Attenuation Compensation of Ultrasonic Wave in Soft Tissue for Acoustic Impedance Measurement of In vivo Bone by Transducer Vibration Method

In this paper, we describe a method of compensating the attenuation of the ultrasound caused by soft tissue in the transducer vibration method for the measurement of the acoustic impedance of in vivo bone. In the in vivo measurement, the acoustic impedance of bone is measured through soft tissue; therefore, the amplitude of the ultrasound reflected from the bone is attenuated. This attenuation causes an error of the order of -20 to -30% when the acoustic impedance is determined from the measured signals. To compensate the attenuation, the attenuation coefficient and length of the soft tissue are measured by the transducer vibration method. In the experiment using a phantom, this method allows the measurement of the acoustic impedance typically with an error as small as -8 to 10%.