| First MR images obtained during megavoltage photon irradiation from a prototype integrated linac-MR system. | |
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MedLine Citation:
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PMID: 19610297 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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The authors report the first magnetic resonance (MR) images produced by their prototype MR system integrated with a radiation therapy source. The prototype consists of a 6 MV linac mounted onto the open end of a biplanar 0.2 T permanent MR system which has 27.9 cm pole-to-pole opening with flat gradients (40 mT/m) running under a TMX NRC console. The distance from the magnet isocenter to the linac target is 80 cm. The authors' design has resolved the mutual interferences between the two devices such that the MR magnetic field does not interfere with the trajectory of the electron in the linac waveguide, and the radiofrequency (RF) signals from each system do not interfere with the operation of the other system. Magnetic and RF shielding calculations were performed and confirmed with appropriate measurements. The prototype is currently on a fixed gantry; however, in the very near future, the linac and MR magnet will rotate in unison such that the linac is always aimed through the opening in the biplanar magnet. MR imaging was found to be fully operational during linac irradiation and proven by imaging a phantom with conventional gradient echo sequences. Except for small changes in SNR, MR images produced during irradiation were visually and quantitatively very similar to those taken with the linac turned off. This prototype system provides proof of concept that the design has decreased the mutual interferences sufficiently to allow the development of real-time MR-guided radiotherapy. Low field-strength systems (0.2-0.5 T) have been used clinically as diagnostic tools. The task of the linac-MR system is, however, to provide MR guidance to the radiotherapy beam. Therefore, the 0.2 T field strength would provide adequate image quality for this purpose and, with the addition of fast imaging techniques, has the potential to provide 4D soft-tissue visualization not presently available in image-guided radiotherapy systems. The authors' initial design incorporates a permanent magnet; however, other types of magnets and field strengths could also be incorporated. Usable MR images were obtained during linac irradiation from the linac-MR prototype. The authors' prototype design can be used as the functional starting point in developing real-time MR guidance offering soft-tissue contrast that can be coupled with tumor tracking for real-time adaptive radiotherapy. |
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Authors:
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B G Fallone; B Murray; S Rathee; T Stanescu; S Steciw; S Vidakovic; E Blosser; D Tymofichuk |
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Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't |
Journal Detail:
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Title: Medical physics Volume: 36 ISSN: 0094-2405 ISO Abbreviation: Med Phys Publication Date: 2009 Jun |
Date Detail:
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Created Date: 2009-07-20 Completed Date: 2009-08-27 Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 0425746 Medline TA: Med Phys Country: United States |
Other Details:
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Languages: eng Pagination: 2084-8 Citation Subset: IM |
Affiliation:
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Department of Medical Physics, Cross Cancer Institute, 11560 University Avenue, Edmonton, Alberta T6G 1Z2, Canada. ginofall@cancerboard.ab.ca |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Computer-Aided Design Equipment Design Equipment Failure Analysis Magnetic Resonance Imaging / instrumentation* Particle Accelerators / instrumentation* Photons / diagnostic use Pilot Projects Reproducibility of Results Sensitivity and Specificity Systems Integration |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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