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Fast MF, Cao M, Parikh P, Sonke JJ. Intrafraction Motion Management With MR-Guided Radiation Therapy. Semin Radiat Oncol 2024; 34:92-106. [PMID: 38105098 DOI: 10.1016/j.semradonc.2023.10.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2023]
Abstract
High quality radiation therapy requires highly accurate and precise dose delivery. MR-guided radiotherapy (MRgRT), integrating an MRI scanner with a linear accelerator, offers excellent quality images in the treatment room without subjecting patient to ionizing radiation. MRgRT therefore provides a powerful tool for intrafraction motion management. This paper summarizes different sources of intrafraction motion for different disease sites and describes the MR imaging techniques available to visualize and quantify intrafraction motion. It provides an overview of MR guided motion management strategies and of the current technical capabilities of the commercially available MRgRT systems. It describes how these motion management capabilities are currently being used in clinical studies, protocols and provides a future outlook.
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Affiliation(s)
- Martin F Fast
- Department of Radiotherapy, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Minsong Cao
- Department of Radiation Oncology, University of California, Los Angeles, CA
| | - Parag Parikh
- Department of Radiation Oncology, Henry Ford Health - Cancer, Detroit, MI
| | - Jan-Jakob Sonke
- Department of Radiation Oncology, The Netherlands Cancer Institute, Amsterdam, The Netherlands.
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2
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Nakayama H, Okamoto H, Nakamura S, Iijima K, Chiba T, Takemori M, Nakaichi T, Mikasa S, Fujii K, Sakasai T, Kuwahara J, Miura Y, Fujiyama D, Tsunoda Y, Hanzawa T, Igaki H, Chang W. Film measurement and analytical approach for assessing treatment accuracy and latency in a magnetic resonance-guided radiotherapy system. J Appl Clin Med Phys 2023; 24:e13915. [PMID: 36934441 PMCID: PMC10161048 DOI: 10.1002/acm2.13915] [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: 05/27/2022] [Revised: 11/25/2022] [Accepted: 01/12/2023] [Indexed: 03/20/2023] Open
Abstract
PURPOSE We measure the dose distribution of gated delivery for different target motions and estimate the gating latency in a magnetic resonance-guided radiotherapy (MRgRT) system. METHOD The dose distribution accuracy of the gated MRgRT system (MRIdian, Viewray) was investigated using an in-house-developed phantom that was compatible with the magnetic field and gating method. This phantom contains a simulated tumor and a radiochromic film (EBT3, Ashland, Inc.). To investigate the effect of the number of beam switching and target velocity on the dose distribution, two types of target motions were applied. One is that the target was periodically moved at a constant velocity of 5 mm/s with different pause times (0, 1, 3, 10, and 20 s) between the motions. During different pause times, different numbers of beams were switched on/off. The other one is that the target was moved at velocities of 3, 5, 8, and 10 mm/s without any pause (i.e., continuous motion). The gated method was applied to these motions at MRIdian, and the dose distributions in each condition were measured using films. To investigate the relation between target motion and dose distribution in the gating method, we compared the results of the gamma analysis of the calculated and measured dose distributions. Moreover, we analytically estimated the gating latencies from the dose distributions measured using films and the gamma analysis results. RESULTS The gamma pass rate linearly decreased with increasing beam switching and target velocity. The overall gating latencies of beam-hold and beam-on were 0.51 ± 0.17 and 0.35 ± 0.05 s, respectively. CONCLUSIONS Film measurements highlighted the factors affecting the treatment accuracy of the gated MRgRT system. Our analytical approach, employing gamma analysis on films, can be used to estimate the overall latency of the gated MRgRT system.
