High-intensity focused ultrasound (HIFU) transducers are a core component of focused ultrasound

ablation surgery (FUAS) systems, whose electric impedance spectrum is an important index to determine working

parameters that significantly affect FUAS systems performance.Real-time online monitoring of this spectrum is significantly

beneficial.In this study, based on pulse response time-domain measurement, by merging the detected

pulse signal serial into the FUAS operational electric driving signal sequence of the HIFU transducer, a real-time online

monitoring system for the electric impedance spectrum of the HIFU transducer was constructed on the Lab-

VIEW platform.Highly reproducible accurate measurements towards the magnitude and phase spectrum of the HIFU

transducer electric impedance were achieved.Subsequently, a monitoring system was applied to determine dynamic

changes in the electric impedance of the HIFU transducer under extreme working conditions.These include

long-time service, high electrical driving power and duty cycle.The results demonstrate that the proposed system accurately

monitors the HIFU transducer eigen frequencies drift, alongside nonlinear changes in impedance magnitude

and phase.This paper presents a technical solution for real-time online monitoring of HIFU transducer impedance

during FUAS, and provides feedback for drive parameter adjustment, which has practical application value for HIFU

transducer design optimization and energy loss mechanisms.