A study on frequency dependence of ultrasound attenuation of biological tissue in the frequency range of 2-40 MHz

We have been measuring ultrasound attenuation of biological tissues in the frequency range of 2.5-40 MHz using a multi-resonance transducer. In this study, we used two additional wideband transducers of 5 and 10 MHz, and we measured liquid-type samples to improve the accuracy of the measurement, especially at frequencies below 10 MHz. Homogenized swine liver tissue was centrifuged to separate it into two samples: a supernatant liquid sample containing water-soluble proteins of liver cells and a sediment sample containing the constituents of the tissue structure. Specific attenuations of both samples were almost the same at frequencies around 10 MHz. However, the exponent values of the two samples were clearly different; the exponent value of the supernatant liquid sample was 1.3 in the entire frequency range of 2-40 MHz, white the exponent value of the sediment sample was 0.7. This result suggests that there is a turning point of the exponent value of the whole liver tissue at about 10 MHz.