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Affiliation(s)
- Hiroki Nakayama
- Radiation Safety and Quality Assurance Division, National Cancer Center Hospital, Chuo-ku, Tokyo, Japan.,Department of Radiological Sciences, Graduate School of Human Health Sciences, Tokyo Metropolitan University, Higashioku, Arakawa-ku, Tokyo, Japan
| | - Hiroyuki Okamoto
- Radiation Safety and Quality Assurance Division, National Cancer Center Hospital, Chuo-ku, Tokyo, Japan
| | - Satoshi Nakamura
- Radiation Safety and Quality Assurance Division, National Cancer Center Hospital, Chuo-ku, Tokyo, Japan
| | - Kotaro Iijima
- Radiation Safety and Quality Assurance Division, National Cancer Center Hospital, Chuo-ku, Tokyo, Japan
| | - Takahito Chiba
- Radiation Safety and Quality Assurance Division, National Cancer Center Hospital, Chuo-ku, Tokyo, Japan.,Department of Radiological Sciences, Graduate School of Human Health Sciences, Tokyo Metropolitan University, Higashioku, Arakawa-ku, Tokyo, Japan
| | - Mihiro Takemori
- Radiation Safety and Quality Assurance Division, National Cancer Center Hospital, Chuo-ku, Tokyo, Japan.,Department of Radiological Sciences, Graduate School of Human Health Sciences, Tokyo Metropolitan University, Higashioku, Arakawa-ku, Tokyo, Japan
| | - Tetsu Nakaichi
- Radiation Safety and Quality Assurance Division, National Cancer Center Hospital, Chuo-ku, Tokyo, Japan
| | - Shohei Mikasa
- Radiation Safety and Quality Assurance Division, National Cancer Center Hospital, Chuo-ku, Tokyo, Japan
| | - Kyohei Fujii
- Department of Radiation Sciences, Komazawa University, Setagaya-ku, Tokyo, Japan
| | - Tatsuya Sakasai
- Department of Radiological Technology, National Cancer Center Hospital, Chuo-ku, Tokyo, Japan
| | - Junichi Kuwahara
- Radiation Safety and Quality Assurance Division, National Cancer Center Hospital, Chuo-ku, Tokyo, Japan.,Department of Radiological Technology, National Cancer Center Hospital, Chuo-ku, Tokyo, Japan
| | - Yuki Miura
- Department of Radiological Technology, National Cancer Center Hospital East, Kashiwa, Chiba, Japan
| | - Daisuke Fujiyama
- Department of Radiological Technology, National Cancer Center Hospital, Chuo-ku, Tokyo, Japan
| | - Yuki Tsunoda
- Department of Radiological Technology, National Cancer Center Hospital, Chuo-ku, Tokyo, Japan
| | - Takuma Hanzawa
- Department of Radiological Technology, National Cancer Center Hospital, Chuo-ku, Tokyo, Japan
| | - Hiroshi Igaki
- Department of Radiation Oncology, National Cancer Center Hospital, Chuo-ku, Tokyo, Japan
| | - Weishan Chang
- Department of Radiological Sciences, Graduate School of Human Health Sciences, Tokyo Metropolitan University, Higashioku, Arakawa-ku, Tokyo, Japan
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3
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Gray M, Spiers L, Coussios C. Effects of human tissue acoustic properties, abdominal wall shape, and respiratory motion on ultrasound-mediated hyperthermia for targeted drug delivery to pancreatic tumors. Int J Hyperthermia 2022; 39:918-934. [PMID: 35853611 PMCID: PMC9612938 DOI: 10.1080/02656736.2022.2091799] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
Background PanDox is a Phase-1 trial of chemotherapeutic drug delivery to pancreatic tumors using ultrasound-mediated hyperthermia to release doxorubicin from thermally sensitive liposomes. This report describes trial-related hyperthermia simulations featuring: (i) new ultrasonic properties of human pancreatic tissues, (ii) abdomen deflections imposed by a water balloon, and (iii) respiration-driven organ motion. Methods Pancreas heating simulations were carried out using three patient body models. Pancreas acoustic properties were varied between values found in the literature and those determined from our human tissue study. Acoustic beam distortion was assessed with and without balloon-induced abdomen deformation. Target heating was assessed for static, normal respiratory, and jet-ventilation-controlled pancreas motion. Results Human pancreatic tumor attenuation is 63% of the literature values, so that pancreas treatments require commensurately higher input intensity to achieve adequate hyperthermia. Abdominal wall deformation decreased the peak field pressure by as much as 3.5 dB and refracted the focal spot by as much as 4.5 mm. These effects were thermally counteracted by sidelobe power deposition, so the net impact on achieving mild hyperthermia was small. Respiratory motion during moving beam hyperthermia produced localized regions overheated by more than 8.0 °C above the 4.0 °C volumetric goal. The use of jet ventilation reduced this excess to 0.7 °C and yielded temperature field uniformity that was nearly identical to having no respiratory motion. Conclusion Realistic modeling of the ultrasonic propagation environment is critical to achieving adequate mild hyperthermia without the use of real time thermometry for targeted drug delivery in pancreatic cancer patients.
