Program Information
Commissioning VMAT with Jaw Tracking in the Raystation Treatment Planning System for a Varian TrueBeam
J Pursley*, Massachusetts General Hospital and Harvard Medical School, Boston, MA
Presentations
TU-C1-GePD-TT-1 (Tuesday, August 1, 2017) 9:30 AM - 10:00 AM Room: Therapy ePoster Theater
Purpose: Jaw tracking has been shown to reduce doses to organs at risk in IMRT and VMAT plans developed in the Eclipse treatment planning system. The purpose of this study was to demonstrate a similar effect for VMAT plans developed in the Raystation treatment planning system, and to confirm accurate dose calculation and delivery of jaw tracking VMAT plans on a Varian TrueBeam with 120 Millennium MLCs.
Methods: Two beam models in Raystation 5.0 were created, one with jaw tracking enabled and one with it disabled. Ten test patient VMAT plans for a variety of sites were created with both beam models using multi-criteria optimization for planning. After final dose computation, deliverable plans with and without jaw tracking were compared by dose-volume histogram metrics. Plans were delivered on a TrueBeam and measured with two QA devices, the ArcCHECK from Sun Nuclear Corporation and COMPASS from IBA Dosimetry. Remaining VMAT commissioning tests were performed using the beam model with jaw tracking enabled.
Results: Raystation 5.0 generated clinically acceptable and deliverable VMAT plans both with and without jaw tracking. Plans generated with jaw tracking enabled showed reduced doses to organs at risk compared to plans generated without jaw tracking, with the reductions primarily occurring in low-dose regions. Patient-specific QA measurements with the ArcCHECK device showed good agreement with the treatment planning system prediction. Patient- and structure-specific 3D QA measurements with gantry-mounted COMPASS also showed good agreement.
Conclusion: VMAT with jaw tracking enabled was successfully modeled in Raystation 5.0 for a Varian TrueBeam. The dosimetric improvements in VMAT plans with jaw tracking in Raystation 5.0 were similar to results previously seen with the Eclipse planning system.
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