Towards Diffuse Beamforming For Specular Reflectors: A Pixel-Level Reflection Tuned Apodization Scheme For Ultrasound Imaging

Abstract

In the case of typical beamforming in ultrasound imaging, apodization schemes assume a geometric delay driven diffuse reflection model and are not robust for specular reflections. Conversely, the beamforming schemes exclusive to emphasizing specularity suppress the diffuse reflections and speckles. This results in separate beamforming modes for normal tissue scanning and specular reflectors like needles. However, most tissue reflections compose of both diffuse and specular components and a synergistic approach is important. Towards this, a novel approach called reflection tuned apodization (RTA) using coherent plane-wave compounding is proposed, where the apodization window is aligned appropriately by analyzing the reflections from the transmitted plane wave angles for each pixel. A reflection similarity measure is estimated from the plane wave angles to differentiate and characterize the tissue reflections. The beamforming results with the proposed RTA on experimental data show a remarkable improvement in the visibility of specular regions without the suppression of diffuse reflections and speckles compared to the conventional apodization approach.