Thermographic investigation of the heating effect of high intensity focused ultrasound.

The purpose of this study was to use thermal imaging camera to investigate the localised heating effect of High intensity focused ultrasound (HIFU), to monitor temperature rise in real time and accurately. In order to visualise thermally induced protein coagulation, a phantom of Polyacrylamide (PAA) gel containing fresh egg albumin was used as tissue mimicking material. A high resolution thermal camera was positioned directly over the samples to record thermal fluctuations. Two modes of ultrasound were investigated, i.e. continuous wave and pulsed wave. Through imaging processing and thermal analysis, the temperature profile of the phantoms during HIFU heating was obtained, and the optimised parameters for protein coagulation were identified. The experiments have shown that thermal imaging is an effective way to measure the bioheating effect of HIFU.