电阻抗成像硬件系统的研究

发布时间：2018-06-17 02:33

本文选题：电阻抗成像 + 直接数字频率合成　；参考：《天津工业大学》2017年硕士论文

【摘要】：电阻抗成像技术是医学成像技术新的发展方向,其受到了相关领域研究者的广泛关注。与现有医学成像技术相比,有着当前已临床应用的成像技术不具有的独特优点,它具有无创、无害、不使用核素和可连续性监测的特点,尤其是更具有功能成像的特点,这对疾病的诊断和预防有着重要意义。当前已有EIT硬件系统电路均需要双电源供电,且系统电路复杂,模拟器件繁多。为了简化EIT硬件系统电路、减小测量设备体积以及提高硬件系统的移动性,本文建立了一套完整的EIH硬件系统,并对建立后的硬件系统进行了实际的实验测量。本文基于单片机和FPGA作为主控电路建立了一套EIH硬件系统。首先确立了一可行易于实现的EIT硬件系统设计方案,其主要包括主控器件的选择、正弦信号激励源的设计及实现、多路模拟开关与电极系统的选择与设计、激励模式的实现以及对被测信号的解调技术实现。根据目前已有的频率合成技术,设计并实现了基于直接数字频率合成技术的信号发生器,能够实现频率、幅值可调;简要分析了目前应用于EIT硬件系统中的常见的电压控制电流源,并根据电流源的特性,对电流源电路进行了优化;根据本系统的设计特点,选取了正交序列解调的方法实现对被测信号的的相敏解调;制作了 16电极盐水槽作为实验测量对象,并选取相邻激励模式实现对被测对象的测量。在EIT硬件系统各个电路部分搭建好之后,分别进行了调试和实验。得到了正弦信号发生器的波形测试结果,对优化后的电流源电路各项参数进行了测量和计算,对建立的实验盐水槽模型进行测量得到了关于通道一致性的曲线。实验结果证明,正弦信号发生器可输出较稳定的信号,电流源具有较好的性能,系统具有一定的通道一致性。本系统能够实现对基于盐水槽模型为对象进行激励和测量,并获得较稳定的测量结果。本文这一实现方法为便携式的EIH硬件系统设计提供了参考。
[Abstract]:Electrical impedance imaging technology is a new development direction of medical imaging technology, which has been widely concerned by researchers in related fields. Compared with existing medical imaging technologies, it has unique advantages that are not available in current clinical applications. It has the characteristics of non-invasive, harmless, non-nuclide use and continuous monitoring, especially functional imaging. This is of great significance to the diagnosis and prevention of diseases. At present, EIT hardware system circuits all need dual power supply, and the system circuit is complex and analog devices are various. In order to simplify the circuit of EIT hardware system, reduce the volume of measuring equipment and improve the mobility of hardware system, a complete EIH hardware system is established in this paper. In this paper, an EIH hardware system is established based on MCU and FPGA as the main control circuit. First, a feasible and easy to implement EIT hardware system design scheme is established, which mainly includes the selection of main control device, the design and implementation of sinusoidal signal excitation source, the selection and design of multi-channel analog switch and electrode system. The actualization of the excitation mode and the demodulation technology of the measured signal. According to the existing frequency synthesis technology, a signal generator based on direct digital frequency synthesis technology is designed and implemented, which can realize frequency and amplitude adjustable. This paper briefly analyzes the common voltage-controlled current source used in EIT hardware system, and optimizes the current source circuit according to the characteristics of the current source, according to the design characteristics of the system, The method of quadrature sequence demodulation is selected to realize the phase sensitive demodulation of the measured signal, and the 16 electrode salt tank is made as the experimental object, and the adjacent excitation mode is selected to realize the measurement of the tested object. After each circuit of EIT hardware system is built up, debugging and experiment are carried out respectively. The waveform test results of the sinusoidal signal generator are obtained. The parameters of the optimized current source circuit are measured and calculated. The curves of channel consistency are obtained by measuring the established salt tank model. The experimental results show that the sinusoidal signal generator can output stable signals, the current source has better performance, and the system has a certain channel consistency. The system can realize the excitation and measurement based on salt flume model, and obtain more stable measurement results. This method provides a reference for the design of portable EIH hardware system.
【学位授予单位】：天津工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：R310;TP391.41

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