Cortical Bone Ultrasonic Imaging Based on Accurate Delay Times

This work proposed a dynamic aperture delay-and-sum method based on velocity reconstruction (DA-DAS-VR) to implement accurate cortical bone ultrasonic imaging. Two identical linear array probes were placed parallelly on the upper and lower sides of the imaging region. The ultrasonic signals were captured with full-matrix mode. After extraction of first arrival time from the ultrasonic data, the travel-time inversion was utilized to reconstruct the velocity distribution in advance. Then, combined with the estimated velocity distribution, Fast Marching method was employed to calculate the accurate delay times of all focused points. Finally, the dynamic aperture delay-and-sum imaging method (DA-DAS) was applied to reconstruct the cortical bone. The experimental results show that the mean relative errors of the estimated sound velocity in the region-of-interest (ROI) are all below 10%.