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Development electric impedance CT using magnetic field

利用磁场开发电阻抗CT

基本信息

批准号：
16500289
负责人：
TAKEMAE Tadashi
金额：
$ 2.3万
依托单位：
Shizuoka University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2004
资助国家：
日本
起止时间：
2004 至 2005
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-16500289/
关键词：
electric impedance CT magnetic field tetrapolar circuit method the least residual method 3 dimensional CT 渦電流逆投影法

项目摘要

In this study, a realizing method of a bio-electrical impedance tomography (EIT) by the tetrapolar circuit using magnetic field was proposed. Based on this method, an instrument was made and model experiments were performed suing some electric model of the bio-substance. This instrument consists of a constant current source, an electromagnetic core and its driving circuit, detection circuit of voltage difference. The detected voltage values are inputted into a computer using D/A converter. The magnetic field is moved using a linear motor and the rotation of measurement direction is performed by a stepping motor. These actions are controlled by a computer. To get the distribution of conductance in the model from voltage difference data, the least residual method was used. Setting method of calculation number and initial value were studied. The obtained results are as follows;1)The total calculation number can be decreased by setting a condition for calculation number, comparing that of obtained under a constant calculation number for all measurement directions.2)By using the final conductance value obtained at the measurement direction θ_<i-1> as initial value at θ_<i-> calculation number can be also decreased.3)The model rotation and the partial change in conductance were reconstructed in the image. Therefore, it is considered that the proposed realization method of CT has a high sensibility for change in conductance.4)It was shown that three dimensional impedance CT would be realized by moving the measuring x-y plane in z-axis direction.To establish a practical impedance CT by this method, it is necessary to get a higher spatial sensibility and a more brief time of acquiring voltage different data.

本研究提出了一种利用磁场的四极电路实现生物电阻抗断层扫描（EIT）的方法。在此基础上，制作了仪器，并利用生物物质的电学模型进行了模型实验。该仪器由恒流源、电磁铁芯及其驱动电路、电压差检测电路组成。检测到的电压值使用D/A转换器输入计算机。使用线性电机移动磁场，并通过步进电机执行测量方向的旋转。这些动作是由计算机控制的。为了从电压差数据获得模型中的电导分布，使用了最小残差法。研究了计算次数和初始值的设定方法。得到的结果如下：1）通过设置计算次数条件，比较所有测量方向在恒定计算次数下获得的总计算次数，可以减少总计算次数。2）使用在测量方向θ_<i-1>处获得的最终电导值作为θ_<i->计算次数的初始值，也可以减少总计算次数。3）在图像中重建模型旋转和电导的部分变化。因此，认为所提出的CT实现方法对电导变化具有较高的灵敏度。4)结果表明，通过在z轴方向移动测量x-y平面可以实现三维阻抗CT。通过该方法建立实用的阻抗CT，需要获得更高的空间灵敏度和更短的获取电压不同数据的时间。