Time-domain laser mammography: separation of scattering and absorption contributions

A technique for properly separating the scattering and absorption contributions in laser mammography is proposed. The technique is based on an empirical model obtained from a series of experiments performed on homogeneous scattering slabs containing a single inclusion. The scattering and absorption contributions are obtained by performing a Fit of an Inhomogeneous Diffusion Model (FIDM). The performance of this new technique is compared to that involving a curve fit of the solution of the diffusion model for a homogeneous slab. The FIDM technique allows a very good discrimination between scattering and absorption inclusions, better than that obtained with a curve fit of the homogeneous diffusion model. The mathematical expressions of the empirical model are extremely simple and allow far a fast calculation (about 1 second for computing two 441 pixel images compared to about 6 minutes with the previous technique). A perturbation analysis of the diffusion model will provide theoretical support to the FIDM technique and should allow its refinement. Although it has not been demonstrated that the separation between absorption and scattering is totally correct when applied to real breast scanning, the method associates some structures to absorption and some other to scattering, which could result in a better specificity of laser mammography.