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Liang X, Yen A, Bai T, Godley A, Shen C, Wu J, Meng B, Lin MH, Medin P, Yan Y, Owrangi A, Desai N, Hannan R, Garant A, Jiang S, Deng J. Bony structure enhanced synthetic CT generation using Dixon sequences for pelvis MR-only radiotherapy. Med Phys 2023; 50:7368-7382. [PMID: 37358195 DOI: 10.1002/mp.16556] [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: 02/03/2023] [Accepted: 05/29/2023] [Indexed: 06/27/2023] Open
Abstract
BACKGROUND MRI-only radiotherapy planning (MROP) is beneficial to patients by avoiding MRI/CT registration errors, simplifying the radiation treatment simulation workflow and reducing exposure to ionizing radiation. MRI is the primary imaging modality for soft tissue delineation. Treatment planning CTs (i.e., CT simulation scan) are redundant if a synthetic CT (sCT) can be generated from the MRI to provide the patient positioning and electron density information. Unsupervised deep learning (DL) models like CycleGAN are widely used in MR-to-sCT conversion, when paired patient CT and MR image datasets are not available for model training. However, compared to supervised DL models, they cannot guarantee anatomic consistency, especially around bone. PURPOSE The purpose of this work was to improve the sCT accuracy generated from MRI around bone for MROP. METHODS To generate more reliable bony structures on sCT images, we proposed to add bony structure constraints in the unsupervised CycleGAN model's loss function and leverage Dixon constructed fat and in-phase (IP) MR images. Dixon images provide better bone contrast than T2-weighted images as inputs to a modified multi-channel CycleGAN. A private dataset with a total of 31 prostate cancer patients were used for training (20) and testing (11). RESULTS We compared model performance with and without bony structure constraints using single- and multi-channel inputs. Among all the models, multi-channel CycleGAN with bony structure constraints had the lowest mean absolute error, both inside the bone and whole body (50.7 and 145.2 HU). This approach also resulted in the highest Dice similarity coefficient (0.88) of all bony structures compared with the planning CT. CONCLUSION Modified multi-channel CycleGAN with bony structure constraints, taking Dixon-constructed fat and IP images as inputs, can generate clinically suitable sCT images in both bone and soft tissue. The generated sCT images have the potential to be used for accurate dose calculation and patient positioning in MROP radiation therapy.
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Affiliation(s)
- Xiao Liang
- Medical Artificial Intelligence and Automation Laboratory and Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Allen Yen
- Medical Artificial Intelligence and Automation Laboratory and Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Ti Bai
- Medical Artificial Intelligence and Automation Laboratory and Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Andrew Godley
- Medical Artificial Intelligence and Automation Laboratory and Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Chenyang Shen
- Medical Artificial Intelligence and Automation Laboratory and Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Junjie Wu
- Medical Artificial Intelligence and Automation Laboratory and Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Boyu Meng
- Medical Artificial Intelligence and Automation Laboratory and Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Mu-Han Lin
- Medical Artificial Intelligence and Automation Laboratory and Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Paul Medin
- Medical Artificial Intelligence and Automation Laboratory and Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Yulong Yan
- Medical Artificial Intelligence and Automation Laboratory and Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Amir Owrangi
- Medical Artificial Intelligence and Automation Laboratory and Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Neil Desai
- Medical Artificial Intelligence and Automation Laboratory and Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Raquibul Hannan
- Medical Artificial Intelligence and Automation Laboratory and Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Aurelie Garant
- Medical Artificial Intelligence and Automation Laboratory and Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Steve Jiang
- Medical Artificial Intelligence and Automation Laboratory and Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Jie Deng
- Medical Artificial Intelligence and Automation Laboratory and Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, Texas, USA
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Dorsch S, Paul K, Beyer C, Karger CP, Jäkel O, Debus J, Klüter S. Quality assurance and temporal stability of a 1.5 T MRI scanner for MR-guided Photon and Particle Therapy. Z Med Phys 2023:S0939-3889(23)00046-6. [PMID: 37150727 DOI: 10.1016/j.zemedi.2023.04.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2022] [Revised: 03/12/2023] [Accepted: 04/04/2023] [Indexed: 05/09/2023]
Abstract
PURPOSE To describe performance measurements, adaptations and time stability over 20 months of a diagnostic MR scanner for integration into MR-guided photon and particle radiotherapy. MATERIAL AND METHODS For realization of MR-guided photon and particle therapy (MRgRT/MRgPT), a 1.5 T MR scanner was installed at the Heidelberg Ion Beam Therapy Center. To integrate MRI into the treatment process, a flat tabletop and dedicated coil holders for flex coils were used, which prevent deformation of the patient external contour and allow for the use of immobilization tools for reproducible positioning. The signal-to-noise ratio (SNR) was compared for the diagnostic and therapy-specific setup using the flat couch top and flexible coils for the a) head & neck and b) abdominal region as well as for different bandwidths and clinical pulse sequences. Additionally, a quality assurance (QA) protocol with monthly measurements of the ACR phantom and measurement of geometric distortions for a large field-of-view (FOV) was implemented to assess the imaging quality parameters of the device over the course of 20 months. RESULTS The SNR measurements showed a decreased SNR for the RT-specific as compared to the diagnostic setup of (a) 26% to 34% and (b) 11% to 33%. No significant bandwidth dependency for this ratio was found. The longitudinal assessment of the image quality parameters with the ACR and distortion phantom confirmed the long-term stability of the MRI device. CONCLUSION A diagnostic MRI was commissioned for use in MR-guided particle therapy. Using a radiotherapy specific setup, a high geometric accuracy and signal homogeneity was obtained after some adaptions and the measured parameters were shown to be stable over a period of 20 months.
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Affiliation(s)
- Stefan Dorsch
- Department of Medical Physics in Radiation Oncology, German Cancer Research Center (DKFZ), INF 280, 69120 Heidelberg, Germany; National Center for Radiation Research in Oncology (NCRO), Heidelberg Institute for Radiation Oncology (HIRO), Heidelberg, Germany; Department of Radiation Oncology, University Hospital Heidelberg, INF 400, 69120 Heidelberg, Germany.
| | - Katharina Paul
- National Center for Radiation Research in Oncology (NCRO), Heidelberg Institute for Radiation Oncology (HIRO), Heidelberg, Germany; Department of Radiation Oncology, University Hospital Heidelberg, INF 400, 69120 Heidelberg, Germany
| | - Cedric Beyer
- National Center for Radiation Research in Oncology (NCRO), Heidelberg Institute for Radiation Oncology (HIRO), Heidelberg, Germany; Department of Radiation Oncology, University Hospital Heidelberg, INF 400, 69120 Heidelberg, Germany
| | - Christian P Karger
- Department of Medical Physics in Radiation Oncology, German Cancer Research Center (DKFZ), INF 280, 69120 Heidelberg, Germany; National Center for Radiation Research in Oncology (NCRO), Heidelberg Institute for Radiation Oncology (HIRO), Heidelberg, Germany
| | - Oliver Jäkel
- Department of Medical Physics in Radiation Oncology, German Cancer Research Center (DKFZ), INF 280, 69120 Heidelberg, Germany; National Center for Radiation Research in Oncology (NCRO), Heidelberg Institute for Radiation Oncology (HIRO), Heidelberg, Germany; Heidelberg Ion-Beam Therapy Center (HIT), Department of Radiation Oncology, Heidelberg University Hospital, Heidelberg, Germany
| | - Jürgen Debus
- National Center for Radiation Research in Oncology (NCRO), Heidelberg Institute for Radiation Oncology (HIRO), Heidelberg, Germany; Department of Radiation Oncology, University Hospital Heidelberg, INF 400, 69120 Heidelberg, Germany; Heidelberg Ion-Beam Therapy Center (HIT), Department of Radiation Oncology, Heidelberg University Hospital, Heidelberg, Germany; Clinical Cooperation Unit Radiation Oncology, German Cancer Research Center (DKFZ), Heidelberg, Germany; Core center Heidelberg, German Cancer Consortium (DKTK), Heidelberg, Germany
| | - Sebastian Klüter
- National Center for Radiation Research in Oncology (NCRO), Heidelberg Institute for Radiation Oncology (HIRO), Heidelberg, Germany; Department of Radiation Oncology, University Hospital Heidelberg, INF 400, 69120 Heidelberg, Germany.
