A new GPU-based Monte Carlo code for helium ion therapy.

purposeThis work presents an effort to extend the capabilities of the previously introduced GPU-based Monte Carlo code ARCHER for helium ion therapy.

methodsARCHER performs helium ion transport simulations in voxelized geometry, covering kinetic energy levels up to 220 MeV/u. The physical processes are modeled using a class II condensed-history algorithm, considering ionization, energy straggling, multiple scattering, and elastic and inelastic nuclear interactions. A new nuclear-event-repeat algorithm is proposed to generate inelastic nuclear reaction products. Secondary protons, deuterons, tritons, and

resultsDose distribution comparisons demonstrate strong agreement between our code and TOPAS. The mean point-by-point local relative errors in the region where the dose exceeds 10% of the maximum dose range from 0.25% to 1.31% for all phantoms. In the strict 1%/1 mm criterion, gamma passing rates for a head-neck case, chest case, and prostate case are 99.8%, 96.9%, and 99.6%, respectively. Except for the lung phantom, ARCHER takes less than 10 s to simulate 10 million primary helium ions using a single NVIDIA GeForce RTX 3080 card (NVIDIA Corporation, Santa Clara, USA), while TOPAS requires several minutes on a computational platform with two Intel Xeon Gold 6348 CPUs (Intel Corporation, Santa Clara, USA) with 56 cores.

conclusionThis work presents the development and benchmarking of the first GPU-based dose engine for helium ion therapy. The code has been proven to achieve high levels of accuracy and efficiency.