title: Initial characterization, dosimetric benchmark and performance validation of Dynamic Wave Arc.
abstract: BACKGROUND
  Dynamic Wave Arc (DWA) is a clinical approach designed to maximize the versatility of Vero SBRT system by synchronizing the gantry-ring noncoplanar movement with D-MLC optimization. The purpose of this study was to verify the delivery accuracy of DWA approach and to evaluate the potential dosimetric benefits.
  
  
  METHODS
  DWA is an extended form of VMAT with a continuous varying ring position. The main difference in the optimization modules of VMAT and DWA is during the angular spacing, where the DWA algorithm does not consider the gantry spacing, but only the Euclidian norm of the ring and gantry angle. A preclinical version of RayStation v4.6 (RaySearch Laboratories, Sweden) was used to create patient specific wave arc trajectories for 31 patients with various anatomical tumor regions (prostate, oligometatstatic cases, centrally-located non-small cell lung cancer (NSCLC) and locally advanced pancreatic cancer-LAPC). DWA was benchmarked against the current clinical approaches and coplanar VMAT. Each plan was evaluated with regards to dose distribution, modulation complexity (MCS), monitor units and treatment time efficiency. The delivery accuracy was evaluated using a 2D diode array that takes in consideration the multi-dimensionality of DWA during dose reconstruction.
  
  
  RESULTS
  In centrally-located NSCLC cases, DWA improved the low dose spillage with 20 %, while the target coverage was increased with 17 % compared to 3D CRT. The structures that significantly benefited from using DWA were proximal bronchus and esophagus, with the maximal dose being reduced by 17 % and 24 %, respectively. For prostate and LAPC, neither technique seemed clearly superior to the other; however, DWA reduced with more than 65 % of the delivery time over IMRT. A steeper dose gradient outside the target was observed for all treatment sites (p < 0.01) with DWA. Except the oligometastatic cases, where the DWA-MCSs indicate a higher modulation, both DWA and VMAT modalities provide plans of similar complexity. The average ɣ (3 % /3 mm) passing rate for DWA plans was 99.2 ± 1 % (range from 96.8 to 100 %).
  
  
  CONCLUSIONS
  DWA proven to be a fully functional treatment technique, allowing additional flexibility in dose shaping, while preserving dosimetrically robust delivery and treatment times comparable with coplanar VMAT.
authors.affiliation: Department of Radiotherapy, Universitair Ziekenhuis Brussel, Vrije Universiteit Brussel, Laarbeeklaan 101, B-1090, Brussels, Belgium. manuela.buleteanu@yahoo.com.|R&D Radiosurgery, BrainLAB AG, Munich, Germany. manuela.buleteanu@yahoo.com.|Babes Bolyai University, Faculty of Physics, Cluj-Napoca, Romania. manuela.buleteanu@yahoo.com.
authors.forename: Manuela
authors.initials: M
authors.lastname: Burghelea
authors.affiliation: Department of Radiotherapy, Universitair Ziekenhuis Brussel, Vrije Universiteit Brussel, Laarbeeklaan 101, B-1090, Brussels, Belgium.
authors.forename: Dirk
authors.initials: D
authors.lastname: Verellen
authors.affiliation: Department of Radiation Oncology, University Hospitals Leuven, Leuven, Belgium.
authors.forename: Kenneth
authors.initials: K
authors.lastname: Poels
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: Mitsuhiro
authors.initials: M
authors.lastname: Nakamura
authors.affiliation: Department of Radiotherapy, Universitair Ziekenhuis Brussel, Vrije Universiteit Brussel, Laarbeeklaan 101, B-1090, Brussels, Belgium.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Dhont
authors.affiliation: Department of Radiotherapy, Universitair Ziekenhuis Brussel, Vrije Universiteit Brussel, Laarbeeklaan 101, B-1090, Brussels, Belgium.
authors.forename: Thierry
authors.initials: T
authors.lastname: Gevaert
authors.affiliation: Department of Radiotherapy, Universitair Ziekenhuis Brussel, Vrije Universiteit Brussel, Laarbeeklaan 101, B-1090, Brussels, Belgium.
authors.forename: Robbe
authors.initials: R
authors.lastname: Van den Begin
authors.affiliation: Department of Radiotherapy, Universitair Ziekenhuis Brussel, Vrije Universiteit Brussel, Laarbeeklaan 101, B-1090, Brussels, Belgium.
authors.forename: Christine
authors.initials: C
authors.lastname: Collen
authors.affiliation: Department of Radiation Oncology and Image-applied Therapy, Kyoto University Graduate School of Medicine, Kyoto, Japan.
authors.forename: Yukinori
authors.initials: Y
authors.lastname: Matsuo
authors.affiliation: Department of Radiation Oncology and Image-applied Therapy, Kyoto University Graduate School of Medicine, Kyoto, Japan.
authors.forename: Takahiro
authors.initials: T
authors.lastname: Kishi
authors.affiliation: Babes Bolyai University, Faculty of Physics, Cluj-Napoca, Romania.
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, Laarbeeklaan 101, B-1090, Brussels, Belgium.
authors.forename: Mark
authors.initials: M
authors.lastname: de Ridder
mesh_terms: D000465:Algorithms; D019985:Benchmarking / Q000379:methods; D002289:Carcinoma, Non-Small-Cell Lung / Q000532:radiotherapy; D016208:Databases, Factual; D006801:Humans; D008175:Lung Neoplasms / Q000532:radiotherapy; D008297:Male; D009362:Neoplasm Metastasis; D009369:Neoplasms / Q000532:radiotherapy*; D058958:Organs at Risk; D010190:Pancreatic Neoplasms / Q000532:radiotherapy; D011471:Prostatic Neoplasms / Q000532:radiotherapy*; D011874:Radiometry / Q000379:methods*; D016634:Radiosurgery / Q000379:methods*; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods*; D015203:Reproducibility of Results; D013997:Time Factors
keywords: 2D diode dosimeter; Dynamic Wave Arc; Noncoplanar delivery