Adaptive broadband electrical impedance tomography method for electrical spectrum characterization

Abstract

The invention relates to an adaptive broadband electrical impedance tomography method for electrical spectrum characterization. The method comprises the following steps that a medium which is to be measured is excited by using a broadband Chirp signal, a Chirp response signal with a complete continuous period is selected after the system finishes collecting a boundary voltage value, frequency spectrum analysis is carried out on the signal by using numerical analysis to obtain an amplitude-frequency diagram, and the first derivative of a amplitude-frequency curve is solved accordingly to obtaina sensitive bandwidth interval in which the electrical characteristics of a current medium change with frequency; a plurality of single frequency points evenly distributed in the sensitive bandwidthinterval are selected, each designated single frequency signal is superimposed into a mixed frequency signal, secondary excitation is carried out on the tested medium, and acquisition and demodulationof boundary voltage values is competed to obtain amplitude and phase at each frequency; and an image reconstruction algorithm is used for reconstructing the media distribution image in the measured field. The adaptive broadband electrical impedance tomography method for the electrical spectrum characterization can improve the signal-to-noise ratio of image reconstruction.

Description

technical field [0001] The invention belongs to the technical field of tomography, and relates to an adaptive broadband electrical impedance tomography method based on the electrical spectrum characterization of biological tissues. By performing broadband excitation on the measured medium, the impedance spectrum information and optimal excitation information of biological materials are obtained. , and then perform frequency mixing excitation to realize the optimal reconstruction of the distribution of the measured medium. Background technique [0002] Under the action of safe excitation current, biological tissue will show certain electrical characteristics due to the influence of conductivity and dielectric constant. Various biological tissues have different electrical impedance characteristics, which contain rich physiological and pathological information. Based on this principle, electrical impedance tomography (Electrical Impedance Tomography, EIT) reconstructs the impe...

AI Technical Summary

Problems solved by technology

Multi-frequency EIT technology adopts two excitation methods: frequency mixing (simultaneous multi-frequency) and frequency sweep (time-division multi-frequency), but the frequency components contained in the two are limited, resulting in the mutual restriction of bandwidth and frequency resolution.

Since the electrical properties of the biological material to be tested are usually unknown, that is, its electrical sensitive bandwidth is uncertain, when it is excited by multiple frequencies, the significant change of electrical properties may happen between two adjacent frequency points, or Outside the bandwidth, the multi-frequency response cannot be measured, which leads to imaging failure or poor effect

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