Modeling, measurement and correction of wavefront distortion produced by breast specimens

Wavefront compensation algorithms can improve contrast resolution by folding ultrasonic scattered energy into the coherent field. Experiments reported in this paper show that contrast resolution can be restored up to -16.8 dB on average by using phase deaberration algorithms alone. Further improvement of contrast resolution requires compensation algorithms that can take refraction and strong scattering into account. Because refraction is not a stationary, stochastic process, there are two tasks required for removing its energy. The first is the recognition of which lobes of bundles of arriving energy are associated with simple scattering and which are not. Since the distribution of coherent interference energy is nonisotropic, geometric techniques may separate them from isotropic scattered energy. The technique we are experimenting with is spatial location diversity. We are able to identify image artifacts from the image lobe. The second is the removal of the refracted energy. We are currently pursuing the second task