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Monte Carlo Modeling of the ELEKTA VersaHD with the Agility Collimator

H Parenica*, N Kirby , K Rasmussen , D Saenz , M Fakhreddine , N Papanikolaou , S Stathakis , UT Health San Antonio, San Antonio, TX


(Sunday, 7/29/2018) 3:00 PM - 6:00 PM

Room: Exhibit Hall

Purpose: To develop and validate a Monte Carlo model of the ELEKTA VersaHD linear accelerator to be used for patient dose calculations.

Methods: Commissioning measurements were performed using a PTW microDiamond chamber in water for field sizes ranging from 1.0x1.0 cm², to 30.0x30.0 cm². For the initial comparison, phase-space files for the ELEKTA VersaHD 6 MV photon beams were created for 5.0x5.0 cm², 10.0x10.0 cm² and 20.0x20.0 cm² using EGSnrc/BEAMnrc user codes. A water phantom was created in DOSXYZnrc with dimensions of 30 x 30 x 30 cm³ and voxel resolution of 2.0 mm in the x and y direction and 0.2-0.5 mm in the z direction. Beam profiles, PDD curves, and output factors were determined for each field size.

Results: All doses calculated in DOSXYZnrc had less than 1% statistical uncertainty. Percent depth-dose curves and beam profiles showed good agreement with the commissioning data. PDDs for all field sizes where within 1% of the measured values. Profiles agreed within 1% and 1 mm in the case of the 5x5 and 10x10 cm², but the agreement for the 20 x 20 cm² field was within 3% of the measured values. The simulated output factors were well within 1% of the measured values.

Conclusion: A Monte Carlo model of the ELEKTA VersaHD linear accelerator has been tested and verified against commissioning data. The results of our Monte Carlo calculations are in good agreement with the measured data. Further simulations are in progress to verify the model and improve agreement between measured and calculated data. The phase-space files produced will be used in further research for dose calculation. Overall, the Monte Carlo model created in this study is an accurate representation of the ELEKTA VersaHD.

Funding Support, Disclosures, and Conflict of Interest: This research was supported, in part, by ELEKTA.


Monte Carlo, Phase Space


TH- External beam- photons: Monte Carlo

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