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Getzmann JM, Deininger-Czermak E, Melissanidis S, Ensle F, Kaushik SS, Wiesinger F, Cozzini C, Sconfienza LM, Guggenberger R. Deep learning-based pseudo-CT synthesis from zero echo time MR sequences of the pelvis. Insights Imaging 2024; 15:202. [PMID: 39120752 PMCID: PMC11315823 DOI: 10.1186/s13244-024-01751-3] [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: 01/23/2024] [Accepted: 06/17/2024] [Indexed: 08/10/2024] Open
Abstract
OBJECTIVES To generate pseudo-CT (pCT) images of the pelvis from zero echo time (ZTE) MR sequences and compare them to conventional CT. METHODS Ninety-one patients were prospectively scanned with CT and MRI including ZTE sequences of the pelvis. Eleven ZTE image volumes were excluded due to implants and severe B1 field inhomogeneity. Out of the 80 data sets, 60 were used to train and update a deep learning (DL) model for pCT image synthesis from ZTE sequences while the remaining 20 cases were selected as an evaluation cohort. CT and pCT images were assessed qualitatively and quantitatively by two readers. RESULTS Mean pCT ratings of qualitative parameters were good to perfect (2-3 on a 4-point scale). Overall intermodality agreement between CT and pCT was good (ICC = 0.88 (95% CI: 0.85-0.90); p < 0.001) with excellent interreader agreements for pCT (ICC = 0.91 (95% CI: 0.88-0.93); p < 0.001). Most geometrical measurements did not show any significant difference between CT and pCT measurements (p > 0.05) with the exception of transverse pelvic diameter measurements and lateral center-edge angle measurements (p = 0.001 and p = 0.002, respectively). Image quality and tissue differentiation in CT and pCT were similar without significant differences between CT and pCT CNRs (all p > 0.05). CONCLUSIONS Using a DL-based algorithm, it is possible to synthesize pCT images of the pelvis from ZTE sequences. The pCT images showed high bone depiction quality and accurate geometrical measurements compared to conventional CT. CRITICAL RELEVANCE STATEMENT: pCT images generated from MR sequences allow for high accuracy in evaluating bone without the need for radiation exposure. Radiological applications are broad and include assessment of inflammatory and degenerative bone disease or preoperative planning studies. KEY POINTS pCT, based on DL-reconstructed ZTE MR images, may be comparable with true CT images. Overall, the intermodality agreement between CT and pCT was good with excellent interreader agreements for pCT. Geometrical measurements and tissue differentiation were similar in CT and pCT images.
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Affiliation(s)
- Jonas M Getzmann
- Institute of Diagnostic and Interventional Radiology, University Hospital Zurich (USZ), Zurich, Switzerland.
- University of Zurich (UZH), Zurich, Switzerland.
- Unit of Diagnostic and Interventional Radiology, IRCCS Istituto Ortopedico Galeazzi, Milan, Italy.
| | - Eva Deininger-Czermak
- Institute of Diagnostic and Interventional Radiology, University Hospital Zurich (USZ), Zurich, Switzerland
- University of Zurich (UZH), Zurich, Switzerland
- Institute of Forensic Medicine, University of Zurich (UZH), Zurich, Switzerland
| | - Savvas Melissanidis
- Institute of Diagnostic and Interventional Radiology, University Hospital Zurich (USZ), Zurich, Switzerland
- University of Zurich (UZH), Zurich, Switzerland
| | - Falko Ensle
- Institute of Diagnostic and Interventional Radiology, University Hospital Zurich (USZ), Zurich, Switzerland
- University of Zurich (UZH), Zurich, Switzerland
| | | | | | | | - Luca M Sconfienza
- Unit of Diagnostic and Interventional Radiology, IRCCS Istituto Ortopedico Galeazzi, Milan, Italy
- University of Milan, Department of Biomedical Sciences for Health, Milan, Italy
| | - Roman Guggenberger
- Institute of Diagnostic and Interventional Radiology, University Hospital Zurich (USZ), Zurich, Switzerland
- University of Zurich (UZH), Zurich, Switzerland
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Cao G, Li Y, Wu S, Li W, Long J, Xie Y, Xia J. Clinical feasibility of MRI-based synthetic CT imaging in the diagnosis of lumbar disc herniation: a comparative study. Acta Radiol 2024; 65:41-48. [PMID: 37071506 PMCID: PMC10798008 DOI: 10.1177/02841851231169173] [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: 07/29/2022] [Accepted: 12/05/2022] [Indexed: 04/19/2023]
Abstract
BACKGROUND Computed tomography (CT) and magnetic resonance imaging (MRI) are indicated for use in preoperative planning and may complicate diagnosis and place a burden on patients with lumbar disc herniation. PURPOSE To investigate the diagnostic potential of MRI-based synthetic CT with conventional CT in the diagnosis of lumbar disc herniation. MATERIAL AND METHODS After obtaining prior institutional review board approval, 19 patients who underwent conventional and synthetic CT imaging were enrolled in this prospective study. Synthetic CT images were generated from the MRI data using U-net. The two sets of images were compared and analyzed qualitatively by two musculoskeletal radiologists. The images were rated on a 4-point scale to determine their subjective quality. The agreement between the conventional and synthetic images for a diagnosis of lumbar disc herniation was determined independently using the kappa statistic. The diagnostic performances of conventional and synthetic CT images were evaluated for sensitivity, specificity, and accuracy, and the consensual results based on T2-weighted imaging were employed as the reference standard. RESULTS The inter-reader and intra-reader agreement were almost moderate for all evaluated modalities (κ = 0.57-0.79 and 0.47-0.75, respectively). The sensitivity, specificity, and accuracy for detecting lumbar disc herniation were similar for synthetic and conventional CT images (synthetic vs. conventional, reader 1: sensitivity = 91% vs. 81%, specificity = 83% vs. 100%, accuracy = 87% vs. 91%; P < 0.001; reader 2: sensitivity = 84% vs. 81%, specificity = 85% vs. 98%, accuracy = 84% vs. 90%; P < 0.001). CONCLUSION Synthetic CT images can be used in the diagnostics of lumbar disc herniation.
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Affiliation(s)
- Gan Cao
- Department of Radiology, Longgang Central Hospital of Shenzhen, Shenzhen, PR China
- Department of Radiology, The First Affiliated Hospital of Shenzhen University, Health Science Center, Shenzhen Second People's Hospital, Shenzhen, PR China
| | - Yafen Li
- School of Health Science and Engineering, University of Shanghai for Science and Technology, Shanghai, PR China
| | - Shibin Wu
- PingAn Technology, Shenzhen, Guangdong, PR China
| | - Wen Li
- Department of Health Technology and Informatics, The Hong Kong Polytechnic University, Kowloon, Hong Kong SAR, PR China
| | - Jia Long
- Department of Radiology, The First Affiliated Hospital of Shenzhen University, Health Science Center, Shenzhen Second People's Hospital, Shenzhen, PR China
| | - Yaoqin Xie
- Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, PR China
| | - Jun Xia
- Department of Radiology, The First Affiliated Hospital of Shenzhen University, Health Science Center, Shenzhen Second People's Hospital, Shenzhen, PR China
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Koivula L, Seppälä T, Collan J, Visapää H, Tenhunen M, Korhonen A. Synthetic computed tomography based dose calculation in prostate cancer patients with hip prostheses for magnetic resonance imaging-only radiotherapy. Phys Imaging Radiat Oncol 2023; 27:100469. [PMID: 37520639 PMCID: PMC10371839 DOI: 10.1016/j.phro.2023.100469] [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: 01/02/2023] [Revised: 07/05/2023] [Accepted: 07/06/2023] [Indexed: 08/01/2023] Open
Abstract
Background and purpose Metallic hip prostheses cause substantial artefacts in both computed tomography (CT) and magnetic resonance (MR) images used in radiotherapy treatment planning (RTP) for prostate cancer patients. The aim of this study was to evaluate the dose calculation accuracy of a synthetic CT (sCT) generation workflow and the improvement in implant visibility using metal artefact reduction sequences. Materials and methods The study included 23 patients with prostate cancer who had hip prostheses, of which 10 patients had bilateral hip implants. An in-house protocol was applied to create sCT images for dose calculation comparison. The study compared prostheses volumes and resulting avoidance sectors against planning target volume (PTV) dose uniformity and organs at risk (OAR) sparing. Results Median PTV dose difference between sCT and CT-based dose calculation among all patients was 0.1 % (-0.4 to 0.4%) (median(range)). Bladder and rectum differences (V50Gy) were 0.2 % (-0.3 to 1.1%) and 0.1 % (-0.9 to 0.5%). The median 3D local gamma pass rate for partial arc cases using a Dixon MR sequence was Γ20%2mm/2% = 99.9%. For the bilateral full arc cases, using a metal artefact reconstruction sequence, the pass rate was Γ20%2mm/2% = 99.0%. Conclusions An in-house protocol for generating sCT images for dose calculation provided clinically feasible dose calculation accuracy for prostate cancer patients with hip implants. PTV median dose difference for uni- and bilateral patients with avoidance sectors remained <0.4%. The Outphase images enhanced implant visibility resulting in smaller avoidance sectors, better OAR sparing, and improved PTV uniformity.
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Affiliation(s)
- Lauri Koivula
- Department of Physics, MATRENA-doctoral programme, University of Helsinki, Gustaf Hällströmin katu 2, 00560 Helsinki, Finland
- Comprehensive Cancer Center, Helsinki University Hospital and University of Helsinki, Haartmaninkatu 4 Building 2, 00290 Helsinki, Finland
| | - Tiina Seppälä
- Comprehensive Cancer Center, Helsinki University Hospital and University of Helsinki, Haartmaninkatu 4 Building 2, 00290 Helsinki, Finland
| | - Juhani Collan
- Comprehensive Cancer Center, Helsinki University Hospital and University of Helsinki, Haartmaninkatu 4 Building 2, 00290 Helsinki, Finland
| | - Harri Visapää
- Comprehensive Cancer Center, Helsinki University Hospital and University of Helsinki, Haartmaninkatu 4 Building 2, 00290 Helsinki, Finland
| | - Mikko Tenhunen
- Comprehensive Cancer Center, Helsinki University Hospital and University of Helsinki, Haartmaninkatu 4 Building 2, 00290 Helsinki, Finland
| | - Arthur Korhonen
- Department of Medical Physics, Kymenlaakso Central Hospital, Kymenlaakso Social and Health Services (KymenHVA), Kotkantie 41, 48210 Kotka, Finland
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Li X, Marcus D, Russell J, Aboagye EO, Ellis LB, Sheeka A, Park WE, Bharwani N, Ghaem‐Maghami S, Rockall AG. An Integrated Clinical-MR Radiomics Model to Estimate Survival Time in Patients With Endometrial Cancer. J Magn Reson Imaging 2023; 57:1922-1933. [PMID: 36484309 PMCID: PMC10947322 DOI: 10.1002/jmri.28544] [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: 08/16/2022] [Revised: 11/11/2022] [Accepted: 11/14/2022] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Determination of survival time in women with endometrial cancer using clinical features remains imprecise. Features from MRI may improve the survival estimation allowing improved treatment planning. PURPOSE To identify clinical features and imaging signatures on T2-weighted MRI that can be used in an integrated model to estimate survival time for endometrial cancer subjects. STUDY TYPE Retrospective. POPULATION Four hundred thirteen patients with endometrial cancer as training (N = 330, 66.41 ± 11.42 years) and validation (N = 83, 67.60 ± 11.89 years) data and an independent set of 82 subjects as testing data (63.26 ± 12.38 years). FIELD STRENGTH/SEQUENCE 1.5-T and 3-T scanners with sagittal T2-weighted spin echo sequence. ASSESSMENT Tumor regions were manually segmented on T2-weighted images. Features were extracted from segmented masks, and clinical variables including age, cancer histologic grade and risk score were included in a Cox proportional hazards (CPH) model. A group least absolute shrinkage and selection operator method was implemented to determine the model from the training and validation datasets. STATISTICAL TESTS A likelihood-ratio test and decision curve analysis were applied to compare the models. Concordance index (CI) and area under the receiver operating characteristic curves (AUCs) were calculated to assess the model. RESULTS Three radiomic features (two image intensity and volume features) and two clinical variables (age and cancer grade) were selected as predictors in the integrated model. The CI was 0.797 for the clinical model (includes clinical variables only) and 0.818 for the integrated model using training and validation datasets, the associated mean AUC value was 0.805 and 0.853. Using the testing dataset, the CI was 0.792 and 0.882, significantly different and the mean AUC was 0.624 and 0.727 for the clinical model and integrated model, respectively. DATA CONCLUSION The proposed CPH model with radiomic signatures may serve as a tool to improve estimated survival time in women with endometrial cancer. EVIDENCE LEVEL 4 TECHNICAL EFFICACY: Stage 2.
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Affiliation(s)
- Xingfeng Li
- Department of Surgery and CancerImperial CollegeLondonUK
| | - Diana Marcus
- Department of Surgery and CancerImperial CollegeLondonUK
- Chelsea and Westminster Hospital NHS Foundation TrustLondonUK
| | - James Russell
- Imaging DepartmentImperial College Healthcare NHS TrustLondonUK
| | | | - Laura Burney Ellis
- Department of Surgery and CancerImperial CollegeLondonUK
- Imaging DepartmentImperial College Healthcare NHS TrustLondonUK
| | | | | | - Nishat Bharwani
- Department of Surgery and CancerImperial CollegeLondonUK
- Imaging DepartmentImperial College Healthcare NHS TrustLondonUK
| | | | - Andrea G. Rockall
- Department of Surgery and CancerImperial CollegeLondonUK
- Imaging DepartmentImperial College Healthcare NHS TrustLondonUK
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Tang B, Liu M, Wang B, Diao P, Li J, Feng X, Wu F, Yao X, Liao X, Hou Q, Orlandini LC. Improving the clinical workflow of a MR-Linac by dosimetric evaluation of synthetic CT. Front Oncol 2022; 12:920443. [PMID: 36106119 PMCID: PMC9464932 DOI: 10.3389/fonc.2022.920443] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Accepted: 08/04/2022] [Indexed: 11/13/2022] Open
Abstract
Adaptive radiotherapy performed on the daily magnetic resonance imaging (MRI) is an option to improve the treatment quality. In the adapt-to-shape workflow of 1.5-T MR-Linac, the contours of structures are adjusted on the basis of patient daily MRI, and the adapted plan is recalculated on the MRI-based synthetic computed tomography (syCT) generated by bulk density assignment. Because dosimetric accuracy of this strategy is a priority and requires evaluation, this study aims to explore the usefulness of adding an assessment of dosimetric errors associated with recalculation on syCT to the clinical workflow. Sixty-one patients, with various tumor sites, treated using a 1.5-T MR-Linac were included in this study. In Monaco V5.4, the target and organs at risk (OARs) were contoured, and a reference CT plan that contains information about the outlined contours, their average electron density (ED), and the priority of ED assignment was generated. To evaluate the dosimetric error of syCT caused by the inherent approximation within bulk density assignment, the reference CT plan was recalculated on the syCT obtained from the reference CT by forcing all contoured structures to their mean ED defined on the reference plan. The dose–volume histogram (DVH) and dose distribution of the CT and syCT plan were compared. The causes of dosimetric discrepancies were investigated, and the reference plan was reworked to minimize errors if needed. For 54 patients, gamma analysis of the dose distribution on syCT and CT show a median pass rate of 99.7% and 98.5% with the criteria of 3%/3 mm and 2%/2 mm, respectively. DVH difference of targets and OARs remained less than 1.5% or 1 Gy. For the remaining patients, factors (i.e., inappropriate ED assignments) influenced the dosimetric agreement of the syCT vs. CT reference DVH by up to 21%. The causes of the errors were promptly identified, and the DVH dosimetry was realigned except for two lung treatments for which a significant discrepancy remained. The recalculation on the syCT obtained from the planning CT is a powerful tool to assess and decrease the minimal error committed during the adaptive plan on the MRI-based syCT.
