Monte Carlo is the recognized *gold standard* computation method for accurate dose calculation across all situations encountered in radiation therapy. Extensive validation ensures Radyalis simulated dose accuracy is within 2%/2mm Gamma agreement with Geant4 10.3.

Shown below are two comparisons between Radyalis *Plum* Monte Carlo and Geant4 for difficult multiple-material cases for photon and proton beams hitting exactly at the material interface. We show a cross-section of the phantom being simulated (upper left), a plot comparing the dose contours of *Plum* and Geant4 (middle), and a variety of 1D projections and error metrics (right).

- Photon Simulation Example:

For this case, 95% of the voxels are better than a 2%/2mm Gamma of 0.755, and 99% of the voxels are better than 0.910.

2. Proton Simulation Example:

For this case, 95% of the voxels are better than a 2%/2mm Gamma of 0.894, and 99% of the voxels are better than 1.114.