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Sreeja S, Muhammad Noorul Mubarak D. Pseudo computed tomography image generation from brain magnetic resonance image using integration of PCA & DCNN-UNET: A comparative analysis. JOURNAL OF INTELLIGENT & FUZZY SYSTEMS 2022. [DOI: 10.3233/jifs-213367] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
MRI-Only Radiation (RT) now avoids some of the issues associated with employing Computed Tomography(CT) in RT chains, such as MRI registration to a separate CT, excess dosage administration, and the cost of recurrent imaging. The fact that MRI signal intensities are unrelated to the biological tissue’s attenuation coefficient poses a problem. This raises workloads, creates uncertainty as a result of the required inter-modality image registrations, and exposes patients to needless radiation. While using only MRI would be preferable, a method for estimating a pseudo-CT (pCT)or synthetic-CT(sCT) for producing electron density maps and patient positioning reference images is required. As Deep Learning(DL) is revolutionized in so many fields these days, an effective and accurate model is required for generating pCT from MRI. So, this paper depicts an efficient DL model in which the following are the stages: a) Data Acquisition where CT and MRI images are collected b) preprocessing these to avoid the anomalies and noises using techniques like outlier elimination, data smoothening and data normalizing c) feature extraction and selection using Principal Component Analysis (PCA) & regression method d) generating pCT from MRI using Deep Convolutional Neural Network and UNET (DCNN-UNET). We here compare both feature extraction (PCA) and classification model (DCNN-UNET) with other methods such as Discrete Wavelet Tranform(DWT), Independent Component Analysis(ICA), Fourier Transform and VGG16, ResNet, AlexNet, DenseNet, CNN (Convolutional Neural Network)respectively. The performance measures used to evaluate these models are Dice Coefficient(DC), Structured Similarity Index Measure(SSIM), Mean Absolute Error(MAE), Mean Squared Error(MSE), Accuracy, Computation Time in which our proposed system outperforms better with 0.94±0.02 over other state-of-art models.
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Affiliation(s)
- S Sreeja
- Department of Computer Science, University of Kerala, Karyavattom Campus, Trivandrum, Kerala, India
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Ito K, Kadoya N, Katsuta Y, Tanaka S, Dobashi S, Takeda K, Jingu K. Evaluation of the electron transport algorithm in magnetic field in EGS5 Monte Carlo code. Phys Med 2021; 93:46-51. [PMID: 34922223 DOI: 10.1016/j.ejmp.2021.12.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/18/2021] [Revised: 11/01/2021] [Accepted: 12/07/2021] [Indexed: 11/30/2022] Open
Abstract
PURPOSE To evaluate the accuracy of electron transport in the magnetic field of Electron Gamma Shower version 5 (EGS5) by using the special Fano cavity test. METHODS To simulate electron transport in the magnetic field, the trajectory of the electron was reconstructed with a short step length to restrict fractional energy loss, and the maximum user step length (mxustep) was set at 0.01 cm or 0.001 cm. For the special Fano cavity test, three-layer slab Fano test geometry was used, and uniform and isotropic per unit mass mono-energetic electrons with 0.01, 0.1, 1.0, and 10 MeV were permitted from the central axis of geometry in 0.35 T and 1.5 T. Furthermore, the magnetic field strength was scaled based on the mass density of the material. The relative difference between the calculated dose to gap and the theoretical value was evaluated. Furthermore, the special Fano cavity test was also performed using EGSnrc with the electron-enhanced electric and magnetic field macros under the same conditions, and the results were compared with those of EGS5. RESULTS Deviations in 0.35 T were within 0.3% regardless of the parameter settings. In 1.5 T, stable results within 0.3% were obtained using 0.001 cm as the mxustep, except for one at 10 MeV. Further, the accuracy of EGSnrc was within 0.2%, except for 10 MeV for a 0.2-cm gap in 1.5 T. CONCLUSIONS EGS5 with the appropriate parameter settings enable electron transport in magnetic fields similar with the accuracy of EGSnrc.
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Affiliation(s)
- Kengo Ito
- Department of Radiation Oncology, Tohoku University Graduate School of Medicine, Sendai, Miyagi 980-8574, Japan.
| | - Noriyuki Kadoya
- Department of Radiation Oncology, Tohoku University Graduate School of Medicine, Sendai, Miyagi 980-8574, Japan
| | - Yoshiyuki Katsuta
- Department of Radiation Oncology, Tohoku University Graduate School of Medicine, Sendai, Miyagi 980-8574, Japan
| | - Shohei Tanaka
- Department of Radiation Oncology, Tohoku University Graduate School of Medicine, Sendai, Miyagi 980-8574, Japan
| | - Suguru Dobashi
- Department of Radiological Technology, School of Health Sciences, Faculty of Medicine, Tohoku University, Sendai, Miyagi 980-8575, Japan
| | - Ken Takeda
- Department of Radiological Technology, School of Health Sciences, Faculty of Medicine, Tohoku University, Sendai, Miyagi 980-8575, Japan
| | - Keiichi Jingu
- Department of Radiation Oncology, Tohoku University Graduate School of Medicine, Sendai, Miyagi 980-8574, Japan
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Rodgers J, Hales R, Whiteside L, Parker J, McHugh L, Cree A, van Herk M, Choudhury A, Hoskin P, McWilliam A, Eccles CL. Comparison of radiographer interobserver image registration variability using cone beam CT and MR for cervix radiotherapy. Br J Radiol 2020; 93:20200169. [PMID: 32543946 PMCID: PMC7446016 DOI: 10.1259/bjr.20200169] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2020] [Revised: 05/21/2020] [Accepted: 05/22/2020] [Indexed: 11/05/2022] Open
Abstract
OBJECTIVES The aim of this study was to assess the consistency of therapy radiographers performing image registration using cone beam computed tomography (CBCT)-CT, magnetic resonance (MR)-CT, and MR-MR image guidance for cervix cancer radiotherapy and to assess that MR-based image guidance is not inferior to CBCT standard practice. METHODS 10 patients receiving cervix radiation therapy underwent daily CBCT guidance and magnetic resonance (MR) imaging weekly during treatment. Offline registration of each MR image, and corresponding CBCT, to planning CT was performed by five radiographers. MR images were also registered to the earliest MR interobserver variation was assessed using modified Bland-Altman analysis with clinically acceptable 95% limits of agreement (LoA) defined as ±5.0 mm. RESULTS 30 CBCT-CT, 30 MR-CT and 20 MR-MR registrations were performed by each observer. Registration variations between CBCT-CT and MR-CT were minor and both strategies resulted in 95% LoA over the clinical threshold in the anteroposterior direction (CBCT-CT ±5.8 mm, MR-CT ±5.4 mm). MR-MR registrations achieved a significantly improved 95% LoA in the anteroposterior direction (±4.3 mm). All strategies demonstrated similar results in lateral and longitudinal directions. CONCLUSION The magnitude of interobserver variations between CBCT-CT and MR-CT were similar, confirming that MR-CT radiotherapy workflows are comparable to CBCT-CT image-guided radiotherapy. Our results suggest MR-MR radiotherapy workflows may be a superior registration strategy. ADVANCES IN KNOWLEDGE This is the first publication quantifying interobserver registration of multimodality image registration strategies for cervix radical radiotherapy patients.
