A Dynamic Impedance Matching System based on Phase Difference Detection for Ultrasonic Generator in Focused Ultrasound Surgery

Focused ultrasound surgery (FUS) has been widely used as a non-invasive treatment for solid tumors and metastatic diseases. Ultrasonic generator is one of the critical parts in FUS therapy system. In order to realize real-time impedance matching of the ultrasonic generator and improve its energy transmission efficiency, a novel dynamic impedance matching system is designed and tested in this study. The proposed system can monitor the transducer impedance variation based on phase difference detection and dynamically adjust the matching circuit parameters through pulse width modulation (PWM) and synchronous switched capacitor. The results show that this system can compensate the impedance variation of ultrasonic transducer elements in real time, and the mean active power has been increased by 13.47% compared with static impedance matching, which demonstrate the feasibility and validity of the proposed system.