Virtual Particle Based Monte Carlo Dose Calculation for Charged Particle Therapy Treatment Planning

A method for generating treatment plan data for use with a charged particle therapy system, the method comprising:

• (a) loading to a shared memory of a graphics processing unit (GPU):
• a pre-calculated continuous-slowing-down-approximation (CSDA) model comprising probability distribution functions (PDFs) of physics parameters associated with soft particle interactions of virtual particles;
• a pre-calculated ionization model comprising PDFs of physics parameters associated with ionization of virtual particles;
• and
• a pre-calculated large angle scattering event (LAE) model comprising PDFs of physics parameters associated with hard particle interactions of virtual particles;
• (b) simulating virtual particles using the GPU, wherein simulating the virtual particles comprises simulating both primary charged particles and secondary particles as virtual particles that start at a same starting location of a primary charged particle by assigning each virtual particle to a thread of the GPU thereby minimizing thread divergence and racing conditions in the GPU, and in each of a plurality of steps:
• calculating a phase space for each virtual particle based on at least one of the CSDA model, the ionization model, or the LAE model;
• and
• updating each virtual particle based on its calculated phase space;
• (c) generating dose distribution data based on dose scoring the simulated virtual particles using a computer system;
• and
• (d) storing the dose distribution data as part of treatment plan data for use with a charged particle therapy system.