Method and means for determining frequency selective tissue attenuation in a baseband ultrasonic imaging system

摘要

Ultrasonic wave attenuation in passing through tissue is determined from frequency changes in reflected ultrasonic waves passing through the tissue. In a baseband ultrasonic imaging system in which transducer generated signals are coherently detected by mixing the signals with a fixed frequency signal both in phase and in phase quadrature, a measure of frequency change in the reflected ultrasonic signal is obtained by measuring phase shift in a side band of the mixed signals.