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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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Rostami A, Robatjazi M, Javadinia SA, Shomoossi N, Shahraini R. The influence of patient positioning and immobilization equipment on MR image quality and image registration in radiation therapy. J Appl Clin Med Phys 2024; 25:e14162. [PMID: 37716368 PMCID: PMC10860429 DOI: 10.1002/acm2.14162] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2023] [Revised: 08/14/2023] [Accepted: 09/07/2023] [Indexed: 09/18/2023] Open
Abstract
INTRODUCTION MRI is preferred for brain tumor assessment, while CT is used for radiotherapy simulation. This study evaluated immobilization equipment's impact on CT-MRI registration accuracy and MR image quality in RT setup. METHODS We included CT and MR images from 11 patients with high-grade glioma, all of whom were immobilized with a thermoplastic mask and headrest. T1- and T2-weighted MR images were acquired using an MR head coil in a diagnostic setup (DS) and a body matrix coil in RT setup. To assess MR image quality, signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were considered in some dedicated regions of interest. We also evaluated the impact of immobilization equipment on CT-MRI rigid registration using line profile and external contour methods. RESULTS The CNR and SNR reduction was in the RT setup of imaging. This was more evident in T1-weighted images than in T2-weighted ones. The SNR decreased by 14.91% and 12.09%, while CNR decreased by 25.12% and 20.15% in T1- and T2-weighted images, respectively. The immobilization equipment in the RT setup decreased the mean error in rigid registration by 1.02 mm. The external contour method yielded Dice similarity coefficients (DSC) of 0.84 and 0.92 for CT-DS MRI and CT-RT MRI registration, respectively. CONCLUSION The image quality reduction in the RT setup was due to the imaged region's anatomy and its position relative to the applied coil. Furthermore, optimizing the pulse sequence is crucial for MR imaging in RT applications. Although the use of immobilization equipment may decrease the image quality in the RT setup, it does not affect organ delineation, and the image quality is still satisfactory for this purpose. Also, the use of immobilization equipment in the RT setup has increased registration accuracy.
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Affiliation(s)
- Atefeh Rostami
- Department of Medical Physics and Radiological SciencesSabzevar University of Medical SciencesSabzevarIran
| | - Mostafa Robatjazi
- Department of Medical Physics and Radiological SciencesSabzevar University of Medical SciencesSabzevarIran
- Non‐Communicable Diseases Research CenterSabzevar University of Medical SciencesSabzevarIran
| | - Seyed Alireza Javadinia
- Non‐Communicable Diseases Research CenterSabzevar University of Medical SciencesSabzevarIran
| | | | - Ramin Shahraini
- Department of RadiologySchool of MedicineSabzevar University of Medical SciencesSabzevarIran
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Putz F, Bock M, Schmitt D, Bert C, Blanck O, Ruge MI, Hattingen E, Karger CP, Fietkau R, Grigo J, Schmidt MA, Bäuerle T, Wittig A. Quality requirements for MRI simulation in cranial stereotactic radiotherapy: a guideline from the German Taskforce "Imaging in Stereotactic Radiotherapy". Strahlenther Onkol 2024; 200:1-18. [PMID: 38163834 PMCID: PMC10784363 DOI: 10.1007/s00066-023-02183-6] [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: 09/01/2023] [Accepted: 11/06/2023] [Indexed: 01/03/2024]
Abstract
Accurate Magnetic Resonance Imaging (MRI) simulation is fundamental for high-precision stereotactic radiosurgery and fractionated stereotactic radiotherapy, collectively referred to as stereotactic radiotherapy (SRT), to deliver doses of high biological effectiveness to well-defined cranial targets. Multiple MRI hardware related factors as well as scanner configuration and sequence protocol parameters can affect the imaging accuracy and need to be optimized for the special purpose of radiotherapy treatment planning. MRI simulation for SRT is possible for different organizational environments including patient referral for imaging as well as dedicated MRI simulation in the radiotherapy department but require radiotherapy-optimized MRI protocols and defined quality standards to ensure geometrically accurate images that form an impeccable foundation for treatment planning. For this guideline, an interdisciplinary panel including experts from the working group for radiosurgery and stereotactic radiotherapy of the German Society for Radiation Oncology (DEGRO), the working group for physics and technology in stereotactic radiotherapy of the German Society for Medical Physics (DGMP), the German Society of Neurosurgery (DGNC), the German Society of Neuroradiology (DGNR) and the German Chapter of the International Society for Magnetic Resonance in Medicine (DS-ISMRM) have defined minimum MRI quality requirements as well as advanced MRI simulation options for cranial SRT.
