2D noninvasive acoustical image reconstruction of a static object through a simulated human skull bone

A new method for 2D visualization of foreign objects in the brain tissue, such as bone fragments, bullets, pieces of shrapnel, etc. is presented. The method uses acoustic ray tracing approach to model the propagation of ultrasonic waves through the skull bone and the brain tissue. The mathematical theory of the method, the preliminary results of computer modeling and laboratory testing are presented. A simulation has been developed to take into account the scattering of acoustical fields transmitted through a human skull bone. The experimental data is processed and an image showing the position of the foreign object is reconstructed. The new algorithm has been designed to work with a linear array of 128 receivers. The model consists of a simulated skull bone (scattering medium) and a reflector as a secondary source of ultrasound. To experimentally check the validity of the algorithm, a skull phantom was prepared for use in the laboratory tests. After passing through the phantom layer, the secondary ultrasound field originated from the reflector is recorded by the array of receivers. Then, the detected field distribution is signal-processed to compensate for the distortion by the scattering layer and to reconstruct an image containing data about the reflector´s position. This method opens the possibility to non-invasively visualize and characterize the inclusions in the brain tissue through the skull.