Parallel adaptive finite element simulation for optical molecular imaging with simplified spherical harmonics approximation

Whole-body optical molecular imaging is rapidly developing for preclinical research. It is essential and necessary to develop novel simulation methods of light propagation for optical imaging, especially when a priori knowledge, large-volume domain and wide-range optical properties need to be considered in the reconstruction algorithm. In this paper, we develop a three dimensional parallel adaptive finite element method with simplified spherical harmonics (SPN) approximation to simulate photon propagation in large-volume heterogeneous tissues. Simulation speed is significantly improved by a posteriori parallel adaptive mesh refinement and dynamic mesh repartitioning. Compared with the diffusion equation, SPN method shows improved performance and the necessity of high-order approximation in heterogeneous domains. Optimal solver selection and time-costing analysis in real mouse geometry further improve the performance of the proposed algorithm.