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Affiliation(s)
- Michael Gray
- Institute of Biomedical Engineering, University of Oxford, Oxford, UK.,NIHR Oxford Biomedical Research Centre, Oxford, UK
| | - Laura Spiers
- NIHR Oxford Biomedical Research Centre, Oxford, UK.,Department of Oncology, University of Oxford, Oxford, UK
| | - Constantin Coussios
- Institute of Biomedical Engineering, University of Oxford, Oxford, UK.,NIHR Oxford Biomedical Research Centre, Oxford, UK
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Keijnemans K, Borman PTS, Uijtewaal P, Woodhead PL, Raaymakers BW, Fast MF. A hybrid 2D/4D-MRI methodology using simultaneous multislice imaging for radiotherapy guidance. Med Phys 2022; 49:6068-6081. [PMID: 35694905 PMCID: PMC9545880 DOI: 10.1002/mp.15802] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Revised: 04/18/2022] [Accepted: 05/27/2022] [Indexed: 11/24/2022] Open
Abstract
Purpose Respiratory motion management is important in abdominothoracic radiotherapy. Fast imaging of the tumor can facilitate multileaf collimator (MLC) tracking that allows for smaller treatment margins, while repeatedly imaging the full field‐of‐view is necessary for 4D dose accumulation. This study introduces a hybrid 2D/4D‐MRI methodology that can be used for simultaneous MLC tracking and dose accumulation on a 1.5 T Unity MR‐linac (Elekta AB, Stockholm, Sweden). Methods We developed a hybrid 2D/4D‐MRI methodology that uses a simultaneous multislice (SMS) accelerated MRI sequence, which acquires two coronal slices simultaneously and repeatedly cycles through slice positions over the image volume. As a result, the fast 2D imaging can be used prospectively for MLC tracking and the SMS slices can be sorted retrospectively into respiratory‐correlated 4D‐MRIs for dose accumulation. Data were acquired in five healthy volunteers with an SMS‐bTFE and SMS‐TSE MRI sequence. For each sequence, a prebeam dataset and a beam‐on dataset were acquired simulating the two phases of MR‐linac treatments. Prebeam data were used to generate a 4D‐based motion model and a reference mid‐position volume, while beam‐on data were used for real‐time motion extraction and reconstruction of beam‐on 4D‐MRIs. In addition, an in‐silico computational phantom was used for validation of the hybrid 2D/4D‐MRI methodology. MLC tracking experiments were performed with the developed methodology, for which real‐time SMS data reconstruction was enabled on the scanner. A 15‐beam 8× 7.5 Gy intensity‐modulated radiotherapy plan for lung stereotactic body radiotherapy with isotropic 3 mm GTV‐to‐PTV margins was created. Dosimetry experiments were performed using a 4D motion phantom. The latency between target motion and updating the radiation beam was determined and compensated. Local gamma analyses were performed to quantify dose differences compared to a static reference delivery, and dose area histograms (DAHs) were used to quantify the GTV and PTV coverage. Results In‐vivo data acquisition and MLC tracking experiments were successfully performed with the developed hybrid 2D/4D‐MRI methodology. Real‐time liver–lung interface motion estimation had a Pearson's correlation