GPUMCD: A new GPU‐oriented Monte Carlo dose calculation platform

Abstract

Purpose:Monte Carlo methods are considered as the gold standard for dosimetric computations in radiotherapy. Their execution time is, however, still an obstacle to the routine use of Monte Carlo packages in a clinical setting. To address this problem, a completely new, and designed from the ground up for the GPU, Monte Carlo dose calculation package for voxelized geometries is proposed:GPUMCD.Method:GPUMCDimplements a coupled photon‐electron Monte Carlo simulation for energies in the range of 0.01–20 MeV. An analog simulation of photon interactions is used and a class II condensed history method has been implemented for the simulation of electrons. A new GPU random number generator, some divergence reduction methods, as well as other optimization strategies are also described.GPUMCDwas run on a NVIDIA GTX480, while single threaded implementations of EGSnrc andDPMwere run on an Intel Core i7 860.Results:Dosimetric results obtained withGPUMCDwere compared to EGSnrc. In all but one test case, 98% or more of all significant voxels passed the gamma criteria of 2%‐2 mm. In terms of execution speed and efficiency,GPUMCDis more than 900 times faster than EGSnrc and more than 200 times faster thanDPM, a Monte Carlo package aiming fast executions. Absolute execution times of less than 0.3 s are found for the simulation of 1M electrons and 4M photons in water for monoenergetic beams of 15 MeV, including GPU‐CPU memory transfers.Conclusion:GPUMCD, a new GPU‐oriented Monte Carlo dose calculation platform, has been compared to EGSnrc andDPMin terms of dosimetric results and execution speed. Its accuracy and speed make it an interesting solution for full Monte Carlo dose calculation in radiation oncology.