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Foltz W, Stanescu T, Lee J, Simeonov A, Jaffray D, Craig T, Chung P, Ménard C. Improved Geometric Performance of Diffusion-Weighted Imaging for Prostate Tumor Delineation Using a Readout-Segmented Echo-Planar-Imaging Technique. Int J Radiat Oncol Biol Phys 2013. [DOI: 10.1016/j.ijrobp.2013.06.448] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Tadic T, Jaffray D, Stanescu T. TU-G-134-02: A Harmonic Field Approach to Quantifying MRI Spatial Accuracy for MRIgRT. Med Phys 2013. [DOI: 10.1118/1.4815480] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Stanescu T, Tadic T, Marle J, Winter J, Petropoulos L, Sweitzer M, Jaffray D. WE-G-WAB-02: BEST IN PHYSICS (JOINT IMAGING-THERAPY)-MR and Linac Magnetic Field Mutual Decoupling for An MRI-Guided Radiation Therapy System. Med Phys 2013. [DOI: 10.1118/1.4815644] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Winter J, Carlone M, Westmore M, Breen S, Stanescu T, Dahan M, Jaffray D. SU-C-103-06: Isocenter Calibration Concept and Feasibility for MR-Guided Radiation Therapy (MRgRT). Med Phys 2013. [DOI: 10.1118/1.4813973] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Tadic T, Jaffray D, Winter J, Petropoulos L, Marle J, Sweitzer M, Stanescu T. WE-G-WAB-07: Commissioning of a Novel Integrated Platform for Online MRIgRT. Med Phys 2013. [DOI: 10.1118/1.4815649] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Stanescu T, Tadic T, Jaffray D. WE-G-WAB-03: 4D Composite MR Image Distortion Field: Quantification and Applications for MRI-Guided Radiotherapy. Med Phys 2013. [DOI: 10.1118/1.4815645] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Stanescu T, Tadic T, Jaffray D. PO-0890: MRI-guided stereotactic body radiation therapy for liver. Radiother Oncol 2013. [DOI: 10.1016/s0167-8140(15)33196-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Stanescu T, Wachowicz K, Jaffray DA. Characterization of tissue magnetic susceptibility-induced distortions for MRIgRT. Med Phys 2012; 39:7185-93. [DOI: 10.1118/1.4764481] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Stanescu T, Chung C, Simeonov A, van Prooijen M, Millar B, Menard C. Quantification of the Magnetic Susceptibility Effects During MRI Guided Radiosurgery of Hemorrhagic Brain Metastases. Int J Radiat Oncol Biol Phys 2012. [DOI: 10.1016/j.ijrobp.2012.07.2209] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Lamey M, Carlone M, Alasti H, Bissonnette JP, Borg J, Breen S, Coolens C, Heaton R, Islam M, van Proojen M, Sharpe M, Stanescu T, Jaffray D. Poster - Thur Eve - 05: Safety systems and failure modes and effects analysis for a magnetic resonance image guided radiation therapy system. Med Phys 2012; 39:4625. [DOI: 10.1118/1.4740112] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Stanescu T, Tadic T, Moseley D, Jaffray D. TU-G-BRA-02: Development of a 4D-MRI Technique for MRgRT. Med Phys 2012. [DOI: 10.1118/1.4736006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Moseley D, Stanescu T. TH-A-BRA-03: Daily IGRT QA Phantom for MR-Guided Linacs. Med Phys 2012. [DOI: 10.1118/1.4736252] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Winter J, Carlone M, Stanescu T, Breen S, Foxcroft S, Guyot B, Dahan M, Dahdal R, Jaffray D. SU-D-213CD-06: Workflow and Safety Systems of a Linac-MR Sim-Brachytherapy MRgRT™ Facility. Med Phys 2012; 39:3618-3619. [PMID: 28517391 DOI: 10.1118/1.4734691] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE To develop the operational workflow and safety systems of a magnetic resonance-guided radiotherapy system (MRgRT™), which comprises an MR scanner on rails that travels between a linac vault, MR simulation room and brachytherapy suite. METHODS To develop a safe and streamlined clinical workflow, we conducted a comprehensive process review based on a layered approach to overall MRgRT safety that included i) facility design, (ii) workflow iii) system design and interlocks and iv) policies and procedures. We applied existing guidelines for MR and radiation safety, and employed system-level failure modes and effects analyses to design the MRgRT facility and clinical procedures. RESULTS In the MRgRT system configuration, the MR and treatment systems are physically decoupled and used independently requiring novel administration of existing MR and radiation guidelines. A key element for the safe operation of the moving MR unit is the concept that all three rooms represent zone 4 areas (American College of Radiology guidelines). Using this concept, we applied MR guidelines to develop safe procedures for the overall suite, including screening of all persons entering the suite in zone 2 and control of ferromagnetic materials. We generated a clinical workflow that ensures expedient and safe transition between MR imaging and treatment delivery in both the linac and brachytherapy rooms. In addition, we designed emergency protocols for MRgRT, which helped drive requirements for the facility and system design, e.g., need for an accessible MR-safe stretcher. CONCLUSIONS We designed the first comprehensive description of the MRgRT workflow, interlocking systems and safety procedures. With this layered approach to safety, we addressed critical aspects regarding safe operation and workflow for the system and provided multiple redundancies for key processes. Coupled with customized staff training, the proposed design ensures the safe operation of the MRgRT facility. This work has received research personnel support from IMRIS.
