| Biomedical Electrical Impedance Tomography is a new kind of non-invasive,functional, real-time monitoring imaging technology. In the future of medical imaging applications have unlimited room for development. The basis of biomedical theory is based on different human tissues and organs in different physiological and pathological conditions with different impedance characteristics and impedance distribution of state characteristics. By arranging a certain number of electrode arrays on the human body surface and applying a voltage /current excitation at a safe frequency,the voltage data of the body surface electrodes were measured and via image reconstruction algorithm reconstructs the distribution of the impedance characteristics of the human body in the form of a tomographic image. And then,obtaining the physiological/pathological information of body’s internal organs and tissues. EIT as an effective means of supplement of clinical diagnostic imaging technology, with non-invasive, safe, radiation-free, low cost, fast, real-time continuous monitoring and other advantages.In this paper, three-dimensional image reconstruction in human thoracic respiration process is mainly studied. From constructing three-dimensional human thoracic model, three-dimensional simulation model is constructed by extracting contours, which improves the model accuracy and suitability. Also, the optimization problem of electrode spacing of three - dimensional EIT system is studied, and the optimized parameters are obtained, the image quality is improved. The tomography of the different profiles was performed, getting a richer image information. Provides a real-time continuous monitoring platform by the MATLAB GUI image simulation platform we developed. Simultaneously, to carry out three-dimensional model simulation test and human lung respiration test,the sensitivity matrix is obtained by constructing a three-dimensional model. Image reconstruction was performed to obtain the respiratory process images of different chasm.The main innovation of this paper are as follows:(1) The thoracic contour of the human body was extracted and the human thoracic model was constructed. In this paper, we use the 3D optical scanning system to scan the chest external contours of healthy male volunteers to get the human thoracic contour model. Volunteer’s lung X-slice was used to obtain the physiological structure information of human lung, a model of lung organ structure with a certain proportion of size was constructed by SolidWorks software.Finally, the model is optimized in its size proportion and position distribution,which makes it close to the most real physiological structure distribution.(2) A three-dimensional forward problem model is built and the inverse problem is solved and optimized. The tomography of the different profiles was performed and the imaging results analyzed. Optimizing two-layer spacing with 16 electrodes,the results show that when the two-layer spacing is 8cm,the imaging results are the best by solving positive problem flow chart and evaluation index of the image reconstruction results. Above-mentioned obtained two-dimensional tomographic image to reconstruct three-dimensional, making the contours of the three-dimensional thoracic more clear, the internal structure of information more abundant.(3) The simulation platform of image reconstruction based on MATLAB GUI is developed. A user interface system for 3D reconstruction of lung respiration was designed by GUIDE,and the system is simple in operation and realizes the integration of data processing and image setting, the algorithm of conjugate gradient image reconstruction based on MATLAB is embedded in it,which provides an intuitive and effective user interface for time continuous monitoring. |
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