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Affiliation(s)
- Bin Tang
- Department of Radiation Oncology, Sichuan Cancer Hospital and Research Institute, affiliated to University of Electronic Science and Technology of China (UESTC), Chengdu, China
- Key Laboratory of Radiation Physics and Technology of the Ministry of Education, Institute of Nuclear Science and Technology, Sichuan University, Chengdu, China
| | - Min Liu
- Department of Radiation Oncology, Sichuan Cancer Hospital and Research Institute, affiliated to University of Electronic Science and Technology of China (UESTC), Chengdu, China
| | - Bingjie Wang
- Faculty of Arts and Science, University of Toronto, Toronto, ON, Canada
| | - Peng Diao
- Department of Radiation Oncology, Sichuan Cancer Hospital and Research Institute, affiliated to University of Electronic Science and Technology of China (UESTC), Chengdu, China
- *Correspondence: Peng Diao,
| | - Jie Li
- Department of Radiation Oncology, Sichuan Cancer Hospital and Research Institute, affiliated to University of Electronic Science and Technology of China (UESTC), Chengdu, China
| | - Xi Feng
- Department of Radiation Oncology, Sichuan Cancer Hospital and Research Institute, affiliated to University of Electronic Science and Technology of China (UESTC), Chengdu, China
| | - Fan Wu
- Department of Radiation Oncology, Sichuan Cancer Hospital and Research Institute, affiliated to University of Electronic Science and Technology of China (UESTC), Chengdu, China
| | - Xinghong Yao
- Department of Radiation Oncology, Sichuan Cancer Hospital and Research Institute, affiliated to University of Electronic Science and Technology of China (UESTC), Chengdu, China
| | - Xiongfei Liao
- Department of Radiation Oncology, Sichuan Cancer Hospital and Research Institute, affiliated to University of Electronic Science and Technology of China (UESTC), Chengdu, China
| | - Qing Hou
- Key Laboratory of Radiation Physics and Technology of the Ministry of Education, Institute of Nuclear Science and Technology, Sichuan University, Chengdu, China
| | - Lucia Clara Orlandini
- Department of Radiation Oncology, Sichuan Cancer Hospital and Research Institute, affiliated to University of Electronic Science and Technology of China (UESTC), Chengdu, China
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Abu-Qasmieh IF, Masad IS, Al-Quran HH, Alawneh KZ. Generation of Synthetic-Pseudo MR Images from Real CT Images. Tomography 2022; 8:1244-1259. [PMID: 35645389 PMCID: PMC9149978 DOI: 10.3390/tomography8030103] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2022] [Revised: 04/24/2022] [Accepted: 04/25/2022] [Indexed: 11/18/2022] Open
Abstract
This study aimed to generate synthetic MR images from real CT images. CT# mean and standard deviation of a moving window across every pixel in the reconstructed CT images were mapped to their corresponding tissue-mimicking types. Identification of the tissue enabled remapping it to its corresponding intrinsic parameters: T1, T2, and proton density (ρ). Lastly, synthetic weighted MR images of a selected slice were generated by simulating a spin-echo sequence using the intrinsic parameters and proper contrast parameters (TE and TR). Experiments were performed on a 3D multimodality abdominal phantom and on human knees at different TE and TR parameters to confirm the clinical effectiveness of the approach. Results demonstrated the validity of the approach of generating synthetic MR images at different weightings using only CT images and the three predefined mapping functions. The slope of the fitting line and percentage root-mean-square difference (PRD) between real and synthetic image vector representations were (0.73, 10%), (0.9, 18%), and (0.2, 8.7%) for T1-, T2-, and ρ-weighted images of the phantom, respectively. The slope and PRD for human knee images, on average, were 0.89% and 18.8%, respectively. The generated MR images provide valuable guidance for physicians with regard to deciding whether acquiring real MR images is crucial.
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Affiliation(s)
- Isam F. Abu-Qasmieh
- Department of Biomedical Systems and Informatics Engineering, Yarmouk University, Irbid 21163, Jordan; (I.F.A.-Q.); (H.H.A.-Q.)
| | - Ihssan S. Masad
- Department of Biomedical Systems and Informatics Engineering, Yarmouk University, Irbid 21163, Jordan; (I.F.A.-Q.); (H.H.A.-Q.)
- Correspondence:
| | - Hiam H. Al-Quran
- Department of Biomedical Systems and Informatics Engineering, Yarmouk University, Irbid 21163, Jordan; (I.F.A.-Q.); (H.H.A.-Q.)
- Department of Biomedical Engineering, Jordan University of Science and Technology, Irbid 22110, Jordan
| | - Khaled Z. Alawneh
- Faculty of Medicine, Jordan University of Science and Technology, King Abdullah University Hospital, Irbid 22110, Jordan;
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Ding S, Liu H, Li Y, Wang B, Li R, Huang X. Dosimetric Accuracy of MR-Guided Online Adaptive Planning for Nasopharyngeal Carcinoma Radiotherapy on 1.5 T MR-Linac. Front Oncol 2022; 12:858076. [PMID: 35463359 PMCID: PMC9022004 DOI: 10.3389/fonc.2022.858076] [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: 01/19/2022] [Accepted: 03/11/2022] [Indexed: 12/04/2022] Open
Abstract
Purpose The aim of this study is to evaluate the dose accuracy of bulk relative electron density (rED) approach for application in 1.5 T MR-Linac and assess the reliability of this approach in the case of online adaptive MR-guided radiotherapy for nasopharyngeal carcinoma (NPC) patients. Methods Ten NPC patients formerly treated on conventional linac were included in this study, with their original planning CT and MRI collected. For each patient, structures such as the targets, organs at risk, bone, and air regions were delineated on the original CT in the Monaco system (v5.40.02). To simulate the online adaptive workflow, firstly all contours were transferred to MRI from the original CT using rigid registration in the Monaco system. Based on the structures, three different types of synthetic CT (sCT) were generated from MRI using the bulk rED assignment approach: the sCTICRU uses the rED values recommended by ICRU46, the sCTtailor uses the patient-specific mean rED values, and the sCTHomogeneity uses homogeneous water equivalent values. The same treatment plan was calculated on the three sCTs and the original CT. Dose calculation accuracy was investigated in terms of gamma analysis, point dose comparison, and dose volume histogram (DVH) parameters. Results Good agreement of dose distribution was observed between sCTtailor and the original CT, with a gamma passing rate (3%/3 mm) of 97.81% ± 1.06%, higher than that of sCTICRU (94.27% ± 1.48%, p = 0.005) and sCTHomogeneity (96.50% ± 1.02%, p = 0.005). For stricter criteria 1%/1 mm, gamma passing rates for plans on sCTtailor, sCTICRU, and sCTHomogeneity were 86.79% ± 4.31%, 79.81% ± 3.63%, and 77.56% ± 4.64%, respectively. The mean point dose difference in PTVnx between sCTtailor and planning CT was −0.14% ± 1.44%, much lower than that calculated on sCTICRU (−8.77% ± 2.33%) and sCTHomogeneity (1.65% ± 2.57%), all with p < 0.05. The DVH differences for the plan based on sCTtailor were much smaller than sCTICRU and sCTHomogeneity. Conclusions The bulk rED-assigned sCT by adopting the patient-specific rED values can achieve a clinically acceptable level of dose calculation accuracy in the presence of a 1.5 T magnetic field, making it suitable for online adaptive MR-guided radiotherapy for NPC patients.
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Affiliation(s)
- Shouliang Ding
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, Guangzhou, China
| | - Hongdong Liu
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, Guangzhou, China
| | - Yongbao Li
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, Guangzhou, China
| | - Bin Wang
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, Guangzhou, China
| | - Rui Li
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, Guangzhou, China
| | - Xiaoyan Huang
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, Guangzhou, China
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Hong KT, Cho Y, Kang CH, Ahn KS, Lee H, Kim J, Hong SJ, Kim BH, Shim E. Lumbar Spine Computed Tomography to Magnetic Resonance Imaging Synthesis Using Generative Adversarial Network: Visual Turing Test. Diagnostics (Basel) 2022; 12:530. [PMID: 35204619 PMCID: PMC8871227 DOI: 10.3390/diagnostics12020530] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2022] [Revised: 02/11/2022] [Accepted: 02/16/2022] [Indexed: 11/16/2022] Open
Abstract
(1) Introduction: Computed tomography (CT) and magnetic resonance imaging (MRI) play an important role in the diagnosis and evaluation of spinal diseases, especially degenerative spinal diseases. MRI is mainly used to diagnose most spinal diseases because it shows a higher resolution than CT to distinguish lesions of the spinal canals and intervertebral discs. When it is inevitable for CT to be selected instead of MR in evaluating spinal disease, evaluation of spinal disease may be limited. In these cases, it is very helpful to diagnose spinal disease with MR images synthesized with CT images. (2) Objective: To create synthetic lumbar magnetic resonance (MR) images from computed tomography (CT) scans using generative adversarial network (GAN) models and assess how closely the synthetic images resembled the true images using visual Turing tests (VTTs). (3) Material and Methods: Overall, 285 patients aged ≥ 40 years who underwent lumbar CT and MRI were enrolled. Based on axial CT and T2-weighted axial MR images from 285 patients, an image synthesis model using a GAN was trained using three algorithms (unsupervised, semi-supervised, and supervised methods). Furthermore, VTT to determine how similar the synthetic lumbar MR images generated from lumbar CT axial images were to the true lumbar MR axial images were conducted with 59 patients who were not included in the model training. For the VTT, we designed an evaluation form comprising 600 randomly distributed axial images (150 true and 450 synthetic images from unsupervised, semi-supervised, and supervised methods). Four readers judged the authenticity of each image and chose their first- and second-choice candidates for the true image. In addition, for the three models, structural similarities (SSIM) were evaluated and the peak signal to noise ratio (PSNR) was compared among the three methods. (4) Results: The mean accuracy for the selection of true images for all four readers for their first choice was 52.0% (312/600). The accuracies of determining the true image for each reader's first and first + second choices, respectively, were as follows: reader 1, 51.3% and 78.0%; reader 2, 38.7% and 62.0%, reader 3, 69.3% and 84.0%, and reader 4, 48.7% and 70.7%. In the case of synthetic images chosen as first and second choices, supervised algorithm-derived images were the most often selected (supervised, 118/600 first and 164/600 second; semi-supervised, 90/600 and 144/600; and unsupervised, 80/600 and 114/600). For image quality, the supervised algorithm received the best score (PSNR: 15.987 ± 1.039, SSIM: 0.518 ± 0.042). (5) Conclusion: This was the pilot study to apply GAN to synthesize lumbar spine MR images from CT images and compare training algorithms of the GAN. Based on VTT, the axial MR images synthesized from lumbar CT using GAN were fairly realistic and the supervised training algorithm was found to provide the closest image to true images.
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Affiliation(s)
- Ki-Taek Hong
- Department of Radiology, Korea University College of Medicine, Korea University Anam Hospital, Seoul 02841, Korea; (K.-T.H.); (Y.C.); (K.-S.A.); (H.L.); (J.K.)
| | - Yongwon Cho
- Department of Radiology, Korea University College of Medicine, Korea University Anam Hospital, Seoul 02841, Korea; (K.-T.H.); (Y.C.); (K.-S.A.); (H.L.); (J.K.)
- AI Center, Korea University Anam Hospital, Seoul 02841, Korea
| | - Chang Ho Kang
- Department of Radiology, Korea University College of Medicine, Korea University Anam Hospital, Seoul 02841, Korea; (K.-T.H.); (Y.C.); (K.-S.A.); (H.L.); (J.K.)
| | - Kyung-Sik Ahn
- Department of Radiology, Korea University College of Medicine, Korea University Anam Hospital, Seoul 02841, Korea; (K.-T.H.); (Y.C.); (K.-S.A.); (H.L.); (J.K.)
| | - Heegon Lee
- Department of Radiology, Korea University College of Medicine, Korea University Anam Hospital, Seoul 02841, Korea; (K.-T.H.); (Y.C.); (K.-S.A.); (H.L.); (J.K.)
| | - Joohui Kim
- Department of Radiology, Korea University College of Medicine, Korea University Anam Hospital, Seoul 02841, Korea; (K.-T.H.); (Y.C.); (K.-S.A.); (H.L.); (J.K.)
| | - Suk Joo Hong
- Korea University Guro Hospital, Seoul 02841, Korea;
| | - Baek Hyun Kim
- Korea University College of Medicine, Korea University Ansan Hospital, Seoul 02841, Korea; (B.H.K.); (E.S.)
| | - Euddeum Shim
- Korea University College of Medicine, Korea University Ansan Hospital, Seoul 02841, Korea; (B.H.K.); (E.S.)
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Yousefi Moteghaed N, Mostaar A, Azadeh P. Generating pseudo-computerized tomography (P-CT) scan images from magnetic resonance imaging (MRI) images using machine learning algorithms based on fuzzy theory for radiotherapy treatment planning. Med Phys 2021; 48:7016-7027. [PMID: 34418104 DOI: 10.1002/mp.15174] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Revised: 07/09/2021] [Accepted: 08/03/2021] [Indexed: 12/26/2022] Open
Abstract
PURPOSE The substitution of computerized tomography (CT) with magnetic resonance imaging (MRI) has been investigated for external radiotherapy treatment planning. The present study aims to use pseudo-CT (P-CT) images created by MRI images to calculate the dose distribution for facilitating the treatment planning process. METHODS In this work, following image segmentation with a fuzzy clustering algorithm, an adaptive neuro-fuzzy algorithm was utilized to design the Hounsfield unit (HU) conversion model based on the features vector of MRI images. The model was generated on the set of extracted features from the gray-level co-occurrence matrices and the gray-level run-length matrices for 14 arbitrarily selected patients with brain malady. The performance of the algorithm was investigated on blind datasets through dose-volume histogram and isodose curve evaluations, using the RayPlan treatment planning system (TPS), along with the gamma analysis and statistical indices. RESULTS In the proposed approach, the mean absolute error within the range of 45.4 HU was found among the test data. Also, the relative dose difference between the planning target volume region of the CT and the P-CT was 0.5%, and the best gamma pass rate for 3%/3 mm was 97.2%. CONCLUSION The proposed method provides a satisfactory average error rate for the generation of P-CT data in the different parts of the brain region from a collection of MRI series. Also, dosimetric parameters evaluation shows good agreement between reference CT and related P-CT images.
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Affiliation(s)
- Niloofar Yousefi Moteghaed
- Department of Medical Physics and Biomedical Engineering, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Ahmad Mostaar
- Department of Medical Physics and Biomedical Engineering, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Payam Azadeh
- Department of Radiation Oncology, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
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Yoo D, Choi YA, Rah CJ, Lee E, Cai J, Min BJ, Kim EH. Signal Enhancement of Low Magnetic Field Magnetic Resonance Image Using a Conventional- and Cyclic-Generative Adversarial Network Models With Unpaired Image Sets. Front Oncol 2021; 11:660284. [PMID: 34046353 PMCID: PMC8144640 DOI: 10.3389/fonc.2021.660284] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Accepted: 04/08/2021] [Indexed: 11/23/2022] Open
Abstract
In this study, the signal enhancement ratio of low-field magnetic resonance (MR) images was investigated using a deep learning-based algorithm. Unpaired image sets (0.06 Tesla and 1.5 Tesla MR images for different patients) were used in this study following three steps workflow. In the first step, the deformable registration of a 1.5 Tesla MR image into a 0.06 Tesla MR image was performed to ensure that the shapes of the unpaired set matched. In the second step, a cyclic-generative adversarial network (GAN) was used to generate a synthetic MR image of the original 0.06 Tesla MR image based on the deformed or original 1.5 Tesla MR image. Finally, an enhanced 0.06 Tesla MR image could be generated using the conventional-GAN with the deformed or synthetic MR image. The results from the optimized flow and enhanced MR images showed significant signal enhancement of the anatomical view, especially in the nasal septum, inferior nasal choncha, nasopharyngeal fossa, and eye lens. The signal enhancement ratio, signal-to-noise ratio (SNR) and correlation factor between the original and enhanced MR images were analyzed for the evaluation of the image quality. A combined method using conventional- and cyclic-GANs is a promising approach for generating enhanced MR images from low-magnetic-field MR.
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Affiliation(s)
- Denis Yoo
- Artificial Intelligence Research Lab, Talos, Sheung Wan, Hong Kong
| | | | - C J Rah
- Artificial Intelligence Research Lab, Talos, Sheung Wan, Hong Kong
| | - Eric Lee
- Artificial Intelligence Research Lab, Talos, Sheung Wan, Hong Kong
| | - Jing Cai
- Department of Health Technology & Informatics, Hong Kong Polytechnic University, Hung Hom, Hong Kong
| | - Byung Jun Min
- Department of Radiation Oncology, Chungbuk National University Hospital, Cheongju, South Korea
| | - Eun Ho Kim
- Department of Biochemistry, School of Medicine, Daegu Catholic University, Daegu, South Korea
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Hou KY, Lu HY, Yang CC. Applying MRI Intensity Normalization on Non-Bone Tissues to Facilitate Pseudo-CT Synthesis from MRI. Diagnostics (Basel) 2021; 11:diagnostics11050816. [PMID: 33946436 PMCID: PMC8147160 DOI: 10.3390/diagnostics11050816] [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: 03/29/2021] [Revised: 04/27/2021] [Accepted: 04/28/2021] [Indexed: 11/16/2022] Open
Abstract
This study aimed to facilitate pseudo-CT synthesis from MRI by normalizing MRI intensity of the same tissue type to a similar intensity level. MRI intensity normalization was conducted through dividing MRI by a shading map, which is a smoothed ratio image between MRI and a three-intensity mask. Regarding pseudo-CT synthesis from MRI, a conversion model based on a three-layer convolutional neural network was trained and validated. Before MRI intensity normalization, the mean value ± standard deviation of fat tissue in 0.35 T chest MRI was 297 ± 73 (coefficient of variation (CV) = 24.58%), which was 533 ± 91 (CV = 17.07%) in 1.5 T abdominal MRI. The corresponding results were 149 ± 32 (CV = 21.48%) and 148 ± 28 (CV = 18.92%) after intensity normalization. With regards to pseudo-CT synthesis from MRI, the differences in mean values between pseudo-CT and real CT were 3, 15, and 12 HU for soft tissue, fat, and lung/air in 0.35 T chest imaging, respectively, while the corresponding results were 3, 14, and 15 HU in 1.5 T abdominal imaging. Overall, the proposed workflow is reliable in pseudo-CT synthesis from MRI and is more practicable in clinical routine practice compared with deep learning methods, which demand a high level of resources for building a conversion model.