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Affiliation(s)
- Florian Putz
- Strahlenklinik, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany.
| | - Michael Bock
- Klinik für Radiologie-Medizinphysik, Universitätsklinikum Freiburg, Freiburg, Germany
| | - Daniela Schmitt
- Klinik für Strahlentherapie und Radioonkologie, Universitätsmedizin Göttingen, Göttingen, Germany
| | - Christoph Bert
- Strahlenklinik, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Oliver Blanck
- Klinik für Strahlentherapie, Universitätsklinikum Schleswig-Holstein, Campus Kiel, Kiel, Germany
| | - Maximilian I Ruge
- Klinik für Stereotaxie und funktionelle Neurochirurgie, Zentrum für Neurochirurgie, Universitätsklinikum Köln, Cologne, Germany
| | - Elke Hattingen
- Institut für Neuroradiologie, Universitätsklinikum Frankfurt, Frankfurt am Main, Germany
| | - Christian P Karger
- Abteilung Medizinische Physik in der Strahlentherapie, Deutsches Krebsforschungszentrum (DKFZ), Heidelberg, Germany
- Nationales Zentrum für Strahlenforschung in der Onkologie (NCRO), Heidelberger Institut für Radioonkologie (HIRO), Heidelberg, Germany
| | - Rainer Fietkau
- Strahlenklinik, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Johanna Grigo
- Strahlenklinik, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Manuel A Schmidt
- Neuroradiologisches Institut, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Tobias Bäuerle
- Radiologisches Institut, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Andrea Wittig
- Klinik und Poliklinik für Strahlentherapie und Radioonkologie, Universitätsklinikum Würzburg, Würzburg, Germany
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Kaza E, Guenette JP, Guthier CV, Hatch S, Marques A, Singer L, Schoenfeld JD. Image quality comparisons of coil setups in 3T MRI for brain and head and neck radiotherapy simulations. J Appl Clin Med Phys 2022; 23:e13794. [PMID: 36285814 PMCID: PMC9797171 DOI: 10.1002/acm2.13794] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2022] [Revised: 07/11/2022] [Accepted: 09/06/2022] [Indexed: 01/01/2023] Open
Abstract
PURPOSE MRI is increasingly used for brain and head and neck radiotherapy treatment planning due to its superior soft tissue contrast. Flexible array coils can be arranged to encompass treatment immobilization devices, which do not fit in diagnostic head/neck coils. Selecting a flexible coil arrangement to replace a diagnostic coil should rely on image quality characteristics and patient comfort. We compared image quality obtained with a custom UltraFlexLarge18 (UFL18) coil setup against a commercial FlexLarge4 (FL4) coil arrangement, relative to a diagnostic Head/Neck20 (HN20) coil at 3T. METHODS The large American College of Radiology (ACR) MRI phantom was scanned monthly in the UFL18, FL4, and HN20 coil setup over 2 years, using the ACR series and three clinical sequences. High-contrast spatial resolution (HCSR), image intensity uniformity (IIU), percent-signal ghosting (PSG), low-contrast object detectability (LCOD), signal-to-noise ratio (SNR), and geometric accuracy were calculated according to ACR recommendations for each series and coil arrangement. Five healthy volunteers were scanned with the clinical sequences in all three coil setups. SNR, contrast-to-noise ratio (CNR) and artifact size were extracted from regions-of-interest along the head for each sequence and coil setup. For both experiments, ratios of image quality parameters obtained with UFL18 or FL4 over those from HN20 were formed for each coil setup, grouping the ACR and clinical sequences. RESULTS Wilcoxon rank-sum tests revealed significantly higher (p < 0.001) LCOD, IIU and SNR, and lower PSG ratios with UFL18 than FL4 on the phantom for the clinical sequences, with opposite PSG and SNR trends for the ACR series. Similar statistical tests on volunteer data corroborated that SNR ratios with UFL18 (0.58 ± 0.19) were significantly higher (p < 0.001) than with FL4 (0.51 ± 0.18) relative to HN20. CONCLUSIONS The custom UFL18 coil setup was selected for clinical application in MR simulations due to the superior image quality demonstrated on a phantom and volunteers for clinical sequences and increased volunteer comfort.
