Ultrasound imaging using SPOMA: Simultaneous Plane-waves with genetic algorithm Optimization and fast delay-multiply-and-sum Multiple Acquisitions

Ultrasound imaging in industrial and NDT applications is an important tool for diagnosis and monitoring. Reducing signal acquisition time is often desirable to, e.g., lower the costs of inspection campaigns, such as in long oil pipelines. Nevertheless, even fast imaging algorithms such as Coherence Plane-Wave Compounding (CPWC) require a fair amount of data, which typically lengthens inspection times. In this paper, we propose an inspection scheme in which plane-waves with different angles are emitted simultaneously in order to further reduce the acquisition time. Using coded excitation in the emission and filter banks in the reception, the signals can be separated for subsequent processing as if they were emitted at different instants. To design both signal shapes and matched filters, we developed a procedure that minimizes the sidelobes of the auto- and cross-correlation using a genetic algorithm. The proposed scheme is denoted by Simultaneous Plane-waves with genetic algorithm Optimization and fast delay-multiply-and-sum Multiple Acquisitions (SPOMA). Results show that the proposed genetic algorithm outperforms other methods from the literature in terms of sidelobe minimization in the simultaneous ultrasound field. Due to hardware limitations in the ultrasound system, the emitted signals could not be generated as arbitrarily as desired, constraining the sidelobe minimization and resulting in artifacts in the reconstructed image. To address these artifacts, a combination of CPWC-delayed samples, spatial apodization, and fast delay-multiply-and-sum techniques was employed, yielding a trade-off between image quality and acquisition time, while keeping the computational cost of post-processing low. Experimental results show that the proposed SPOMA scheme achieves better image quality using less acquisition time when compared to conventional non-simultaneous plane-wave imaging.