FPGA based Adaptive Receive Apodization Design for Diagnostic Ultrasound Imaging

Field programmable gate array (FPGA) implementation of delay and sum beamforming (DASB) for ultrasound (US) imaging systems has been proposed in the literature. However, the homogeneous diffuse assumption in estimating receive sensor weights in DASB is violated for specular reflectors like bones or needles in guided interventions which generate highly directive reflections challenging their visualization in the US images. To address this, apodization coefficients need to be dynamically determined according to reflection directivity. This work introduces a novel approach called raster apodization design (RAD) to dynamically adjust apodization coefficients at the pixel level on hardware, taking into account the directivity of reflections. RAD allows for the simultaneous estimation of apodization coefficients for all pixels at a fixed depth, resembling a raster scan while reusing a single apodization window. The design is implemented on a Xilinx XCZ7010clg400-1 FPGA and compares resource and power estimates at pixel level and for a region of interest. A comparison of the performance of DASB with hardware and software RAD coefficients is also illustrated to emphasize the accuracy and efficiency of the proposed design.