Final Report Summary - THERACAV (Harnessing Cavitation for Therapy)
The TheraCav project was dedicated to developing an essential understanding of cavitation-bubble dynamics, under typical therapeutic ultrasound exposure, and reconciling that activity directly to the acoustic emissions generated. A state-of-the-art high speed imaging facility was constructed and meaningfully implemented, incorporating two high-speed cameras and synchronous pulsed laser illumination for shadowgraphic imaging of cavitation behaviour at nanosecond temporal resolutions. In parallel, intimate acoustic detection with a range of medical, commercial and in-house developed bespoke detectors, was conducted.
The results conclusively demonstrate that non-linear cavitation emissions can be mediated via periodic shock scattering from repeated bubble collapses. These findings are disruptive to the literature on the topic, to-date, and can account for all non-linear emission components, dependent on focused ultrasound driving parameters.
Throughout the history of cavitation research, there has been a pervasive tendency to classify cavitation activity – and cavitation mediated effects – as either ‘stable’ or ‘inertial’, based on the components of non-linear acoustic emissions detected. TheraCav research has generated persuasive evidence to suggest that all non-linear cavitation emissions are shock wave mediated (a conventionally inertial effect). This indicates that the enduring conventional classification is, at best, inadequate and likely unhelpful. Rather, cavitation typical of medical therapy, displays the characteristics associated with both stable and inertial categories.
The TheraCav project has overhauled fundamental understanding of cavitation activity, exposed to focused ultrasound typical of medical therapy. In particular, the research has shed new light on the acoustic signals generated by driven bubbles, for a new understanding of the interaction with detection devices. Moreover, exciting insights to potential mechanisms of therapy and unwanted bioeffect have been made, subject to in-vivo validation.