Development electric impedance CT using magnetic field

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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.