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01.12.2016 | Methodology | Ausgabe 1/2016 Open Access

Radiation Oncology 1/2016

Initial characterization, dosimetric benchmark and performance validation of Dynamic Wave Arc

Zeitschrift:
Radiation Oncology > Ausgabe 1/2016
Autoren:
Manuela Burghelea, Dirk Verellen, Kenneth Poels, Cecilia Hung, Mitsuhiro Nakamura, Jennifer Dhont, Thierry Gevaert, Robbe Van den Begin, Christine Collen, Yukinori Matsuo, Takahiro Kishi, Viorica Simon, Masahiro Hiraoka, Mark de Ridder
Wichtige Hinweise

Electronic supplementary material

The online version of this article (doi:10.​1186/​s13014-016-0633-7) contains supplementary material, which is available to authorized users.

Competing interests

This collaborative work was supported by the Flemish government through the Hercules foundation and corporate funding from BrainLAB AG. This research was supported in part by the Practical Research for Innovative Cancer Control (15Ack0106151h0001) from Japan Agency for Medical Research and Development, AMED. MB and CH are financially supported by BrainLAB AG. The other authors have no conflict of interest.

Authors’ contributions

MB participated in the conception and design, the acquisition, analysis and interpretation of the data and drafted the manuscript. DV, CH and KP participated in the study design, interpreted data and revised the manuscript critically. MN and TK participated in the data acquisition. RVDB, CC and YM participated in patient selection and results discussion. JD, TG and VS revised the manuscript critically. All authors read and approved the final manuscript.

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.
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