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Title
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A complementary dual-modality verification for tumor tracking on a gimbaled linac system
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Author
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Abstract
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| Background and purpose: For dynamic tracking of moving tumors, robust intra-fraction verification was required, to assure that tumor motion was properly managed during the course of radiotherapy. A dual-modality verification system, consisting of an on-board orthogonal kV and planar MV imaging device, was validated and applied retrospectively to patient data. Methods and materials: Real-time tumor tracking (RTTT) was managed by applying PAN and TILT angular corrections to the therapeutic beam using a gimbaled linac. In this study, orthogonal X-ray imaging and MV EPID fluoroscopy was acquired simultaneously. The tracking beam position was derived from respectively real-time gimbals log files and the detected field outline on EPID. For both imaging modalities, the moving target was localized by detection of an implanted fiducial. The dual-modality tracking verification was validated against a high-precision optical camera in phantom experiments and applied to clinical tracking data from a liver and two lung cancer patients. Results: Both verification modalities showed a high accuracy (<0.3 mm) during validation on phantom. Marker detection on EPID was influenced by low image contrast. For the clinical cases, gimbaled tracking showed a 90th percentile error (E90) of 3.45 (liver), 2.44 (lung A) and 3.40 mm (lung B) based on EPID fluoroscopy and good agreement with XR-log file data by an E90 of 3.13, 1.92 and 3.33 mm, respectively, during beam on. Conclusion: Dual-modality verification was successfully implemented, offering the possibility of detailed reporting on RTTT performance. (C) 2013 Elsevier Ireland Ltd. All rights reserved. |
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Language
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English
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Source (journal)
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Radiotherapy and oncology. - Amsterdam
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Publication
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Amsterdam
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2013
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ISSN
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0167-8140
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DOI
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10.1016/J.RADONC.2013.10.005
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Volume/pages
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109
:3
(2013)
, p. 469-474
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ISI
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000329482000026
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Full text (Publisher's DOI)
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