Abstract
The echograph by ultrasound is widely utilized. Because of the complex structure inside of the body, however, the image is affected. Usually, it is assumed that the transmitted pulse progresses without phase distortion, and only the amplitude decay is compensated in imaging. The estimation of the internal structure by reflected ultrasound is formulated as a problem, where the reflected wave from the transmitted pulse is observed on the body surface, based on which the characteristic impedance of the cascade structure is to be estimated. When there is an attenuation, however, this problem is improperly-posed and the solution is not unique. This paper examines to what extent the solution obtained by the conventional method deviates from the actual structure, considering the phase distortion of the waveform.