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Affiliation(s)
- Evangelia Kaza
- Radiation Oncology, Brigham and Women's HospitalDana‐Farber Cancer Institute, Harvard Medical SchoolBostonMassachusettsUSA
| | - Jeffrey P. Guenette
- Division of Neuroradiology, Brigham and Women's HospitalDana‐Farber Cancer Institute, Harvard Medical SchoolBostonMassachusettsUSA
| | - Christian V. Guthier
- Radiation Oncology, Brigham and Women's HospitalDana‐Farber Cancer Institute, Harvard Medical SchoolBostonMassachusettsUSA
| | - Steven Hatch
- Radiation Oncology, Brigham and Women's HospitalDana‐Farber Cancer Institute, Harvard Medical SchoolBostonMassachusettsUSA
| | - Alexander Marques
- Radiation Oncology, Brigham and Women's HospitalDana‐Farber Cancer Institute, Harvard Medical SchoolBostonMassachusettsUSA
| | - Lisa Singer
- Radiation Oncology, Brigham and Women's HospitalDana‐Farber Cancer Institute, Harvard Medical SchoolBostonMassachusettsUSA,Radiation OncologyUniversity of CaliforniaSan FranciscoCaliforniaUSA
| | - Jonathan D. Schoenfeld
- Radiation Oncology, Brigham and Women's HospitalDana‐Farber Cancer Institute, Harvard Medical SchoolBostonMassachusettsUSA
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Yuan J, Poon DMC, Lo G, Wong OL, Cheung KY, Yu SK. A narrative review of MRI acquisition for MR-guided-radiotherapy in prostate cancer. Quant Imaging Med Surg 2022; 12:1585-1607. [PMID: 35111651 PMCID: PMC8739116 DOI: 10.21037/qims-21-697] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Accepted: 08/20/2021] [Indexed: 08/24/2023]
Abstract
Magnetic resonance guided radiotherapy (MRgRT), enabled by the clinical introduction of the integrated MRI and linear accelerator (MR-LINAC), is a novel technique for prostate cancer (PCa) treatment, promising to further improve clinical outcome and reduce toxicity. The role of prostate MRI has been greatly expanded from the traditional PCa diagnosis to also PCa screening, treatment and surveillance. Diagnostic prostate MRI has been relatively familiar in the community, particularly with the development of Prostate Imaging - Reporting and Data System (PI-RADS). But, on the other hand, the use of MRI in the emerging clinical practice of PCa MRgRT, which is substantially different from that in PCa diagnosis, has been so far sparsely presented in the medical literature. This review attempts to give a comprehensive overview of MRI acquisition techniques currently used in the clinical workflows of PCa MRgRT, from treatment planning to online treatment guidance, in order to promote MRI practice and research for PCa MRgRT. In particular, the major differences in the MRI acquisition of PCa MRgRT from that of diagnostic prostate MRI are demonstrated and explained. Limitations in the current MRI acquisition for PCa MRgRT are analyzed. The future developments of MRI in the PCa MRgRT are also discussed.
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Affiliation(s)
- Jing Yuan
- Medical Physics and Research Department, Hong Kong Sanatorium & Hospital, Hong Kong, China
| | - Darren M. C. Poon
- Comprehensive Oncology Centre, Hong Kong Sanatorium & Hospital, Hong Kong, China
| | - Gladys Lo
- Department of Diagnostic & Interventional Radiology, Hong Kong Sanatorium & Hospital, Hong Kong, China
| | - Oi Lei Wong
- Medical Physics and Research Department, Hong Kong Sanatorium & Hospital, Hong Kong, China
| | - Kin Yin Cheung
- Medical Physics and Research Department, Hong Kong Sanatorium & Hospital, Hong Kong, China
| | - Siu Ki Yu
- Medical Physics and Research Department, Hong Kong Sanatorium & Hospital, Hong Kong, China
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Kang Y, Chen Y, Fang J, Huang Y, Wang H, Gong Z, Zhan S, Tan W. Performance of a Flexible 12-Channel Head Coil in Comparison to Commercial 16- And 24-Channel Rigid Head Coils. Magn Reson Med Sci 2021; 21:623-631. [PMID: 34544923 PMCID: PMC9618927 DOI: 10.2463/mrms.mp.2021-0084] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Purpose: To compare the performance of a 12-channel flexible head coil (HFC12) with commercial 16-channel (HRC16) and 24-channel (HRC24) rigid coils. Methods: The phantom study was performed on a 1.5 T MR scanner with HFC12, HRC16, and HRC24. The SNR and noise correlation matrix of T1WI, T2WI, and diffusion weighted imaging (DWI) were measured. The SNR profiles were created according to the SNR. In addition, 1/g-factors were calculated in different acceleration directions. In the in vivo study, T1WI, T2WI, and DWI were performed in one healthy volunteer with three different coils. The SNR and noise correlation matrix were measured. Results: In the phantom study and in vivo study, the SNR of HFC12 in the transverse, sagittal, and coronal planes was the highest, followed by HRC24, and that of HRC16 was the lowest. The SNR profiles showed that the SNR at the edge of HFC12 was the highest. The mean value of the noise correlation matrix of HFC12 was the highest. The 1/g-factor results showed that HFC12 obtained the best acceleration ability in the head–foot acceleration direction when the reduction factor was set to two. The SNR of HFC12 in most cortices was significantly higher than that of HRC16 and HRC24, except in the occipital cortex. The SNR of HRC24 in the occipital cortex was higher than that of HFC12. Conclusion: The SNR of HFC12 in T1WI, T2WI, and DWI was better than that of the HRC24 and HFC16. The SNR of HFC12 in the cortex was significantly higher than that of the commercial rigid head coil, except in the occipital cortex.
