Research on adjacent and polar driving in electrical impedance tomography

    YOU Fuª²Sheng, DONG Xiuª²Zhen, SHI Xueª²Tao, FU Feng, LIU Ruiª²Gang, LI Jiang

    Department of Medical Electronic Engineering, School of Biomedical Engineering, Fourth Military Medical University, Xi¡¯an 710033, China

    ¡¾Abstract¡¿ 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 constantª²current(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. ......