本文選題：電阻抗成像 + 肺呼吸成像�。� 參考：《天津科技大學(xué)》2016年碩士論文

【摘要】：電阻抗斷層成像(Electrical Impedance Tomography,EIT)技術(shù)是根據(jù)生物體內(nèi)不同組織或同一組織在不同生理、病理狀態(tài)下具有不同電導(dǎo)率的特征,來(lái)得到機(jī)體內(nèi)部圖像的無(wú)損傷成像技術(shù)。通過(guò)在生物體表面施加安全電流(電壓),并測(cè)量表面其他測(cè)量點(diǎn)電壓,由計(jì)算機(jī)根據(jù)電學(xué)斷層圖像重建算法重構(gòu)出被測(cè)生物體內(nèi)部電阻抗分布圖像。它是將人體組織或器官的生物阻抗的分布和變化以2D/3D圖像的形式直觀的展現(xiàn)出來(lái),為被測(cè)組織或器官進(jìn)行診斷和評(píng)價(jià)提供依據(jù)。EIT技術(shù)以其非侵入、安全無(wú)輻射、成本低廉、成像速度快、可連續(xù)測(cè)量且實(shí)時(shí)可視化等優(yōu)點(diǎn)在醫(yī)學(xué)成像技術(shù)領(lǐng)域備受關(guān)注。本文從EIT技術(shù)的物理模型出發(fā),深入研究了三維EIT系統(tǒng)的測(cè)量機(jī)理,設(shè)計(jì)并構(gòu)建了包括信號(hào)源模塊、數(shù)據(jù)采集模塊、FPGA控制模塊等的2D/3D電阻抗成像系統(tǒng),采用VHDL語(yǔ)言編寫(xiě)了整套系統(tǒng)的應(yīng)用程序,在物理模型-試驗(yàn)水槽上實(shí)現(xiàn)了二維及三維靜態(tài)和動(dòng)態(tài)電阻抗成像,驗(yàn)證了系統(tǒng)可靠性及穩(wěn)定性,最后對(duì)人體肺呼吸過(guò)程進(jìn)行了電阻抗成像,取得較好效果。主要的研究工作如下:1.設(shè)計(jì)了一套兩層共32電極的三維高精度電阻抗成像系統(tǒng)硬件。該系統(tǒng)以PC機(jī)作為主控制器利用LabVIEW編寫(xiě)的上位機(jī)軟件進(jìn)行發(fā)送指令和將上傳的數(shù)據(jù)處理并調(diào)用Matlab進(jìn)行成像。FPGA作為從控制器負(fù)責(zé)激勵(lì)信號(hào)的產(chǎn)生、電極通道的切換、程控放大器增益的選擇及數(shù)據(jù)的采集與處理,采集到的數(shù)據(jù)通過(guò)串口與上位機(jī)進(jìn)行通信。實(shí)驗(yàn)結(jié)果表明該系統(tǒng)測(cè)量精度達(dá)0.082%,信噪比為60.3dB,空間分辨率達(dá)到0.29%。2.針對(duì)正交序列數(shù)字解調(diào)算法中參考信號(hào)與測(cè)量信號(hào)頻率不一致而引起的解調(diào)結(jié)果不準(zhǔn)確影響成像質(zhì)量的問(wèn)題,提出無(wú)需數(shù)字解調(diào)直接提取幅值進(jìn)行電阻抗成像的方法:通過(guò)多次采樣比較和算術(shù)平均濾波法獲取幅值進(jìn)行EIT成像。經(jīng)理論和實(shí)驗(yàn)結(jié)果證明,驗(yàn)證了直接提取阻抗幅值方法的可行性,提高了數(shù)據(jù)采集精度和系統(tǒng)的穩(wěn)定性,改善了圖像成像質(zhì)量。3.對(duì)構(gòu)建的EIT系統(tǒng)進(jìn)行二維成像的模擬試驗(yàn)。利用COMSOL軟件對(duì)二維系統(tǒng)進(jìn)行建模,基于共軛梯度算法,采用MATLAB對(duì)采集的數(shù)據(jù)進(jìn)行處理,實(shí)現(xiàn)了二維靜態(tài)及動(dòng)態(tài)成像。成像結(jié)果較清晰的顯示了目標(biāo)物體在試驗(yàn)水槽中的個(gè)數(shù)、形狀、大小、位置、運(yùn)動(dòng)狀態(tài)等信息。4.在人體上實(shí)現(xiàn)肺呼吸過(guò)程的電阻抗二維動(dòng)態(tài)成像。利用COMSOL構(gòu)造了帶有先驗(yàn)信息的二維肺部物理仿真模型,結(jié)合MATLAB編程,計(jì)算靈敏度矩陣。在志愿者胸腔進(jìn)行了數(shù)據(jù)采集,通過(guò)共軛梯度算法,獲得了肺呼吸過(guò)程的二維電阻抗圖像,成像質(zhì)量良好。5.在水槽模型上進(jìn)行了三維電阻抗成像實(shí)驗(yàn)。利用COMSOL軟件構(gòu)建三維水槽的物理仿真模型,采用準(zhǔn)對(duì)角激勵(lì)和同層相鄰測(cè)量的工作模式,結(jié)合MATLAB編程,計(jì)算得到新的靈敏度矩陣。在試驗(yàn)水槽上下兩層電極上進(jìn)行了三維數(shù)據(jù)采集及靜動(dòng)態(tài)成像。成像結(jié)果準(zhǔn)確地反映了目標(biāo)物體在試驗(yàn)水槽中的個(gè)數(shù)、形狀、大小、位置、運(yùn)動(dòng)狀態(tài)、高度等信息。6.人體呼吸過(guò)程三維電阻抗數(shù)據(jù)采集實(shí)驗(yàn)。在志愿者胸腔外圍均勻粘貼兩層共32個(gè)心電電極,在準(zhǔn)對(duì)角激勵(lì)和同層相鄰測(cè)量的工作模式下,采集呼吸過(guò)程邊界電壓并對(duì)采集數(shù)據(jù)進(jìn)行了分析。該系統(tǒng)為EIT系統(tǒng)的完善與系統(tǒng)性能的提升以及深入開(kāi)展肺功能評(píng)價(jià)研究及呼吸過(guò)程的床旁監(jiān)護(hù)和幫助醫(yī)生做出正確的疾病診斷提供了一種有效的解決方案。本文最后在總結(jié)研究工作的基礎(chǔ)上還提出了一些改進(jìn)性的建議。
[Abstract]:Electrical Impedance Tomography (EIT) technology is based on the characteristics of different electrical conductivity of different tissues or the same tissue in different physiological and pathological conditions. The non damage imaging technology of the internal image of the organism is applied to the surface of the organism by applying the safe current (voltage) on the surface of the organism and measuring the other surface. The measuring point voltage