A light-scattering technique for investigating the destruction of ultrasound contrast agents

A technique that utilizes light-scattering from a low-powered laser to probe ultrasound contrast agents is described. A He-Ne laser illuminates the focal zone of a high-intensity focused ultrasound (HIFU) source operating at 1.1 MHz. A focusing lens is used to collect the scattered light from bubbles in the focal region, focusing the scattered light onto a photodetector. During application of the HIFU source, the bubbles oscillate, and the resulting fluctuation in the light-scattering signal is detected by the photodetector. Measurements of the light fluctuation can be correlated with bubble activity, especially inertial cavitation. A description of the technique, and preliminary results of measurements with ultrasound contrast agents are shown.