Real-time cavitation mapping in photo-sono therapy for microvessel removal using Doppler OCT

Photo-sono therapy (PST) combines nanosecond laser pulses with ultrasound bursts to induce cavitation, enabling selective vascular destruction while preserving nearby tissues. Traditional passive cavitation detection (PCD) is often used to evaluate cavitation activity but suffers from limited spatial resolution, complicating integration with PST systems. To address this, we developed a system integrating Doppler optical coherence tomography (OCT) with PST to visualize cavitation dynamics in real-time. The system comprises a 100 kHz VCSEL sweptsource Doppler OCT and a PST module utilizing a 0.5 MHz High-Intensity Focused Ultrasound (HIFU) transducer and a 532 nm nanosecond pulse laser. The system was validated using both blood vessel phantoms and in vivo rabbit ear vessels. Doppler OCT effectively monitored blood flow changes induced by cavitation, with results corroborated by high-speed imaging and PCD. This integrated system facilitates simultaneous monitoring of microvascular morphology and cavitation activity, showcasing its potential for advancing PWS treatment and other cavitationbased therapies.