The Electrical Impedance Tomography System Used In Monitoring Pulmonary Function

Electrical impedance tomography (EIT) is a new imaging technology, which has good application prospect in both clinical image monitoring and the functional image, with the characteristic of low-cost, safety, easy to be operated etc. As a new medical imaging technology, electrical impedance tomography (EIT) aims at reconstructing the impedance distribution of the human body by means of the potentials collected on the electrode surface through the injected current on the measured body.From the aspect of bio-electrical impedance, this thesis studies EIT system for the application of monitoring pathological changes in lung by building a simulation thorax model. The main work and results are as follows:1. The method of measuring the complex impedance of biologic tissues is proposed based on Agilent 4294A Impedance Analyzer, complex impedance of various tissues in pig's thorax is measured; data is processed by Least Square Method; characteristic parameters are calculated according to Cole-Cole theory.2. Prony demodulation is employed, and this method can abstract all frequency signal through one modeling.3. Some vivo experiments are carried out. Pulmonary model is built, and image is reconstructed using the experimental data. Results show that the imaging quality of pulmonary model is much better than the circular model.4. The maximum entropy regularization based on Tikhonov regularization is proposed. On one hand, this method has the properties of fast speed and directness; on the other hand, this method finds a solution with non-negative elements which can enhance anti-noise capability.