The possibility to obtain imaging of biological tissues by using visible or NIR radiation is widely investigated. One of the most studied problems is breast imaging, since it is desirable to have a non invasive method, alternative to x-ray mammography, to be used for early detection of tumors. Biological tissues are highly scattering media and photon migration occurs with many scattering events. Therefore trajectories of photons can vary greatly from straight lines causing a decrease in contrast and in spatial resolution. Some methods to improve imaging have been developed based on measurements both in the time domain and in the frequency domain1-5. The purpose of this work was to determine, by means of numerical simulations, the effect of a discrete inhomogeneity on photons migrating through an otherwise homogeneous slab of diffusers. The slab was assumed as a simple model for a breast compressed between two plane parallel plates. The presence of a tumor was simulated with an absorbing sphere. The image of the inhomogeneity was obtained moving a coaxial source-receiver system with respect to the inhomogeneity and plotting some parameters related to the received signal.
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