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Affiliation(s)
- YingJie Kang
- Department of Radiology, Shuguang Hospital Affiliated with Shanghai University of Traditional Chinese Medicine
| | - YiLei Chen
- Department of Radiology, Shuguang Hospital Affiliated with Shanghai University of Traditional Chinese Medicine
| | - JieMing Fang
- Department of Diagnostic Radiology, City of Hope Medical Center
| | - YanWen Huang
- Department of Radiology, Shuguang Hospital Affiliated with Shanghai University of Traditional Chinese Medicine
| | - Hui Wang
- Department of Radiology, Shuguang Hospital Affiliated with Shanghai University of Traditional Chinese Medicine
| | - ZhiGang Gong
- Department of Radiology, Shuguang Hospital Affiliated with Shanghai University of Traditional Chinese Medicine
| | - SongHua Zhan
- Department of Radiology, Shuguang Hospital Affiliated with Shanghai University of Traditional Chinese Medicine
| | - WenLi Tan
- Department of Radiology, Shuguang Hospital Affiliated with Shanghai University of Traditional Chinese Medicine
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Yuan J, Law SCK, Wong KK, Lo GG, Kam MKM, Kwan WH, Xue C, Wong OL, Yu SK, Cheung KY. 3D T1-weighted turbo spin echo contrast-enhanced MRI at 1.5 T for frameless brain metastases radiotherapy. J Cancer Res Clin Oncol 2021; 148:1749-1759. [PMID: 34363123 DOI: 10.1007/s00432-021-03755-8] [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: 06/03/2021] [Accepted: 07/31/2021] [Indexed: 11/27/2022]
Abstract
PURPOSE Performance of 3D-T1W-TSE has been proven superior to 3D-MP-GRE at 3 T on brain metastases (BM) contrast-enhanced (CE) MRI. However, its performance at 1.5 T is largely unknown and sparsely reported. This study aims to assess image quality, lesion detectability and conspicuity of 1.5 T 3D-T1W-TSE on planning MRI of frameless BM radiotherapy. METHODS 94 BM patients to be treated by frameless brain radiotherapy were scanned using 3D-T1W-TSE with immobilization on multi-vendor 1.5 T MRI-simulators. BMs were jointly diagnosed by 4 reviewers. Enhanced lesion conspicuity was quantitatively assessed by calculating contrast ratio (CR) and contrast-to-noise ratio (CNR). Signal-to-noise ratio (SNR) reduction of white matter due to the use of flexible coil was assessed. Lesion detectability and conspicuity were compared between 1.5 T planning MRI and 3 T diagnostic MRI by an oncologist and a radiologist in 10 patients. RESULTS 497 BMs were jointly diagnosed. The CR and CNR were 75.2 ± 39.9% and 14.2 ± 8.1, respectively. SNR reduced considerably from 31.7 ± 8.3 to 21.9 ± 5.4 with the longer distance to coils. 3 T diagnostic MRI and 1.5 T planning MRI yielded exactly the same detection of 84 BMs. Qualitatively, lesion conspicuity at 1.5 T was not inferior to that at 3 T. Quantitatively, lower brain SNR and lesion CNR were found at 1.5 T, while lesion CR at 1.5 T was highly comparable to that at 3 T. CONCLUSION 1.5 T 3D-T1W-TSE planning MRI of frameless BM radiotherapy was comprehensively assessed. Highly comparable BM detectability and conspicuity were achieved by 1.5 T planning MRI compared to 3 T diagnostic MRI. 1.5 T 3D-T1W-TSE should be valuable for frameless brain radiotherapy planning.
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Affiliation(s)
- Jing Yuan
- Medical Physics and Research Department, Hong Kong Sanatorium and Hospital, 8/F, Li Shu Fan Block, 2 Village Road, Happy Valley, Hong Kong SAR, China.
