Estimation method for sound velocity distribution for high-resolution ultrasonic tomographic imaging.

Abstract

With commercial ultrasonic equipment, the sound velocity is fixed to a constant value of 1530 or 1540m/s, which is used for beam formation. However, the assumption of a constant sound velocity is not optimal, as the sound velocity in a living body is heterogeneous. In this study, a novel method was proposed to estimate the distribution of the sound velocity in a region of interest. The sound velocity distribution was estimated by fitting the theoretical propagation time of the ultrasonic wave from the scatterer to each of the probe elements with measured values. In a phantom experiment, the sound velocity distribution was estimated by the proposed method with a maximum estimation error of 0.6%, and the resultant local sound velocity values successfully improved the quality of the ultrasonic image. The proposed method has the potential to improve ultrasonic image quality in in vivo experiments by estimating the sound velocity distribution.