| Electrical Impedance Tomography (EIT), a new generation of non-invasive imaging technology appeared since 1980's after the form and structure imaging, is one of the most important research projects in biomedical engineering field. Through the electrode array configuration on the body surface, Electrical Impedance Tomography can extract the electrical properties information of tissue or organs which is related to human physiological and pathological conditions. So it not only shows us the information on the anatomical structure, but also provides the very useful and important functional images, which is impossible in X-CT, MRI and other imaging technology. Electrical Impedance Tomography does not take use of radionuclide or radiation, which is absolutely harmful to humans, and it can be reused, frequently so, it can be widely used as hospital equipments to monitor the patients without causing injury or discomfort for a long term. Moreover, because of its low cost and no requirement with a special working environment, it is an ideal technology with a bright future in non-invasive medical imaging and image monitoring.By analyzing and studying the former achievements on the reconstruction calculation of Electrical Impedance Tomography home and abroad, this paper focuses on developing an effective EIT algorithm with practical application speed, rapid and high resolution by using virtual instrument software - LabVIEW, that is the improved the equi-potential back-projection algorithm.This paper works as follows:(1) To introduce the significance of the EIT imaging technology and its imaging principles, and outlines the wide applications of this new technology home and abroad.(2) To study the forward problem of the EIT. This paper establishes a theoretical model of the forward problem by using finite element method. It illustrates the influence of the alteration of conductivity distribution on the electrical potentials of border points. It includes increasing and decreasing conductivity, expanding the area, and changing conductivities in different area.(3) To improve the equi-potential back-projection algorithm of EIT. This paper improves the Sheffield equi-potential back-projection algorithm, provides the calculation formula of projection length, so that the reconstructed images are more clear than before, and the forged traces are minimized. Meanwhile, it studies the improved properties of equi-potential back-projection algorithm including different conductivity imaging in the same area, imaging in different regions with the same conductivity, single target imaging, two goals imaging in a long distance or short distance, three goals imaging. The research results show that back projection algorithm can not only accurately determine the location of target, but also have good resolution. When the situation changes within the conductivity distribution area, reconstruction image can reflect the changes.(4) This paper focuses on establishing the EIT simulation algorithm based on the platform of LabVIEW software. It completes automatic division of the finite element, analyzes the numbering rule of the Finite Element nodes and the triangular modules, and gives block diagram of Gaussian elimination method and forward problem, and explains the block diagram of improving equi-potential back-projection algorithm. Finite element model can modify in software, it is very useful for theoretic simulation research.Finally, this paper summarizes the major research achievements, as well as the existing problems and deficiencies. At the end of this paper, the author points out the further researches on this topic. |
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