Estimation of a-priori using photon measurement density function to improve the ill-posedness of diffuse optical tomography reconstruction

The inverse problem of diffused optical tomography is highly ill-posed as well as often nonunique and unstable. The ill-posedness can be reduced by reducing the number of unknown values (i.e., adding soft or hard-prior). In this paper, the a-priori or the location of inhomogeneities is estimated by using photon measurement density function (PMDF) and steady state boundary measurements. The PMDF is calculated using perturbation method and then the intensity deviation from the homogeneous phantom is backprojected for each source-detector pair. Summation of all the backprojected data for each element followed by a low pass filter gives the pseudo map of the absorption coefficient. The region of inclusions is extracted and this a-priori is used in the model based iterative reconstruction method. Simulation results with different inclusions are illustrated to show the potential of the proposed method. Use of steady state measurement and single imaging modality make the system inexpensive as well.