title: Geometric Verification of Dynamic Wave Arc Delivery With the Vero System Using Orthogonal X-ray Fluoroscopic Imaging.
abstract: OBJECTIVE
  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
  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° with 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°.
authors.affiliation: Department of Radiotherapy, Universitair Ziekenhuis Brussel, Vrije Universiteit Brussel, Brussels, Belgium; Faculty of Physics, Babes Bolyai University, Cluj-Napoca, Romania; R&D Radiosurgery, BrainLAB AG, Munich, Germany. Electronic address: manuela.buleteanu@yahoo.com.
authors.forename: Manuela
authors.initials: M
authors.lastname: Burghelea
authors.affiliation: Department of Radiotherapy, Universitair Ziekenhuis Brussel, Vrije Universiteit Brussel, Brussels, Belgium.
authors.forename: Dirk
authors.initials: D
authors.lastname: Verellen
authors.affiliation: Department of Radiotherapy, Universitair Ziekenhuis Brussel, Vrije Universiteit Brussel, Brussels, Belgium.
authors.forename: Kenneth
authors.initials: K
authors.lastname: Poels
authors.affiliation: Department of Radiotherapy, Universitair Ziekenhuis Brussel, Vrije Universiteit Brussel, Brussels, Belgium.
authors.forename: Thierry
authors.initials: T
authors.lastname: Gevaert
authors.affiliation: Department of Radiation Oncology, University Hospitals Leuven, Leuven, Belgium.
authors.forename: Tom
authors.initials: T
authors.lastname: Depuydt
authors.affiliation: Department of Radiotherapy, Universitair Ziekenhuis Brussel, Vrije Universiteit Brussel, Brussels, Belgium.
authors.forename: Koen
authors.initials: K
authors.lastname: Tournel
authors.affiliation: R&D Radiosurgery, BrainLAB AG, Munich, Germany.
authors.forename: Cecilia
authors.initials: C
authors.lastname: Hung
authors.affiliation: Department of Radiation Oncology and Image-applied Therapy, Kyoto University Graduate School of Medicine, Kyoto, Japan.
authors.forename: Viorica
authors.initials: V
authors.lastname: Simon
authors.affiliation: Department of Radiation Oncology and Image-applied Therapy, Kyoto University Graduate School of Medicine, Kyoto, Japan.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Hiraoka
authors.affiliation: Department of Radiotherapy, Universitair Ziekenhuis Brussel, Vrije Universiteit Brussel, Brussels, Belgium.
authors.forename: Mark
authors.initials: M
authors.lastname: de Ridder
mesh_terms: D000465:Algorithms; D002138:Calibration; D003952:Diagnostic Imaging; D004867:Equipment Design; D005471:Fluoroscopy; D006801:Humans; D019047:Phantoms, Imaging; D061089:Radiotherapy, Image-Guided / Q000295:instrumentation* / Q000379:methods; D050397:Radiotherapy, Intensity-Modulated / Q000295:instrumentation* / Q000379:methods; D012399:Rotation; D012680:Sensitivity and Specificity