| | - Stephen C K Law
- Comprehensive Oncology Centre, Hong Kong Sanatorium and Hospital, Happy Valley, Hong Kong SAR, China
| | - Ka Kin Wong
- Department of Diagnostic and Interventional Radiology, Hong Kong Sanatorium and Hospital, Happy Valley, Hong Kong SAR, China
| | - Gladys G Lo
- Department of Diagnostic and Interventional Radiology, Hong Kong Sanatorium and Hospital, Happy Valley, Hong Kong SAR, China
| | - Michael K M Kam
- Comprehensive Oncology Centre, Hong Kong Sanatorium and Hospital, Happy Valley, Hong Kong SAR, China
| | - Wing Hong Kwan
- Comprehensive Oncology Centre, Hong Kong Sanatorium and Hospital, Happy Valley, Hong Kong SAR, China
| | - Cindy Xue
- Medical Physics and Research Department, Hong Kong Sanatorium and Hospital, 8/F, Li Shu Fan Block, 2 Village Road, Happy Valley, Hong Kong SAR, China
| | - Oi Lei Wong
- Medical Physics and Research Department, Hong Kong Sanatorium and Hospital, 8/F, Li Shu Fan Block, 2 Village Road, Happy Valley, Hong Kong SAR, China
| | - Siu Ki Yu
- Medical Physics and Research Department, Hong Kong Sanatorium and Hospital, 8/F, Li Shu Fan Block, 2 Village Road, Happy Valley, Hong Kong SAR, China
| | - Kin Yin Cheung
- Medical Physics and Research Department, Hong Kong Sanatorium and Hospital, 8/F, Li Shu Fan Block, 2 Village Road, Happy Valley, Hong Kong SAR, China
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Lee HB, Jang JS, Lee KB, Kim SM. Image quality assessments according to the angle of tilt of a flex tilt coil supporting device: An ACR phantom study. J Appl Clin Med Phys 2021; 22:110-116. [PMID: 33934495 PMCID: PMC8130245 DOI: 10.1002/acm2.13218] [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: 10/14/2020] [Revised: 02/05/2021] [Accepted: 02/15/2021] [Indexed: 11/08/2022] Open
Abstract
In this study, we assessed how image quality depends on the angle of tilt of a flex tilt coil supporting device during an MRI examination. All measurements were performed with an American College of Radiology (ACR) MRI phantom using a flex tilt coil supporting device. All images were analyzed using an automatic assessment method following the ACR MRI accreditation guidance. Image quality was compared between acquisitions grouped according to the angle of tilt of the coil supporting device: group A (Flat mode), group B (10˚), and group C (18˚). All measured image qualities were within the ACR recommended criteria, regardless of the angle of tilt of the flex tilt coil supporting device. However, statistically significant differences between the three groups were found for slice thickness, position accuracy, image intensity uniformity, and SNR (P < 0.05, ANOVA). The flex tilt coil supporting device can provide sufficient image quality, passing the criteria of the ACR MRI guideline, despite differences in slice thickness, slice position accuracy, image intensity uniformity, and SNR according to the angle of tilt.
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Affiliation(s)
- Ho Beom Lee
- Department of Medical Device Industry, Dongguk University, Seoul, South Korea
| | - Ji Sung Jang
- Departments of Radiology and Research Institute of Radiology, Asan Medical Center, University of Ulsan, College of Medicine, Seoul, South Korea
| | - Ki Baek Lee
- Biomedical Engineering Research Center, Asan Institute for Life Sciences, Asan Medical Center, Seoul, South Korea
| | - Sung Min Kim
- Department of Medical Device Industry, Dongguk University, Seoul, South Korea
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Comparison of treatment position with mask immobilization and standard diagnostic setup in intracranial MRI radiotherapy simulation. Strahlenther Onkol 2021; 197:614-621. [PMID: 33881558 DOI: 10.1007/s00066-021-01776-3] [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: 11/12/2020] [Accepted: 03/23/2021] [Indexed: 10/21/2022]
Abstract
PURPOSE This study aims to compare the quality of images resulting from magnetic resonance imaging of patients who underwent intracranial MRI simulation using two different setups (treatment position with mask immobilization and standard diagnostic setup). Due to a larger number of channels and lack of mask immobilization in the standard diagnostic setup, we would like to evaluate whether this is an appropriate technique for MRI treatment planning. METHODS In total, 70 patients who underwent MR imaging of the brain at 1.5T were included in the study (48 for 6‑channel flex coil, 22 for 24-channel HNU face bill coil). Contrast-enhanced 3D T1w and T2 FLAIR images were acquired. Images were subjectively compared for artifact appearance and general image quality by three radiographers. Objective comparison of contrast rate, contrast-to-noise ratio, and signal-to-noise ratio was also performed. RESULTS FLAIR and contrast-enhanced 3D T1w images showed various artifacts, such as susceptibility and movement artifacts. There were no statistically significant differences regarding the evaluation of movement artifacts between two coils and two different immobilization methods. There were also no statistically significant differences (p > 0.05) between the 6‑channel flex coil and 24-channel HNU face bill coil regarding qualitative general image quality and objective measures. CONCLUSION There were no statistically significant differences between the occurrence of movement artifacts, overall image quality, and objective image quality in treatment position with mask immobilization and standard diagnostic setup. Based on this result, we can conclude that a standard diagnostic setup is also applicable in intracranial MRI treatment planning with no loss to image quality. Registration of the imaging plans was not performed in this study; therefore, it might still be necessary to perform measurements of tumor delineation matching and geometrical accuracy acceptance in our institution.
