A fast tube of response ray-tracer.

A ray-tracing algorithm is proposed to quickly approximate volumes of intersection between an arbitrary tube of response and a voxel array. The method is based on the idea of the Wu antialiased line tracer that is well known in the computer graphics community. However, our method works in three dimensions and supports arbitrary symmetrical response profile functions. The inner loop implementation does not use any conditional branching and is aware of low-level optimization strategies. The running speed of a fast incremental Siddon routine appears to be about 60% slower than our algorithm.