Phase aberrations correction: application to in-vivo bone images

The aim of the study is to present a phase aberration correction method in the Calcaneus bone. We used a QUS transmission device, the BEAM Scanner which is based on a matrix technology of 24×24 elements, at 500 kHz central frequency. Strong hypothesis are made at the beginning : the aberrating medium is modelled as an homogeneous and thin phase aberrating screen close to the emitter transducers. The objective is to reconstitute a spherical wave front which is the base hypothesis of the beam forming process applied in homogenous medium (wave celerity=C_water). We rephased bone signals acquired inside the acoustical aperture. The method of cross-correlation between neighbouring elements in the aperture allowed to retrieve, in most cases, a quasi-spherical wave front. Nevertheless, when the bone volume investigated by the acquisition aperture integrates important heterogeneity, the method reaches its limit and does not improve the reconstructed image.