The effect of scatterer statistics on diffraction corrections

The acoustic field generated by an ultrasonic transducer radiating into a homogeneous medium is well understood, but generally accepted scattering models for biological tissue do not exist. To investigate the effects of scatterer model on diffraction filtering, two cases were considered. In both cases particles were randomly distributed in space; in one case random scattering amplitudes were allowed and in the other case particles behaved identically. In both cases the diffraction filter was a low-pass effect. However, at low frequencies the diffraction filter for identical scatterers was found to be steeper by a factor of three in slope (dB/MHz) for reasonable values of scatterer number density. The results of this study demonstrate that the characteristics of the scattering medium can significantly affect acoustic measurements.