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Affiliation(s)
- John Rodgers
- Department of Radiotherapy, The Christie NHS Foundation Trust, Manchester, UK,
| | - Rosie Hales
- Department of Radiotherapy, The Christie NHS Foundation Trust, Manchester, UK,
| | - Lee Whiteside
- Department of Radiotherapy, The Christie NHS Foundation Trust, Manchester, UK,
| | - Jacqui Parker
- Department of Radiotherapy, The Christie NHS Foundation Trust, Manchester, UK,
| | - Louise McHugh
- Department of Radiotherapy, The Christie NHS Foundation Trust, Manchester, UK,
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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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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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Winkel D, Bol GH, Werensteijn-Honingh AM, Kiekebosch IH, van Asselen B, Intven MP, Eppinga WS, Raaymakers BW, Jürgenliemk-Schulz IM, Kroon PS. Evaluation of plan adaptation strategies for stereotactic radiotherapy of lymph node oligometastases using online magnetic resonance image guidance. Phys Imaging Radiat Oncol 2019; 9:58-64. [PMID: 33458426 PMCID: PMC7807584 DOI: 10.1016/j.phro.2019.02.003] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2018] [Revised: 02/11/2019] [Accepted: 02/19/2019] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND AND PURPOSE Recent studies have shown that the use of magnetic resonance (MR) guided online plan adaptation yields beneficial dosimetric values and reduces unplanned violations of the dose constraints for stereotactic body radiation therapy (SBRT) of lymph node oligometastases. The purpose of this R-IDEAL stage 0 study was to determine the optimal plan adaptation approach for MR-guided SBRT treatment of lymph node oligometastases. MATERIALS AND METHODS Using pre-treatment computed tomography (CT) and repeated MR data from five patients with in total 17 pathological lymph nodes, six different methods of plan adaptation were performed on the daily MRI and contours. To determine the optimal plan adaptation approach for treatment of lymph node oligometastases, the adapted plans were evaluated using clinical dose criteria and the time required for performing the plan adaptation. RESULTS The average time needed for the different plan adaptation methods ranged between 11 and 119 s. More advanced adaptation methods resulted in more plans that met the clinical dose criteria [range, 0-16 out of 17 plans]. The results show a large difference between target coverage achieved by the different plan adaptation methods. CONCLUSION Results suggested that multiple plan adaptation methods, based on plan adaptation on the daily anatomy, were feasible for MR-guided SBRT treatment of lymph node oligometastases. The most advanced method, in which a full online replanning was performed by segment shape and weight optimization after fluence optimization, yielded the most favourable dosimetric values and could be performed within a time-frame acceptable (<5 min) for MR-guided treatment.
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Affiliation(s)
- Dennis Winkel
- Department of Radiotherapy, University Medical Center, Utrecht, the Netherlands
| | - Gijsbert H. Bol
- Department of Radiotherapy, University Medical Center, Utrecht, the Netherlands
| | | | - Ilse H. Kiekebosch
- Department of Radiotherapy, University Medical Center, Utrecht, the Netherlands
| | - Bram van Asselen
- Department of Radiotherapy, University Medical Center, Utrecht, the Netherlands
| | - Martijn P.W. Intven
- Department of Radiotherapy, University Medical Center, Utrecht, the Netherlands
| | - Wietse S.C. Eppinga
- Department of Radiotherapy, University Medical Center, Utrecht, the Netherlands
| | - Bas W. Raaymakers
- Department of Radiotherapy, University Medical Center, Utrecht, the Netherlands
| | | | - Petra S. Kroon
- Department of Radiotherapy, University Medical Center, Utrecht, the Netherlands
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Kumar S, Rai R, Moses D, Choong C, Holloway L, Vinod SK, Liney G. MRI in radiotherapy for lung cancer: A free-breathing protocol at 3T. Pract Radiat Oncol 2017; 7:e175-e183. [DOI: 10.1016/j.prro.2016.10.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2016] [Revised: 09/12/2016] [Accepted: 10/14/2016] [Indexed: 01/22/2023]
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Edmund JM, Nyholm T. A review of substitute CT generation for MRI-only radiation therapy. Radiat Oncol 2017; 12:28. [PMID: 28126030 PMCID: PMC5270229 DOI: 10.1186/s13014-016-0747-y] [Citation(s) in RCA: 236] [Impact Index Per Article: 33.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2016] [Accepted: 12/21/2016] [Indexed: 12/13/2022] Open
Abstract
Radiotherapy based on magnetic resonance imaging as the sole modality (MRI-only RT) is an area of growing scientific interest due to the increasing use of MRI for both target and normal tissue delineation and the development of MR based delivery systems. One major issue in MRI-only RT is the assignment of electron densities (ED) to MRI scans for dose calculation and a similar need for attenuation correction can be found for hybrid PET/MR systems. The ED assigned MRI scan is here named a substitute CT (sCT). In this review, we report on a collection of typical performance values for a number of main approaches encountered in the literature for sCT generation as compared to CT. A literature search in the Scopus database resulted in 254 papers which were included in this investigation. A final number of 50 contributions which fulfilled all inclusion criteria were categorized according to applied method, MRI sequence/contrast involved, number of subjects included and anatomical site investigated. The latter included brain, torso, prostate and phantoms. The contributions geometric and/or dosimetric performance metrics were also noted. The majority of studies are carried out on the brain for 5–10 patients with PET/MR applications in mind using a voxel based method. T1 weighted images are most commonly applied. The overall dosimetric agreement is in the order of 0.3–2.5%. A strict gamma criterion of 1% and 1mm has a range of passing rates from 68 to 94% while less strict criteria show pass rates > 98%. The mean absolute error (MAE) is between 80 and 200 HU for the brain and around 40 HU for the prostate. The Dice score for bone is between 0.5 and 0.95. The specificity and sensitivity is reported in the upper 80s% for both quantities and correctly classified voxels average around 84%. The review shows that a variety of promising approaches exist that seem clinical acceptable even with standard clinical MRI sequences. A consistent reference frame for method benchmarking is probably necessary to move the field further towards a widespread clinical implementation.
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Affiliation(s)
- Jens M Edmund
- Radiotherapy Research Unit, Department of Oncology, Herlev & Gentofte Hospital, Copenhagen University, Herlev, Denmark. .,Niels Bohr Institute, Copenhagen University, Copenhagen, Denmark.
| | - Tufve Nyholm
- Department of Radiation Sciences, Umeå University, Umeå, SE-901 87, Sweden.,Medical Radiation Physics, Department of Immunology, Genetics and Pathology, Uppsala University, Uppsala, Sweden
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Paulson ES, Crijns SPM, Keller BM, Wang J, Schmidt MA, Coutts G, van der Heide UA. Consensus opinion on MRI simulation for external beam radiation treatment planning. Radiother Oncol 2016; 121:187-192. [PMID: 27838146 DOI: 10.1016/j.radonc.2016.09.018] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2016] [Revised: 09/08/2016] [Accepted: 09/09/2016] [Indexed: 11/26/2022]
Abstract
AIM To determine the levels at which consensus could be reached regarding general and site-specific principles of MRI simulation for offline MRI-aided external beam radiation treatment planning. METHODS A process inspired by the Delphi method was employed to determine levels of consensus using a series of questionnaires interspersed with controlled opinion feedback. RESULTS In general, full consensus was reached regarding general principles of MRI simulation. However, the level of consensus decreased when site-specific principles of MRI simulation were considered. CONCLUSIONS These results indicate variability in MRI simulation approaches that are largely explained by the use of MRI in combination with CT.
