This is just a simple MC-like approach to resampling radial dose point kernels. Specifically, resampling Graves et al Medical Physics 2019 radial dose point kernels into voxel S values. Some test data is also included to show levels of agreement with prior published data.
It is generalizable to anisotropic voxel sizes, which was the original reason for writing this function. Authored by Justin Mikell with contributions from Ben Van.