The Ultrasound-Stimulated Acoustic Emission (USAE) In Tissue And Its Application Study In Medicine

The dual-frequency confocal ultrasound wave can produce a radiation force of low frequency in the confocal volume that locates inside tissue. Under the vibration radiation force the tissue in the confocal volume will vibrate along the acoustic axial, and emit low-frequency wave toward the surroundings, this is named ultrasound stimulated acoustic emission (USAE). It is verified that the USAE signal contains the elastic modulus and acoustic absorbing information of the tissue in the confocal volume. So it has important meaning to the studies of pathology variety of the tissue. If the two incident waves are at low power, by using the confocal ultrasound waves to scan the tissue in the focal plane, and recording the amplitude of USAE received by low-frequency hydrophone at different positions, an image that incarnate the tissue characteristics is obtained. The technique is called vibro-acoustography. When radiating in high power, the confocal transducer works in the dual-frequency HIFU mode. Due to existing the USAE signal and difference frequency signal brought by nonlinearity, dual-frequency HIFU has very different effect on the tissue of focal region compared with conventional single-frequency HIFU.In this paper, taking dual-frequency confocal ultrasound wave as foundation, the ultrasound-stimulated acoustic emission (USAE), the ultrasound-stimulated vibro-acoustography (USVA), and dual-frequency HIFU are studied in both theory and experiment. The main research contents include three parts:1. After introducing the creation of radiate force and USAE principle in detail, the theory researches are carried out in two aspects. One is firstly putting forward vibrating-ball model to describe USAE field radiation rule, and using this model to analyze the effect of USAE caused by four important parameters, including acoustical...