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Affiliation(s)
- Kuei-Yuan Hou
- Department of Radiology, Cathay General Hospital, Taipei 106, Taiwan;
- Department of Biomedical Imaging and Radiological Sciences, National Yang-Ming Chiao-Tung University, Taipei 711, Taiwan
| | - Hao-Yuan Lu
- Institute of Radiological Sciences, Tzu-Chi University of Science and Technology, Hualien 970, Taiwan;
| | - Ching-Ching Yang
- Department of Medical Imaging and Radiological Sciences, Kaohsiung Medical University, Kaohsiung 807, Taiwan
- Department of Medical Research, Kaohsiung Medical University Chung-Ho Memorial Hospital, Kaohsiung 807, Taiwan
- Correspondence:
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Franken-CT: Head and Neck MR-Based Pseudo-CT Synthesis Using Diverse Anatomical Overlapping MR-CT Scans. APPLIED SCIENCES-BASEL 2021. [DOI: 10.3390/app11083508] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Typically, pseudo-Computerized Tomography (CT) synthesis schemes proposed in the literature rely on complete atlases acquired with the same field of view (FOV) as the input volume. However, clinical CTs are usually acquired in a reduced FOV to decrease patient ionization. In this work, we present the Franken-CT approach, showing how the use of a non-parametric atlas composed of diverse anatomical overlapping Magnetic Resonance (MR)-CT scans and deep learning methods based on the U-net architecture enable synthesizing extended head and neck pseudo-CTs. Visual inspection of the results shows the high quality of the pseudo-CT and the robustness of the method, which is able to capture the details of the bone contours despite synthesizing the resulting image from knowledge obtained from images acquired with a completely different FOV. The experimental Zero-Normalized Cross-Correlation (ZNCC) reports 0.9367 ± 0.0138 (mean ± SD) and 95% confidence interval (0.9221, 0.9512); the experimental Mean Absolute Error (MAE) reports 73.9149 ± 9.2101 HU and 95% confidence interval (66.3383, 81.4915); the Structural Similarity Index Measure (SSIM) reports 0.9943 ± 0.0009 and 95% confidence interval (0.9935, 0.9951); and the experimental Dice coefficient for bone tissue reports 0.7051 ± 0.1126 and 95% confidence interval (0.6125, 0.7977). The voxel-by-voxel correlation plot shows an excellent correlation between pseudo-CT and ground-truth CT Hounsfield Units (m = 0.87; adjusted R2 = 0.91; p < 0.001). The Bland–Altman plot shows that the average of the differences is low (−38.6471 ± 199.6100; 95% CI (−429.8827, 352.5884)). This work serves as a proof of concept to demonstrate the great potential of deep learning methods for pseudo-CT synthesis and their great potential using real clinical datasets.
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13
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Ding S, Liu H, Li Y, Wang B, Li R, Liu B, Ouyang Y, Wu D, Huang X. Assessment of dose accuracy for online MR-guided radiotherapy for cervical carcinoma. JOURNAL OF RADIATION RESEARCH AND APPLIED SCIENCES 2021. [DOI: 10.1080/16878507.2021.1888243] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Affiliation(s)
- Shouliang Ding
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, Guangzhou, China
- Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - Hongdong Liu
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, Guangzhou, China
| | - Yongbao Li
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, Guangzhou, China
| | - Bin Wang
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, Guangzhou, China
| | - Rui Li
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, Guangzhou, China
| | - Biaoshui Liu
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, Guangzhou, China
| | - Yi Ouyang
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, Guangzhou, China
| | - Dehua Wu
- Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - Xiaoyan Huang
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, Guangzhou, China
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Jans LBO, Chen M, Elewaut D, Van den Bosch F, Carron P, Jacques P, Wittoek R, Jaremko JL, Herregods N. MRI-based Synthetic CT in the Detection of Structural Lesions in Patients with Suspected Sacroiliitis: Comparison with MRI. Radiology 2020; 298:343-349. [PMID: 33350891 DOI: 10.1148/radiol.2020201537] [Citation(s) in RCA: 88] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Background Evaluation of structural lesions in the sacroiliac (SI) joints can improve the accuracy for diagnosis of spondyloarthritis. However, structural lesions, such as erosions, are difficult to assess on routine T1-weighted MRI scans. Purpose To determine the diagnostic performance of MRI-based synthetic CT (sCT) in the depiction of erosions, sclerosis, and ankylosis of the SI joints compared with T1-weighted MRI, with CT as the reference standard. Materials and Methods A prospective study (clinical trial registration no. B670201837885) was performed from February 2019 to November 2019. Adults were referred from a tertiary hospital rheumatology outpatient clinic with clinical suspicion of inflammatory sacroiliitis. MRI and CT of the SI joints were performed on the same day. SCT images were generated from MRI scans using a commercially available deep learning-based image synthesis method. Two readers independently recorded if structural lesions (erosions, sclerosis, and ankylosis) were present on T1-weighted MRI, sCT, and CT scans in different reading sessions, with readers blinded to clinical information and other images. Diagnostic performance of sCT and T1-weighted MRI scans were analyzed using generalized estimating equation models, with consensus results of CT as the reference standard. Results Thirty participants were included (16 men, 14 women; mean age, 40 years ± 10 [standard deviation]). Diagnostic accuracy of sCT was higher than that of T1-weighted MRI for erosion (94% vs 86%, P = .003), sclerosis (97% vs 81%, P < .001), and ankylosis (92% vs 84%, P = .04). With sCT, specificity for erosion detection (96% [95% CI: 90, 98] vs 89% [95% CI: 81, 94], P = .01] and sensitivity for detection of sclerosis [94% [95% CI: 87, 97] vs 20% [95% CI: 10, 35], P < .001] and ankylosis (93% [95% CI: 78, 98] vs 70% [95% CI: 47, 87], P = .001) were improved. Conclusion With CT as the reference standard, synthetic CT of the sacroiliac joints has better diagnostic performance in the detection of structural lesions in individuals suspected of having sacroiliitis compared with routine T1-weighted MRI. © RSNA, 2020 Online supplemental material is available for this article. See also the editorial by Fritz in this issue.
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Affiliation(s)
- Lennart B O Jans
- From the Departments of Radiology (L.B.O.J., M.C., N.H.) and Rheumatology (D.E., F.V.d.B., P.C., P.J., R.W.), Ghent University Hospital, Corneel Heymanslaan 10, 9000 Ghent, Belgium; VIB Center for Inflammation Research, Unit for Molecular Immunology and Inflammation, Ghent University, Ghent, Belgium (D.E., F.v.d.B., P.C., P.J., R.W.); and Department of Radiology & Diagnostic Imaging, University of Alberta Hospital, Edmonton, Canada (J.L.J.)
| | - Min Chen
- From the Departments of Radiology (L.B.O.J., M.C., N.H.) and Rheumatology (D.E., F.V.d.B., P.C., P.J., R.W.), Ghent University Hospital, Corneel Heymanslaan 10, 9000 Ghent, Belgium; VIB Center for Inflammation Research, Unit for Molecular Immunology and Inflammation, Ghent University, Ghent, Belgium (D.E., F.v.d.B., P.C., P.J., R.W.); and Department of Radiology & Diagnostic Imaging, University of Alberta Hospital, Edmonton, Canada (J.L.J.)
| | - Dirk Elewaut
- From the Departments of Radiology (L.B.O.J., M.C., N.H.) and Rheumatology (D.E., F.V.d.B., P.C., P.J., R.W.), Ghent University Hospital, Corneel Heymanslaan 10, 9000 Ghent, Belgium; VIB Center for Inflammation Research, Unit for Molecular Immunology and Inflammation, Ghent University, Ghent, Belgium (D.E., F.v.d.B., P.C., P.J., R.W.); and Department of Radiology & Diagnostic Imaging, University of Alberta Hospital, Edmonton, Canada (J.L.J.)
| | - Filip Van den Bosch
- From the Departments of Radiology (L.B.O.J., M.C., N.H.) and Rheumatology (D.E., F.V.d.B., P.C., P.J., R.W.), Ghent University Hospital, Corneel Heymanslaan 10, 9000 Ghent, Belgium; VIB Center for Inflammation Research, Unit for Molecular Immunology and Inflammation, Ghent University, Ghent, Belgium (D.E., F.v.d.B., P.C., P.J., R.W.); and Department of Radiology & Diagnostic Imaging, University of Alberta Hospital, Edmonton, Canada (J.L.J.)
| | - Philippe Carron
- From the Departments of Radiology (L.B.O.J., M.C., N.H.) and Rheumatology (D.E., F.V.d.B., P.C., P.J., R.W.), Ghent University Hospital, Corneel Heymanslaan 10, 9000 Ghent, Belgium; VIB Center for Inflammation Research, Unit for Molecular Immunology and Inflammation, Ghent University, Ghent, Belgium (D.E., F.v.d.B., P.C., P.J., R.W.); and Department of Radiology & Diagnostic Imaging, University of Alberta Hospital, Edmonton, Canada (J.L.J.)
| | - Peggy Jacques
- From the Departments of Radiology (L.B.O.J., M.C., N.H.) and Rheumatology (D.E., F.V.d.B., P.C., P.J., R.W.), Ghent University Hospital, Corneel Heymanslaan 10, 9000 Ghent, Belgium; VIB Center for Inflammation Research, Unit for Molecular Immunology and Inflammation, Ghent University, Ghent, Belgium (D.E., F.v.d.B., P.C., P.J., R.W.); and Department of Radiology & Diagnostic Imaging, University of Alberta Hospital, Edmonton, Canada (J.L.J.)
| | - Ruth Wittoek
- From the Departments of Radiology (L.B.O.J., M.C., N.H.) and Rheumatology (D.E., F.V.d.B., P.C., P.J., R.W.), Ghent University Hospital, Corneel Heymanslaan 10, 9000 Ghent, Belgium; VIB Center for Inflammation Research, Unit for Molecular Immunology and Inflammation, Ghent University, Ghent, Belgium (D.E., F.v.d.B., P.C., P.J., R.W.); and Department of Radiology & Diagnostic Imaging, University of Alberta Hospital, Edmonton, Canada (J.L.J.)
| | - Jacob L Jaremko
- From the Departments of Radiology (L.B.O.J., M.C., N.H.) and Rheumatology (D.E., F.V.d.B., P.C., P.J., R.W.), Ghent University Hospital, Corneel Heymanslaan 10, 9000 Ghent, Belgium; VIB Center for Inflammation Research, Unit for Molecular Immunology and Inflammation, Ghent University, Ghent, Belgium (D.E., F.v.d.B., P.C., P.J., R.W.); and Department of Radiology & Diagnostic Imaging, University of Alberta Hospital, Edmonton, Canada (J.L.J.)
| | - Nele Herregods
- From the Departments of Radiology (L.B.O.J., M.C., N.H.) and Rheumatology (D.E., F.V.d.B., P.C., P.J., R.W.), Ghent University Hospital, Corneel Heymanslaan 10, 9000 Ghent, Belgium; VIB Center for Inflammation Research, Unit for Molecular Immunology and Inflammation, Ghent University, Ghent, Belgium (D.E., F.v.d.B., P.C., P.J., R.W.); and Department of Radiology & Diagnostic Imaging, University of Alberta Hospital, Edmonton, Canada (J.L.J.)
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Feasibility of Multiparametric Positron Emission Tomography/Magnetic Resonance Imaging as a One-Stop Shop for Radiation Therapy Planning for Patients with Head and Neck Cancer. Int J Radiat Oncol Biol Phys 2020; 108:1329-1338. [DOI: 10.1016/j.ijrobp.2020.07.024] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2020] [Revised: 06/03/2020] [Accepted: 07/10/2020] [Indexed: 11/23/2022]
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Precise magnetic resonance imaging-guided sonodynamic therapy for drug-resistant bacterial deep infection. Biomaterials 2020; 264:120386. [PMID: 32979656 DOI: 10.1016/j.biomaterials.2020.120386] [Citation(s) in RCA: 58] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Revised: 09/04/2020] [Accepted: 09/14/2020] [Indexed: 12/13/2022]
Abstract
The precise treatment of drug-resistant deep bacterial infections remains a huge challenge in clinic. Herein, a polymer-peptide-porphyrin conjugate (PPPC), which can be real-time monitored in infectious site, is developed for accurate and deep sonodynamic therapy (SDT) based on "in vivo self-assembly" strategy. The PPPC contains four moieties, i.e., a hyperbranched polymer backbone, a self-assembled peptide linked with an enzyme-cleavable peptide-poly (ethylene glycol) terminal, a bacterial targeting peptide, and a porphyrin sonosensitizer (MnTCPP) segment. Once PPPC nanoparticles reach the infectious area, the protecting PEG layers are removed due to the over-expressed gelatinase, leading to the secondary assembly into large nanoaggregates and resultant enhanced accumulation of sonosensitizer. The nanoaggregates exhibit enhanced interaction with bacterial membrane and decrease the minimum inhibitory concentration (MIC) significantly. Meanwhile, compared with free MnTCPP, the concentration of which can not be accurately quantified, the accumulation amount of MnTCPP in PPPCs at infectious site can be in situ monitored by magnetic resonance imaging (MRI) using T1 combined with T2. When the concentration of PPPC-1 reaches MIC, the drug-resistant bacterial infection area is exposed to ultrasound irradiation, causing the precise and efficient elimination of bacteria. Therefore, the MRI-guided SDT system shows extraordinary tissue penetration depth, drug concentration monitoring, morphology-transformation induced accumulation and improved treatment capacity toward drug-resistant bacteria.
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Yousefi Moteghaed N, Mostaar A, Maghooli K, Houshyari M, Ameri A. Estimation and evaluation of pseudo-CT images using linear regression models and texture feature extraction from MRI images in the brain region to design external radiotherapy planning. Rep Pract Oncol Radiother 2020; 25:738-745. [PMID: 32684863 DOI: 10.1016/j.rpor.2020.05.005] [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: 01/03/2020] [Revised: 05/05/2020] [Accepted: 05/25/2020] [Indexed: 10/23/2022] Open
Abstract
Aim The aim of this study is to construct and evaluate Pseudo-CT images (P-CTs) for electron density calculation to facilitate external radiotherapy treatment planning. Background Despite numerous benefits, computed tomography (CT) scan does not provide accurate information on soft tissue contrast, which often makes it difficult to precisely differentiate target tissues from the organs at risk and determine the tumor volume. Therefore, MRI imaging can reduce the variability of results when registering with a CT scan. Materials and methods In this research, a fuzzy clustering algorithm was used to segment images into different tissues, also linear regression methods were used to design the regression model based on the feature extraction method and the brightness intensity values. The results of the proposed algorithm for dose-volume histogram (DVH), Isodose curves, and gamma analysis were investigated using the RayPlan treatment planning system, and VeriSoft software. Furthermore, various statistical indices such as Mean Absolute Error (MAE), Mean Error (ME), and Structural Similarity Index (SSIM) were calculated. Results The MAE of a range of 45-55 was found from the proposed methods. The relative difference error between the PTV region of the CT and the Pseudo-CT was 0.5, and the best gamma rate was 95.4% based on the polar coordinate feature and proposed polynomial regression model. Conclusion The proposed method could support the generation of P-CT data for different parts of the brain region from a collection of MRI series with an acceptable average error rate by different evaluation criteria.
