Application of Common Midpoint Gathers to Medical Pulse-Echo Ultrasound for Optimal Coherence and Improved Sound Speed Estimation in Layered Media

In seismic imaging, common midpoint (CMP) gathers are collections of time-series data organized by source-receiver pairs having a common midpoint. CMP gathers have been used in geophysics to image the subsurface of the Earth and estimate wave velocity as a function of depth. According to the Van Cittert-Zernike (VCZ) theorem, if the signals from a CMP gather are focused using an ideal set of delays based on the true speed of sound in the medium, there should be a perfect correlation between any two signals in the CMP gather in the absence of noise. In ultrasound imaging, Walker et al. have applied this concept to translating transmit and receive apertures. The goal of this work is to apply CMP gathers to pulse-echo ultrasound imaging in order to improve coherence-based sound speed estimation in layered media.