Use of Passive Arrays for Characterization and Mapping of Cavitation Activity during HIFU Exposure

Inertial cavitation occurring during HIFU exposure act both as a promoter and as a marker of heat deposition, bubbles re-radiate part of the incident field as noise emissions that are detectable over a frequency far removed from the main HIFU excitation frequency. In present work, a commercially available ultrasound scanning (with the transmit signal turned off) and linear array are to detect the emissions emanating from cavitating bubbles on 64 independent channels during HIFU exposure. A algorithm is presented that enables localization and of cavitation activity, both for the case of a single and in the context of contiguous, disjoint cavitating . By contrast to B-mode hyperechogenicity imaging that is used in ultrasound-guided HIFU systems but can only whilst the HIFU is off, the passive imaging technique here can be implemented during HIFU exposure, thus a potential means of real-time treatment monitoring ablation. ©2008 IEEE