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"Evaluation of 6MV Photon Beam Modeled in RayStation 5 Using Vendor-Supplied Dosimetric Data"

J Borsavage

J Borsavage1*, MD Belley1,2,3 , RA Rodgers1,2,3 , MJ Price1,2,3 (1) University of Rhode Island, Kingston, RI (2) Lifespan Cancer Institute, Providence, RI (3) Warren Alpert Medical School of Brown University, Providence, RI


SU-I-GPD-T-423 (Sunday, July 30, 2017) 3:00 PM - 6:00 PM Room: Exhibit Hall

Purpose: Evaluate the accuracy of a photon-beam model generated using a vendor-supplied beam data set to commission a TrueBeam linear accelerator in RaySearch’s RayStation 5 treatment planning system.

Methods: 6MV square fields derived from Varian’s (Varian Medical Systems, Palo Alto, CA) Golden Beam data set were imported into RayStation (RaySearch Americas Inc., Garden City, NY) for modeling: 3x3-, 4x4-, 10x10-, 20x20-, 30x30-, and 40x40-cm² PDDs and profiles. Beam modeling was carried out per vendor instruction using automodeling and further manual tuning of beam parameters to match modeled and commissioning data. Model goodness was evaluated using 1D gamma analysis (3mm/3% & 1mm/1% criteria). Predicted PDDs and profiles for a variety of field sizes were then compared to data measured by a 3D scanning water tank using 1D gamma evaluation.

Results: Gamma evaluation (1%/1mm) of modeled and vendor-supplied data resulted in 100% pass rate for deep regions of PDDs and infield regions of profiles for all fields and depths. Evaluation at 3%/3mm resulted in 100% pass rate of all comparisons. Gamma evaluation (1%/1mm) of the modeled curves and measured data (including 5x5-, 8x8- and 15x15-cm² fields not included in the vendor-supplied data set), resulted in >95% pass rates in all regions of PDDs for all fields and infield regions of profiles, excluding profiles of the largest field at shallowest depth. Evaluation at 3%/3mm produced 100% pass rate for all regions of all profiles, similarly excluding tail regions of the largest field size at depths > 20 cm.

Conclusion: Results indicate that vendor-supplied data may be potentially utilized for photon beam modeling in RayStation 5. A sensitivity analysis is being conducted to determine the threshold for the minimum amount of measured data required to model photon beams sufficiently using said data.

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