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Monte Carlo Modeling and Patient Dose Calculation Using DOSXYZnrc for the ELEKTA Versa HD with the Agility Collimator

H Parenica1*, C Kabat1 , K Fischer1 , N Kirby1 , K Rasmussen1 , D Saenz1 , P Myers1 , P Mavroidis2 , N Papanikolaou1 , S Stathakis1 , (1) UT Health Science Center San Antonio, San Antonio, TX, (2) Univ North Carolina, Chapel Hill, NC


(Sunday, 7/14/2019)  

Room: ePoster Forums

Purpose: To develop and validate a Monte Carlo model of the ELEKTA VersaHD linear accelerator and calculate dose in a patient with this model.

Methods: For the initial comparison, phase-space files for the ELEKTA VersaHD 6 MV photon beams were created for 5.0x5.0, 10.0x10.0 and 20.0x20.0 cm² using EGSnrc/BEAMnrc user codes. Beam profiles, PDD curves, and output factors were determined for each field size in DOSXYZnrc, and compared to commissioning measurements. In the Pinnacle Treatment Planning System (TPS), a patient treated with a 6 MV PA beam was selected for dose calculation in DOSXYZnrc. A phantom was created from the patient CT using the ctcreate code, and the dose for the 6 MV PA beam was calculated in DOSXYZnrc. Dose distributions from Pinnacle and DOSXYZnrc were compared using MATLAB.

Results: All doses calculated in DOSXYZnrc had less than 1% statistical uncertainty. PDDs for all field sizes were within 1% of the measured values. Profiles agreed within 1% and 1mm in the case of the 5.0x5.0 and 10.0x10.0 cm², but the agreement for the 20.0 x 20.0 cm² field was within 2% of the measured values. Dose calculated for the patient plan in DOSXYZnrc showed good agreement with the dose calculated in Pinnacle.

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 and the patient dose calculated in Pinnacle. This model is being further developed to simulate more complex treatment plans (e.g. VMAT). 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 is supported by the Cancer Prevention and Research Institute of Texas Research Training Award (RP170345).


Monte Carlo, EGS4, Modeling


TH- External beam- photons: Monte Carlo

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