of 0.996 (in‐vivo) and 0.998 (in‐silico). A median (5th–95th percentile) error of 0.0 (−0.9 to 0.7) mm and 0.0 (−0.2 to 0.2) mm was found for real‐time motion estimation for in‐vivo and in‐silico, respectively. Target motion prediction beyond the liver–lung interface had a median root mean square error of 1.6 mm (in‐vivo) and 0.5 mm (in‐silico). Beam‐on 4D MRI reconstruction required a median amount of data equal to an acquisition time of 2:21–3:17 min, which was 20% less data compared to the prebeam‐derived 4D‐MRI. System latency was reduced from 501 ± 12 ms to −1 ± 3 ms (SMS‐TSE) and from 398 ± 10 ms to −10 ± 4 ms (SMS‐bTFE) by a linear regression prediction filter. The local gamma analysis agreed within −3.8% to 3.3% (SMS‐bTFE) and −5.3% to 10% (SMS‐TSE) with a reference MRI sequence. The DAHs revealed a relative D98% GTV coverage between 97% and 100% (SMS‐bTFE) and 100% and 101% (SMS‐TSE) compared to the static reference. Conclusions The presented 2D/4D‐MRI methodology demonstrated the potential for accurately extracting real‐time motion for MLC tracking in abdominothoracic radiotherapy, while simultaneously reconstructing contiguous respiratory‐correlated 4D‐MRIs for dose accumulation.
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Affiliation(s)
- Katrinus Keijnemans
- Department of Radiotherapy, University Medical Center Utrecht, Heidelberglaan 100, 3584 CX Utrecht, The Netherlands
| | - Pim T S Borman
- Department of Radiotherapy, University Medical Center Utrecht, Heidelberglaan 100, 3584 CX Utrecht, The Netherlands
| | - Prescilla Uijtewaal
- Department of Radiotherapy, University Medical Center Utrecht, Heidelberglaan 100, 3584 CX Utrecht, The Netherlands
| | - Peter L Woodhead
- Department of Radiotherapy, University Medical Center Utrecht, Heidelberglaan 100, 3584 CX Utrecht, The Netherlands.,Elekta AB, kungstensgatan 18, 113 57 Stockholm, Sweden
| | - Bas W Raaymakers
- Department of Radiotherapy, University Medical Center Utrecht, Heidelberglaan 100, 3584 CX Utrecht, The Netherlands
| | - Martin F Fast
- Department of Radiotherapy, University Medical Center Utrecht, Heidelberglaan 100, 3584 CX Utrecht, The Netherlands
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Freedman JN, Gurney-Champion OJ, Nill S, Shiarli AM, Bainbridge HE, Mandeville HC, Koh DM, McDonald F, Kachelrieß M, Oelfke U, Wetscherek A. Rapid 4D-MRI reconstruction using a deep radial convolutional neural network: Dracula. Radiother Oncol 2021; 159:209-217. [PMID: 33812914 PMCID: PMC8216429 DOI: 10.1016/j.radonc.2021.03.034] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Revised: 03/07/2021] [Accepted: 03/26/2021] [Indexed: 11/16/2022]
Abstract
BACKGROUND AND PURPOSE 4D and midposition MRI could inform plan adaptation in lung and abdominal MR-guided radiotherapy. We present deep learning-based solutions to overcome long 4D-MRI reconstruction times while maintaining high image quality and short scan times. METHODS Two 3D U-net deep convolutional neural networks were trained to accelerate the 4D joint MoCo-HDTV reconstruction. For the first network, gridded and joint MoCo-HDTV-reconstructed 4D-MRI were used as input and target data, respectively, whereas