Initial development of goCMC: a GPU-oriented fast cross-platform Monte Carlo engine for carbon ion therapy

Area of Science:

• Medical Physics
• Computational Biology
• Radiotherapy

Background:

• Monte Carlo (MC) simulation is the gold standard for accurate absorbed dose and biological effect calculations in carbon ion therapy.
• Existing MC methods face computational efficiency challenges, limiting their widespread clinical adoption.
• The development of faster simulation tools is crucial for advancing carbon ion therapy research and application.

Purpose of the Study:

• To develop a GPU-oriented fast Monte Carlo package, goCMC, to improve the computational efficiency of carbon ion therapy simulations.
• To validate the accuracy and efficiency of goCMC against established simulation tools like Geant4.
• To assess the portability and performance of goCMC across different hardware platforms (GPUs and CPUs).

Main Methods:

• Developed goCMC using an OpenCL framework for GPU and multi-core CPU compatibility.
• Implemented a Class II condensed history simulation scheme with continuous slowing down approximation, modeling energy straggling, multiple scattering, and δ-electron deposition.
• Incorporated four types of nuclear interactions (C-H, C-C, C-O, C-Ca) using Geant4 cross-section data and sampled secondary particle distributions.

Main Results:

• goCMC demonstrated good agreement with Geant4 in dose distributions and range estimations across various phantom types and a patient case.
• Mean relative statistical uncertainty was below 1% in regions with >10% maximum dose.
• 3D gamma passing rates achieved >90% (1%/1 mm) and >96% (2%/1 mm) criteria, indicating high accuracy.

Conclusions:

• goCMC significantly improves computational efficiency for carbon ion therapy simulations, with computation times substantially reduced on GPUs compared to CPUs.
• The package exhibits high accuracy, validated against Geant4, ensuring reliable dose calculations.
• goCMC's combined accuracy, efficiency, and portability make it a valuable tool for both research and clinical applications in carbon ion therapy.