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Affiliation(s)
| | | | | | - Jihong Wang
- MD Anderson Cancer Center, Houston, United States
| | - Maria A Schmidt
- The Royal Marsden NHS Foundation Trust and Institute of Cancer Research, Sutton, United Kingdom
| | - Glyn Coutts
- The Christie NHS Foundation Trust, Manchester, United Kingdom
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Vogel WV, Lam MGEH, Pameijer FA, van der Heide UA, van de Kamer JB, Philippens ME, van Vulpen M, Verheij M. Functional Imaging in Radiotherapy in the Netherlands: Availability and Impact on Clinical Practice. Clin Oncol (R Coll Radiol) 2016; 28:e206-e215. [PMID: 27692741 DOI: 10.1016/j.clon.2016.09.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2016] [Revised: 07/10/2016] [Accepted: 07/11/2016] [Indexed: 12/25/2022]
Abstract
AIMS Functional imaging with positron emission tomography/computed tomography (PET/CT) and multiparametric magnetic resonance (mpMR) is increasingly applied for radiotherapy purposes. However, evidence and experience are still limited, and this may lead to clinically relevant differences in accessibility, interpretation and decision making. We investigated the current patterns of care in functional imaging for radiotherapy in the Netherlands in a care evaluation study. MATERIALS AND METHODS The availability of functional imaging in radiotherapy centres in the Netherlands was evaluated; features available in >80% of academic and >80% of non-academic centres were considered standard of care. The impact of functional imaging on clinical decision making was evaluated using case questionnaires on lung, head/neck, breast and prostate cancer, with multiple-choice questions on primary tumour delineation, nodal involvement, distant metastasis and incidental findings. Radiation oncologists were allowed to discuss cases in a multidisciplinary approach. Ordinal answers were evaluated by median and interquartile range (IQR) to identify the extent and variability of clinical impact; additional patterns were evaluated descriptively. RESULTS Information was collected from 18 radiotherapy centres in the Netherlands (all except two). PET/CT was available for radiotherapy purposes to 94% of centres; 67% in the treatment position and 61% with integrated planning CT. mpMR was available to all centres; 61% in the treatment position. Technologists collaborated between departments to acquire PET/CT or mpMR for radiotherapy in 89%. All sites could carry out image registration for target definition. Functional imaging generally showed a high clinical impact (average median 4.3, scale 1-6) and good observer agreement (average IQR 1.1, scale 0-6). However, several issues resulted in ignoring functional imaging (e.g. positional discrepancies, central necrosis) or poor observer agreement (atelectasis, diagnostic discrepancies, conformation strategies). CONCLUSIONS Access to functional imaging with PET/CT and mpMR for radiotherapy purposes, with collaborating technologists and multimodal delineation, can be considered standard of care in the Netherlands. For several specific clinical situations, the interpretation of images may benefit from further standardisation.
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Affiliation(s)
- W V Vogel
- Department of Radiation Oncology, the Netherlands Cancer Institute, Amsterdam, The Netherlands; Department of Nuclear Medicine, the Netherlands Cancer Institute, Amsterdam, The Netherlands; Department of Radiation Oncology, University Medical Center Utrecht, Utrecht, The Netherlands.
| | - M G E H Lam
- Department of Radiology and Nuclear Medicine, University Medical Center Utrecht, Utrecht, The Netherlands
| | - F A Pameijer
- Department of Radiology and Nuclear Medicine, University Medical Center Utrecht, Utrecht, The Netherlands
| | - U A van der Heide
- Department of Radiation Oncology, the Netherlands Cancer Institute, Amsterdam, The Netherlands
| | - J B van de Kamer
- Department of Radiation Oncology, the Netherlands Cancer Institute, Amsterdam, The Netherlands
| | - M E Philippens
- Department of Radiation Oncology, University Medical Center Utrecht, Utrecht, The Netherlands
| | - M van Vulpen
- Department of Radiation Oncology, University Medical Center Utrecht, Utrecht, The Netherlands
| | - M Verheij
- Department of Radiation Oncology, the Netherlands Cancer Institute, Amsterdam, The Netherlands
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Abstract
The use of magnetic resonance imaging (MRI) in radiotherapy (RT) planning is rapidly expanding. We review the wide range of image contrast mechanisms available to MRI and the way they are exploited for RT planning. However a number of challenges are also considered: the requirements that MR images are acquired in the RT treatment position, that they are geometrically accurate, that effects of patient motion during the scan are minimized, that tissue markers are clearly demonstrated, that an estimate of electron density can be obtained. These issues are discussed in detail, prior to the consideration of a number of specific clinical applications. This is followed by a brief discussion on the development of real-time MRI-guided RT.
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Affiliation(s)
- Maria A Schmidt
- Cancer Research UK Cancer Imaging Centre, Royal Marsden Hospital and the Institute of Cancer Research, Downs Road, Sutton, Surrey, SM2 5PT, UK
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Vicens RA, Rodriguez J, Sheplan L, Mayo C, Mayo L, Jensen C. Brachytherapy in pelvic malignancies: a review for radiologists. ABDOMINAL IMAGING 2015; 40:2645-2659. [PMID: 25820802 DOI: 10.1007/s00261-015-0407-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Brachytherapy, also known as sealed source or internal radiation therapy, involves placement of a radioactive source immediately adjacent to or within tumor, thus enabling delivery of a localized high dose of radiation. Compared with external beam radiation which must first pass through non-target tissues, brachytherapy results in less radiation dose to normal tissues. In the past decade, brachytherapy use has markedly increased, thus radiologists are encountering brachytherapy devices and their associated post-treatment changes to increasing degree. This review will present a variety of brachytherapy devices that radiologists may encounter during diagnostic pelvic imaging with a focus on prostate and gynecologic malignancies. The reader will become familiar with the function, correct position, and potential complications of brachytherapy devices in an effort to improve diagnostic reporting and communication with clinicians.
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Affiliation(s)
- Rafael A Vicens
- Department of Radiology, Hospital Auxilio Mutuo, Hato Rey, PR, 00919, USA.
