Microprocessor-base system for ultrasonic tissue characterization

A microprocessor-based ultrasonic data acquisiton and analysis system has been developed for measuring acoustic parameters of biologic media in a controlled environment. The system consists of commercially available pulse-echo electronics and both minicomputers and microcomputers. Measurements were made on various biologic tissues, both freshly excised and formalin fixed. Propagation velocity measurements were made using the substitution technique. Peak amplitude and log power spectra difference methods were used for attenuation measurements. Measured results indicate that propagation velocity in the soft tissues was in the range of 1530-1580 m/sec at 20 degrees C. Velocity variation among tissues at any given frequency was less than 2%; dispersion in the frequency range 1-10 MHz was approximately 1.5%. Attenuation coefficients showed a marked dependence on frequency increasing in a linear fashion. The slope of the attenuation frequency curve varied with tissue type and could be used for tissue characterization.