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Wong OL, Yuan JI, Zhou Y, Yu SK, Cheung KY. Longitudinal acquisition repeatability of MRI radiomics features: An ACR MRI phantom study on two MRI scanners using a 3D T1W TSE sequence. Med Phys 2021; 48:1239-1249. [PMID: 33370474 DOI: 10.1002/mp.14686] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Revised: 12/14/2020] [Accepted: 12/18/2020] [Indexed: 12/19/2022] Open
Abstract
PURPOSE The purpose of this study was to quantitatively assess the longitudinal acquisition repeatability of MRI radiomics features in a three-dimensional (3D) T1-weighted (T1W) TSE sequence via a well-controlled prospective phantom study. METHODS Thirty consecutive daily datasets of an ACR-MRI phantom were acquired on two 1.5T MRI simulators using a 3D T1W TSE sequence. Images were blindly segmented by two observers. Post-acquisition processing was minimized but an intensity discretization (fixed bin size of 25). One hundred and one radiomics features (shape n = 12; first order n = 16; texture n = 73) were extracted. Longitudinal repeatability of each feature was evaluated by Pearson correlation and coefficient of variance (CV68% ). Interobserver feature value agreement was also quantified using intraclass correlation coefficient (ICC) and Bland-Altman analysis. A most repeatable radiomics feature set on both scanners was determined by feature coefficient of variance (CV68% <5%), ICC (>0.75), and the ratio of the interobserver difference to the interobserver mean δ<5%. RESULTS No trend of radiomics feature value changed with time. Longitudinal feature repeatability CV68% ranged 0.01-38.60% (mean/median: 12.5%/9.9%), and 0.01-40.47%, (8.49%/7.34%) on the scanners A and B. Shape features exhibited significantly better repeatability than first-order and texture features (all P < 0.01). Significant longitudinal repeatability difference was observed in texture features (P < 0.001) between the two scanners, but not in shape and first-order features (P > 0.30). First-order and texture features had smaller interobserver-dependent variation than acquisition-dependent variation. They also showed good interobserver agreement on both scanners (A:ICC = 0.80 ± 0.23; B:ICC = 0.80 ± 0.22), independent of acquisition repeatability. The repeatable radiomics features in common on both scanners, including 12 shape features, 0 first-order features, and 3 texture features, were determined as the most repeatable MRI radiomics feature set. CONCLUSIONS Radiomics features exhibited heterogeneous longitudinal repeatability, while the shape features were the most repeatable, in this phantom study with a 3D T1W TSE acquisition. The most repeatable radiomics feature set derived in this study should be helpful for the selection of reliable radiomics features in the future clinical use.
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Affiliation(s)
- Oi Lei Wong
- Medical Physics and Research Department, Hong Kong Sanatorium & Hospital, Happy Valley, Hong Kong SAR, China
| | - JIng Yuan
- Medical Physics and Research Department, Hong Kong Sanatorium & Hospital, Happy Valley, Hong Kong SAR, China
| | - Yihang Zhou
- Medical Physics and Research Department, Hong Kong Sanatorium & Hospital, Happy Valley, Hong Kong SAR, China
| | - Siu Ki Yu
- Medical Physics and Research Department, Hong Kong Sanatorium & Hospital, Happy Valley, Hong Kong SAR, China
| | - Kin Yin Cheung
- Medical Physics and Research Department, Hong Kong Sanatorium & Hospital, Happy Valley, Hong Kong SAR, China
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11
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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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12
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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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13
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Tyagi N, Zakian KL, Italiaander M, Almujayyaz S, Lis E, Yamada J, Topf J, Hunt M, Deasy JO. Technical Note: A custom-designed flexible MR coil array for spine radiotherapy treatment planning. Med Phys 2020; 47:3143-3152. [PMID: 32304237 DOI: 10.1002/mp.14184] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2019] [Revised: 03/20/2020] [Accepted: 03/27/2020] [Indexed: 01/05/2023] Open
Abstract
PURPOSE To assess the performance and optimize the MR image quality when using a custom-built flexible radiofrequency (RF) spine coil array fitted between the immobilization device and the patient for spine radiotherapy treatment planning. METHODS A 32 channel flexible custom-designed receive-only coil array has been developed for spine radiotherapy simulation for a 3 T Philips MR scanner. Coil signal-to-noise performance and interactions with standard vendor hardware were assessed. In four volunteers, immobilization molds were created with a dummy version of the array within the mold, and subjects were scanned using the custom array in the mold. Phantoms and normal volunteers were scanned with both the custom spine coil array and the vendor's FDA-approved in-table posterior coil array to compare performance. RESULTS The superior-inferior field of view for the custom spine array was ~30 cm encompassing at least 10 vertebrae. A noise correlation matrix showed at least 25 dB isolation between all coil elements. Signal-to-noise ratio (SNR) calculated on a phantom scan at the depth of the spinal cord was a factor of 3 higher with the form-fit spine array as compared to the vendor's posterior coil array. The body coil B1 transmit map was equivalent with and without the spine array in place demonstrating that the elements are decoupled from the body coil. Volunteer imaging showed improved SNR as compared to the vendor's posterior coil array. The custom array permitted a high degree of acceleration making possible the acquisition of isotropic high-resolution 1.1 × 1.1 × 1.1 mm3 three-dimensional data set over a 30-cm section of the spine in less than 5 min. CONCLUSION The custom-designed form-fitting flexible spine coil array provided enhanced SNR and increased acceleration compared to the vendor's posterior array. Future studies will assess MR-based spinal cord imaging with the custom coil in comparison to CT myelogram.