the second network was trained to directly calculate the midposition image. For both networks, input and target data had dimensions of 256 × 256 voxels (2D) and 16 respiratory phases. Deep learning-based MRI were verified against joint MoCo-HDTV-reconstructed MRI using the structural similarity index (SSIM) and the naturalness image quality evaluator (NIQE). Moreover, two experienced observers contoured the gross tumour volume and scored the images in a blinded study. RESULTS For 12 subjects, previously unseen by the networks, high-quality 4D and midposition MRI (1.25 × 1.25 × 3.3 mm3) were each reconstructed from gridded images in only 28 seconds per subject. Excellent agreement was found between deep-learning-based and joint MoCo-HDTV-reconstructed MRI (average SSIM ≥ 0.96, NIQE scores 7.94 and 5.66). Deep-learning-based 4D-MRI were clinically acceptable for target and organ-at-risk delineation. Tumour positions agreed within 0.7 mm on midposition images. CONCLUSION Our results suggest that the joint MoCo-HDTV and midposition algorithms can each be approximated by a deep convolutional neural network. This rapid reconstruction of 4D and midposition MRI facilitates online treatment adaptation in thoracic or abdominal MR-guided radiotherapy.
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Affiliation(s)
- Joshua N Freedman
- Joint Department of Physics, The Institute of Cancer Research and The Royal Marsden NHS Foundation Trust, London, United Kingdom.
| | - Oliver J Gurney-Champion
- Joint Department of Physics, The Institute of Cancer Research and The Royal Marsden NHS Foundation Trust, London, United Kingdom; Department of Radiology and Nuclear Medicine, Cancer Center Amsterdam, Amsterdam UMC, University of Amsterdam, The Netherlands.
| | - Simeon Nill
- Joint Department of Physics, The Institute of Cancer Research and The Royal Marsden NHS Foundation Trust, London, United Kingdom.
| | - Anna-Maria Shiarli
- Department of Radiotherapy, The Institute of Cancer Research and The Royal Marsden NHS Foundation Trust, London, United Kingdom.
| | - Hannah E Bainbridge
- Department of Radiotherapy, The Institute of Cancer Research and The Royal Marsden NHS Foundation Trust, London, United Kingdom; Department of Radiotherapy, Portsmouth Hospitals University NHS Trust, Queen Alexandra Hospital, United Kingdom.
| | - Henry C Mandeville
- Department of Radiotherapy, The Institute of Cancer Research and The Royal Marsden NHS Foundation Trust, London, United Kingdom.
| | - Dow-Mu Koh
- Department of Radiology, The Royal Marsden NHS Foundation Trust, London, United Kingdom.
| | - Fiona McDonald
- Department of Radiotherapy, The Institute of Cancer Research and The Royal Marsden NHS Foundation Trust, London, United Kingdom.
| | - Marc Kachelrieß
- Division of X-Ray Imaging and CT, German Cancer Research Center (DKFZ), Heidelberg, Germany.
| | - Uwe Oelfke
- Joint Department of Physics, The Institute of Cancer Research and The Royal Marsden NHS Foundation Trust, London, United Kingdom.
| | - Andreas Wetscherek
- Joint Department of Physics, The Institute of Cancer Research and The Royal Marsden NHS Foundation Trust, London, United Kingdom.