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Affiliation(s)
- Niloofar Yousefi Moteghaed
- Department of Biomedical Engineering and Medical Physics, Faculty of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Ahmad Mostaar
- Department of Biomedical Engineering and Medical Physics, Faculty of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran.,Radiation Biology Research Center, Iran University of Medical Sciences, Tehran, Iran
| | - Keivan Maghooli
- Department of Biomedical Engineering, Islamic Azad University, Science and Research Branch, Tehran, Iran
| | - Mohammad Houshyari
- Department of Radiation Oncology, Shohada-e-Tajrish Hospital, Faculty of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Ahmad Ameri
- Department of Radiation Oncology, Imam Hossein Hospital, Faculty of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
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Generation of Pseudo-CT using High-Degree Polynomial Regression on Dual-Contrast Pelvic MRI Data. Sci Rep 2020; 10:8118. [PMID: 32415138 PMCID: PMC7229007 DOI: 10.1038/s41598-020-64842-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2019] [Accepted: 04/20/2020] [Indexed: 01/06/2023] Open
Abstract
Increasing interests in using magnetic resonance imaging only in radiation therapy require methods for predicting the computed tomography numbers from MRI data. Here we propose a simple voxel method to generate the pseudo-CT (pCT) image using dual-contrast pelvic MRI data. The method is first trained with the CT data and dual-contrast MRI data (two sets of MRI with different sequences) of multiple patients, where the anatomical structures in the images after deformable image registration are segmented into several regions, and after MRI intensity normalizations a regression analysis is used to determine a two-variable polynomial function for each region to relate a voxel’s two MRI intensity values to its CT number. We first evaluate the accuracy via the Hounsfield unit (HU) difference between the pseudo-CT and reference-CT (rCT) images and obtain the average mean absolute error as 40.3 ± 2.9 HU from leave-one-out-cross-validation (LOOCV) across all six patients, which is better than most previous results and comparable to another study using the more complicated atlas-based method. We also perform a dosimetric evaluation of the treatment plans based on pCT and rCT images and find the average passing rate within 2% dose difference to be 95.4% in point-to-point dose comparisons. Therefore, our method shows encouraging results in predicting the CT numbers. This polynomial method needs less computer storage than the interpolation method and can be readily extended to the case of more than two MRI sequences.
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Jung SH, Kim J, Chung Y, Keserci B, Pyo H, Park HC, Park W. Magnetic resonance image-based tomotherapy planning for prostate cancer. Radiat Oncol J 2020; 38:52-59. [PMID: 32229809 PMCID: PMC7113151 DOI: 10.3857/roj.2020.00101] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Accepted: 03/20/2020] [Indexed: 11/25/2022] Open
Abstract
Purpose To evaluate and compare the feasibilities of magnetic resonance (MR) image-based planning using synthetic computed tomography (sCT) versus CT (pCT)-based planning in helical tomotherapy for prostate cancer. Materials and Methods A retrospective evaluation was performed in 16 patients with prostate cancer who had been treated with helical tomotherapy. MR images were acquired using a dedicated therapy sequence; sCT images were generated using magnetic resonance for calculating attenuation (MRCAT). The three-dimensional dose distribution according to sCT was recalculated using a previously optimized plan and was compared with the doses calculated using pCT. Results The mean planning target volume doses calculated by sCT and pCT differed by 0.65% ± 1.11% (p = 0.03). Three-dimensional gamma analysis at a 2%/2 mm dose difference/distance to agreement yielded a pass rate of 0.976 (range, 0.658 to 0.986). Conclusion The dose distribution results obtained using tomotherapy from MR-only simulations were in good agreement with the dose distribution results from simulation CT, with mean dose differences of less than 1% for target volume and normal organs in patients with prostate cancer.
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Affiliation(s)
- Sang Hoon Jung
- Department of Radiation Oncology, Samsung Medical Center, Seoul, Korea
| | - Jinsung Kim
- Department of Radiation Oncology, Yonsei Cancer Center, Yonsei University College of Medicine, Seoul, Korea
| | - Yoonsun Chung
- Department of Nuclear Engineering, Hanyang University, Seoul, Korea
| | - Bilgin Keserci
- Department of Radiology, School of Medical Sciences, Universiti Sains Malaysia, Kelantan, Malaysia.,Department of Radiology, Hospital Universiti Sains Malaysia (USM), Kelantan, Malaysia
| | - Hongryull Pyo
- Department of Radiation Oncology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Hee Chul Park
- Department of Radiation Oncology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Won Park
- Department of Radiation Oncology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
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Kim MJ, Lee SR, Song KH, Baek HM, Choe BY, Suh TS. Development of a hybrid magnetic resonance/computed tomography-compatible phantom for magnetic resonance guided radiotherapy. JOURNAL OF RADIATION RESEARCH 2020; 61:314-324. [PMID: 32030420 PMCID: PMC7246062 DOI: 10.1093/jrr/rrz094] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/10/2019] [Revised: 05/12/2019] [Accepted: 12/10/2019] [Indexed: 06/10/2023]
Abstract
The purpose of the present study was to develop a hybrid magnetic resonance/computed tomography (MR/CT)-compatible phantom and tissue-equivalent materials for each MR and CT image. Therefore, the essential requirements necessary for the development of a hybrid MR/CT-compatible phantom were determined and the development process is described. A total of 12 different tissue-equivalent materials for each MR and CT image were developed from chemical components. The uniformity of each sample was calculated. The developed phantom was designed to use 14 plugs that contained various tissue-equivalent materials. Measurement using the developed phantom was performed using a 3.0-T scanner with 32 channels and a Somatom Sensation 64. The maximum percentage difference of the signal intensity (SI) value on MR images after adding K2CO3 was 3.31%. Additionally, the uniformity of each tissue was evaluated by calculating the percent image uniformity (%PIU) of the MR image, which was 82.18 ±1.87% with 83% acceptance, and the average circular-shaped regions of interest (ROIs) on CT images for all samples were within ±5 Hounsfield units (HU). Also, dosimetric evaluation was performed. The percentage differences of each tissue-equivalent sample for average dose ranged from -0.76 to 0.21%. A hybrid MR/CT-compatible phantom for MR and CT was investigated as the first trial in this field of radiation oncology and medical physics.
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Affiliation(s)
- Min-Joo Kim
- Department of Radiation Oncology, Yonsei Cancer Center, Yonsei University College of Medicine, Yonsei University Health System, Seoul, 120-752, Korea
- Department of Biomedical Engineering, Research Institute of Biomedical Engineering, The Catholic University of Korea College of Medicine, Seoul, 137-701, Korea
| | - Seu-Ran Lee
- Department of Biomedical Engineering, Research Institute of Biomedical Engineering, The Catholic University of Korea College of Medicine, Seoul, 137-701, Korea
| | - Kyu-Ho Song
- Department of Radiology, Washington University, Saint Louis, Missouri, 63130, United States
| | - Hyeon-Man Baek
- Department of Health Sciences and Technology, GAIHST, Gachon University, Incheon, 21999, Korea
| | - Bo-Young Choe
- Department of Biomedical Engineering, Research Institute of Biomedical Engineering, The Catholic University of Korea College of Medicine, Seoul, 137-701, Korea
| | - Tae Suk Suh
- Department of Biomedical Engineering, Research Institute of Biomedical Engineering, The Catholic University of Korea College of Medicine, Seoul, 137-701, Korea
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Tie X, Lam SK, Zhang Y, Lee KH, Au KH, Cai J. Pseudo-CT generation from multi-parametric MRI using a novel multi-channel multi-path conditional generative adversarial network for nasopharyngeal carcinoma patients. Med Phys 2020; 47:1750-1762. [PMID: 32012292 DOI: 10.1002/mp.14062] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2020] [Revised: 01/08/2020] [Accepted: 01/27/2020] [Indexed: 12/17/2022] Open
Abstract
PURPOSE To develop and evaluate a novel method for pseudo-CT generation from multi-parametric MR images using multi-channel multi-path generative adversarial network (MCMP-GAN). METHODS Pre- and post-contrast T1-weighted (T1-w), T2-weighted (T2-w) MRI, and treatment planning CT images of 32 nasopharyngeal carcinoma (NPC) patients were employed to train a pixel-to-pixel MCMP-GAN. The network was developed based on a 5-level Residual U-Net (ResU-Net) with the channel-based independent feature extraction network to generate pseudo-CT images from multi-parametric MR images. The discriminator with five convolutional layers was added to distinguish between the real CT and pseudo-CT images, improving the nonlinearity and prediction accuracy of the model. Eightfold cross validation was implemented to validate the proposed MCMP-GAN. The pseudo-CT images were evaluated against the corresponding planning CT images based on mean absolute error (MAE), peak signal-to-noise ratio (PSNR), Dice similarity coefficient (DSC), and Structural similarity index (SSIM). Similar comparisons were also performed against the multi-channel single-path GAN (MCSP-GAN), the single-channel single-path GAN (SCSP-GAN). RESULTS It took approximately 20 h to train the MCMP-GAN model on a Quadro P6000, and less than 10 s to generate all pseudo-CT images for the subjects in the test set. The average head MAE between pseudo-CT and planning CT was 75.7 ± 14.6 Hounsfield Units (HU) for MCMP-GAN, significantly (P-values < 0.05) lower than that for MCSP-GAN (79.2 ± 13.0 HU) and SCSP-GAN (85.8 ± 14.3 HU). For bone only, the MCMP-GAN yielded a smaller mean MAE (194.6 ± 38.9 HU) than MCSP-GAN (203.7 ± 33.1 HU), SCSP-GAN (227.0 ± 36.7 HU). The average PSNR of MCMP-GAN (29.1 ± 1.6) was found to be higher than that of MCSP-GAN (28.8 ± 1.2) and SCSP-GAN (28.2 ± 1.3). In terms of metrics for image similarity, MCMP-GAN achieved the highest SSIM (0.92 ± 0.02) but did not show significantly improved bone DSC results in comparison with MCSP-GAN. CONCLUSIONS We developed a novel multi-channel GAN approach for generating pseudo-CT from multi-parametric MR images. Our preliminary results in NPC patients showed that the MCMP-GAN method performed apparently superior to the U-Net-GAN and SCSP-GAN, and slightly better than MCSP-GAN.
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Affiliation(s)
- Xin Tie
- The Hong Kong Polytechnic University, Hong Kong SAR, China.,Nanjing University, Nanjing, China
| | - Sai-Kit Lam
- The Hong Kong Polytechnic University, Hong Kong SAR, China
| | | | - Kar-Ho Lee
- Queen Elizabeth Hospital, Hong Kong SAR, China
| | | | - Jing Cai
- The Hong Kong Polytechnic University, Hong Kong SAR, China
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Sensitivity of radiomic features to inter-observer variability and image pre-processing in Apparent Diffusion Coefficient (ADC) maps of cervix cancer patients. Radiother Oncol 2020; 143:88-94. [DOI: 10.1016/j.radonc.2019.08.008] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2019] [Revised: 07/30/2019] [Accepted: 08/07/2019] [Indexed: 01/30/2023]
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Neppl S, Landry G, Kurz C, Hansen DC, Hoyle B, Stöcklein S, Seidensticker M, Weller J, Belka C, Parodi K, Kamp F. Evaluation of proton and photon dose distributions recalculated on 2D and 3D Unet-generated pseudoCTs from T1-weighted MR head scans. Acta Oncol 2019; 58:1429-1434. [PMID: 31271093 DOI: 10.1080/0284186x.2019.1630754] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Introduction: The recent developments of magnetic resonance (MR) based adaptive strategies for photon and, potentially for proton therapy, require a fast and reliable conversion of MR images to X-ray computed tomography (CT) values. CT values are needed for photon and proton dose calculation. The improvement of conversion results employing a 3D deep learning approach is evaluated. Material and methods: A database of 89 T1-weighted MR head scans with about 100 slices each, including rigidly registered CTs, was created. Twenty-eight validation patients were randomly sampled, and four patients were selected for application. The remaining patients were used to train a 2D and a 3D U-shaped convolutional neural network (Unet). A stack size of 32 slices was used for 3D training. For all application cases, volumetric modulated arc therapy photon and single-field uniform dose pencil-beam scanning proton plans at four different gantry angles were optimized for a generic target on the CT and recalculated on 2D and 3D Unet-based pseudoCTs. Mean (absolute) error (MAE/ME) and a gradient sharpness estimate were used to quantify the image quality. Three-dimensional gamma and dose difference analyses were performed for photon (gamma criteria: 1%, 1 mm) and proton dose distributions (gamma criteria: 2%, 2 mm). Range (80% fall off) differences for beam's eye view profiles were evaluated for protons. Results: Training 36 h for 1000 epochs in 3D (6 h for 200 epochs in 2D) yielded a maximum MAE of 147 HU (135 HU) for the application patients. Except for one patient gamma pass rates for photon and proton dose distributions were above 96% for both Unets. Slice discontinuities were reduced for 3D training at the cost of sharpness. Conclusions: Image analysis revealed a slight advantage of 2D Unets compared to 3D Unets. Similar dose calculation performance was reached for the 2D and 3D network.
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Affiliation(s)
- Sebastian Neppl
- Department of Radiation Oncology, University Hospital, LMU Munich, Munich, Germany
- Department of Medical Physics, Faculty of Physics, Ludwig-Maximilians-Universität München (LMU Munich), Garching bei München, Germany
| | - Guillaume Landry
- Department of Radiation Oncology, University Hospital, LMU Munich, Munich, Germany
- Department of Medical Physics, Faculty of Physics, Ludwig-Maximilians-Universität München (LMU Munich), Garching bei München, Germany
| | - Christopher Kurz
- Department of Radiation Oncology, University Hospital, LMU Munich, Munich, Germany
- Department of Medical Physics, Faculty of Physics, Ludwig-Maximilians-Universität München (LMU Munich), Garching bei München, Germany
| | - David C. Hansen
- Department of Medical Physics, Aarhus University Hospital, Aarhus, Denmark
| | - Ben Hoyle
- University Observatory, Faculty of Physics, Ludwig-Maximilians-Universität München (LMU Munich), Munich, Germany
| | - Sophia Stöcklein
- Department of Radiology, University Hospital, LMU Munich, Munich, Germany
| | - Max Seidensticker
- Department of Radiology, University Hospital, LMU Munich, Munich, Germany
| | - Jochen Weller
- University Observatory, Faculty of Physics, Ludwig-Maximilians-Universität München (LMU Munich), Munich, Germany
- Optical and Interpretative Astronomy, Max Planck Institute for Extraterrestrial Physics, Garching bei München, Germany
| | - Claus Belka
- Department of Radiation Oncology, University Hospital, LMU Munich, Munich, Germany
- German Cancer Consortium (DKTK), Partner site Munich, Munich, Germany
| | - Katia Parodi
- Department of Medical Physics, Faculty of Physics, Ludwig-Maximilians-Universität München (LMU Munich), Garching bei München, Germany
| | - Florian Kamp
- Department of Radiation Oncology, University Hospital, LMU Munich, Munich, Germany
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Shafai-Erfani G, Lei Y, Liu Y, Wang Y, Wang T, Zhong J, Liu T, McDonald M, Curran WJ, Zhou J, Shu HK, Yang X. MRI-Based Proton Treatment Planning for Base of Skull Tumors. Int J Part Ther 2019; 6:12-25. [PMID: 31998817 DOI: 10.14338/ijpt-19-00062.1] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2019] [Accepted: 08/15/2019] [Indexed: 01/22/2023] Open
Abstract
Purpose To introduce a novel, deep-learning method to generate synthetic computed tomography (SCT) scans for proton treatment planning and evaluate its efficacy. Materials and Methods 50 Patients with base of skull tumors were divided into 2 nonoverlapping training and study cohorts. Computed tomography and magnetic resonance imaging pairs for patients in the training cohort were used for training our novel 3-dimensional generative adversarial network (cycleGAN) algorithm. Upon completion of the training phase, SCT scans for patients in the study cohort were predicted based on their magnetic resonance images only. The SCT scans obtained were compared against the corresponding original planning computed tomography scans as the ground truth, and mean absolute errors (in Hounsfield units [HU]) and normalized cross-correlations were calculated. Proton plans of 45 Gy in 25 fractions with 2 beams per plan were generated for the patients based on their planning computed tomographies and recalculated on SCT scans. Dose-volume histogram endpoints were compared. A γ-index analysis along 3 cardinal planes intercepting at the isocenter was performed. Proton distal range along each beam was calculated. Results Image quality metrics show agreement between the generated SCT scans and the ground truth with mean absolute error values ranging from 38.65 to 65.12 HU and an average of 54.55 ± 6.81 HU and a normalized cross-correlation average of 0.96 ± 0.01. The dosimetric evaluation showed no statistically significant differences (p > 0.05) within planning target volumes for dose-volume histogram endpoints and other metrics studied, with the exception of the dose covering 95% of the target volume, with a relative difference of 0.47%. The γ-index analysis showed an average passing rate of 98% with a 10% threshold and 2% and 2-mm criteria. Proton ranges of 48 of 50 beams (96%) in this study were within clinical tolerance adopted by 4 institutions. Conclusions This study shows our method is capable of generating SCT scans with acceptable image quality, dose distribution agreement, and proton distal range compared with the ground truth. Our results set a promising approach for magnetic resonance imaging-based proton treatment planning.