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Affiliation(s)
- Neelam Tyagi
- Department of Medical Physics, Memorial Sloan-Kettering Cancer Center, New York, NY, 10065, USA
| | - Kristen L Zakian
- Department of Medical Physics, Memorial Sloan-Kettering Cancer Center, New York, NY, 10065, USA.,Department of Radiology, Memorial Sloan-Kettering Cancer Center, New York, NY, 10065, USA
| | | | | | - Eric Lis
- Department of Radiology, Memorial Sloan-Kettering Cancer Center, New York, NY, 10065, USA
| | - Josh Yamada
- Department of Radiation Oncology, Memorial Sloan-Kettering Cancer Center, New York, NY, 10065, USA
| | - Jill Topf
- Department of Radiation Oncology, Memorial Sloan-Kettering Cancer Center, New York, NY, 10065, USA
| | - Margie Hunt
- Department of Medical Physics, Memorial Sloan-Kettering Cancer Center, New York, NY, 10065, USA
| | - Joseph O Deasy
- Department of Medical Physics, Memorial Sloan-Kettering Cancer Center, New York, NY, 10065, USA
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14
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Magnetic resonance imaging for brain stereotactic radiotherapy : A review of requirements and pitfalls. Strahlenther Onkol 2020; 196:444-456. [PMID: 32206842 PMCID: PMC7182639 DOI: 10.1007/s00066-020-01604-0] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2020] [Accepted: 03/03/2020] [Indexed: 12/29/2022]
Abstract
Due to its superior soft tissue contrast, magnetic resonance imaging (MRI) is essential for many radiotherapy treatment indications. This is especially true for treatment planning in intracranial tumors, where MRI has a long-standing history for target delineation in clinical practice. Despite its routine use, care has to be taken when selecting and acquiring MRI studies for the purpose of radiotherapy treatment planning. Requirements on MRI are particularly demanding for intracranial stereotactic radiotherapy, where accurate imaging has a critical role in treatment success. However, MR images acquired for routine radiological assessment are frequently unsuitable for high-precision stereotactic radiotherapy as the requirements for imaging are significantly different for radiotherapy planning and diagnostic radiology. To assure that optimal imaging is used for treatment planning, the radiation oncologist needs proper knowledge of the most important requirements concerning the use of MRI in brain stereotactic radiotherapy. In the present review, we summarize and discuss the most relevant issues when using MR images for target volume delineation in intracranial stereotactic radiotherapy.
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15
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Adjeiwaah M, Garpebring A, Nyholm T. Sensitivity analysis of different quality assurance methods for magnetic resonance imaging in radiotherapy. Phys Imaging Radiat Oncol 2020; 13:21-27. [PMID: 33458303 PMCID: PMC7807625 DOI: 10.1016/j.phro.2020.03.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2019] [Revised: 02/27/2020] [Accepted: 03/02/2020] [Indexed: 11/30/2022] Open
Abstract
BACKGROUND AND PURPOSE There are currently no standard quality assurance (QA) methods for magnetic resonance imaging (MRI) in radiotherapy (RT). This work was aimed at evaluating the ability of two QA protocols to detect common events that affect quality of MR images under RT settings. MATERIALS AND METHODS The American College of Radiology (ACR) MRI QA phantom was repeatedly scanned using a flexible coil and action limits for key image quality parameters were derived. Using an exploratory survey, issues that reduce MR image quality were identified. The most commonly occurring events were introduced as provocations to produce MR images with degraded quality. From these images, detection sensitivities of the ACR MRI QA protocol and a commercial geometric accuracy phantom were determined. RESULTS Machine-specific action limits for key image quality parameters set at mean ± 3 σ were comparable with the ACR acceptable values. For the geometric accuracy phantom, provocations from uncorrected gradient nonlinearity effects and a piece of metal in the bore of the scanner resulted in worst distortions of 22.2 mm and 3.4 mm, respectively. The ACR phantom was sensitive to uncorrected signal variations, electric interference and a piece of metal in the bore of the scanner but could not adequately detect individual coil element failures. CONCLUSIONS The ACR MRI QA phantom combined with the large field-of-view commercial geometric accuracy phantom were generally sensitive in identifying some common MR image quality issues. The two protocols when combined may provide a tool to monitor the performance of MRI systems in the radiotherapy environment.
