ASA 126th Meeting Denver 1993 October 4-8

4pPA9. Characterizing scatterer size via measurements of multiple acoustic parameters.

Peng Jiang Robert E. Apfel

Dept. of Mech. Eng., Yale Univ., New Haven, CT 06520

A multiple parameter approach for characterizing mixtures has been investigated. It is found that one can characterize scatterers (droplets) in immiscible mixtures of water, fat (oil), and protein, in term of volume fraction and size, from measurements of the mixture's effective acoustic parameters (density, sound speed, the acoustic nonlinear parameter, and attenuation). Mixture laws [P. Jiang et al., Ultrasound Med. Biol. 17(8), 829--838 (1991)] were used to determine the composition of a mixture. A procedure for choosing a reliable composition predictor was proposed. Good agreement between the predicted compositions and the known values has been demonstrated. After the volume fraction of the scattering droplet was found, an effective radius of the droplets was obtained by using an appropriate attenuation law with the measured frequency-dependent attenuation. The deduced radius is close to that of the majority of droplets observed under an optical microscope. A discussion is given on how to apply the technique to characterize the size distribution of scatterers. [Work supported by NIH through grant R01-GM30419.]