本文選題：電阻抗成像 + 直接數(shù)字頻率合成　； 參考：《天津工業(yè)大學》2017年碩士論文

【摘要】：電阻抗成像技術是醫(yī)學成像技術新的發(fā)展方向,其受到了相關領域研究者的廣泛關注。與現(xiàn)有醫(yī)學成像技術相比,有著當前已臨床應用的成像技術不具有的獨特優(yōu)點,它具有無創(chuàng)、無害、不使用核素和可連續(xù)性監(jiān)測的特點,尤其是更具有功能成像的特點,這對疾病的診斷和預防有著重要意義。當前已有EIT硬件系統(tǒng)電路均需要雙電源供電,且系統(tǒng)電路復雜,模擬器件繁多。為了簡化EIT硬件系統(tǒng)電路、減小測量設備體積以及提高硬件系統(tǒng)的移動性,本文建立了一套完整的EIH硬件系統(tǒng),并對建立后的硬件系統(tǒng)進行了實際的實驗測量。本文基于單片機和FPGA作為主控電路建立了一套EIH硬件系統(tǒng)。首先確立了一可行易于實現(xiàn)的EIT硬件系統(tǒng)設計方案,其主要包括主控器件的選擇、正弦信號激勵源的設計及實現(xiàn)、多路模擬開關與電極系統(tǒng)的選擇與設計、激勵模式的實現(xiàn)以及對被測信號的解調技術實現(xiàn)。根據(jù)目前已有的頻率合成技術,設計并實現(xiàn)了基于直接數(shù)字頻率合成技術的信號發(fā)生器,能夠實現(xiàn)頻率、幅值可調;簡要分析了目前應用于EIT硬件系統(tǒng)中的常見的電壓控制電流源,并根據(jù)電流源的特性,對電流源電路進行了優(yōu)化;根據(jù)本系統(tǒng)的設計特點,選取了正交序列解調的方法實現(xiàn)對被測信號的的相敏解調;制作了 16電極鹽水槽作為實驗測量對象,并選取相鄰激勵模式實現(xiàn)對被測對象的測量。在EIT硬件系統(tǒng)各個電路部分搭建好之后,分別進行了調試和實驗。得到了正弦信號發(fā)生器的波形測試結果,對優(yōu)化后的電流源電路各項參數(shù)進行了測量和計算,對建立的實驗鹽水槽模型進行測量得到了關于通道一致性的曲線。實驗結果證明,正弦信號發(fā)生器可輸出較穩(wěn)定的信號,電流源具有較好的性能,系統(tǒng)具有一定的通道一致性。本系統(tǒng)能夠實現(xiàn)對基于鹽水槽模型為對象進行激勵和測量,并獲得較穩(wěn)定的測量結果。本文這一實現(xiàn)方法為便攜式的EIH硬件系統(tǒng)設計提供了參考。
[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.
【學位授予單位】：天津工業(yè)大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：R310;TP391.41

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