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6
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Hu Q, Yu VY, Yang Y, Hu P, Sheng K, Lee PP, Kishan AU, Raldow AC, O'Connell DP, Woods KE, Cao M. Practical Safety Considerations for Integration of Magnetic Resonance Imaging in Radiation Therapy. Pract Radiat Oncol 2020; 10:443-453. [PMID: 32781246 DOI: 10.1016/j.prro.2020.07.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Revised: 07/16/2020] [Accepted: 07/28/2020] [Indexed: 12/29/2022]
Abstract
Interest in integrating magnetic resonance imaging (MRI) in radiation therapy (RT) practice has increased dramatically in recent years owing to its unique advantages such as excellent soft tissue contrast and capability of measuring biological properties. Continuous real-time imaging for intrafractional motion tracking without ionizing radiation serves as a particularly attractive feature for applications in RT. Despite its many advantages, the integration of MRI in RT workflows is not straightforward, with many unmet needs. MR safety remains one of the key challenges and concerns in the clinical implementation of MR simulators and MR-guided radiation therapy systems in radiation oncology. Most RT staff are not accustomed to working in an environment with a strong magnetic field. There are specific requirements in RT that are different from diagnostic applications. A large variety of implants and devices used in routine RT practice do not have clear MR safety labels. RT-specific imaging pulse sequences focusing on fast acquisition, high spatial integrity, and continuous, real-time acquisition require additional MR safety testing and evaluation. This article provides an overview of MR safety tailored toward RT staff, followed by discussions on specific requirements and challenges associated with MR safety in the RT environment. Strategies and techniques for developing an MR safety program specific to RT are presented and discussed.
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Affiliation(s)
- Qiongge Hu
- Department of Radiation Oncology, Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Victoria Y Yu
- Department of Medical Physics, Memorial Sloan Kettering Cancer Center, New York, New York
| | - Yingli Yang
- Department of Radiation Oncology, University of California, Los Angeles, California
| | - Peng Hu
- Department of Radiology, University of California, Los Angeles, California
| | - Ke Sheng
- Department of Radiation Oncology, University of California, Los Angeles, California
| | - Percy P Lee
- Department of Radiation Oncology, University of Texas MD Anderson Cancer Center, Houston, Texas
| | - Amar U Kishan
- Department of Radiation Oncology, University of California, Los Angeles, California
| | - Ann C Raldow
- Department of Radiation Oncology, University of California, Los Angeles, California
| | - Dylan P O'Connell
- Department of Radiation Oncology, University of California, Los Angeles, California
| | - Kaley E Woods
- Department of Radiation Oncology, University of California, Los Angeles, California
| | - Minsong Cao
- Department of Radiation Oncology, University of California, Los Angeles, California.
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Keiper TD, Tai A, Chen X, Paulson E, Lathuilière F, Bériault S, Hébert F, Cooper DT, Lachaine M, Li XA. Feasibility of real‐time motion tracking using cine MRI during MR‐guided radiation therapy for abdominal targets. Med Phys 2020; 47:3554-3566. [DOI: 10.1002/mp.14230] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2019] [Revised: 03/31/2020] [Accepted: 04/30/2020] [Indexed: 12/25/2022] Open
Affiliation(s)
- Timothy D. Keiper
- Department of Radiation Oncology Medical College of Wisconsin 8701 Watertown Plank Rd Milwaukee WI 53226 USA
| | - An Tai
- Department of Radiation Oncology Medical College of Wisconsin 8701 Watertown Plank Rd Milwaukee WI 53226 USA
| | - Xinfeng Chen
- Department of Radiation Oncology Medical College of Wisconsin 8701 Watertown Plank Rd Milwaukee WI 53226 USA
| | - Eric Paulson
- Department of Radiation Oncology Medical College of Wisconsin 8701 Watertown Plank Rd Milwaukee WI 53226 USA
| | | | | | - François Hébert
- Elekta 2050 Rue de Bleury Suite 200 Montréal QC H3A 2J5 Canada
| | - David T. Cooper
- Elekta 2050 Rue de Bleury Suite 200 Montréal QC H3A 2J5 Canada
| | - Martin Lachaine
- Elekta 2050 Rue de Bleury Suite 200 Montréal QC H3A 2J5 Canada
| | - X. Allen Li
- Department of Radiation Oncology Medical College of Wisconsin 8701 Watertown Plank Rd Milwaukee WI 53226 USA
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8
