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Title: Geometric Verification of Dynamic Wave Arc Delivery With the Vero System Using Orthogonal X-ray Fluoroscopic Imaging

Purpose: The purpose of this study was to define an independent verification method based on on-board orthogonal fluoroscopy to determine the geometric accuracy of synchronized gantry–ring (G/R) rotations during dynamic wave arc (DWA) delivery available on the Vero system. Methods and Materials: A verification method for DWA was developed to calculate O-ring-gantry (G/R) positional information from ball-bearing positions retrieved from fluoroscopic images of a cubic phantom acquired during DWA delivery. Different noncoplanar trajectories were generated in order to investigate the influence of path complexity on delivery accuracy. The G/R positions detected from the fluoroscopy images (DetPositions) were benchmarked against the G/R angulations retrieved from the control points (CP) of the DWA RT plan and the DWA log files recorded by the treatment console during DWA delivery (LogActed). The G/R rotational accuracy was quantified as the mean absolute deviation ± standard deviation. The maximum G/R absolute deviation was calculated as the maximum 3-dimensional distance between the CP and the closest DetPositions. Results: In the CP versus DetPositions comparison, an overall mean G/R deviation of 0.13°/0.16° ± 0.16°/0.16° was obtained, with a maximum G/R deviation of 0.6°/0.2°. For the LogActed versus DetPositions evaluation, the overall mean deviation was 0.08°/0.15° ± 0.10°/0.10° withmore » a maximum G/R of 0.3°/0.4°. The largest decoupled deviations registered for gantry and ring were 0.6° and 0.4° respectively. No directional dependence was observed between clockwise and counterclockwise rotations. Doubling the dose resulted in a double number of detected points around each CP, and an angular deviation reduction in all cases. Conclusions: An independent geometric quality assurance approach was developed for DWA delivery verification and was successfully applied on diverse trajectories. Results showed that the Vero system is capable of following complex G/R trajectories with maximum deviations during DWA below 0.6°.« less
Authors:
 [1] ;  [2] ;  [3] ; ; ;  [1] ;  [4] ;  [1] ;  [5] ; ;  [6] ;  [1]
  1. Department of Radiotherapy, Universitair Ziekenhuis Brussel, Vrije Universiteit Brussel, Brussels (Belgium)
  2. (Romania)
  3. (Germany)
  4. Department of Radiation Oncology, University Hospitals Leuven, Leuven (Belgium)
  5. R&D Radiosurgery, BrainLAB AG, Munich (Germany)
  6. Department of Radiation Oncology and Image-applied Therapy, Kyoto University Graduate School of Medicine, Kyoto (Japan)
Publication Date:
OSTI Identifier:
22462369
Resource Type:
Journal Article
Resource Relation:
Journal Name: International Journal of Radiation Oncology, Biology and Physics; Journal Volume: 92; Journal Issue: 4; Other Information: Copyright (c) 2015 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
62 RADIOLOGY AND NUCLEAR MEDICINE; ACCURACY; BALL BEARINGS; COMPARATIVE EVALUATIONS; DELIVERY; FLUOROSCOPY; GEOMETRY; PHANTOMS; QUALITY ASSURANCE; RADIATION DOSES; ROTATION; THREE-DIMENSIONAL CALCULATIONS; VERIFICATION; X RADIATION