3D-EIT系统电极优化设计

发布时间：2018-09-19 18:01

【摘要】：探究三维电阻抗成像系统电极结构对数据测量及图像重建的影响。考虑到电极形状和电极在边界上的分布状态对成像效果的影响,在构建的3D电阻抗系统模型及层间准对角激励相邻(QBD)测量工作模式下,对方形电极(I型)、圆形电极(II型)、同心圆复合电极(III型)和方圆复合电极(IV型)4种形状电极,就0.2到0.7之间8种不同电极占空比(DR)情况进行对比研究。采用重建图像的相关度R,敏感场的灵敏度均匀性P,测量电压动态范围D进行评价。对比结果表明,在DR为0.4~0.5之间,4种电极结构下的图像相关度R均优于其他DR情况,而且IV型电极的R和P指标略优于I~III型,但复合型电极(III和IV型)在DR为0.3和0.35时边界测量电压动态范围D偏大,稳定性差。对三维场域中5个高度不等(7.5~30 cm之间)、电导率相同的物体,采用共轭梯度算法进行图像重建。数据经归一化处理,截取2个电极层、1个电极间层及2个电极外层共5个等间隔的不同断层图像进行对比,4种电极模型下的成像结果均与真实分布相吻合,IV型电极所成图像伪影略小,效果较好,与指标评价结果一致。本研究为QBD模式的三维电阻抗成像系统确定了电极形状及电极分布,为进一步研究三维空间的电阻抗分布奠定基础。
[Abstract]:To explore the effect of electrode structure on data measurement and image reconstruction in three dimensional electrical impedance imaging system. Considering the influence of electrode shape and electrode distribution on the imaging effect, the 3D impedance system model and the adjacent (QBD) measurement mode with quasi-diagonal excitation between layers are constructed. Four kinds of shaped electrodes, I. e., I type, II type, III type and IV type, were compared and studied. Eight different duty cycle ratios (DR) were compared between 0. 2 and 0. 7. The correlation degree of the reconstructed image and the sensitivity uniformity of the sensitive field are used to evaluate the dynamic range D of the voltage. The results show that the image correlation R of the four electrode structures is better than that of other DR, and the R and P indexes of IV type electrode are slightly better than that of I~III type electrode. However, the boundary voltage dynamic range D is larger and the stability is poor when the composite electrode (III and IV type) is 0.3 and 0.35 DR. The conjugate gradient algorithm is used to reconstruct five objects with the same conductivity and different heights (between 7.5 cm and 30 cm) in 3D field domain. The data is normalized, Two electrode layers, one interelectrode layer and two electrode outer layers with 5 equal intervals were intercepted and compared. The imaging results of the four kinds of electrode models were all consistent with the true distribution. The image artifacts of the IV type electrode were slightly smaller and the effect was better. It is consistent with the result of index evaluation. In this paper, the electrode shape and electrode distribution are determined for the three-dimensional electrical impedance imaging system of QBD mode, which lays a foundation for the further study of the electrical impedance distribution in three-dimensional space.
【作者单位】：天津科技大学电子信息与自动化学院;中国民航大学航空自动化学院;
【基金】：国家自然科学基金重点项目(50937005) 天津市科委自然科学基金(12JCYBJC19500)
【分类号】：R318.6

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