Nonuniqueness in optical tomography: relevance of the P1 approximation

The question of whether a unique distribution of the absorption coefficient, the scattering coefficient, and the refractive index of a turbid medium can be reconstructed by optical tomography is considered. A recent publication [Opt. Lett. 23, 882 (1998)] established that such reconstruction is not possible when photon transport is well modeled by the diffusion equation. A simple proof is offered that, when measurements at high modulation frequencies are included, the more exact P1 model of light transport suggests that this reconstruction may be possible.