High volume rate 3D ultrasound imaging based on synthetic aperture sequential beamforming

Synthetic aperture sequential beamforming (SASB) is a two-stage process, with fixed transmit and receive beamforming in the first stage, followed by dynamic receive beamforming in the second stage. Compared to 3D synthetic aperture ultrasound (SAU) imaging, 3D SASB has low computational complexity at the front-end, making it suitable for portable devices. Unfortunately, 3D SASB has low volume rate since typically only one subaperture transmits and receives at a time. To increase the volume rate, we propose to transmit and receive multiple subapertures simultaneously. A straight-forward implementation of such a scheme, for even four simultaneous firings, results in an increase in grating lobe and sidelobe levels. To address these issues, we use bin-based random sparse array to reduce the grating lobes caused by the three other transmits, and then optimize the locations of the active receive elements to minimize the sidelobe. Compared to a contemporary 3D SASB method, the proposed multiple-firing sparse array method increases the volume rate from 11 to 45 volumes per second, without increasing computational complexity at the front-end and with only a small degradation in imaging quality.