| | - Joshua Rodriguez
- School of Medicine, Ponce Health Sciences University, Ponce, PR, USA
| | - Lawrence Sheplan
- Department of Radiation Oncology, Hospital Auxilio Mutuo, Hato Rey, PR, USA
| | - Cody Mayo
- Department of Diagnostic Imaging, University of Virgina, Charlottesville, VA, USA
| | - Lauren Mayo
- Department of Radiation Oncology, MD Anderson Cancer Center, Houston, TX, USA
| | - Corey Jensen
- Department of Radiology, MD Anderson Cancer Center, Houston, TX, USA
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van de Schoot AJAJ, de Boer P, Buist MR, Stoker J, Bleeker MCG, Stalpers LJA, Rasch CRN, Bel A. Quantification of delineation errors of the gross tumor volume on magnetic resonance imaging in uterine cervical cancer using pathology data and deformation correction. Acta Oncol 2015; 54:224-31. [PMID: 25437811 DOI: 10.3109/0284186x.2014.983655] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
BACKGROUND To safely optimize target volumes using magnetic resonance imaging (MRI) for uterine cervical cancer radiation therapy, MRI findings need to be validated. The aim of this study was to correlate pre-operatively acquired MRI and surgical specimen imaging for uterine cervical cancer patients using deformable image registration and quantify gross tumor volume (GTV) delineation discrepancies. MATERIAL AND METHODS For 16 retrospectively selected early-stage uterine cervical cancer patients, the cervix-uterus structure, uterine cavity and the GTV were delineated on 2D pathology photos after macroscopic intersection and corresponding pre-operatively acquired T2-weighted 2D sagittal MR images. Segmentations of pathology photos and MR images were simultaneously registered using a three-step multi-image registration strategy. The registration outcome was evaluated by the Dice similarity coefficient (DSC) and the surface distance error (SDE). In addition, GTV expansions within the cervix-uterus structure needed to obtain 95% GTV coverage were determined. RESULTS After three-step multi-image registration, the median DSC and median SDE were 0.98 and 0.4 mm (cervix-uterus) and 0.90 and 0.4 mm (uterine cavity), respectively. The average SDE around the GTV was 0.7 mm (range, 0.1 mm - 2.6 mm). An underestimation of MRI-based GTV delineations was found when no margin was applied, indicated by a mean GTV coverage of 61%. To obtain 95% GTV coverage for 90% of the patients, a minimum 12.0 mm margin around MRI-based GTVs was needed. CONCLUSION The presented three-step multi-image registration strategy was suitable and accurate to correlate MRI and pathology data for uterine cervical cancer patients. To cover the pathology-based GTV, a margin of at least 12.0 mm around GTV delineations on T2-weighted MRI is needed.
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16
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Position shifts and volume changes of pelvic and para-aortic nodes during IMRT for patients with cervical cancer. Radiother Oncol 2014; 111:442-5. [DOI: 10.1016/j.radonc.2014.05.013] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2013] [Revised: 03/10/2014] [Accepted: 05/03/2014] [Indexed: 11/18/2022]
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17
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Korsholm ME, Waring LW, Edmund JM. A criterion for the reliable use of MRI-only radiotherapy. Radiat Oncol 2014; 9:16. [PMID: 24405515 PMCID: PMC3909342 DOI: 10.1186/1748-717x-9-16] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2013] [Accepted: 12/23/2013] [Indexed: 12/25/2022] Open
Abstract
BACKGROUND MRI-only radiotherapy will eliminate the systematic registration errors introduced when transferring MRI information to the CT. However, challenges concerning the missing information on electron density, necessary for dose calculation and patient setup on bony anatomy are introduced. This study presents a possible statistical approach to evaluate, if deviations based on MRI-only radiotherapy as compared to the CT based radiotherapy are acceptable. METHODS 18 head-and-neck, 21 prostate, 10 vesica and 8 pelvic patients were included in the study. Data from each patient contained a CT and a T2-weighted MRI scan, a structure set and a clinically approved CT based treatment plan, which was re-calculated with identical parameters on the density corrected MRI scans. A statistical analysis including a 95% confidence interval was performed in clinically relevant DVH points. RESULTS The mean differences in the investigated DVH points were in the order of 1.5% for the PTV and up to 4.2% for organs at risk. In addition, a proposed criterion of 2% dose difference in the PTV coverage for 95% of the patients was fulfilled for all diagnostic groups for a bulk segmented MRI in the DVH points, D(median) and D2%, while only head-and-neck and prostate further fulfilled the criterion in D98%. CONCLUSION Here, we suggested a method for establishing a reliable use of MRI-only radiotherapy. A population-based study comparing CT based dose calculations with those obtained on a suggested segmentation of MRI should be initiated and acceptable deviations in clinically relevant DVH points should be established. Such a population-based approach could form a part of the clinical commissioning of MRI-only radiotherapy.
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Affiliation(s)
- Marie E Korsholm
- Department of Oncology, Radiotherapy Research Unit (52AA), Herlev Hospital, University of Copenhagen, Herlev, Denmark
| | - Line W Waring
- Department of Biomedical Sciences and The Danish National Research Foundation Centre for Cardiac Arrhythmia, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Jens M Edmund
- Department of Oncology, Radiotherapy Research Unit (52AA), Herlev Hospital, University of Copenhagen, Herlev, Denmark
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Shaw W, Rae WID, Alber ML. Equivalence of Gyn GEC-ESTRO guidelines for image guided cervical brachytherapy with EUD-based dose prescription. Radiat Oncol 2013; 8:266. [PMID: 24225184 PMCID: PMC3842680 DOI: 10.1186/1748-717x-8-266] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2013] [Accepted: 11/08/2013] [Indexed: 11/17/2022] Open
Abstract
Background To establish a generalized equivalent uniform dose (gEUD) -based prescription method for Image Guided Brachytherapy (IGBT) that reproduces the Gyn GEC-ESTRO WG (GGE) prescription for cervix carcinoma patients on CT images with limited soft tissue resolution. Methods The equivalence of two IGBT planning approaches was investigated in 20 patients who received external beam radiotherapy (EBT) and 5 concomitant high dose rate IGBT treatments. The GGE planning strategy based on dose to the most exposed 2 cm3 (D2cc) was used to derive criteria for the gEUD-based planning of the bladder and rectum. The safety of gEUD constraints in terms of GGE criteria was tested by maximizing dose to the gEUD constraints for individual fractions. Results The gEUD constraints of 3.55 Gy for the rectum and 5.19 Gy for the bladder were derived. Rectum and bladder gEUD-maximized plans resulted in D2cc averages very similar to the initial GGE criteria. Average D2ccs and EUDs from the full treatment course were comparable for the two techniques within both sets of normal tissue constraints. The same was found for the tumor doses. Conclusions The derived gEUD criteria for normal organs result in GGE-equivalent IGBT treatment plans. The gEUD-based planning considers the entire dose distribution of organs in contrast to a single dose-volume-histogram point.
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Affiliation(s)
- William Shaw
- Department of Medical Physics (G68), University of the Free State, Nelson Mandela Drive, Park West, Bloemfontein 9300, South Africa.
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19
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Thakur P, Revannasiddaiah S, Rastogi M, Gupta MK, Seam RK, Gupta M. Uncertainty concerning the 4-field box technique for Stage-IB2 carcinoma of the uterine cervix. J Med Phys 2013; 38:41-3. [PMID: 23531883 PMCID: PMC3607345 DOI: 10.4103/0971-6203.106604] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2012] [Revised: 10/26/2012] [Accepted: 10/26/2012] [Indexed: 11/04/2022] Open
Abstract
Radiation Therapy (RT) plays a pivotal role in the curative approach for carcinoma of the cervix. Inspite of the emergence of various new conformal techniques in RT, conventional techniques still hold vital importance. Majority of the patients worldwide are treated with 2D-RT techniques. 2D-RT techniques have been proven to be non-inferior and simpler in comparison to 3D-RT in the context of carcinoma of the cervix. However, inadequate target volume coverage with improper portal design can preclude the chances of cure. We demonstrate the need for abolishing guesswork in terms of target volume determination through the example of a patient's sagittal magnetic resonance image showing a case of the retroverted uterus which would have been likely to be missed from the treatment portals if they were designed using definitions based on bony landmarks.