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Affiliation(s)
- Ghazal Shafai-Erfani
- Department of Radiation Oncology and Winship Cancer Institute, Emory University, Atlanta, GA 30322, USA
| | - Yang Lei
- Department of Radiation Oncology and Winship Cancer Institute, Emory University, Atlanta, GA 30322, USA
| | - Yingzi Liu
- Department of Radiation Oncology and Winship Cancer Institute, Emory University, Atlanta, GA 30322, USA
| | - Yinan Wang
- Department of Radiation Oncology and Winship Cancer Institute, Emory University, Atlanta, GA 30322, USA
| | - Tonghe Wang
- Department of Radiation Oncology and Winship Cancer Institute, Emory University, Atlanta, GA 30322, USA
| | - Jim Zhong
- Department of Radiation Oncology and Winship Cancer Institute, Emory University, Atlanta, GA 30322, USA
| | - Tian Liu
- Department of Radiation Oncology and Winship Cancer Institute, Emory University, Atlanta, GA 30322, USA
| | - Mark McDonald
- Department of Radiation Oncology and Winship Cancer Institute, Emory University, Atlanta, GA 30322, USA
| | - Walter J Curran
- Department of Radiation Oncology and Winship Cancer Institute, Emory University, Atlanta, GA 30322, USA
| | - Jun Zhou
- Department of Radiation Oncology and Winship Cancer Institute, Emory University, Atlanta, GA 30322, USA
| | - Hui-Kuo Shu
- Department of Radiation Oncology and Winship Cancer Institute, Emory University, Atlanta, GA 30322, USA
| | - Xiaofeng Yang
- Department of Radiation Oncology and Winship Cancer Institute, Emory University, Atlanta, GA 30322, USA
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Fu J, Yang Y, Singhrao K, Ruan D, Chu FI, Low DA, Lewis JH. Deep learning approaches using 2D and 3D convolutional neural networks for generating male pelvic synthetic computed tomography from magnetic resonance imaging. Med Phys 2019; 46:3788-3798. [PMID: 31220353 DOI: 10.1002/mp.13672] [Citation(s) in RCA: 59] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2018] [Revised: 06/05/2019] [Accepted: 06/10/2019] [Indexed: 01/17/2023] Open
Abstract
PURPOSE The improved soft tissue contrast of magnetic resonance imaging (MRI) compared to computed tomography (CT) makes it a useful imaging modality for radiotherapy treatment planning. Even when MR images are acquired for treatment planning, the standard clinical practice currently also requires a CT for dose calculation and x-ray-based patient positioning. This increases workloads, introduces uncertainty due to the required inter-modality image registrations, and involves unnecessary irradiation. While it would be beneficial to use exclusively MR images, a method needs to be employed to estimate a synthetic CT (sCT) for generating electron density maps and patient positioning reference images. We investigated 2D and 3D convolutional neural networks (CNNs) to generate a male pelvic sCT using a T1-weighted MR image and compare their performance. METHODS A retrospective study was performed using CTs and T1-weighted MR images of 20 prostate cancer patients. CTs were deformably registered to MR images to create CT-MR pairs for training networks. The proposed 2D CNN, which contained 27 convolutional layers, was modified from the state-of-the-art 2D CNN to save computational memory and prepare for building the 3D CNN. The proposed 2D and 3D models were trained from scratch to map intensities of T1-weighted MR images to CT Hounsfield Unit (HU) values. Each sCT was generated in a fivefold cross-validation framework and compared with the corresponding deformed CT (dCT) using voxel-wise mean absolute error (MAE). The sCT geometric accuracy was evaluated by comparing bone regions, defined by thresholding at 150 HU in the dCTs and the sCTs, using dice similarity coefficient (DSC), recall, and precision. To evaluate sCT patient positioning accuracy, bone regions in dCTs and sCTs were rigidly registered to the corresponding cone-beam CTs. The resulting paired Euler transformation vectors were compared by calculating translation vector distances and absolute differences of Euler angles. Statistical tests were performed to evaluate the differences among the proposed models and Han's model. RESULTS Generating a pelvic sCT required approximately 5.5 s using the proposed models. The average MAEs within the body contour were 40.5 ± 5.4 HU (mean ± SD) and 37.6 ± 5.1 HU for the 2D and 3D CNNs, respectively. The average DSC, recall, and precision for the bone region (thresholding the CT at 150 HU) were 0.81 ± 0.04, 0.85 ± 0.04, and 0.77 ± 0.09 for the 2D CNN, and 0.82 ± 0.04, 0.84 ± 0.04, and 0.80 ± 0.08 for the 3D CNN, respectively. For both models, mean translation vector distances are less than 0.6 mm with mean absolute differences of Euler angles less than 0.5°. CONCLUSIONS The 2D and 3D CNNs generated accurate pelvic sCTs for the 20 patients using T1-weighted MR images. Statistical tests indicated that the proposed 3D model was able to generate sCTs with smaller MAE and higher bone region precision compared to 2D models. Results of patient alignment tests suggested that sCTs generated by the proposed CNNs can provide accurate patient positioning. The accuracy of the dose calculation using generated sCTs will be tested and compared for the proposed models in the future.
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Affiliation(s)
- Jie Fu
- David Geffen School of Medicine, University of California, Los Angeles, 10833 Le Conte Ave, Los Angeles, 90095, CA, USA.,Department of Radiation Oncology, University of California, Los Angeles, 200 Suite B265, Medical Plaza Driveway, Los Angeles, 90095, CA, USA
| | - Yingli Yang
- Department of Radiation Oncology, University of California, Los Angeles, 200 Suite B265, Medical Plaza Driveway, Los Angeles, 90095, CA, USA
| | - Kamal Singhrao
- David Geffen School of Medicine, University of California, Los Angeles, 10833 Le Conte Ave, Los Angeles, 90095, CA, USA.,Department of Radiation Oncology, University of California, Los Angeles, 200 Suite B265, Medical Plaza Driveway, Los Angeles, 90095, CA, USA
| | - Dan Ruan
- Department of Radiation Oncology, University of California, Los Angeles, 200 Suite B265, Medical Plaza Driveway, Los Angeles, 90095, CA, USA
| | - Fang-I Chu
- Department of Radiation Oncology, University of California, Los Angeles, 200 Suite B265, Medical Plaza Driveway, Los Angeles, 90095, CA, USA
| | - Daniel A Low
- Department of Radiation Oncology, University of California, Los Angeles, 200 Suite B265, Medical Plaza Driveway, Los Angeles, 90095, CA, USA
| | - John H Lewis
- Department of Radiation Oncology, University of California, Los Angeles, 200 Suite B265, Medical Plaza Driveway, Los Angeles, 90095, CA, USA
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[Radiotherapy treatment planning of prostate cancer using magnetic resonance imaging]. Cancer Radiother 2019; 23:281-289. [PMID: 31151816 DOI: 10.1016/j.canrad.2018.09.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2018] [Revised: 09/10/2018] [Accepted: 09/27/2018] [Indexed: 11/21/2022]
Abstract
PURPOSE Magnetic resonance imaging (MRI) plays an increasing role in radiotherapy dose planning. Indeed, MRI offers superior soft tissue contrast compared to computerized tomography (CT) and therefore could provide a better delineation of target volumes and organs at risk than CT for radiotherapy. Furthermore, an MRI-only radiotherapy workflow would suppress registration errors inherent to the registration of MRI with CT. However, the estimation of the electronic density of tissues using MRI images is still a challenging issue. The purpose of this work was to design and evaluate a pseudo-CT generation method for prostate cancer treatments. MATERIALS AND METHODS A pseudo-CT was generated for ten prostate cancer patients using an elastic deformation based method. For each patient, dose delivered to the patient was calculated using both the planning CT and the pseudo-CT. Dose differences between CT and pseudo-CT were investigated. RESULTS Mean dose relative difference in the planning target volume is 0.9% on average and ranges from 0.1% to 1.7%. In organs at risks, this value is 1.8%, 0.8%, 0.8% and 1% on average in the rectum, the right and left femoral heads, and the bladder respectively. CONCLUSION The dose calculated using the pseudo-CT is very close to the dose calculated using the CT for both organs at risk and PTV. These results confirm that pseudo-CT images generated using the proposed method could be used to calculate radiotherapy treatment doses on MRI images.
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DC2Anet: Generating Lumbar Spine MR Images from CT Scan Data Based on Semi-Supervised Learning. APPLIED SCIENCES-BASEL 2019. [DOI: 10.3390/app9122521] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Magnetic resonance imaging (MRI) plays a significant role in the diagnosis of lumbar disc disease. However, the use of MRI is limited because of its high cost and significant operating and processing time. More importantly, MRI is contraindicated for some patients with claustrophobia or cardiac pacemakers due to the possibility of injury. In contrast, computed tomography (CT) scans are much less expensive, are faster, and do not face the same limitations. In this paper, we propose a method for estimating lumbar spine MR images based on CT images using a novel objective function and a dual cycle-consistent adversarial network (DC 2 Anet) with semi-supervised learning. The objective function includes six independent loss terms to balance quantitative and qualitative losses, enabling the generation of a realistic and accurate synthetic MR image. DC 2 Anet is also capable of semi-supervised learning, and the network is general enough for supervised or unsupervised setups. Experimental results prove that the method is accurate, being able to construct MR images that closely approximate reference MR images, while also outperforming four other state-of-the-art methods.
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Ranta I, Kemppainen R, Keyriläinen J, Suilamo S, Heikkinen S, Kapanen M, Saunavaara J. Quality assurance measurements of geometric accuracy for magnetic resonance imaging-based radiotherapy treatment planning. Phys Med 2019; 62:47-52. [PMID: 31153398 DOI: 10.1016/j.ejmp.2019.04.022] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/15/2019] [Revised: 03/29/2019] [Accepted: 04/24/2019] [Indexed: 10/26/2022] Open
Abstract
BACKGROUND Using magnetic resonance imaging (MRI) as the only imaging method for radiotherapy treatment planning (RTP) is becoming more common as MRI-only RTP solutions have evolved. The geometric accuracy of MR images is an essential factor of image quality when determining the suitability of MRI for RTP. The need is therefore clear for clinically feasible quality assurance (QA) methods for the geometric accuracy measurement. MATERIALS AND METHODS This work evaluates long-term stability of geometric accuracy and the validity of a 2D geometric accuracy QA method compared to a prototype 3D method and analysis software in routine QA. The long-term follow-up measurements were conducted on one of the 1.5 T scanners over a period of 19 months using both methods. Inter-scanner variability of geometric distortions was also evaluated in three 1.5 T and three 3 T MRI scanners from a single vendor by using the prototype 3D QA method. RESULTS The geometric accuracy of the magnetic resonance for radiotherapy (MR-RT) platform remained stable within 2 mm at distances of <250 mm from isocenter. All scanners achieved good geometric accuracy with mean geometric distortions of <1 mm at <150 mm and <2 mm at <250 mm from the isocenter. Both measurement methods provided relevant information about geometric distortions. CONCLUSIONS Geometric distortions are often considered a limitation of MRI-only RTP. Results indicate that geometric accuracy of modern scanners remain within acceptable limits by default even after many years of clinical use based on the 3D QA evaluation.
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Affiliation(s)
- Iiro Ranta
- Department of Physics and Astronomy, University of Turku, Vesilinnantie 5, FI-20014 Turku, Finland; Department of Medical Physics, Turku University Hospital, Hämeentie 11, P.O. Box 52, FI-20521 Turku, Finland; Department of Oncology and Radiotherapy, Turku University Hospital, Hämeentie 11, P.O. Box 52, FI-20521 Turku, Finland.
| | | | - Jani Keyriläinen
- Department of Physics and Astronomy, University of Turku, Vesilinnantie 5, FI-20014 Turku, Finland; Department of Medical Physics, Turku University Hospital, Hämeentie 11, P.O. Box 52, FI-20521 Turku, Finland; Department of Oncology and Radiotherapy, Turku University Hospital, Hämeentie 11, P.O. Box 52, FI-20521 Turku, Finland
| | - Sami Suilamo
- Department of Medical Physics, Turku University Hospital, Hämeentie 11, P.O. Box 52, FI-20521 Turku, Finland; Department of Oncology and Radiotherapy, Turku University Hospital, Hämeentie 11, P.O. Box 52, FI-20521 Turku, Finland
| | - Samuli Heikkinen
- Department of Medical Physics, Turku University Hospital, Hämeentie 11, P.O. Box 52, FI-20521 Turku, Finland
| | - Mika Kapanen
- Department of Medical Physics, Medical Imaging Center, Tampere University Hospital, P.O. Box 2000, FI-33521 Tampere, Finland; Department of Oncology, Unit of Radiotherapy, Tampere University Hospital, P.O. Box 2000, FI-33521 Tampere, Finland
| | - Jani Saunavaara
- Department of Medical Physics, Turku University Hospital, Hämeentie 11, P.O. Box 52, FI-20521 Turku, Finland
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Shafai-Erfani G, Wang T, Lei Y, Tian S, Patel P, Jani AB, Curran WJ, Liu T, Yang X. Dose evaluation of MRI-based synthetic CT generated using a machine learning method for prostate cancer radiotherapy. Med Dosim 2019; 44:e64-e70. [PMID: 30713000 DOI: 10.1016/j.meddos.2019.01.002] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2018] [Revised: 01/07/2019] [Accepted: 01/16/2019] [Indexed: 11/24/2022]
Abstract
Magnetic resonance imaging (MRI)-only radiotherapy treatment planning is attractive since MRI provides superior soft tissue contrast over computed tomographies (CTs), without the ionizing radiation exposure. However, it requires the generation of a synthetic CT (SCT) from MRIs for patient setup and dose calculation. In this study, we aim to investigate the accuracy of dose calculation in prostate cancer radiotherapy using SCTs generated from MRIs using our learning-based method. We retrospectively investigated a total of 17 treatment plans from 10 patients, each having both planning CTs (pCT) and MRIs acquired before treatment. The SCT was registered to the pCT for generating SCT-based treatment plans. The original pCT-based plans served as ground truth. Clinically-relevant dose volume histogram (DVH) metrics were extracted from both ground truth and SCT-based plans for comparison and evaluation. Gamma analysis was performed for the comparison of absorbed dose distributions between SCT- and pCT-based plans of each patient. Gamma analysis of dose distribution on pCT and SCT within 1%/1 mm at 10% dose threshold showed greater than 99% pass rate. The average differences in DVH metrics for planning target volumes (PTVs) were less than 1%, and similar metrics for organs at risk (OAR) were not statistically different. The SCT images created from MR images using our proposed machine learning method are accurate for dose calculation in prostate cancer radiation treatment planning. This study also demonstrates the great potential for MRI to completely replace CT scans in the process of simulation and treatment planning. However, MR images are needed to further analyze geometric distortion effects. Digitally reconstructed radiograph (DRR) can be generated within our method, and their accuracy in patient setup needs further analysis.
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Affiliation(s)
- Ghazal Shafai-Erfani
- Department of Radiation Oncology and Winship Cancer Institute, Emory University, Atlanta, GA 30322, USA
| | - Tonghe Wang
- Department of Radiation Oncology and Winship Cancer Institute, Emory University, Atlanta, GA 30322, USA
| | - Yang Lei
- Department of Radiation Oncology and Winship Cancer Institute, Emory University, Atlanta, GA 30322, USA
| | - Sibo Tian
- Department of Radiation Oncology and Winship Cancer Institute, Emory University, Atlanta, GA 30322, USA
| | - Pretesh Patel
- Department of Radiation Oncology and Winship Cancer Institute, Emory University, Atlanta, GA 30322, USA
| | - Ashesh B Jani
- Department of Radiation Oncology and Winship Cancer Institute, Emory University, Atlanta, GA 30322, USA
| | - Walter J Curran
- Department of Radiation Oncology and Winship Cancer Institute, Emory University, Atlanta, GA 30322, USA
| | - Tian Liu
- Department of Radiation Oncology and Winship Cancer Institute, Emory University, Atlanta, GA 30322, USA
| | - Xiaofeng Yang
- Department of Radiation Oncology and Winship Cancer Institute, Emory University, Atlanta, GA 30322, USA.
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Zou W, Dong L, Kevin Teo BK. Current State of Image Guidance in Radiation Oncology: Implications for PTV Margin Expansion and Adaptive Therapy. Semin Radiat Oncol 2018; 28:238-247. [PMID: 29933883 DOI: 10.1016/j.semradonc.2018.02.008] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Image guidance technology has evolved and seen widespread application in the past several decades. Advancements in the diagnostic imaging field have found new applications in radiation oncology and promoted the development of therapeutic devices with advanced imaging capabilities. A recent example is the development of linear accelerators that offer magnetic resonance imaging for real-time imaging and online adaptive planning. Volumetric imaging, in particular, offers more precise localization of soft tissue targets and critical organs which reduces setup uncertainty and permit the use of smaller setup margins. We present a review of the status of current imaging modalities available for radiation oncology and its impact on target margins and use for adaptive therapy.
