Design of a sparse planar array for optimized 3D medical ultrasound imaging

Two-dimensional apertures provide fully electronic scanning for 3D medical ultrasound imaging. The design of planar arrays with a limited number of active elements yielding real-time 3D high-quality imaging, for all beam scanning orientations, is one of the current challenges. In this paper, an innovative transmission/reception solution, that involves a compact fully sampled 256-element array as transmitter and an optimized 256-element sparse array as receiver, able to fulfill all the previous requirements, is proposed. The sparse array is made up of a thinned version of the transmitter dense array (i.e., a proper subset of elements is used both to transmit and receive) surrounded by an annular sparse off-the-grid array. Both the positions and the weights of the sparse array are jointly optimized by minimizing a novel cost function by means of simulated annealing algorithm. The proposed solution is well suited for real-time 3D imaging over 360° of azimuth and ±40° of inclination.