基于功率耦合和检波的高强度聚焦超声驱动功率监测技术

Measurement technique of high-intensity focused ultrasound driving power based on power coupler and detector

为了实现易于集成到高强度聚焦超声(HIFU)系统中的驱动功率监测技术,通过监测驱动功率间接监测声功率,进而确保热消融的有效性和安全性,采用C5948双定向耦合器与AD8363均方根功率检波器,搭建驱动功率在线监测装置.该装置包括功率耦合单元、功率检测单元和数据采集单元.使用电压峰峰值为20~200mV的不同频率的信号源,将该装置接入HIFU系统并测量入射功率、反射功率及实际加载功率.HIFU系统的现有功率监测方法主要有2种,即测量HIFU换能器电压、电流及其相位差和使用商用功率计,将这2种方法与所提出装置进行对比.结果表明使用本装置测量入射功率和反射功率的误差低于10%,实际加载功率的测量误差低于5%,且误差来源于耦合器的方向性.

To implement a driving power measurement technique that can be easily integrated in existing highintensity focused ultrasound(HIFU)systems,to indirectly monitor the acoustic power output by the measurement of the driving power,and then to ensure the efficacy and the safety of the HIFU thermal ablation,an on-line power monitor was designed based on C5948 dual directional coupler and AD8363 root mean square power detector.The equipment was composed of power coupling module,power detecting module and data acquisition module.It was connected in HIFU system to measure the forward and reflected powers as well as the net power using signals of different frequencies with the peak-peak voltages ranging from 20 mV to 200 mV.There are two existing main methods of power monitoring in the HIFU system,i.e.measuring the voltage,current and phase difference of the HIFU transducer as well as using the commercial power meter.The proposed equipment was compared with the above two methods.Results demonstrated that the errors of measuring forward and reflected powers were lower than 10%using the proposed equipment.The measurement error of actual loaded power was lower than 5%,and the errors might come from the directivity of the used coupler.