Hua P, Woo E J, Webster J G, Tompkins W J
Applied Research Group, Siemens Gammasonics Inc., IL 60195.
IEEE Trans Biomed Eng. 1993 Jan;40(1):29-34. doi: 10.1109/10.204768.
In electrical impedance tomography, we inject currents and measure voltages to estimate an object's resistivity distribution. The electrode configuration affects measured voltage data because the electrode-skin contact impedance is high and varies with electrode location. We developed a compound electrode which is composed of two electrodes: a large outer electrode to inject current and a small inner electrode to sense voltage. We used these compound electrodes to measure voltages from a physical phantom. We showed that the measured voltages from the compound electrodes are smaller in amplitude than those from conventional electrodes. This demonstrates that the compound electrode can minimize contact impedance voltage drop from the measured data. We used a finite element model for the compound electrode and incorporated the model into the regularized Newton-Raphson reconstruction algorithm. We performed a sensitivity study and showed that the reconstructed resistivity distributions are less dependent on the unknown contact resistance values for a compound electrode than a conventional electrode and that the use of a compound electrode results in improved images for the reconstruction algorithm.
在电阻抗断层成像中，我们注入电流并测量电压以估计物体的电阻率分布。电极配置会影响测量的电压数据，因为电极与皮肤的接触阻抗很高且会随电极位置而变化。我们开发了一种复合电极，它由两个电极组成：一个用于注入电流的大的外部电极和一个用于感应电压的小的内部电极。我们使用这些复合电极来测量来自物理模型的电压。我们表明，复合电极测量的电压幅度比传统电极测量的电压幅度小。这表明复合电极可以将测量数据中的接触阻抗电压降降至最低。我们为复合电极使用了有限元模型，并将该模型纳入正则化牛顿 - 拉夫森重建算法中。我们进行了灵敏度研究，结果表明，与传统电极相比，复合电极重建的电阻率分布对未知接触电阻值的依赖性较小，并且使用复合电极可使重建算法生成的图像得到改善。
