多通道开放式磁感应成像测量系统研究

Study of the Multi-channel Open Magnetic Induction Tomographic Measurement System

磁感应成像是一种无创伤非接触的医学电磁成像技术。文中介绍了一种多通道开放式磁感应成像测量系统。系统以二次磁场的相位变化作为检测信号,包括开放式磁感应传感器、16通道信号处理电路和基于锁相放大器的相位检测电路。系统提供的激励电流幅值为300 mA,最大频率为120 kHz,相位稳定性在-0.03°～0.05°,相位灵敏度达到0.185°/S.m-1,能够检测的电导率最小值为0.2 S/m。系统在球型水槽实验平台上完成了模拟颅脑血肿的成像实验,得到了反映电导率相对大小分布的二维直接插值成像结果。实验结果表明,系统可以检测浅层电导率异常目标,同时对多目标检测有较好的分辨能力。

Magnetic induction tomography is a noninvasive and contactless electromagnetic biomedical imaging method.This paper presented a multi-channel open magnetic induction tomography measurement system.The system used phase difference information of the secondary magnetic field as the detection data.And the hardware was composed of 16 open magnetic inducting sensors,signal processing circuit and phase detecting circuit based on the lock-in amplifier.The excitation current was 300 mA in amplitude and 120 kHz in maximum frequency.The phase stability of this system was-0.03° ～ 0.05°,and phase sensitivity was 0.185 ° / S.m-1.The minimum conductivity which could be detected by this system was 0.2 S /m.In order to simulate the brain hematoma situation,a spheric water tank was used,and the relative conductivity distribution was obtained by 2D direct interpolation imaging method.The experiment results demonstrated that the present system could obviously detect the abnormal conductivity target near the surface and distinguish multi-targets.