医学电阻抗图像重建系统

作者设计了基于DSP的主从式MEIT数据采集系统。PC机作为主控机，DSP控制电极选通、数据采集及与上位机的通讯。采用直接数字合成(DDS)技术构建双路正弦波及同步方波发生器，实现幅值、频率、相位等连续调节；调制信号经同相与正交解调，获取实部与虚部信息，利用加权反投影算法进行图像重建。试验测试与成像结果表明，本系统不仅采集速度快，而且图像分辨率高。

Medical Electrical Impedance Tomography System

A master-slave data acquisition system based on DSP is designed. The master PC is responsible for image reconstruction and real-time display, while DSP carries out the electrode selection, data acquisition and communication with the master. Based on DDS technique, the signal generator can create two signals, i.e. the sinewave and the square wave signals, and its amplitude, frequency and phase can be continuously adjusted. The measured signal is demodulated by an analog multiplier, and the information of real and imaginary components are obtained, then the image can be constructed by weighted back projection algorithm. The test and quality reconstructed images show that the MEIT system has high data acquisition speed and image resolution.