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Stanescu T, Jaffray D. OC-0192 MRIGRT: CHARACTERIZATION OF THE COMPOSITE MR IMAGE DISTORTION FIELD ASSOCIATED WITH ORGAN MOTION. Radiother Oncol 2012. [DOI: 10.1016/s0167-8140(12)70531-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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Lamey M, Carlone M, Alasti H, Bissonnette J, Borg J, Breen S, Coolens C, Heaton R, Islam M, Sharpe M, Stanescu T, van Prooijen M, Jaffray D. SU-E-T-252: Safety Systems and Failure Modes and Effects Analysis for a Linear Accelerator - Magnetic Resonance Imager - Brachytherapy System. Med Phys 2011. [DOI: 10.1118/1.3612203] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Stanescu T, Wachowicz K, Jaffray D. WE-G-214-04: MR Simulation Environment for MR-Guided Radiation Therapy. Med Phys 2011. [DOI: 10.1118/1.3613425] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Wachowicz K, Stanescu T, Thomas SD, Fallone BG. Implications of tissue magnetic susceptibility-related distortion on the rotating magnet in an MR-linac design. Med Phys 2010; 37:1714-21. [PMID: 20443492 DOI: 10.1118/1.3355856] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
PURPOSE One of the recently published concepts that combine the soft-tissue imaging capabilities of MRI with external beam radiotherapy involves the rigid coupling of a linac with a rotating biplanar low-field MR imaging system. While such a system would prevent possible image distortion resulting from relative motion between the magnet and the linac, the rotation of the magnet around the patient can itself introduce possibilities for image distortion that need to be addressed. While there are straightforward techniques in the literature for correcting distortions from gradient nonlinearities and nonuniform magnetic fields during image reconstruction, the correction of distortions related to tissue magnetic susceptibility is more complex. This work investigates the extent of this latter distortion type under the regime of a rotating magnetic field. METHODS CT images covering patient anatomy in the head, lung, and male pelvic regions were obtained and segmented into components of air, bone, and soft tissue. Each of these three components was assigned bulk magnetic susceptibility values in accordance with those found in the literature. A finite-difference algorithm was then implemented to solve for magnetic field distortion maps should the anatomies be placed in the uniform polarizing field of an MR system. The algorithm was repeated multiple times as the polarizing field was rotated axially about the virtual patient in 15 degrees increments. In this way, a map of maximum distortion, and the range of distortion as the magnetic field is rotated about each anatomical region could be determined. The consequence of these susceptibility distortions in terms of geometric signal shift was calculated for 0.2 T, as well as another low-field system (0.5 T), and a higher field 1.5 T system for comparison, using the assumption of a frequency encoding gradient strength of 5 mT/m. RESULTS At 0.2 T, the susceptibility-related distortion was limited to less than 0.5 mm given an encoding gradient strength of 5 mT/m or higher. To maintain this same level of geometric accuracy, the 0.5 T system would require a moderately higher minimum gradient strength of 11 mT/m, and at a typical MR field strength of 1.5 T this minimum gradient strength would increase to 33 mT/m. The influence of magnetic susceptibility on mean frequency shift as the field orientation was rotated was also investigated and found to account for less than half a millimeter at 1.5 T, and negligible for low-field systems. CONCLUSIONS A study of three sites (head, lung, and prostate) that are vulnerable to magnetic susceptibility-related distortions were studied, and showed that in the context of a rotating polarizing magnet, low-field systems can maintain geometric accuracy of 0.5 mm with at most moderate limitations on sequence parameters. This conclusion will likely apply only to endogenous tissues, as implanted materials such as titanium can create field distortions much in excess of what may normally be induced in the body. Items containing such materials (hip prostheses, for example) will require individual scrutiny.
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Fallone B, Murray B, Rathee S, Stanescu T, Steciw S, Vidakovic S, Blosser E, Tymofichuk D. TU-E-BRC-05: First MR Images Obtained During Megavoltage Photon Irradiation From An Integrated Linac-MR System. Med Phys 2009. [DOI: 10.1118/1.3182419] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Stanescu T, Wachowicz K, Fallone B. WE-C-BRB-04: MR Image Susceptibility Distortions: Quantification of Impact On the Radiation Treatment Planning of Cancer Sites. Med Phys 2009. [DOI: 10.1118/1.3182462] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Fallone BG, Murray B, Rathee S, Stanescu T, Steciw S, Vidakovic S, Blosser E, Tymofichuk D. First MR images obtained during megavoltage photon irradiation from a prototype integrated linac-MR system. Med Phys 2009; 36:2084-8. [DOI: 10.1118/1.3125662] [Citation(s) in RCA: 272] [Impact Index Per Article: 18.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Kirkby C, Stanescu T, Rathee S, Carlone M, Murray B, Fallone BG. Erratum: “Patient dosimetry for hybrid MRI-radiotherapy systems” [Med. Phys. 35, 1019-1027 (2008)]. Med Phys 2009. [DOI: 10.1118/1.3078698] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Kirkby C, Stanescu T, Fallone BG. Magnetic field effects on the energy deposition spectra of MV photon radiation. Phys Med Biol 2008; 54:243-57. [DOI: 10.1088/0031-9155/54/2/005] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Stanescu T, Kirkby C, Jans H, Wachowicz K, Rathee S, Carlone M, Murray B, Fallone G. Sci-Fri PM: Planning-02: MRI-based radiation treatment planning for an MRI-linac system. Med Phys 2008; 35:3412. [DOI: 10.1118/1.2965974] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Kirkby C, Stanescu T, Murray B, Rathee S, Carlone M, Fallone B. SU-GG-T-502: A Fast Algorithm to Predict Dose Distribution Perturbations in An MRI-Linac Hybrid System. Med Phys 2008. [DOI: 10.1118/1.2962251] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Stanescu T, Jans HS, Pervez N, Stavrev P, Fallone BG. A study on the magnetic resonance imaging (MRI)-based radiation treatment planning of intracranial lesions. Phys Med Biol 2008; 53:3579-93. [DOI: 10.1088/0031-9155/53/13/013] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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