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Affiliation(s)
- Wei Zou
- Department of Radiation Oncology, University of Pennsylvania, Philadelphia, PA.
| | - Lei Dong
- Department of Radiation Oncology, University of Pennsylvania, Philadelphia, PA
| | - Boon-Keng Kevin Teo
- Department of Radiation Oncology, University of Pennsylvania, Philadelphia, PA
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Chen S, Qin A, Zhou D, Yan D. Technical Note: U-net-generated synthetic CT images for magnetic resonance imaging-only prostate intensity-modulated radiation therapy treatment planning. Med Phys 2018; 45:5659-5665. [PMID: 30341917 DOI: 10.1002/mp.13247] [Citation(s) in RCA: 65] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2018] [Revised: 08/30/2018] [Accepted: 10/09/2018] [Indexed: 11/07/2022] Open
Abstract
PURPOSE Clinical implementation of magnetic resonance imaging (MRI)-only radiotherapy requires a method to derive synthetic CT image (S-CT) for dose calculation. This study investigated the feasibility of building a deep convolutional neural network for MRI-based S-CT generation and evaluated the dosimetric accuracy on prostate IMRT planning. METHODS A paired CT and T2-weighted MR images were acquired from each of 51 prostate cancer patients. Fifteen pairs were randomly chosen as tested set and the remaining 36 pairs as training set. The training subjects were augmented by applying artificial deformations and feed to a two-dimensional U-net which contains 23 convolutional layers and 25.29 million trainable parameters. The U-net represents a nonlinear function with input an MR slice and output the corresponding S-CT slice. The mean absolute error (MAE) of Hounsfield unit (HU) between the true CT and S-CT images was used to evaluate the HU estimation accuracy. IMRT plans with dose 79.2 Gy prescribed to the PTV were applied using the true CT images. The true CT images then were replaced by the S-CT images and the dose matrices were recalculated on the same plan and compared to the one obtained from the true CT using gamma index analysis and absolute point dose discrepancy. RESULTS The U-net was trained from scratch in 58.67 h using a GP100-GPU. The computation time for generating a new S-CT volume image was 3.84-7.65 s. Within body, the (mean ± SD) of MAE was (29.96 ± 4.87) HU. The 1%/1 mm and 2%/2 mm gamma pass rates were over 98.03% and 99.36% respectively. The DVH parameters discrepancy was less than 0.87% and the maximum point dose discrepancy within PTV was less than 1.01% respect to the prescription. CONCLUSION The U-net can generate S-CT images from conventional MR image within seconds with high dosimetric accuracy for prostate IMRT plan.
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Affiliation(s)
- Shupeng Chen
- Department of Radiation Oncology, William Beaumont Hospital, 3601 W. 13 Mile Rd, Royal Oak, MI, 48073, USA
| | - An Qin
- Department of Radiation Oncology, William Beaumont Hospital, 3601 W. 13 Mile Rd, Royal Oak, MI, 48073, USA
| | - Dingyi Zhou
- Department of Oncology, Renmin Hospital of Wuhan University, Wuhan, Hubei, China
| | - Di Yan
- Department of Radiation Oncology, William Beaumont Hospital, 3601 W. 13 Mile Rd, Royal Oak, MI, 48073, USA
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Largent A, Barateau A, Nunes JC, Lafond C, Greer PB, Dowling JA, Saint-Jalmes H, Acosta O, de Crevoisier R. Pseudo-CT Generation for MRI-Only Radiation Therapy Treatment Planning: Comparison Among Patch-Based, Atlas-Based, and Bulk Density Methods. Int J Radiat Oncol Biol Phys 2018; 103:479-490. [PMID: 30336265 DOI: 10.1016/j.ijrobp.2018.10.002] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2018] [Revised: 08/15/2018] [Accepted: 10/01/2018] [Indexed: 12/25/2022]
Abstract
PURPOSE Methods have been recently developed to generate pseudo-computed tomography (pCT) for dose calculation in magnetic resonance imaging (MRI)-only radiation therapy. This study aimed to propose an original nonlocal mean patch-based method (PBM) and to compare this PBM to an atlas-based method (ABM) and to a bulk density method (BDM) for prostate MRI-only radiation therapy. MATERIALS AND METHODS Thirty-nine patients received a volumetric modulated arc therapy for prostate cancer. In addition to the planning computed tomography (CT) scans, T2-weighted MRI scans were acquired. pCTs were generated from MRIs using 3 methods: an original nonlocal mean PBM, ABM, and BDM. The PBM was performed using feature extraction and approximate nearest neighbor search in a training cohort. The PBM accuracy was evaluated in a validation cohort by using imaging and dosimetric endpoints. Imaging endpoints included mean absolute error and mean error between Hounsfield units of the pCT and the reference CT (CTref). Dosimetric endpoints were based on dose-volume histograms calculated from the CTref and the pCTs for various volumes of interest and on 3-dimensional gamma analyses. The PBM uncertainties were compared with those of the ABM and BDM. RESULTS The mean absolute error and mean error obtained from the PBM were 41.1 and -1.1 Hounsfield units. The PBM dose-volume histogram differences were 0.7% for prostate planning target volume V95%, 0.5% for rectum V70Gy, and 0.2% for bladder V50Gy. Compared with ABM and BDM, PBM provided significantly lower dose uncertainties for the prostate planning target volume (70-78 Gy), the rectum (8.5-29 Gy, 40-48 Gy, and 61-73 Gy), and the bladder (12-78 Gy). The PBM mean gamma pass rate (99.5%) was significantly higher than that of ABM (94.9%) or BDM (96.1%). CONCLUSIONS The proposed PBM provides low uncertainties with dose planned on CTref. These uncertainties were smaller than those of ABM and BDM and are unlikely to be clinically significant.
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Affiliation(s)
- Axel Largent
- Univ Rennes, CLCC Eugène Marquis, INSERM, LTSI - UMR 1099, F-35000 Rennes, France.
| | - Anaïs Barateau
- Univ Rennes, CLCC Eugène Marquis, INSERM, LTSI - UMR 1099, F-35000 Rennes, France
| | - Jean-Claude Nunes
- Univ Rennes, CLCC Eugène Marquis, INSERM, LTSI - UMR 1099, F-35000 Rennes, France
| | - Caroline Lafond
- Univ Rennes, CLCC Eugène Marquis, INSERM, LTSI - UMR 1099, F-35000 Rennes, France
| | - Peter B Greer
- School of Mathematical and Physical Sciences, University of Newcastle, Newcastle, Australia
| | - Jason A Dowling
- CSIRO Australian e-Health Research Centre, Herston, Queensland, Australia
| | - Hervé Saint-Jalmes
- Univ Rennes, CLCC Eugène Marquis, INSERM, LTSI - UMR 1099, F-35000 Rennes, France
| | - Oscar Acosta
- Univ Rennes, CLCC Eugène Marquis, INSERM, LTSI - UMR 1099, F-35000 Rennes, France
| | - Renaud de Crevoisier
- Univ Rennes, CLCC Eugène Marquis, INSERM, LTSI - UMR 1099, F-35000 Rennes, France
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Lei Y, Jeong JJ, Wang T, Shu HK, Patel P, Tian S, Liu T, Shim H, Mao H, Jani AB, Curran WJ, Yang X. MRI-based pseudo CT synthesis using anatomical signature and alternating random forest with iterative refinement model. J Med Imaging (Bellingham) 2018; 5:043504. [PMID: 30840748 PMCID: PMC6280993 DOI: 10.1117/1.jmi.5.4.043504] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2018] [Accepted: 11/12/2018] [Indexed: 12/20/2022] Open
Abstract
We develop a learning-based method to generate patient-specific pseudo computed tomography (CT) from routinely acquired magnetic resonance imaging (MRI) for potential MRI-based radiotherapy treatment planning. The proposed pseudo CT (PCT) synthesis method consists of a training stage and a synthesizing stage. During the training stage, patch-based features are extracted from MRIs. Using a feature selection, the most informative features are identified as an anatomical signature to train a sequence of alternating random forests based on an iterative refinement model. During the synthesizing stage, we feed the anatomical signatures extracted from an MRI into the sequence of well-trained forests for a PCT synthesis. Our PCT was compared with original CT (ground truth) to quantitatively assess the synthesis accuracy. The mean absolute error, peak signal-to-noise ratio, and normalized cross-correlation indices were 60.87 ± 15.10 HU , 24.63 ± 1.73 dB , and 0.954 ± 0.013 for 14 patients' brain data and 29.86 ± 10.4 HU , 34.18 ± 3.31 dB , and 0.980 ± 0.025 for 12 patients' pelvic data, respectively. We have investigated a learning-based approach to synthesize CTs from routine MRIs and demonstrated its feasibility and reliability. The proposed PCT synthesis technique can be a useful tool for MRI-based radiation treatment planning.
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Affiliation(s)
- Yang Lei
- Emory University, Winship Cancer Institute, Department of Radiation Oncology, Atlanta, Georgia, United States
| | - Jiwoong Jason Jeong
- Emory University, Winship Cancer Institute, Department of Radiation Oncology, Atlanta, Georgia, United States
| | - Tonghe Wang
- Emory University, Winship Cancer Institute, Department of Radiation Oncology, Atlanta, Georgia, United States
| | - Hui-Kuo Shu
- Emory University, Winship Cancer Institute, Department of Radiation Oncology, Atlanta, Georgia, United States
| | - Pretesh Patel
- Emory University, Winship Cancer Institute, Department of Radiation Oncology, Atlanta, Georgia, United States
| | - Sibo Tian
- Emory University, Winship Cancer Institute, Department of Radiation Oncology, Atlanta, Georgia, United States
| | - Tian Liu
- Emory University, Winship Cancer Institute, Department of Radiation Oncology, Atlanta, Georgia, United States
| | - Hyunsuk Shim
- Emory University, Winship Cancer Institute, Department of Radiation Oncology, Atlanta, Georgia, United States
- Emory University, Winship Cancer Institute, Department of Radiology and Imaging Sciences, Atlanta, Georgia, United States
| | - Hui Mao
- Emory University, Winship Cancer Institute, Department of Radiology and Imaging Sciences, Atlanta, Georgia, United States
| | - Ashesh B. Jani
- Emory University, Winship Cancer Institute, Department of Radiation Oncology, Atlanta, Georgia, United States
| | - Walter J. Curran
- Emory University, Winship Cancer Institute, Department of Radiation Oncology, Atlanta, Georgia, United States
| | - Xiaofeng Yang
- Emory University, Winship Cancer Institute, Department of Radiation Oncology, Atlanta, Georgia, United States
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Morris ED, Price RG, Kim J, Schultz L, Siddiqui MS, Chetty I, Glide-Hurst C. Using synthetic CT for partial brain radiation therapy: Impact on image guidance. Pract Radiat Oncol 2018; 8:342-350. [PMID: 29861348 PMCID: PMC6123249 DOI: 10.1016/j.prro.2018.04.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Revised: 02/22/2018] [Accepted: 04/02/2018] [Indexed: 02/08/2023]
Abstract
PURPOSE Recent advancements in synthetic computed tomography (synCT) from magnetic resonance (MR) imaging data have made MRI-only treatment planning feasible in the brain, although synCT performance for image guided radiation therapy (IGRT) is not well understood. This work compares geometric equivalence of digitally reconstructed radiographs (DRRs) from CTs and synCTs for brain cancer patients and quantifies performance for partial brain IGRT. METHODS AND MATERIALS Ten brain cancer patients (12 lesions, 7 postsurgical) underwent MR-SIM and CT-SIM. SynCTs were generated by combining ultra-short echo time, T1, T2, and fluid attenuation inversion recovery datasets using voxel-based weighted summation. SynCT and CT DRRs were compared using patient-specific thresholding and assessed via overlap index, Dice similarity coefficient, and Jaccard index. Planar IGRT images for 22 fractions were evaluated to quantify differences between CT-generated DRRs and synCT-generated DRRs in 6 quadrants. Previously validated software was implemented to perform 2-dimensional (2D)-2D rigid registrations using normalized mutual information. Absolute (planar image/DRR registration) and relative (differences between synCT and CT DRR registrations) shifts were calculated for each axis and 3-dimensional vector difference. A total of 1490 rigid registrations were assessed. RESULTS DRR agreements in anteroposterior and lateral views for overlap index, Dice similarity coefficient, and Jaccard index were >0.95. Normalized mutual information results were equivalent in 75% of quadrants. Rotational registration results were negligible (<0.07°). Statistically significant differences between CT and synCT registrations were observed in 9/18 matched quadrants/axes (P < .05). The population average absolute shifts were 0.77 ± 0.58 and 0.76 ± 0.59 mm for CT and synCT, respectively, for all axes/quadrants. Three-dimensional vectors were <2 mm in 77.7 ± 10.8% and 76.5 ± 7.2% of CT and synCT registrations, respectively. SynCT DRRs were sensitive in postsurgical cases (vector displacements >2 mm in affected quadrants). CONCLUSIONS DRR synCT geometry was robust. Although statistically significant differences were observed between CT and synCT registrations, results were not clinically significant. Future work will address synCT generation in postsurgical settings.
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Affiliation(s)
- Eric D Morris
- Department of Radiation Oncology, Henry Ford Health System, Detroit, Michigan; Department of Radiation Oncology, Wayne State University School of Medicine, Detroit, Michigan
| | - Ryan G Price
- Department of Radiation Oncology, University of Washington, Seattle, Washington
| | - Joshua Kim
- Department of Radiation Oncology, Henry Ford Health System, Detroit, Michigan
| | - Lonni Schultz
- Department of Public Health Sciences, Henry Ford Health System, Detroit, Michigan
| | - M Salim Siddiqui
- Department of Radiation Oncology, Henry Ford Health System, Detroit, Michigan
| | - Indrin Chetty
- Department of Radiation Oncology, Henry Ford Health System, Detroit, Michigan; Department of Radiation Oncology, Wayne State University School of Medicine, Detroit, Michigan
| | - Carri Glide-Hurst
- Department of Radiation Oncology, Henry Ford Health System, Detroit, Michigan; Department of Radiation Oncology, Wayne State University School of Medicine, Detroit, Michigan.
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Lei Y, Shu HK, Tian S, Jeong JJ, Liu T, Shim H, Mao H, Wang T, Jani AB, Curran WJ, Yang X. Magnetic resonance imaging-based pseudo computed tomography using anatomic signature and joint dictionary learning. J Med Imaging (Bellingham) 2018; 5:034001. [PMID: 30155512 DOI: 10.1117/1.jmi.5.3.034001] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2018] [Accepted: 08/06/2018] [Indexed: 12/30/2022] Open
Abstract
Magnetic resonance imaging (MRI) provides a number of advantages over computed tomography (CT) for radiation therapy treatment planning; however, MRI lacks the key electron density information necessary for accurate dose calculation. We propose a dictionary-learning-based method to derive electron density information from MRIs. Specifically, we first partition a given MR image into a set of patches, for which we used a joint dictionary learning method to directly predict a CT patch as a structured output. Then a feature selection method is used to ensure prediction robustness. Finally, we combine all the predicted CT patches to obtain the final prediction for the given MR image. This prediction technique was validated for a clinical application using 14 patients with brain MR and CT images. The peak signal-to-noise ratio (PSNR), mean absolute error (MAE), normalized cross-correlation (NCC) indices and similarity index (SI) for air, soft-tissue and bone region were used to quantify the prediction accuracy. The mean ± std of PSNR, MAE, and NCC were: 22.4±1.9 dB , 82.6±26.1 HU, and 0.91±0.03 for the 14 patients. The SIs for air, soft-tissue, and bone regions are 0.98±0.01 , 0.88±0.03 , and 0.69±0.08 . These indices demonstrate the CT prediction accuracy of the proposed learning-based method. This CT image prediction technique could be used as a tool for MRI-based radiation treatment planning, or for PET attenuation correction in a PET/MRI scanner.
