Microsecond-Range Dynamics of Tissues Under the Action of Acoustic Radiation Force

The results of theoretical and experimental studies are presented for the action of acoustic radiation force (ARF) generated by short (microsecond range) ultrasonic pulses on the liquid-liquid and liquid-gel interfaces, which mimic the boundaries within soft biological tissues. For the boundaries between two liquids, the Laplace equation for the nearfield zone of the interface is solved. For the liquid-gel interface, the shear motions and the effect of viscosity were also considered. Both "pushing" and "pulling" action on the interface are described. In the experiments, the sub-nanometer range displacements induced by ARF in phantoms mimicking soft tissues were evaluated by measuring the interface velocity. The theoretical findings are in agreement with the experimental results.