J Martinez*, H Soysal, C Yang, University of Mississippi Medical Center, Jackson, MS

• 
  J Martinez

PO-GePV-T-234 (Sunday, 7/25/2021)   [Eastern Time (GMT-4)]

Purpose: To determine if there is any significant difference between two different dose calculation algorithms of two different treatment planning systems.

Methods: Five Head and Neck VMAT plans generated in RayStation (version 9A) using collapsed cone algorithm were exported to and recalculated in Monaco (version 5.11.02) treatment planning system using Monte Carlo dose calculation algorithm. The five plans consisted of two arcs and each were recalculated on a Delta 4 QA phantom (Delta 4) with a voxel size of 3 mm. These calculated plans were compared to measurements using Delta 4. RayStation and Monaco algorithms were commissioned for an Elekta Versa HD Linac with Agility MLC and for 6 MV and 6 MV FFF photon beams. Point-dose measurements using a CC13 ion chamber in a large water tank were also taken to compare RayStation and Monaco calculated values.

Results: Using 1% for the dose difference and 2mm for the DTA, the gamma analysis for the composite fields using Monaco was 94.0%, while for the convoluted cone was 90.3%. The two-tailed P value equals 0.037, which is statistically significant. Increasing up to 3% in dose difference and 3 mm in DTA, there was no statistically significant difference between the two calculations compared to measurements. For the point-dose measurements, RayStation showed less than 0.3% for different points, while Monaco showed 0.6% for 6 MV. For 6 MV FFF, Raystation showed 0.05% and Monaco 0.20% agreement for 17 different fields.

Conclusion: The beam models in Monaco and RayStation are comparable when compared to point dose measurements. Monaco may generate a better dose agreement with measurement when using a tighter QA passing criteria than RayStation. However, they do not show a statistically significant difference in agreement between calculation and measurement when using the common passing criteria of 3% and 3 mm.

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Keywords

Not Applicable / None Entered.

Taxonomy

TH- External Beam- Photons: Computational dosimetry engines- Monte Carlo

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