摘要
目的 :在单激励源条件下 ,比较临近驱动和对向驱动模式对体表测量信号的幅值、动态范围、精度及中心区域的敏感性等的影响 ,为阻抗成像寻求相对较优的驱动模式 .方法 :基于自行研制的 32电极高精度电阻抗断层成像实验系统 ,在直径 30cm的圆形物理模型上 ,采用幅值 1mA、频率 5 0kHz恒流激励 ,分别对临近驱动和对向驱动模式下的测量信号从幅值、动态范围、精度和变化量等方面进行研究 .结果 :相同测量条件下 ,相对于临近驱动 ,对向驱动使边界电压的平均值提高了 4 .3倍 ,动态范围降低了 2 1 .3dB ,平均测量精度从 0 .6 4 %提高到 0 .0 4 % .对向驱动时 ,中心区域放置直径 4 .1cm铜管时引起的绝对变化量为 6 .6～ - 2 8.8mV ,临近驱动为 1 2 .4～ - 2 .4mV ,对向驱动时总相对变化量为 - 2 8.7,临近驱动时为 - 1 3.7.结论 :对向驱动模式下能得到精度较高、对中心区域较为敏感的测量信号 ,在高精度阻抗成像中 。
AIM: To find a better driving mode for single driving source in electrical impedance tomography (EIT), the different effects caused by adjacent and polar driving to the amplitude, dynamic range, accuracy and sensitivity to center area of boundary signals were compared. METHODES: Based on self designed high accuracy EIT experiment system with 32 electrodes and circular physical phantom ( d =30 cm), applying constant current(A=1 mA, f=50 kHz)for adjacent and polar driving, we studied and analysed the difference of the amplitude, dynamic range, accuracy and sensitivity to center area of boundary signals. RESULTS: At the same condition, compared with adjacent driving, polar driving improved 4.3 times to the boundary voltage, reduced 21.3 dB to the dynamic range, increased the mean measurement accuracy from 0.64% to 0.04%. For polar driving the absolute changes caused by a copper tube ( d =4.1 cm) in the center of the phantom is 6.6 to -28.8 mV, the total relative changes is -28.7 mV. For adjacent driving they are 12.4 to -2.4 mV and total -13.7 mV, respectively. CONCLUSION: For polar driving the measured signals have higher accuracy and higher sensitivity to center area than that of adjacent driving. In high accuracy EIT system, polar driving should be used.
出处
《第四军医大学学报》
北大核心
2004年第1期88-91,共4页
Journal of the Fourth Military Medical University
基金
国家科技部"九五"攻关课题 (96 92 0 1 2 0 4 )
关键词
电阻抗断层成像
临近驱动
对向驱动
物理模型
electrical impedance tomography
adjacent driving
polar driving
physical phantom
