Detection of heterogeneities embedded within a turbid slab media using time- and frequency-domain methods: application to the mammography

During the last decade, several methods have been devoted to the detection and imaging of tumor-like objects embedded in turbid slab media. Optical methods are broadly investigated as potential non-invasive medical diagnosis used for the detection of tumors. In this paper, we model the photon migration due to a pulsed source laser, through a multiple scattering slab to locate and characterize heterogeneities of different optical properties. The time-dependent diffusion equation is used and solved by means of a finite element model, taking into account air-tissue boundary conditions. The transmitted time-spectra associated to their Fast Fourier Transforms are used to detect embedded objects within diffusive slab media. We show that for an inclusion of identical scattering coefficient to the surrounding medium, the phase shift increases as the absorption coefficient of the inclusion is increased. For a homogeneous absorption, the phase shift is very sensitive to local variations in scattering properties. We then compare these results with those reported by other workers and conclude that the computational model allows the lateral detection of these inclusions, so it should be possible to enhance the detection of a malignant tumor surrounded by the healthy breast tissue.