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Affiliation(s)
- Priyanka Thakur
- Department of Radiation Therapy and Oncology, Regional Cancer Centre, Indira Gandhi Medical College, Shimla, India
| | - Swaroop Revannasiddaiah
- Department of Radiation Therapy and Oncology, Regional Cancer Centre, Indira Gandhi Medical College, Shimla, India,Address for correspondence: Dr. Swaroop Revannasiddaiah, Department of Radiation Therapy and Oncology, Regional Cancer Centre, Indira Gandhi Medical College, Shimla 171 001, Himachal Pradesh, India. E-mail:
| | - Madhup Rastogi
- Department of Radiation Therapy and Oncology, Regional Cancer Centre, Indira Gandhi Medical College, Shimla, India
| | - Manoj Kumar Gupta
- Department of Radiation Therapy and Oncology, Regional Cancer Centre, Indira Gandhi Medical College, Shimla, India
| | - Rajeev Kumar Seam
- Department of Radiation Therapy and Oncology, Regional Cancer Centre, Indira Gandhi Medical College, Shimla, India
| | - Manish Gupta
- Department of Radiation Therapy and Oncology, Regional Cancer Centre, Indira Gandhi Medical College, Shimla, India
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The departmental impact of magnetic resonance imaging in the management of cervical cancer brachytherapy: a discussion paper. JOURNAL OF RADIOTHERAPY IN PRACTICE 2012. [DOI: 10.1017/s1460396911000288] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
AbstractThis discussion paper will explore the impact of using Magnetic Resonance Imaging (MRI) in the treatment of cervical cancer with brachytherapy. It is written from the perspective of current departmental practice in the UK and aims to highlight the issues associated with using MRI as a tool for image guided brachytherapy planning. To support the discussion, a literature review was undertaken focussing specifically on the use of MRI in brachytherapy treatment planning for cervical cancer. Results from planning case studies and clinical series were analysed, and the literature showed that image guided brachytherapy treatment planning is a promising development. MRI assisted planning could theoretically be implemented in centres that have access to a MRI scanner. Alternative brachytherapy technologies (e.g. Computed Tomography (CT) assisted planning), and alternative radiotherapy modalities (e.g. an external beam radiotherapy boost), were not found to be superior in effect or of implementation. Although MRI shows great promise, the evidence base for MRI in brachytherapy planning for cervical cancer is currently limited and therefore careful implementation and evaluation is required. It is suggested by the authors that new methods of working are devised to ensure consistency and quality in implementation and delivery, and that outcomes are measured and audited to evaluate efficacy.
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Conibear J, Lowe G, Hoskin PJ. High-precision MRI-guided adaptive brachytherapy for cervical carcinoma. Int J Hyperthermia 2012; 28:501-8. [PMID: 22834543 DOI: 10.3109/02656736.2012.683847] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Over the past 20 years advances in radiological technology have led to dramatic changes in cervical cancer management. External beam radiotherapy has evolved radically as a result of these changes. More recently, though, three-dimensional (3D) image guidance and volume-based prescribing has been adopted into cervical cancer brachytherapy. This overview covers the science and technology behind magnetic resonance imaging (MRI)-guided adaptive brachytherapy and explains why it is now considered the new international standard of care.
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Affiliation(s)
- J Conibear
- Mount Vernon Centre for Cancer Treatment, Northwood, Middlesex, UK.
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22
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Dean CJ, Sykes JR, Cooper RA, Hatfield P, Carey B, Swift S, Bacon SE, Thwaites D, Sebag-Montefiore D, Morgan AM. An evaluation of four CT-MRI co-registration techniques for radiotherapy treatment planning of prone rectal cancer patients. Br J Radiol 2012; 85:61-8. [PMID: 22190750 DOI: 10.1259/bjr/11855927] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
OBJECTIVES MRI is the preferred staging modality for rectal carcinoma patients. This work assesses the CT-MRI co-registration accuracy of four commercial rigid-body techniques for external beam radiotherapy treatment planning for patients treated in the prone position without fiducial markers. METHODS 17 patients with biopsy-proven rectal carcinoma were scanned with CT and MRI in the prone position without the use of fiducial markers. A reference co-registration was performed by consensus of a radiologist and two physicists. This was compared with two automated and two manual techniques on two separate treatment planning systems. Accuracy and reproducibility were analysed using a measure of target registration error (TRE) that was based on the average distance of the mis-registration between vertices of the clinically relevant gross tumour volume as delineated on the CT image. RESULTS An automated technique achieved the greatest accuracy, with a TRE of 2.3 mm. Both automated techniques demonstrated perfect reproducibility and were significantly faster than their manual counterparts. There was a significant difference in TRE between registrations performed on the two planning systems, but there were no significant differences between the manual and automated techniques. CONCLUSION For patients with rectal cancer, MRI acquired in the prone treatment position without fiducial markers can be accurately registered with planning CT. An automated registration technique offered a fast and accurate solution with associated uncertainties within acceptable treatment planning limits.
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Affiliation(s)
- C J Dean
- Department of Medical Physics, St James's Institute of Oncology, Leeds, UK.
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Karotki A, Mah K, Meijer G, Meltsner M. Comparison of bulk electron density and voxel-based electron density treatment planning. J Appl Clin Med Phys 2011; 12:3522. [PMID: 22089006 PMCID: PMC5718732 DOI: 10.1120/jacmp.v12i4.3522] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2010] [Revised: 05/10/2011] [Accepted: 05/13/2011] [Indexed: 12/04/2022] Open
Abstract
The use of magnetic resonance imaging (MRI) alone for radiation planning is limited by the lack of electron density for dose calculations. The purpose of this work is to evaluate the dosimetric accuracy of using bulk electron density as a substitute for computed tomography (CT)‐derived electron density in intensity‐modulated radiation therapy (IMRT) treatment planning of head and neck (HN) cancers. Ten clinically‐approved, CT‐based IMRT treatment plans of HN cancer were used for this study. Three dose distributions were calculated and compared for each treatment plan. The first calculation used CT‐derived density and was assumed to be the most accurate. The second calculation used a homogeneous patient density of 1 g/cm3. For the third dose calculation, bone and air cavities were contoured and assigned a uniform density of 1.5 g/cm3 and 0 g/cm3, respectively. The remaining tissues were assigned a density of 1 g/cm3. The use of homogeneous anatomy resulted in up to 4%–5% deviations in dose distribution as compared to CT‐derived electron density calculations. Assigning bulk density to bone and air cavities significantly improved the accuracy of the dose calculations. All parameters used to describe planning target volume coverage were within 2% of calculations based on CT‐derived density. For organs at risk, most of the parameters were within 2%, with the few exceptions located in low‐dose regions. The data presented here show that if bone and air cavities are overridden with the proper density, it is feasible to use a bulk electron density approach for accurate dose calculation in IMRT treatment planning of HN cancers. This may overcome the problem of the lack of electron density information should MRI‐only simulation be performed. PACS number: 87.55.D‐
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Affiliation(s)
- Aliaksandr Karotki
- Department of Medical Physics, Sunnybrook Health Sciences Center, Toronto, ON, Canada.
