VHF UHF RANGE BIOULTRASONIC SPECTROSCOPY SYSTEM AND METHOD

A new system and method for characterizing biological tissues in vitro and liquids in the VHF and UHF ranges is described. Bulk acoustic pro perties such as the sound velocity, attenuation, acoustic impedance, a nd density are determined in reflection and transmission modes, with t he biological tissue/liquid specimen sandwiched between the parallel s urfaces of synthetic silica glass buffer rods having ZnO piezoelectric film transducers on their opposite ends, The method is an ultrasonic transmission line comparison method wherein the reference medium is di stilled water, for which all acoustic properties are known, Measuremen t errors due to diffraction losses in the acoustic media and to mode c onversion at the buffer/sample interfaces are corrected, Special techn iques for achieving precise parallelism between the two rod surfaces, for movement to adjust the gap distance, and for signal processing are employed in order to obtain high measurement accuracy, Attenuation an d reflection coefficients are determined using the gated pulse echo me thod, The sound velocity is determined with the gated pulse interferen ce method by sweeping the ultrasonic frequency, or by changing the gap distance, Results of measurements on castor oil, cottonseed oil, sili cone oil, and bovine liver, in the frequency range from 10 to 500 MHz, are presented and compared with results of earlier reports.