Cavitation index as a function of time in two regions of interest separated by the tissue mimicking material (i.e., focal ROI-II and pre-focal ROI-I, n=15) produced at a PRF of 2 Hz without (a, b) and with (c, d) the jet. Pre-focally, cavitation index is higher without (open circles) than with (open squares) the jet. In the focus, cavitation index is greater with (solid squares) than without (solid circles) the jet. Representative high-speed shadowgraph images were captured using a framing rate of ~18,000 frames/second with an exposure time of 10 μs (H = 50 mm).