Fig. 5.
Free-field histotripsy receiver phase variation (A) and amplitude (B) across rings at varying histotripsy focal pressures. Receiver amplitude increased linearly across all rings of the histotripsy array with increasing focal pressure, but shockwave arrival increased non-linearly with increasing focal pressure with upwards of a half-wavelength difference between the outer- and inner-most rings at the highest focal pressure. Phase differences in shockwave arrival (generated with a 63 MPa focal pressure bubble cloud) are projected onto a rendering of the histotripsy array (C). Each ring exhibited low phase variance indicating a pre-focal shift of origin of the front edge of the shockwave.