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Affiliation(s)
- Yang Lei
- Emory University, Winship Cancer Institute, Department of Radiation Oncology, Atlanta, Georgia, United States
| | - Hui-Kuo Shu
- Emory University, Winship Cancer Institute, Department of Radiation Oncology, Atlanta, Georgia, United States
| | - Sibo Tian
- Emory University, Winship Cancer Institute, Department of Radiation Oncology, Atlanta, Georgia, United States
| | - Jiwoong Jason Jeong
- Emory University, Winship Cancer Institute, Department of Radiation Oncology, Atlanta, Georgia, United States
| | - Tian Liu
- Emory University, Winship Cancer Institute, Department of Radiation Oncology, Atlanta, Georgia, United States
| | - Hyunsuk Shim
- Emory University, Winship Cancer Institute, Department of Radiation Oncology, Atlanta, Georgia, United States.,Emory University, Winship Cancer Institute, Department of Radiology and Imaging Sciences, Atlanta, Georgia, United States
| | - Hui Mao
- Emory University, Winship Cancer Institute, Department of Radiology and Imaging Sciences, Atlanta, Georgia, United States
| | - Tonghe Wang
- Emory University, Winship Cancer Institute, Department of Radiation Oncology, Atlanta, Georgia, United States
| | - Ashesh B Jani
- Emory University, Winship Cancer Institute, Department of Radiation Oncology, Atlanta, Georgia, United States
| | - Walter J Curran
- Emory University, Winship Cancer Institute, Department of Radiation Oncology, Atlanta, Georgia, United States
| | - Xiaofeng Yang
- Emory University, Winship Cancer Institute, Department of Radiation Oncology, Atlanta, Georgia, United States
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Hsu SH, Zawisza I, O’Grady K, Peng Q, Tomé WA. Towards abdominal MRI-based treatment planning using population-based Hounsfield units for bulk density assignment. ACTA ACUST UNITED AC 2018; 63:155003. [DOI: 10.1088/1361-6560/aacfb1] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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37
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Tenhunen M, Korhonen J, Kapanen M, Seppälä T, Koivula L, Collan J, Saarilahti K, Visapää H. MRI-only based radiation therapy of prostate cancer: workflow and early clinical experience. Acta Oncol 2018; 57:902-907. [PMID: 29488426 DOI: 10.1080/0284186x.2018.1445284] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
BACKGROUND Magnetic resonance imaging (MRI) is the most comprehensive imaging modality for radiation therapy (RT) target delineation of most soft tissue tumors including prostate cancer. We have earlier presented step by step the MRI-only based workflow for RT planning and image guidance for localized prostate cancer. In this study we present early clinical experiences of MRI-only based planning. MATERIAL AND METHODS We have analyzed the technical planning workflow of the first 200 patients having received MRI-only planned radiation therapy for localized prostate cancer in Helsinki University Hospital Cancer center. Early prostate specific antigen (PSA) results were analyzed from n = 125 MRI-only patients (n = 25 RT only, n = 100 hormone treatment + RT) and were compared with the corresponding computed tomography (CT) planned patient group. RESULTS Technically the MRI-only planning procedure was suitable for 92% of the patients, only 8% of the patients required supplemental CT imaging. Early PSA response in the MRI-only planned group showed similar treatment results compared with the CT planned group and with an equal toxicity level. CONCLUSION Based on this retrospective study, MRI-only planning procedure is an effective and safe way to perform RT for localized prostate cancer. It is suitable for the majority of the patients.
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Affiliation(s)
- Mikko Tenhunen
- Cancer Centre, Helsinki University Hospital, Helsinki, Finland
| | - Juha Korhonen
- Cancer Centre, Helsinki University Hospital, Helsinki, Finland
| | - Mika Kapanen
- Cancer Centre, Helsinki University Hospital, Helsinki, Finland
| | - Tiina Seppälä
- Cancer Centre, Helsinki University Hospital, Helsinki, Finland
| | - Lauri Koivula
- Cancer Centre, Helsinki University Hospital, Helsinki, Finland
| | - Juhani Collan
- Cancer Centre, Helsinki University Hospital, Helsinki, Finland
| | | | - Harri Visapää
- Cancer Centre, Helsinki University Hospital, Helsinki, Finland
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Usui K, Sasai K, Ogawa K. Effect of region extraction and assigned mass-density values on the accuracy of dose calculation with magnetic resonance-based volumetric arc therapy planning. Radiol Phys Technol 2018. [PMID: 29542016 DOI: 10.1007/s12194-018-0452-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
This study aimed to verify the validity of generating treatment plans for volumetric arc therapy (VMAT) for prostate cancer using magnetic resonance (MR) imaging with a dose calculation algorithm in Acuros XB (Eclipse version 13.6; Varian Medical Systems, Palo Alto, CA, USA) based on deterministically solving the linear Boltzmann transport equations. Four different classes were applied to prostate MR images: MRW (all water equivalent); MRW+B (water and bone); MRS+B (soft tissue and bone); and MRS+B+G (soft tissue, bone, and rectal gas). Each of these regions was assigned a mass density for calculating doses. The assigned mass-density values were then altered in three ways. Using initial planning and optimization parameters, MR-based VMAT plans were generated and compared with corresponding forward-calculated computed tomography-based plans for doses to the target volumes and organs at risk using dose-volume histograms and γ analyses. In the MRW plans, the mean doses for TVs were overestimated by approximately 1.3%. The MRW+B plans revealed reduced differences within 0.5%. Further segmentation (MRS+B) did not result in substantial improvement. Dose deviations affected by the changes in the mass densities assigned to soft tissue were as small as approximately 1.0%, whereas larger deviations were revealed in bone and rectal gas, especially those with > 5% error. Assignment of accurate mass-density values acquired from MR images is needed for MR-based radiation treatment planning. Multiple MR sequences should be acquired for segmentation and mass-density conversion purposes. Segmented MR-based VMAT planning is feasible with a density assignment method using Acuros XB.
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Affiliation(s)
- Keisuke Usui
- Department of Radiation Oncology, Juntendo University, 2-1-1 Hongo, Bunkyo-ku, Tokyo, 113-8421, Japan.
| | - Keisuke Sasai
- Department of Radiation Oncology, Juntendo University, 2-1-1 Hongo, Bunkyo-ku, Tokyo, 113-8421, Japan
| | - Koichi Ogawa
- Faculty of Science and Engineering, Hosei University, 3-7-3 Kajino, Koganei, Tokyo, 184-8584, Japan
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Abstract
Over the past decade, the application of magnetic resonance imaging (MRI) has increased, and there is growing evidence to suggest that improvements in the accuracy of target delineation in MRI-guided radiation therapy may improve clinical outcomes in a variety of cancer types. However, some considerations should be recognized including patient motion during image acquisition and geometric accuracy of images. Moreover, MR-compatible immobilization devices need to be used when acquiring images in the treatment position while minimizing patient motion during the scan time. Finally, synthetic CT images (i.e. electron density maps) and digitally reconstructed radiograph images should be generated from MRI images for dose calculation and image guidance prior to treatment. A short review of the concepts and techniques that have been developed for implementation of MRI-only workflows in radiation therapy is provided in this document.
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Affiliation(s)
- Amir M. Owrangi
- Department of Radiation Oncology, UT Southwestern Medical Center, Dallas, Texas
| | - Peter B. Greer
- School of Mathematical and Physical Sciences, University of Newcastle, Newcastle, NSW, 2308, Australia
- Department of Radiation Oncology, Calvary Mater Hospital, Newcastle, NSW, 2298, Australia
| | - Carri K. Glide-Hurst
- Department of Radiation Oncology, Henry Ford Health System, Detroit, Michigan
- Department of Radiation Oncology, Wayne State University School of Medicine, Detroit, Michigan
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Pathmanathan AU, van As NJ, Kerkmeijer LGW, Christodouleas J, Lawton CAF, Vesprini D, van der Heide UA, Frank SJ, Nill S, Oelfke U, van Herk M, Li XA, Mittauer K, Ritter M, Choudhury A, Tree AC. Magnetic Resonance Imaging-Guided Adaptive Radiation Therapy: A "Game Changer" for Prostate Treatment? Int J Radiat Oncol Biol Phys 2018; 100:361-373. [PMID: 29353654 DOI: 10.1016/j.ijrobp.2017.10.020] [Citation(s) in RCA: 118] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2017] [Revised: 10/09/2017] [Accepted: 10/12/2017] [Indexed: 01/25/2023]
Abstract
Radiation therapy to the prostate involves increasingly sophisticated delivery techniques and changing fractionation schedules. With a low estimated α/β ratio, a larger dose per fraction would be beneficial, with moderate fractionation schedules rapidly becoming a standard of care. The integration of a magnetic resonance imaging (MRI) scanner and linear accelerator allows for accurate soft tissue tracking with the capacity to replan for the anatomy of the day. Extreme hypofractionation schedules become a possibility using the potentially automated steps of autosegmentation, MRI-only workflow, and real-time adaptive planning. The present report reviews the steps involved in hypofractionated adaptive MRI-guided prostate radiation therapy and addresses the challenges for implementation.
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Affiliation(s)
- Angela U Pathmanathan
- The Institute of Cancer Research, London, United Kingdom; The Royal Marsden National Health Service Foundation Trust, London, United Kingdom
| | - Nicholas J van As
- The Institute of Cancer Research, London, United Kingdom; The Royal Marsden National Health Service Foundation Trust, London, United Kingdom
| | | | | | | | - Danny Vesprini
- Sunnybrook Health Sciences Centre, University of Toronto, Toronto, Ontario, Canada
| | - Uulke A van der Heide
- Department of Radiation Oncology, The Netherlands Cancer Institute, Amsterdam, The Netherlands
| | - Steven J Frank
- The University of Texas MD Anderson Cancer Center, Houston, Texas
| | - Simeon Nill
- The Institute of Cancer Research, London, United Kingdom; The Royal Marsden National Health Service Foundation Trust, London, United Kingdom
| | - Uwe Oelfke
- The Institute of Cancer Research, London, United Kingdom; The Royal Marsden National Health Service Foundation Trust, London, United Kingdom
| | - Marcel van Herk
- Manchester Cancer Research Centre, University of Manchester, Manchester Academic Health Science Centre, The Christie National Health Service Foundation Trust, Manchester, United Kingdom; National Institute of Health Research, Manchester Biomedical Research Centre, Central Manchester University Hospitals National Health Service Foundation Trust, Manchester Academic Health Science Centre, Manchester, United Kingdom
| | - X Allen Li
- Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Kathryn Mittauer
- University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin
| | - Mark Ritter
- University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin
| | - Ananya Choudhury
- Manchester Cancer Research Centre, University of Manchester, Manchester Academic Health Science Centre, The Christie National Health Service Foundation Trust, Manchester, United Kingdom; National Institute of Health Research, Manchester Biomedical Research Centre, Central Manchester University Hospitals National Health Service Foundation Trust, Manchester Academic Health Science Centre, Manchester, United Kingdom.
| | - Alison C Tree
- The Institute of Cancer Research, London, United Kingdom; The Royal Marsden National Health Service Foundation Trust, London, United Kingdom
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Zeinali-Rafsanjani B, Faghihi R, Mosleh-Shirazi MA, Saeedi-Moghadam M, Jalli R, Sina S. Effect of age-dependent bone electron density on the calculated dose distribution from kilovoltage and megavoltage photon and electron radiotherapy in paediatric MRI-only treatment planning. Br J Radiol 2018; 91:20170511. [PMID: 29091480 PMCID: PMC5966214 DOI: 10.1259/bjr.20170511] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2017] [Revised: 10/17/2017] [Accepted: 10/26/2017] [Indexed: 12/31/2022] Open
Abstract
OBJECTIVE MRI-only treatment planning (TP) can be advantageous in paediatric radiotherapy. However, electron density extraction is necessary for dose calculation. Normally, after bone segmentation, a bulk density is assigned. However, the variation of bone bulk density in patients makes the creation of pseudo CTs challenging. This study aims to assess the effects of bone density variations in children on radiation attenuation and dose calculation for MRI-only TP. METHODS Bone contents of <15-year-old children were calculated, and substituted in the Oak Ridge National Laboratory paediatric phantoms. The percentage depth dose and beam profile of 150 kVp and 6 MV photon and 6 MeV electron beams were then calculated using Xcom, MCNPX (Monte Carlo N-particle version X) and ORLN phantoms. RESULTS Using 150 kVp X-rays, the difference in attenuation coefficient was almost 5% between an 11-year-old child and a newborn, and ~8% between an adult and a newborn. With megavoltage radiation, the differences were smaller but still important. For an 18 MV photon beam, the difference of radiation attenuation between an 11-year-old child and a newborn was 4% and ~7.4% between an adult and a newborn. For 6 MeV electrons, dose differences were observed up to the 2 cm depth. The percentage depth dose difference between 1 and 10-year-olds was 18.5%, and between 10 and 15-year-olds was 24%. CONCLUSION The results suggest that for MRI-only TP of photon- or electron-beam radiotherapy, the bone densities of each age group should be defined separately for accurate dose calculation. Advances in knowledge: This study highlights the need for more age-specific determination of bone electron density for accurate dose calculations in paediatric MRI-only radiotherapy TP.
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Affiliation(s)
- B Zeinali-Rafsanjani
- Department of Nuclear Engineering, School of Mechanical Engineering, Shiraz University, Shiraz, Iran
| | | | | | - M Saeedi-Moghadam
- Medical Imaging Research Center, Shiraz University of Medical Sciences, Shiraz, Iran
| | - R Jalli
- Medical Imaging Research Center, Shiraz University of Medical Sciences, Shiraz, Iran
| | - S Sina
- Radiation Research Center, School of Mechanical Engineering, Shiraz University, Shiraz, Iran
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McNabb E, Wong R, Noseworthy MD. Localizing implanted fiducial markers using undersampled co-RASOR MR imaging. Magn Reson Imaging 2017; 48:1-9. [PMID: 29229307 DOI: 10.1016/j.mri.2017.12.009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2017] [Accepted: 12/04/2017] [Indexed: 01/04/2023]
Abstract
The goal of this work was to use an undersampled, dual-plane centre-out radial sampling acquisition pulse sequence, with off-resonance reception, to localize fiducial markers with reduced acquisition time. Two iterative reconstruction techniques, conjugate gradient CG-SENSE and the variational penalty Total Generalized Variation (TGV), were investigated to minimize the undersampling artifacts in off-resonant radial imaging. Simulations of a field perturber were performed at sub-millimeter resolution and reconstructed to display signal pileups that can be radially compressed towards the geometric centre of the perturber for high contrast visualization, but contrast is non-recoverable as the echo time increases. A cylindrical platinum fiducial marker, placed in a phantom parallel and perpendicular to the B0-field was imaged with a short-TE half-echo readout. Contrast-to-Noise (CNR) between the signal of the fiducial its adjacent surrounding shell and half-maximum area were used to compare reconstruction methods and undersampling factors. For single slice acquisitions centred about the fiducial, each slice can be performed in as little as 2.8s. The total acquisition time to localize the fiducial marker in a phantom was reduced to 73s by undersampling (R=8) 37 axial and 15 coronal slices, effectively encoding 1.4s/slice. The noise present in undersampled images, for both scan planes and fiducial orientations, decreased significantly using TGV and CG-SENSE reconstructions, with TGV displaying better spatial resolution from reduced half-maximum area.
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Affiliation(s)
- Evan McNabb
- McMaster School of Biomedical Engineering, McMaster University, Hamilton, Canada
| | - Raimond Wong
- Juravinksi Cancer Centre, Hamilton, Ontario, Canada; Department of Oncology, McMaster University, Hamilton, Ontario, Canada; Department of Medicine, McMaster University, Hamilton, Ontario, Canada
| | - Michael D Noseworthy
- McMaster School of Biomedical Engineering, McMaster University, Hamilton, Canada; Imaging Research Centre, St. Joseph's Healthcare, Hamilton, Ontario, Canada; Department of Electrical and Computer Engineering, McMaster University, Hamilton, Ontario, Canada; Department of Radiology, McMaster University, Hamilton, Ontario, Canada.
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Dosimetric feasibility of magnetic resonance (MR)-based dose calculation of prostate radiotherapy using multilevel threshold algorithm. JOURNAL OF RADIOTHERAPY IN PRACTICE 2017. [DOI: 10.1017/s1460396917000310] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
AbstractObjectiveThe development of magnetic resonance (MR) imaging systems has been extended for the entire radiotherapy process. However, MR images provide voxel values that are not directly related to electron densities, thus MR images cannot be used directly for dose calculation. The aim of this study is to investigate the feasibility of dose calculations to be performed on MR images and evaluate the necessity of re-planning.MethodsA prostate cancer patient was imaged using both MR and computed tomography (CT). The multilevel threshold (MLT) algorithm was used to categorise voxel values in the MR images into three segments (air, water and bone) with homogeneous Hounsfield units (HU). An intensity-modulated radiation therapy plan was generated from CT images of the patient. The plan was then copied to the segmented MR datasets and the doses were recalculated using pencil beam (PB) and collapsed cone (CC) algorithms and Monte Carlo (MC) modelling.ResultsγEvaluation showed that the percentage of points in regions of interest withγ<1 (3%/3 mm) were more than 94% in the segmented MR. Compared with the planning CT plan, the segmented MR plan resulted in a dose difference of –0·3, 0·8 and –1·3% when using PB, CC and MC algorithms, respectively.ConclusionThe segmentation and conversion of MR images into HU data using the MLT algorithm, used in this feasibility study, can be used for dose calculation. This method can be used as a dosimetric assessment tool and can be easily implemented in the clinic.
