Relation between statistical properties of sound speed distribution and average sound speed estimation

摘要

The speed of sound (SOS), which is the propagation speed of longitudinal waves, is a promising index for early detection and monitoring of diseases, and many measurement methods have been proposed. It has already been found that the average SOS can be easily and reasonably estimated for a homogeneous medium based on time-delay processing by utilizing the method using backscattered waves, which enables the use of handheld probes. However, the error caused by the application of the method to an inhomogeneous medium has not yet been clarified. In this study, we investigate the relationship between statistical properties of the SOS distribution and the measurement error through a simulation and a phantom experiment. As a result, it is revealed that if the spatial variation of the SOS distribution is below a certain level, the average SOS can be estimated under the assumption of a homogeneous medium.