Fig. 4.

Optically measured location of the front edge of the cavitation expansion shockwave relative to the 90° axis of the histotripsy transducer. Single-bubble cavitation exhibited no significant change in shockwave edge across all measured angles but also exhibited high standard deviation due to inconsistency of the location of cavitation initiation. The multi-bubble cloud exhibited slight increase in shockwave front edge location and with increasing angle from transducer axis but also exhibited relatively high standard deviation across all angles. The robust (63 MPa P-) histotripsy cloud exhibited significant increase in shockwave edge distance with decreasing angle from axial direction of the transducer also exhibited very low standard deviation of shockwave location across all angles.