Fig. 1.

Schematic of the experimental setup. All pulsed HIFU exposures of the transparent polyacrylamide gel phantoms were performed in a large water tank with a 1.27 MHz transducer. Cavitation activity in the sample was monitored by three separate techniques simultaneously: passive cavitation detection (PCD) using a single element focused transducer, aligned confocally and coaxially with the HIFU transducer; active cavitation detection using the linear ultrasound imaging probe ATL L7-4 connected to a Verasonics imaging system; and visual observation of bubble activity using a high-speed camera. Acoustic absorbers were positioned behind the sample to avoid reverberations inside the tank.