Results of theoretical and experimental research on development of the radio tomography method are presented. An emphasis is on the problem of localization of radiation interaction with a medium. Combined use of the physical and mathematical focusing is proposed for solution of the problem. High efficiency of the proposed approach for inhomogeneous medium tomography is demonstrated experimentally with the use of two sensing schemes: in transmitted and reflected light, as well as multiposition and multifrequency sensing. About 1 cm resolution is achieved for test and real inhomogeneities.