Detection of Orientation of Dermis Tissue by Ultrasonic Sound Velocity

Abstract

We tried to detect the orientation of dermis tissues just beneath skin surface as directional characteristics of sound velocity. We made a pair of transducers, a transmitter and a receiver, to measure sound velocity parallel to skin surface using the inverted phase output of side face of a transducer which usually emits sound waves at right angle with skin surface for ultrasonic observation. First we measured squids which have directional tissues and confirmed that the direction of the tissues was the same with the maximum sound velocity direction. In this case, in order to know how the directional property of tissues is, we adopt the way to see spatial spectrum of changing sound velocity as a function of direction. As a result, it was shown that the direction property was single frequency with a period of π. In addition, as the way to measure the precise maximum sound velocity direction, assuming the change of directional sound velocity as a cosine function and seeing the corelation between them. We used analytical method to regard the shifted phase with maximum corelation value as the precise direction of maximum sound velocity. When we boiled squids and tore them, the direction of torn squid tissues coincided with the direction of maximum sound velocity. Then, we tried to measure the sound velocity of human skin, of forehand and we could confirm a clear directional property, like in the case of squids. This result was the same with the tendency of the result by anatomical study.