Identification of inhomogeneities is one of the main problems in medical diagnosis, particularly in tissue characterization. Often the backscatter signal does not permit discrimination between inhomogeneities in the tissue. Despite high effectiveness of the B-mode diagnostic systems, at the present time ultrasonography does not provide a sufficient degree of diagnostic confidence in identification of pathology. Diffraction tomography promises to extend these observations quantitatively and provide information about tissue properties. The main goal of this work is to present a theoretical basis of the scattering process on inhomogeneities and provide some preliminary experimental results confirming theoretical investigations and numerical simulations. The method of integral equations for solving forward and inverse scattering problems is used, and scattering diagrams are presented. Experimental setup is based on one transmitting and seven receiving elements. Presented experimental resuls support numerical simulations.