For visualization in medical imaging, a hybrid volume and surface renderer uses unified path tracing. Rather than separately rasterizing the surface and path tracing the volume, a same path or set of paths is used for both the volume and the surface. The path tracing accounts for scattering by the surface as well as the volume. Given the repetition of stochastic scattering of many modeled photons or light rays, using stochastic scattering from the surface as part of the path tracing for the volume allows for two-way interaction between the surface and volume.