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| Electrode Optimization Design of 3D Electrical Impedance Tomography System |
1 School of Electrical Information and Automation, Tianjin University of Science and Technology, Tianjin 300222, China
2 Aeronautical Auto, Civil Aviation University of China, Tianjin 300300, China |
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Abstract The aim of this work is to explore influences of electrode structure parameters on data measurement and the image reconstruction of 3D medical electrical impedance tomography (EIT) system. Considering the influences of the shape and distribution of electrodes on image reconstruction, four kinds of electrode structure are designed: square (I), round (II), concentric cylindrical combination electrode (III), and squareround combination electrode (IV). Based on QBD (quasiopposite drive between two layers) working pattern, eight different duty ratios between 0.2 and 0.7 were studied comparatively. By studying the targets as correlation coefficient of the images R, the uniformity of sensitivity field distribution P and the voltage dynamic range D, the measured data and reconstructed images are evaluated under the four electrode structures. Results showed that the four types achieved satisfied R between 0.4～0.5 exceed other DR, among them type IV gets better R and P than others types. But when DR 0.3 and 0.35, the compound electrodes (Type III and IV) were unstable with higher D than others. Images were reconstructed after regularization for five different layers from the bottom to the top including two electrodes layers, internal layer and external layers. The five targets with same conductivity but in different height (from 7.5 cm to 30 cm with equal intervals) were placed inside the tank. The images are coincident with the real distribution. The images by type IV appear less artifacts and higher imaging quality which is fitted with the targets analysis results. This research gives a light in considering the electrode configuration in three dimensional EIT with QBD working pattern and makes a foundation for 3DEIT further research.
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