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Koivula L, Kapanen M, Seppälä T, Collan J, Dowling JA, Greer PB, Gustafsson C, Gunnlaugsson A, Olsson LE, Wee L, Korhonen J. Intensity-based dual model method for generation of synthetic CT images from standard T2-weighted MR images - Generalized technique for four different MR scanners. Radiother Oncol 2017; 125:411-419. [PMID: 29097012 DOI: 10.1016/j.radonc.2017.10.011] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2017] [Revised: 10/09/2017] [Accepted: 10/10/2017] [Indexed: 11/17/2022]
Abstract
BACKGROUND AND PURPOSE Recent studies have shown that it is possible to conduct entire radiotherapy treatment planning (RTP) workflow using only MR images. This study aims to develop a generalized intensity-based method to generate synthetic CT (sCT) images from standard T2-weighted (T2w) MR images of the pelvis. MATERIALS AND METHODS This study developed a generalized dual model HU conversion method to convert standard T2w MR image intensity values to synthetic HU values, separately inside and outside of atlas-segmented bone volume contour. The method was developed and evaluated with 20 and 35 prostate cancer patients, respectively. MR images with scanning sequences in clinical use were acquired with four different MR scanners of three vendors. RESULTS For the generated synthetic CT (sCT) images of the 35 prostate patients, the mean (and maximal) HU differences in soft and bony tissue volumes were 16 ± 6 HUs (34 HUs) and -46 ± 56 HUs (181 HUs), respectively, against the true CT images. The average of the PTV mean dose difference in sCTs compared to those in true CTs was -0.6 ± 0.4% (-1.3%). CONCLUSIONS The study provides a generalized method for sCT creation from standard T2w images of the pelvis. The method produced clinically acceptable dose calculation results for all the included scanners and MR sequences.
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Affiliation(s)
- Lauri Koivula
- Department of Radiation Oncology, Cancer Center, Helsinki University Central Hospital, Finland; Department of Physics, University of Helsinki, Finland; Medical Imaging and Radiation Therapy, Kymenlaakso Central Hospital, Kymenlaakso Social and Health Services (Carea), Kotka, Finland.
| | - Mika Kapanen
- Department of Medical Physics, Medical Imaging Center, Tampere University Hospital, Finland
| | - Tiina Seppälä
- Department of Radiation Oncology, Cancer Center, Helsinki University Central Hospital, Finland
| | - Juhani Collan
- Department of Radiation Oncology, Cancer Center, Helsinki University Central Hospital, Finland
| | - Jason A Dowling
- CSIRO Health and Biosecurity, The Australian e-Health & Research Centre, Herston, Australia
| | - Peter B Greer
- School of Mathematical and Physical Sciences, The University of Newcastle, Australia; Department of Radiation Oncology, Calvary Mater Newcastle Hospital, Australia
| | - Christian Gustafsson
- Department of Hematology, Oncology and Radiation Physics, Skåne University Hospital, Lund, Sweden; Department of Medical Physics, Lund University, Malmö, Sweden
| | - Adalsteinn Gunnlaugsson
- Department of Hematology, Oncology and Radiation Physics, Skåne University Hospital, Lund, Sweden
| | - Lars E Olsson
- Department of Medical Physics, Lund University, Malmö, Sweden; Department of Translational Sciences, Lund University, Skåne University Hospital, Malmö, Sweden
| | - Leonard Wee
- MAASTRO Clinic, School of Oncology and Developmental Biology, Maastricht University, The Netherlands; Department of Medical Physics, Oncology Services, Vejle Hospital, Denmark
| | - Juha Korhonen
- Department of Radiation Oncology, Cancer Center, Helsinki University Central Hospital, Finland; Medical Imaging and Radiation Therapy, Kymenlaakso Central Hospital, Kymenlaakso Social and Health Services (Carea), Kotka, Finland; Department of Radiology, Helsinki University Central Hospital, Finland; Department of Nuclear Medicine, Helsinki University Central Hospital, Finland
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Aouadi S, Vasic A, Paloor S, Torfeh T, McGarry M, Petric P, Riyas M, Hammoud R, Al-Hammadi N. Generation of synthetic CT using multi-scale and dual-contrast patches for brain MRI-only external beam radiotherapy. Phys Med 2017; 42:174-184. [DOI: 10.1016/j.ejmp.2017.09.132] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/16/2017] [Revised: 08/31/2017] [Accepted: 09/20/2017] [Indexed: 11/27/2022] Open
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Johnstone E, Wyatt JJ, Henry AM, Short SC, Sebag-Montefiore D, Murray L, Kelly CG, McCallum HM, Speight R. Systematic Review of Synthetic Computed Tomography Generation Methodologies for Use in Magnetic Resonance Imaging-Only Radiation Therapy. Int J Radiat Oncol Biol Phys 2017; 100:199-217. [PMID: 29254773 DOI: 10.1016/j.ijrobp.2017.08.043] [Citation(s) in RCA: 210] [Impact Index Per Article: 30.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2017] [Revised: 07/07/2017] [Accepted: 08/30/2017] [Indexed: 10/18/2022]
Abstract
Magnetic resonance imaging (MRI) offers superior soft-tissue contrast as compared with computed tomography (CT), which is conventionally used for radiation therapy treatment planning (RTP) and patient positioning verification, resulting in improved target definition. The 2 modalities are co-registered for RTP; however, this introduces a systematic error. Implementing an MRI-only radiation therapy workflow would be advantageous because this error would be eliminated, the patient pathway simplified, and patient dose reduced. Unlike CT, in MRI there is no direct relationship between signal intensity and electron density; however, various methodologies for MRI-only RTP have been reported. A systematic review of these methods was undertaken. The PRISMA guidelines were followed. Embase and Medline databases were searched (1996 to March, 2017) for studies that generated synthetic CT scans (sCT)s for MRI-only radiation therapy. Sixty-one articles met the inclusion criteria. This review showed that MRI-only RTP techniques could be grouped into 3 categories: (1) bulk density override; (2) atlas-based; and (3) voxel-based techniques, which all produce an sCT scan from MR images. Bulk density override techniques either used a single homogeneous or multiple tissue override. The former produced large dosimetric errors (>2%) in some cases and the latter frequently required manual bone contouring. Atlas-based techniques used both single and multiple atlases and included methods incorporating pattern recognition techniques. Clinically acceptable sCTs were reported, but atypical anatomy led to erroneous results in some cases. Voxel-based techniques included methods using routine and specialized MRI sequences, namely ultra-short echo time imaging. High-quality sCTs were produced; however, use of multiple sequences led to long scanning times increasing the chances of patient movement. Using nonroutine sequences would currently be problematic in most radiation therapy centers. Atlas-based and voxel-based techniques were found to be the most clinically useful methods, with some studies reporting dosimetric differences of <1% between planning on the sCT and CT and <1-mm deviations when using sCTs for positional verification.
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Affiliation(s)
- Emily Johnstone
- Leeds Institute of Cancer and Pathology, University of Leeds, Leeds, United Kingdom.
| | - Jonathan J Wyatt
- The Northern Centre for Cancer Care, The Newcastle-upon-Tyne NHS Foundation Trust, Newcastle-upon-Tyne, United Kingdom
| | - Ann M Henry
- Leeds Institute of Cancer and Pathology, University of Leeds, Leeds, United Kingdom; Leeds Cancer Centre, Leeds Teaching Hospitals NHS Trust, Leeds, United Kingdom
| | - Susan C Short
- Leeds Institute of Cancer and Pathology, University of Leeds, Leeds, United Kingdom; Leeds Cancer Centre, Leeds Teaching Hospitals NHS Trust, Leeds, United Kingdom
| | - David Sebag-Montefiore
- Leeds Institute of Cancer and Pathology, University of Leeds, Leeds, United Kingdom; Leeds Cancer Centre, Leeds Teaching Hospitals NHS Trust, Leeds, United Kingdom
| | - Louise Murray
- Leeds Institute of Cancer and Pathology, University of Leeds, Leeds, United Kingdom; Leeds Cancer Centre, Leeds Teaching Hospitals NHS Trust, Leeds, United Kingdom
| | - Charles G Kelly
- The Northern Centre for Cancer Care, The Newcastle-upon-Tyne NHS Foundation Trust, Newcastle-upon-Tyne, United Kingdom
| | - Hazel M McCallum
- The Northern Centre for Cancer Care, The Newcastle-upon-Tyne NHS Foundation Trust, Newcastle-upon-Tyne, United Kingdom
| | - Richard Speight
- Leeds Cancer Centre, Leeds Teaching Hospitals NHS Trust, Leeds, United Kingdom
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Largent A, Nunes JC, Lafond C, Périchon N, Castelli J, Rolland Y, Acosta O, de Crevoisier R. [MRI-based radiotherapy planning]. Cancer Radiother 2017; 21:788-798. [PMID: 28690126 DOI: 10.1016/j.canrad.2017.02.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2016] [Revised: 02/09/2017] [Accepted: 02/27/2017] [Indexed: 12/11/2022]
Abstract
MRI-based radiotherapy planning is a topical subject due to the introduction of a new generation of treatment machines combining a linear accelerator and a MRI. One of the issues for introducing MRI in this task is the lack of information to provide tissue density information required for dose calculation. To cope with this issue, two strategies may be distinguished from the literature. Either a synthetic CT scan is generated from the MRI to plan the dose, or a dose is generated from the MRI based on physical underpinnings. Within the first group, three approaches appear: bulk density mapping assign a homogeneous density to different volumes of interest manually defined on a patient MRI; machine learning-based approaches model local relationship between CT and MRI image intensities from multiple data, then applying the model to a new MRI; atlas-based approaches use a co-registered training data set (CT-MRI) which are registered to a new MRI to create a pseudo CT from spatial correspondences in a final fusion step. Within the second group, physics-based approaches aim at computing the dose directly from the hydrogen contained within the tissues, quantified by MRI. Excepting the physics approach, all these methods generate a synthetic CT called "pseudo CT", on which radiotherapy planning will be finally realized. This literature review shows that atlas- and machine learning-based approaches appear more accurate dosimetrically. Bulk density approaches are not appropriate for bone localization. The fastest methods are machine learning and the slowest are atlas-based approaches. The less automatized are bulk density assignation methods. The physical approaches appear very promising methods. Finally, the validation of these methods is crucial for a clinical practice, in particular in the perspective of adaptive radiotherapy delivered by a linear accelerator combined with an MRI scanner.
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Affiliation(s)
- A Largent
- Laboratoire traitement du signal et de l'image, campus de Beaulieu, université de Rennes 1, 263, avenue du Général-Leclerc, 35042 Rennes, France; Inserm, UMR 1099, 263, avenue du Général-Leclerc, 35042 Rennes, France
| | - J-C Nunes
- Laboratoire traitement du signal et de l'image, campus de Beaulieu, université de Rennes 1, 263, avenue du Général-Leclerc, 35042 Rennes, France; Inserm, UMR 1099, 263, avenue du Général-Leclerc, 35042 Rennes, France
| | - C Lafond
- Département de radiothérapie, centre régional de lutte contre le cancer Eugène-Marquis, avenue de la Bataille-Flandres-Dunkerque, 35042 Rennes, France
| | - N Périchon
- Département de radiothérapie, centre régional de lutte contre le cancer Eugène-Marquis, avenue de la Bataille-Flandres-Dunkerque, 35042 Rennes, France
| | - J Castelli
- Laboratoire traitement du signal et de l'image, campus de Beaulieu, université de Rennes 1, 263, avenue du Général-Leclerc, 35042 Rennes, France; Département de radiothérapie, centre régional de lutte contre le cancer Eugène-Marquis, avenue de la Bataille-Flandres-Dunkerque, 35042 Rennes, France; Inserm, UMR 1099, 263, avenue du Général-Leclerc, 35042 Rennes, France
| | - Y Rolland
- Laboratoire traitement du signal et de l'image, campus de Beaulieu, université de Rennes 1, 263, avenue du Général-Leclerc, 35042 Rennes, France; Département d'imagerie médicale, centre régional de lutte contre le cancer Eugène-Marquis, avenue de la Bataille-Flandres-Dunkerque, 35042 Rennes, France
| | - O Acosta
- Laboratoire traitement du signal et de l'image, campus de Beaulieu, université de Rennes 1, 263, avenue du Général-Leclerc, 35042 Rennes, France; Inserm, UMR 1099, 263, avenue du Général-Leclerc, 35042 Rennes, France
| | - R de Crevoisier
- Laboratoire traitement du signal et de l'image, campus de Beaulieu, université de Rennes 1, 263, avenue du Général-Leclerc, 35042 Rennes, France; Département de radiothérapie, centre régional de lutte contre le cancer Eugène-Marquis, avenue de la Bataille-Flandres-Dunkerque, 35042 Rennes, France; Inserm, UMR 1099, 263, avenue du Général-Leclerc, 35042 Rennes, France.
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Arivarasan I, Anuradha C, Subramanian S, Anantharaman A, Ramasubramanian V. Magnetic resonance image guidance in external beam radiation therapy planning and delivery. Jpn J Radiol 2017; 35:417-426. [DOI: 10.1007/s11604-017-0656-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2017] [Accepted: 05/29/2017] [Indexed: 12/14/2022]
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Pollard JM, Wen Z, Sadagopan R, Wang J, Ibbott GS. The future of image-guided radiotherapy will be MR guided. Br J Radiol 2017; 90:20160667. [PMID: 28256898 DOI: 10.1259/bjr.20160667] [Citation(s) in RCA: 135] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Advances in image-guided radiotherapy (RT) have allowed for dose escalation and more precise radiation treatment delivery. Each decade brings new imaging technologies to help improve RT patient setup. Currently, the most frequently used method of three-dimensional pre-treatment image verification is performed with cone beam CT. However, more recent developments have provided RT with the ability to have on-board MRI coupled to the teleradiotherapy unit. This latest tool for treating cancer is known as MR-guided RT. Several varieties of these units have been designed and installed in centres across the globe. Their prevalence, history, advantages and disadvantages are discussed in this review article. In preparation for the next generation of image-guided RT, this review also covers where MR-guided RT might be heading in the near future.
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Affiliation(s)
| | - Zhifei Wen
- UT MD Anderson Cancer Center, Houston, TX, USA
| | | | - Jihong Wang
- UT MD Anderson Cancer Center, Houston, TX, USA
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Han X. MR-based synthetic CT generation using a deep convolutional neural network method. Med Phys 2017; 44:1408-1419. [PMID: 28192624 DOI: 10.1002/mp.12155] [Citation(s) in RCA: 431] [Impact Index Per Article: 61.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2016] [Revised: 01/31/2017] [Accepted: 02/05/2017] [Indexed: 01/17/2023] Open
Abstract
PURPOSE Interests have been rapidly growing in the field of radiotherapy to replace CT with magnetic resonance imaging (MRI), due to superior soft tissue contrast offered by MRI and the desire to reduce unnecessary radiation dose. MR-only radiotherapy also simplifies clinical workflow and avoids uncertainties in aligning MR with CT. Methods, however, are needed to derive CT-equivalent representations, often known as synthetic CT (sCT), from patient MR images for dose calculation and DRR-based patient positioning. Synthetic CT estimation is also important for PET attenuation correction in hybrid PET-MR systems. We propose in this work a novel deep convolutional neural network (DCNN) method for sCT generation and evaluate its performance on a set of brain tumor patient images. METHODS The proposed method builds upon recent developments of deep learning and convolutional neural networks in the computer vision literature. The proposed DCNN model has 27 convolutional layers interleaved with pooling and unpooling layers and 35 million free parameters, which can be trained to learn a direct end-to-end mapping from MR images to their corresponding CTs. Training such a large model on our limited data is made possible through the principle of transfer learning and by initializing model weights from a pretrained model. Eighteen brain tumor patients with both CT and T1-weighted MR images are used as experimental data and a sixfold cross-validation study is performed. Each sCT generated is compared against the real CT image of the same patient on a voxel-by-voxel basis. Comparison is also made with respect to an atlas-based approach that involves deformable atlas registration and patch-based atlas fusion. RESULTS The proposed DCNN method produced a mean absolute error (MAE) below 85 HU for 13 of the 18 test subjects. The overall average MAE was 84.8 ± 17.3 HU for all subjects, which was found to be significantly better than the average MAE of 94.5 ± 17.8 HU for the atlas-based method. The DCNN method also provided significantly better accuracy when being evaluated using two other metrics: the mean squared error (188.6 ± 33.7 versus 198.3 ± 33.0) and the Pearson correlation coefficient(0.906 ± 0.03 versus 0.896 ± 0.03). Although training a DCNN model can be slow, training only need be done once. Applying a trained model to generate a complete sCT volume for each new patient MR image only took 9 s, which was much faster than the atlas-based approach. CONCLUSIONS A DCNN model method was developed, and shown to be able to produce highly accurate sCT estimations from conventional, single-sequence MR images in near real time. Quantitative results also showed that the proposed method competed favorably with an atlas-based method, in terms of both accuracy and computation speed at test time. Further validation on dose computation accuracy and on a larger patient cohort is warranted. Extensions of the method are also possible to further improve accuracy or to handle multi-sequence MR images.
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Affiliation(s)
- Xiao Han
- Elekta Inc., Maryland Heights, MO, 63043, USA
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