Results for GPU-based MC Dose Calculation 30 Case # Source type # of Histories Stan Dev CPU (%) Stan Dev GPU (%) T CPU (min) T GPU (min) T CPU /T GPU 1Electron10 7 0.660.658.31.84.5 2Photon10 9 0.41 94175.5 ~5x speedup compared to an Intel Xeon 2.27 GHz CPU < 3 min for 1% sigma for photon beams