The Electrical Impedance Tomography System Used In Pulmonary Function

Bioelectrical Impedance Tomography, following the morphological and structural imaging, as a new functional imaging technology emerges in the recent two decades, which extracts the biomedical information related with patients'pathologic condition from electrical changes of biologic tissue or organ. This technology possesses many merits, such as non-invasive, non-radiate, quick-response and low-cost.At present, EIT technology has been applied in the study of human organs, such as heart, brain, stomach and correlated circulation systems. This thesis studies EIT system for the application of monitoring pathological changes in lung and estimating pulmonary circulation. 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. The thorax model is built; impedance tomography algorithm is emulated, which proves that EIT system is able to monitor impedance changes in lung respiration. Some vivo experiments are carried out.3. Original EIT hardware system is improved, an integrated EIT system with 16 electrodes have been built. At the same time, a resistor net has been designed to test EIT system.4. System software based on dialog box is developed by MFC of VC++. Serial communication is realized using multi-thread serial program tool-CSerialPort Class,and the stability of communication is increased. The speed of drawing and transplant in various platforms are reformed with OpenGL.5. Some measures for improving the system performance have been proposed.