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Affiliation(s)
- Mary Adjeiwaah
- Department of Radiation Sciences, Umeå University, Umeå, Sweden
| | | | - Tufve Nyholm
- Department of Radiation Sciences, Umeå University, Umeå, Sweden
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16
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Sun Q, Dong MJ, Tao XF, Jiang MD, Yang C. Selection and application of coils in temporomandibular joint MRI. Dentomaxillofac Radiol 2019; 49:20190002. [PMID: 31559845 PMCID: PMC7068082 DOI: 10.1259/dmfr.20190002] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022] Open
Abstract
Objective: To compare and evaluate the signal-to-noise ratio (SNR) and the contrast-to-noise ratio (CNR) values between a 15-channel phased array head coil and 6-channel dS Flex M surface coil in the MRI of temporomandibular joint. Methods: 300 patients were randomly assigned to two groups: 150 patients were examined by using a 15-channel phased array head coil and the other 150 patients were scanned by using a 6-channel dS Flex M surface coil. All of the data were set in the same 6 regions of interest including the temporal lobe, condyle neck, lateral pterygoid muscle, parotid gland, the adipose area and an area of the background noise). SNR and CNR values were measured respectively. Results: The numerical variation law of SNR and CNR values measured in regionsof interest of each group was similar, although different coils were used. There were statistically significant differences of SNR values in all of the oblique sagittal (OSag) proton density-weighted imaging, the part of OSag T2 weighted image (T2WI) except for SNR4 and SNR5. and oblique coronal (OCor) T2WI sequence except for SNR2. On the contrary, SNR4 and SNR5 values in the OCor T2WI and SNR5 values in OSag T2WI sequences by using the surface coil were higher than those by using the head coil. There were no statistically significant intergroup differences of CNR values in OSag proton density-weighted imaging sequence except CNR1 and in OSag T2WI sequence except CNR5. But, statistically significant differences of all the values in the OCor T2WI sequence except for CNR1 were observed. Conclusion: Both the phased array head coil and dS Flex M surface coil can be used for temporomandibular joint MRI.
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Affiliation(s)
- Qi Sun
- Department of Radiology, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Min-Jun Dong
- Department of Radiology, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Xiao-Feng Tao
- Department of Radiology, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Meng-da Jiang
- Department of Radiology, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Chi Yang
- Department of Oral Surgery, Ninth People's Hospital, Shanghai Key Lab of Stomatology, Shanghai, China
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17
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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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18
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Zhou Y, Yuan J, Wong OL, Fung WWK, Cheng KF, Cheung KY, Yu SK. Assessment of positional reproducibility in the head and neck on a 1.5-T MR simulator for an offline MR-guided radiotherapy solution. Quant Imaging Med Surg 2018; 8:925-935. [PMID: 30505721 DOI: 10.21037/qims.2018.10.03] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Background Recently, a shuttle-based offline magnetic resonance-guided radiotherapy (MRgRT) approach was proposed. This study aims to evaluate the positional reproducibility in the immobilized head and neck using a 1.5-T MR-simulator (MR-sim) on healthy volunteers. Methods A total of 159 scans of 14 healthy volunteers were conducted on a 1.5-T MR-sim with thermoplastic mask immobilization. MR images with isotropic 1.053 mm3 voxel size were rigidly registered to the first scan based on fiducial, anatomical and gross positions. Mean and standard deviation of positional displacements in translation and rotation were assessed. Systematic error and random errors of positioning in the head and neck on the MR-sim were determined in the translation of, and in the rotation of roll, pitch and yaw. Results The systematic error (Σ) of translation in left-right (LR), anterior-posterior (AP) and superior-inferior (SI) direction was 0.57, 0.22 and 0.26 mm for fiducial displacement, 0.28, 0.10 and 0.52 mm for anatomical displacement, and 0.53, 0.22 and 0.49 mm for gross displacement, respectively. The random error (σ) in corresponding translation direction was 2.07, 0.54 and 1.32 mm for fiducial displacement, 1.34, 0.73 and 2.04 mm for anatomical displacement, and 2.24, 0.86 and 2.61 mm for gross displacement. The systematic error and random error of rotation were generally smaller than 1°. Conclusions Our results suggested that high gross positional reproducibility (<1 mm translational and <1° rotational systematic error) could be achieved on an MR-sim for the proposed offline MRgRT.
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Affiliation(s)
- Yihang Zhou
- Medical Physics and Research Department, Hong Kong Sanatorium & Hospital, Hong Kong, China
| | - Jing Yuan
- Medical Physics and Research Department, Hong Kong Sanatorium & Hospital, Hong Kong, China
| | - Oi Lei Wong
- Medical Physics and Research Department, Hong Kong Sanatorium & Hospital, Hong Kong, China
| | - Winky Wing Ki Fung
- Department of Radiotherapy, Hong Kong Sanatorium & Hospital, Hong Kong, China
| | - Ka Fai Cheng
- Department of Radiotherapy, Hong Kong Sanatorium & Hospital, Hong Kong, China
| | - Kin Yin Cheung
- Medical Physics and Research Department, Hong Kong Sanatorium & Hospital, Hong Kong, China
| | - Siu Ki Yu
- Medical Physics and Research Department, Hong Kong Sanatorium & Hospital, Hong Kong, China
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