I. Introduction
Histotripsy is a therapeutic ultrasound technique for non-invasively ablating tissue. A focused transducer is used to cause tissue fractionation by applying short, high-amplitude ultrasound bursts that induce cavitation. The collapse of these bubbles mechanically destroys the tissue [1]. Typically, an extracorporeal transducer (50–145-mm diameter) is used to generate the histotripsy pulses through soft tissue, at a focal depth of 70–150 mm [2]–[5]. This has been investigated in pre-clinical studies for several indications, especially liver cancer [6]–[10]. Schuster et al. [11] conducted an in-human trial to assess the clinical safety of histotripsy for the treatment of symptomatic benign prostatic enlargement using an extracorporeal 700 kHz, 36-element transducer with an 11-cm focal distance, observed with transrectal ultrasound imaging. Applying histotripsy to neurosurgery is appreciably more challenging due to the presence of the skull, which strongly attenuates the signal and produces aberrations at the focus, reducing accuracy.