Improving Signal-to-Noise Ratio and Field of View of Ultrasound CT Images by Using a Virtual Sound Source

Abstract

As a non-invasive, quantitative, and multi-index medical-imaging technology, ultrasound computed tomography (USCT) is very promising to be applied to early screening for breast cancer. A recently developed USCT prototype using a ring array can realize fully directional scanning, which is suitable for reconstructing sectional images from the transmission signal. However, its field of view, signal-to-noise (S/N) ratio, and accuracy for conventional incident patterns of plane-wave and spherical-wave are limited. We proposed a virtual-source incident pattern, formed by adjusting emission channels and focusing distance. It combines the merits of traditional plane-wave and spherical-wave while avoiding their demerits, and is experimentally shown to be effective for enlarging field of view while maintaining high S/N ratio and accuracy. Compared with the traditional patterns, the proposed virtual-source incident pattern makes it possible to expand applicable ranges of measurement conditions while using the same USCT hardware for imaging larger objects with higher attenuation.