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Kron T, Eyles D, Schreiner LJ, Battista J. Magnetic resonance imaging for adaptive cobalt tomotherapy: A proposal. J Med Phys 2011; 31:242-54. [PMID: 21206640 PMCID: PMC3004099 DOI: 10.4103/0971-6203.29194] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2006] [Accepted: 08/01/2006] [Indexed: 11/04/2022] Open
Abstract
Magnetic resonance imaging (MRI) provides excellent soft tissue contrast for oncology applications. We propose to combine a MRI scanner with a helical tomotherapy (HT) system to enable daily target imaging for improved conformal radiation dose delivery to a patient. HT uses an intensity-modulated fan-beam that revolves around a patient, while the patient slowly advances through the plane of rotation, yielding a helical beam trajectory. Since the use of a linear accelerator to produce radiation may be incompatible with the pulsed radiofrequency and the high and pulsed magnetic fields required for MRI, it is proposed that a radioactive Cobalt-60 ((60)Co) source be used instead to provide the radiation. An open low field (0.25 T) MRI system is proposed where the tomotherapy ring gantry is located between two sets of Helmholtz coils that can generate a sufficiently homogenous main magnetic field.It is shown that the two major challenges with the design, namely acceptable radiation dose rate (and therefore treatment duration) and moving parts in strong magnetic field, can be addressed. The high dose rate desired for helical tomotherapy delivery can be achieved using two radiation sources of 220TBq (6000Ci) each on a ring gantry with a source to axis-of-rotation distance of 75 cm. In addition to this, a dual row multi-leaf collimator (MLC) system with 15 mm leaf width at isocentre and relatively large fan beam widths between 15 and 30 mm per row shall be employed. In this configuration, the unit would be well-suited for most pelvic radiotherapy applications where the soft tissue contrast of MRI will be particularly beneficial. Non-magnetic MRI compatible materials must be used for the rotating gantry. Tungsten, which is non-magnetic, can be used for primary collimation of the fan-beam as well as for the MLC, which allows intensity modulated radiation delivery. We propose to employ a low magnetic Cobalt compound, sycoporite (CoS) for the Cobalt source material itself.Rotational delivery is less susceptible to problems related to the use of a low energy megavoltage photon source while the helical delivery reduces the negative impact of the relatively large penumbra inherent in the use of Cobalt sources for radiotherapy. On the other hand, the use of a (60)Co source ensures constant dose rate with gantry rotation and makes dose calculation in a magnetic field as easy as the range of secondary electrons is limited.The MR-integrated Cobalt tomotherapy unit, dubbed 'MiCoTo,' uses two independent physical principles for image acquisition and treatment delivery. It would offer excellent target definition and will allow following target motion during treatment using fast imaging techniques thus providing the best possible input for adaptive radiotherapy. As an additional bonus, quality assurance of the radiation delivery can be performed in situ using radiation sensitive gels imaged by MRI.
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Affiliation(s)
- Tomas Kron
- Peter MacCallum Cancer Centre, Melbourne, Australia
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25
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Contrast enhanced MR imaging of female pelvic cancers: Established methods and emerging applications. Eur J Radiol 2011; 78:2-11. [DOI: 10.1016/j.ejrad.2010.03.010] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2010] [Accepted: 03/11/2010] [Indexed: 01/30/2023]
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D'Souza D, Baldassarre F, Morton G, Falkson C, Batchelar D. Imaging technologies for high dose rate brachytherapy for cervical cancer: a systematic review. Clin Oncol (R Coll Radiol) 2011; 23:460-75. [PMID: 21441017 DOI: 10.1016/j.clon.2011.02.014] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2010] [Revised: 09/02/2010] [Accepted: 12/16/2010] [Indexed: 11/17/2022]
Abstract
The aim of this overview was to assess the utility of various imaging technologies (fluoroscopy, ultrasound, computed tomography, magnetic resonance imaging and positron emission tomography) for the treatment planning of high dose rate brachytherapy for cervical cancer. Reviews and primary studies comparing different imaging technologies used during high dose rate brachytherapy for cervical cancer and published from 1988 to 2008 were sought by searching MEDLINE and EMBASE databases, the Cochrane Library, personal files and reference lists of identified studies, and by contacting experts. Study selection, study quality assessment and data extraction were carried out in duplicate. Twelve studies met the inclusion criteria. No systematic reviews or randomised controlled studies (RCTs) were located. The validity assessment revealed that the quality of the existing studies is very variable. This is the first systematic review in the area of imaging technologies for cervix brachytherapy. No RCTs have been located and it is possible that an RCT is not the optimal methodology to assess imaging technologies. However, in this area there is a need for more prospective studies and for studies that consider the expertise of the operators in their design. The studies found supported the use of three-dimensional imaging as opposed to the traditional two-dimensional imaging. However, apart from the effectiveness of visualising tumours and surrounding tissues, the utility of imaging technologies in clinical practice is determined by other contextual factors, such as their availability, accessibility and ease of use.
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Affiliation(s)
- D D'Souza
- Department of Radiation Oncology, University of Western Ontario, Victoria Hospital, London, Ontario, Canada
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Role of MRI in Intracavitary Brachytherapy for Cervical Cancer: What the Radiologist Needs to Know. AJR Am J Roentgenol 2011; 196:W341-7. [DOI: 10.2214/ajr.10.5050] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Jürgenliemk-Schulz IM, Toet-Bosma MZ, de Kort GA, Schreuder HW, Roesink JM, Tersteeg RJ, van der Heide UA. Internal motion of the vagina after hysterectomy for gynaecological cancer. Radiother Oncol 2011; 98:244-8. [DOI: 10.1016/j.radonc.2010.10.026] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2009] [Revised: 10/20/2010] [Accepted: 10/26/2010] [Indexed: 10/18/2022]
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Morton G, Walker-Dilks C, Baldassarre F, D’Souza D, Falkson C, Batchelar D, Gutierrez E, Bak K. Delivery of Brachytherapy for Cervical Cancer: Organisational and Technical Advice to Facilitate High-quality Care. Clin Oncol (R Coll Radiol) 2010; 22:605-14. [DOI: 10.1016/j.clon.2010.05.020] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2009] [Revised: 01/26/2010] [Accepted: 05/20/2010] [Indexed: 11/29/2022]
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Kerkhof EM, Balter JM, Vineberg K, Raaymakers BW. Treatment plan adaptation for MRI-guided radiotherapy using solely MRI data: a CT-based simulation study. Phys Med Biol 2010; 55:N433-40. [DOI: 10.1088/0031-9155/55/16/n01] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Applicator reconstruction for HDR cervix treatment planning using images from 0.35 T open MR scanner. Radiother Oncol 2009; 94:346-52. [PMID: 19931929 DOI: 10.1016/j.radonc.2009.10.015] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2009] [Revised: 10/05/2009] [Accepted: 10/07/2009] [Indexed: 11/21/2022]
Abstract
BACKGROUND AND PURPOSES Magnetic resonance (MR) imaging is widely recognised as the modality of choice for imaging soft tissue such as the target volume and critical structures relevant to high dose rate (HDR) brachytherapy of the cervix. This work sets out to assess some of the issues faced when introducing this technique clinically compared to the more widely used computed tomography (CT). MR can be used either as the sole imaging modality, or in conjunction with CT. MATERIALS AND METHODS Distortion of the images produced by the MR scanner was assessed with a geometrical phantom. Distortion local to the titanium applicators, introduced by the susceptibility of the applicators themselves, was also measured. The technique used to reconstruct applicators is briefly described. An inter-operator study was performed to assess the variability of applicator reconstruction between operators when MR images are used alone to reconstruct the applicators. RESULTS A 14-cm cube within which distortion was less than 2mm at all points was identified. The inter-operator study showed some variability in applicator reconstruction with both MR and CT (median MR/CT 1.3mm/0.9 mm, range 0-3.6mm/0-3.3mm). Inter-operator variation in planning target volume (PTV) V 100% and PTV D 90% for MR/CT was 6.1%/3.0% and 7.4%/6.3%, respectively, and D(2cc) OAR doses varied by up to 1.0 Gy between operators for both MR and CT. CONCLUSIONS In this study distortion was minimal within a defined volume and inter-observer errors were comparable on MR and CT when used to define applicators and when applied to dose-volume histograms (DVHs). However this does not assure the technique is appropriate with other scanners and applicator sets without further commissioning.
