Figure 12.

(a) Predicted critical number of cycles prior to microbubble cloud formation determined using (15). Maxwell et al (2011) observed that between 3–4 cycles were required to initiate microbubble cloud formation at 19 MPa peak rarefactional pressure (diamond). (b) Predicted axial extent of microbubble cloud using equation (16) when the number of cycles required for cloud formation was less than the pulse duration, and equation (17) when the number of cycles required for cloud formation was greater than the pulse duration. The pulse duration is indicated in the legend. A histotripsy pulse with a fundamental frequency of 1 MHz was employed for these computations.