sphere was 1.0 mm (left-right), 0.9 mm (anteroposterior), and 0.9 mm (craniocaudal). CONCLUSIONS With a UTE sequence, the endorectal applicator and individual channels can be adequately visualized in both phantom and patients. The geometrical fidelity is within an acceptable range.
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Affiliation(s)
- Roy P J van den Ende
- Department of Radiation Oncology, Leiden University Medical Center, Leiden, the Netherlands.
| | - Ece Ercan
- C.J. Gorter Center for High Field MRI, Department of Radiology, Leiden University Medical Center, Leiden, the Netherlands
| | - Rick Keesman
- Department of Radiation Oncology, The Netherlands Cancer Institute, Amsterdam, the Netherlands
| | - Ellen M Kerkhof
- Department of Radiation Oncology, Leiden University Medical Center, Leiden, the Netherlands
| | - Corrie A M Marijnen
- Department of Radiation Oncology, Leiden University Medical Center, Leiden, the Netherlands; Department of Radiation Oncology, The Netherlands Cancer Institute, Amsterdam, the Netherlands
| | - Uulke A van der Heide
- Department of Radiation Oncology, Leiden University Medical Center, Leiden, the Netherlands; Department of Radiation Oncology, The Netherlands Cancer Institute, Amsterdam, the Netherlands
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Alzahrani M, Broadbent DA, Chuter R, Al-Qaisieh B, Jackson S, Michael H, Johnstone RI, Shah S, Wetscherek A, Chick HJ, Wyatt JJ, McCallum HM, Speight R. Audit feasibility for geometric distortion in magnetic resonance imaging for radiotherapy. Phys Imaging Radiat Oncol 2020; 15:80-84. [PMID: 33163632 PMCID: PMC7607582 DOI: 10.1016/j.phro.2020.07.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2020] [Revised: 06/27/2020] [Accepted: 07/22/2020] [Indexed: 11/02/2022] Open
Abstract
BACKGROUND AND PURPOSE Magnetic Resonance Imaging (MRI) is increasingly being used in radiotherapy (RT). However, geometric distortions are a known challenge of using MRI in RT. The aim of this study was to demonstrate feasibility of a national audit of MRI geometric distortions. This was achieved by assessing large field of view (FOV) MRI distortions on a number of scanners used clinically for RT. MATERIALS AND METHODS MRI scans of a large FOV MRI geometric distortion phantom were acquired on 11 MRI scanners that are used clinically for RT in the UK. The mean and maximum distortions and variance between scanners were reported at different distances from the isocentre. RESULTS For a small FOV representing a brain (100-150 mm from isocentre) all distortions were < 2 mm except for the maximum distortion of one scanner. For a large FOV representing a head and neck/pelvis (200-250 mm from isocentre) mean distortions were < 2 mm except for one scanner, maximum distortions were > 10 mm in some cases. The variance between scanners was low and was found to increase with distance from isocentre. CONCLUSIONS This study demonstrated feasibility of the technique to be repeated in a country wide geometric distortion audit of all MRI scanners used clinically for RT. Recommendations were made for performing such an audit and how to derive acceptable limits of distortion in such an audit.
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Affiliation(s)
- Meshal Alzahrani
- Department of Diagnostic Radiology, Faculty of Applied Medical Sciences, King Abdulaziz University, Jeddah, Saudi Arabia
- Biomedical Imaging Science Department, Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, UK
| | - David A Broadbent
- Department of Medical Physics and Engineering, Leeds Teaching Hospitals NHS Trust, Leeds, UK
| | - Robert Chuter
- Christie Medical Physics and Engineering (CMPE), The Christie NHS Foundation Trust, Manchester, UK
- Division of Cancer Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK
| | - Bashar Al-Qaisieh
- Department of Medical Physics and Engineering, Leeds Teaching Hospitals NHS Trust, Leeds, UK
| | - Steven Jackson
- Christie Medical Physics and Engineering (CMPE), The Christie NHS Foundation Trust, Manchester, UK
| | - Hutton Michael
- Christie Medical Physics and Engineering (CMPE), The Christie NHS Foundation Trust, Manchester, UK
| | | | - Simon Shah
- Guy’s and St Thomas’ NHS Foundation Trust, London, UK
| | - Andreas Wetscherek
- Joint Department of Physics at the Institute of Cancer Research and the Royal Marsden NHS Foundation Trust, London, UK
| | - H. Joan Chick
- Joint Department of Physics at the Institute of Cancer Research and the Royal Marsden NHS Foundation Trust, London, UK
| | - Jonathan J Wyatt
- Northern Centre for Cancer Care, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle, UK
- Centre for Cancer, Newcastle University, Newcastle, UK
| | - Hazel Mhairi McCallum
- Northern Centre for Cancer Care, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle, UK
- Centre for Cancer, Newcastle University, Newcastle, UK
| | - Richard Speight
- Department of Medical Physics and Engineering, Leeds Teaching Hospitals NHS Trust, Leeds, UK
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Measuring geometric accuracy in magnetic resonance imaging with 3D-printed phantom and nonrigid image registration. MAGMA (NEW YORK, N.Y.) 2019; 33:401-410. [PMID: 31646408 PMCID: PMC7230057 DOI: 10.1007/s10334-019-00788-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/16/2019] [Revised: 10/04/2019] [Accepted: 10/11/2019] [Indexed: 11/16/2022]
Abstract
Objective We aimed to develop a vendor-neutral and interaction-free quality assurance protocol for measuring geometric accuracy of head and brain magnetic resonance (MR) images. We investigated the usability of nonrigid image registration in the analysis and looked for the optimal registration parameters. Materials and methods We constructed a 3D-printed phantom and imaged it with 12 MR scanners using clinical sequences. We registered a geometric-ground-truth computed tomography (CT) acquisition to the MR images using an open-source nonrigid-registration-toolbox with varying parameters. We applied the transforms to a set of control points in the CT image and compared their locations to the corresponding visually verified reference points in the MR images. Results With optimized registration parameters, the mean difference (and standard deviation) of control point locations when compared to the reference method was (0.17 ± 0.02) mm for the 12 studied scanners. The maximum displacements varied from 0.50 to 1.35 mm or 0.89 to 2.30 mm, with vendors’ distortion correction on or off, respectively. Discussion Using nonrigid CT–MR registration can provide a robust and relatively test-object-agnostic method for estimating the intra- and inter-scanner variations of the geometric distortions.
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