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Dedicated Magnetic Resonance Imaging in the Radiotherapy Clinic. Int J Radiat Oncol Biol Phys 2009; 74:644-51. [DOI: 10.1016/j.ijrobp.2009.01.065] [Citation(s) in RCA: 118] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2008] [Revised: 01/09/2009] [Accepted: 01/14/2009] [Indexed: 11/21/2022]
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Perez-Calatayud J, Kuipers F, Ballester F, Granero D, Richart J, Rodriguez S, Tormo A, Santos M. Exclusive MRI-based tandem and colpostats reconstruction in gynaecological brachytherapy treatment planning. Radiother Oncol 2009; 91:181-6. [DOI: 10.1016/j.radonc.2008.09.004] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2007] [Revised: 05/09/2008] [Accepted: 09/06/2008] [Indexed: 10/21/2022]
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Kerkhof EM, Raaymakers BW, van der Heide UA, van de Bunt L, Jürgenliemk-Schulz IM, Lagendijk JJW. Online MRI guidance for healthy tissue sparing in patients with cervical cancer: an IMRT planning study. Radiother Oncol 2008; 88:241-9. [PMID: 18490068 DOI: 10.1016/j.radonc.2008.04.009] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2008] [Revised: 04/10/2008] [Accepted: 04/19/2008] [Indexed: 10/22/2022]
Abstract
BACKGROUND AND PURPOSE During cervical cancer treatment, target volumes change position and shape due to organ motion and tumour regression. An MRI-accelerator will provide information on these changes by online magnetic resonance imaging (MRI) guidance throughout each treatment fraction. The purpose of this intensity-modulated radiation therapy (IMRT) planning study is to assess the benefit of online MRI guidance in healthy tissue sparing. MATERIALS AND METHODS Weekly MRI scans of 11 cervical cancer patients were used. We created four IMRT plans per patient, based on these weekly MRI scans, to simulate an online-IMRT approach. We applied a primary and nodal planning target volume (PTV) margin of 4 mm. As reference, we created an IMRT plan based on the pre-treatment MRI scan (pre-IMRT) using a primary and nodal PTV margin of 15 and 10 mm. The weekly defined bladder, rectum, bowel, and sigmoid contours were evaluated on the online-IMRT and pre-IMRT dose distributions at six dose levels (V10(Gy), V20(Gy), V30(Gy), V40(Gy), V42.8(Gy), and V45(Gy)). RESULTS Online-IMRT compared to pre-IMRT significantly reduced the volume of healthy tissue irradiated to all dose levels, except V10(Gy). CONCLUSIONS Online MRI guidance reduces healthy tissue involvement in patients with cervical cancer.
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Affiliation(s)
- Ellen M Kerkhof
- Department of Radiotherapy, University Medical Center Utrecht, Utrecht, The Netherlands.
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Motion and deformation of the target volumes during IMRT for cervical cancer: what margins do we need? Radiother Oncol 2008; 88:233-40. [PMID: 18237798 DOI: 10.1016/j.radonc.2007.12.017] [Citation(s) in RCA: 108] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2007] [Revised: 12/10/2007] [Accepted: 12/12/2007] [Indexed: 11/21/2022]
Abstract
BACKGROUND AND PURPOSE For cervical cancer patients the CTV consists of multiple structures, exhibiting complex inter-fraction changes. The purpose of this study is to use weekly MR imaging to derive PTV margins that accommodate these changes. MATERIALS AND METHODS Twenty patients with cervical cancer underwent a T2-weighted MRI exam before and weekly during IMRT. The CTV, GTV and surrounding organs were delineated. PTV margins were derived from the boundaries of the GTV and CTV in the six main directions and correlated with changes in the volumes of organs at risk. RESULTS Around the GTV a margin of 12, 14, 12, 11, 4 and 8mm to the anterior, posterior, right lateral, left lateral, superior and inferior directions was needed. The CTV required margins of 24, 17, 12, 16, 11 and 8 mm. The shift of the GTV and CTV in the AP directions correlated weakly with the change in rectal volume. For the bladder the correlations were even weaker. CONCLUSIONS We used weekly MRI scans to derive inhomogeneous PTV margins that accommodate changes in GTV and CTV. The weak correlations with rectum and bladder volume suggest that measures to control filling status of these organs may not be very effective.
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Lecchi M, Fossati P, Elisei F, Orecchia R, Lucignani G. Current concepts on imaging in radiotherapy. Eur J Nucl Med Mol Imaging 2007; 35:821-37. [PMID: 17972074 DOI: 10.1007/s00259-007-0631-y] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2007] [Accepted: 10/02/2007] [Indexed: 11/29/2022]
Abstract
New high-precision radiotherapy (RT) techniques, such as intensity-modulated radiation therapy (IMRT) or hadrontherapy, allow better dose distribution within the target and spare a larger portion of normal tissue than conventional RT. These techniques require accurate tumour volume delineation and intrinsic characterization, as well as verification of target localisation and monitoring of organ motion and response assessment during treatment. These tasks are strongly dependent on imaging technologies. Among these, computed tomography (CT), magnetic resonance imaging (MRI), ultrasonography (US) and positron emission tomography (PET) have been applied in high-precision RT. For tumour volume delineation and characterization, PET has brought an additional dimension to the management of cancer patients by allowing the incorporation of crucial functional and molecular images in RT treatment planning, i.e. direct evaluation of tumour metabolism, cell proliferation, apoptosis, hypoxia and angiogenesis. The combination of PET and CT in a single imaging system (PET/CT) to obtain a fused anatomical and functional dataset is now emerging as a promising tool in radiotherapy departments for delineation of tumour volumes and optimization of treatment plans. Another exciting new area is image-guided radiotherapy (IGRT), which focuses on the potential benefit of advanced imaging and image registration to improve precision, daily target localization and monitoring during treatment, thus reducing morbidity and potentially allowing the safe delivery of higher doses. The variety of IGRT systems is rapidly expanding, including cone beam CT and US. This article examines the increasing role of imaging techniques in the entire process of high-precision radiotherapy.
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Affiliation(s)
- Michela Lecchi
- Institute of Radiological Sciences, University of Milan, Milan, Italy
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Tournat H, Chilles A, Charra-Brunaud C, Peiffert D, Ahmad F, Métayer Y. Curiethérapie utérovaginale de bas débit pulsé: influence du support dosimétrique. Cancer Radiother 2007; 11:188-96. [PMID: 17604674 DOI: 10.1016/j.canrad.2007.05.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2007] [Revised: 03/18/2007] [Accepted: 05/31/2007] [Indexed: 10/23/2022]
Abstract
PURPOSE To evaluate two dosimetric supports used in pulse dose rate brachytherapy (PDR): coverage of target volumes, dose to organs at risk, residual tumor after surgery, survival. PATIENTS AND METHODS Twenty patients treated for uterine cervix tumor first by brachytherapy PDR had a dosimetric CT-scan after implantation. For 9 patients, the treatment was planned from standard radiographies and then reported on CT-scan images. For 11 patients, it was directly planned from CT-scan. Six weeks after, 18 patients underwent surgery. RESULTS With a median follow-up of 22 months, 2 year actuarial survival was 89%. Six patients developed grade II urinary or gynecological complications (LENT SOMA scale). No residual tumor was found for 12 patients (7 with a 3D treatment and 5 a 2 D treatment). Ninety-five percent of CTVHR received 53 Gy (2D treatment) or 63 Gy (3D treatment). Two cm3 of bladder wall received 63 Gy (2D) or 74 Gy (3D) although 2 cm3 of rectal wall received 37 Gy (2D) and 35 Gy (3D). CONCLUSION Using CT-scan made us improve the coverage of the uterine cervix but increase the dose received by the bladder, without increasing the rate of histological remission after surgery. We should be prudent before changing our practice.
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Affiliation(s)
- H Tournat
- Hôpital Saint-André, 1, rue Jean-Burguet, 33075 Bordeaux cedex, France.
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