1F-1 The Threshold for Bubble Collapse in Tubes and in Gel Embedded Microtunnels

A series of experiments involving an ultrasound contrast agent injected into different diameter polyester microtubes and in micrometer diameter tunnels embedded in gel is presented. The pressure amplitude threshold for bubble collapse, as recorded by broadband acoustic emission, was investigated as a function of the vessel diameter and microbubble concentration. This threshold was found to be dependent on the vessel diameter with an increase for smaller diameters. The motivation of this study lies in the possibility of obtaining a better understanding of microbubble behavior in confined geometries in order to optimize techniques involving microbubble disruption for medical applications of ultrasound