人体复阻抗断层成像系统

Electrical impedance tomography system for body complex impedance

设计了一种基于DSP的主从式人体复阻抗断层成像系统。系统采用PC机作为主控机,DSP控制电极选通、数据采集并与上位机通讯;采用直接数字合成(DDS)技术构建正弦波发生器,幅值、频率、相位等连续可调;加入反馈环节,有效提高了压控电流源的线性度和稳定性;采用欠采样和数字解调技术,获取人体复阻抗虚实部信息;利用反投影算法进行图像重建。试验测试与成像结果表明,该系统改进了数据采集速度和图像分辨率。

A master-slave electrical impedance tomography (EIT) system for body complex impedance based on digital signal processor (DSP) is designed in this paper. Used as the master computer, a PC performs the image reconstruction and display on time, while DSP carries out such tasks as electrode selection, data acquisition and data communication with the master. Based on DDS technique, the signal generator can create the sine wave signals, and it's amplitude, frequency and phase can be continuously adjusted. The designed feedback unit can improve the linearity and the stability of the voltage-controlled current source effectively. Undersampling technology and digital demodulation technology are used in this system in order to attain the information of real and imaginary components of the body complex impedance. Back projection method is adopted to reconstruct the image in this system. Experimental results show that this system improves the data acquisition speed and the image resolution.