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Mickevicius NJ, Nencka AS, Paulson ES. Generalized simultaneous multi-orientation 2D imaging. Magn Reson Med 2019; 84:847-856. [PMID: 31872496 DOI: 10.1002/mrm.28150] [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: 08/12/2019] [Revised: 12/02/2019] [Accepted: 12/06/2019] [Indexed: 11/09/2022]
Abstract
PURPOSE Flexibility in slice prescription is critical for precise motion monitoring during MR-guided therapies. Adding more slices to improve spatial coverage during rapid 2D cine imaging often hampers temporal resolution. This work describes a framework to simultaneously acquire multiple arbitrarily oriented slices which share a common frequency encoding axis. This framework allows for higher frame rates for a given number of slices compared to conventional interleaved-slice multi-orientation cine imaging. THEORY AND METHODS A framework to calculate zeroth gradient moments to be played out between sequentially excited slices with multiple orientations is described here. Experiments were performed in phantom, and in vivo in the head/neck and abdomen of patients. RESULTS Images arbitrarily rotated relative to one another were successfully obtained in phantom and in vivo. Simultaneous multi-orientation (SMO) images were also acquired with additional in-plane acceleration to demonstrate the capability of this method to rapidly image objects moving with physiological motion. CONCLUSIONS The technical feasibility of the generalized SMO imaging framework was tested in this study. It shows promise for continued development for motion monitoring during MR-guided therapies.
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Affiliation(s)
| | - Andrew S Nencka
- Department of Radiology, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Eric S Paulson
- Department of Radiation Oncology, Medical College of Wisconsin, Milwaukee, WI, USA.,Department of Radiology, Medical College of Wisconsin, Milwaukee, WI, USA
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9
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Simultaneous acquisition of orthogonal plane cine imaging and isotropic 4D-MRI using super-resolution. Radiother Oncol 2019; 136:121-129. [DOI: 10.1016/j.radonc.2019.04.005] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2018] [Revised: 03/30/2019] [Accepted: 04/03/2019] [Indexed: 11/19/2022]
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10
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Borman PTS, Bos C, Stemkens B, Moonen CTW, Raaymakers BW, Tijssen RHN. Assessment of 3D motion modeling performance for dose accumulation mapping on the MR-linac by simultaneous multislice MRI. Phys Med Biol 2019; 64:095004. [PMID: 30917353 DOI: 10.1088/1361-6560/ab13e3] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Hybrid MR-linac systems enable intrafraction motion monitoring during radiation therapy. Since time-resolved 3D MRI is still challenging, various motion models have been developed that rely on time-resolved 2D imaging. Continuous validation of these models is important for accurate dose accumulation mapping. In this study we used 2D simultaneous multislice (SMS) imaging to improve the PCA-based motion modeling method developed previously (Stemkens et al 2016 Phys. Med. Biol. 61 5335-55). From the additional simultaneously acquired slices, several independent motion models could be generated, which allowed for an assessment of the sensitivity of the motion model to the location of the time-resolved 2D slices. Additionally, the best model could be chosen at every time-point, increasing the method's robustness. Imaging experiments were performed in six healthy volunteers using three simultaneous slices, which generated three independent models per volunteer. For each model the motion traces of the liver tip and both kidneys were estimated. We found that the location of the 2D slices influenced the model's error in five volunteers significantly with a p -value <0.05, and that selecting the best model at every time-point can improve the method. This allows for more accurate and robust motion characterization in MR-guided radiotherapy.
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Affiliation(s)
- P T S Borman
- Department of Radiotherapy, University Medical Center Utrecht. Heidelberglaan 100, 3584 CX, Utrecht, The Netherlands. Imaging Division, University Medical Center Utrecht. Heidelberglaan 100, 3584 CX, Utrecht, The Netherlands. Author to whom any correspondence should be addressed
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