is reconstructed by the computer based on the electrical fault image reconstruction algorithm. It shows the distribution and change of the biological impedance of human tissues or organs in the form of 2D/3D image, and provides the basis of.EIT technology for the diagnosis and evaluation of the tissues or organs. The advantages of non-invasive, safe and non radiation, low cost, fast imaging speed, continuous measurement and real-time visualization have attracted much attention in the field of medical imaging technology. This paper, starting from the physical model of EIT technology, deeply studies the measurement mechanism of 3D EIT system, and designs and constructs the module of signal source, data acquisition module and FPGA control module. The 2D/3D electrical impedance imaging system, using the VHDL language to write the application program of the whole system, realized the two-dimensional and three-dimensional static and dynamic electrical impedance imaging on the physical model test sink, verified the reliability and stability of the system. Finally, the electrical impedance imaging of the human lung respiration process was carried out. The main research results were achieved. The work is as follows: 1. a set of three dimensional high precision electrical impedance imaging system hardware with a total of two layers of 32 electrodes is designed. The system uses PC as the main controller to send instructions by the host computer software written in LabVIEW and processing the uploaded data and invoking Matlab for imaging.FPGA as an incentive signal from the controller. The switching of the channel, the selection of the gain of the program control amplifier and the acquisition and processing of the data, the data collected are communicated with the host computer through the serial port. The experimental results show that the measurement accuracy of the system is 0.082%, the signal to noise ratio is 60.3dB, the spatial resolution reaches 0.29%.2., and the frequency of the reference signal and the measured signal is not frequency in the orthogonal sequence digital demodulation algorithm. The unaccurate result of unaccurate demodulation results in the image quality is inaccurate, and the method of electrical impedance imaging is proposed without digital demodulation. The amplitude of EIT is obtained by multiple sampling comparison and arithmetic average filtering. The feasibility of direct extraction of impedance amplitude method is proved by theoretical and experimental results. The accuracy of data acquisition and the stability of the system are improved, and the image imaging quality.3. is improved to simulate the two-dimensional imaging of the constructed EIT system. The two-dimensional system is modeled by the COMSOL software. Based on the conjugate gradient algorithm, the acquired data is processed with MATLAB, and the two-dimensional static and dynamic imaging results are realized. It clearly shows the two-dimensional dynamic electrical impedance imaging of the number, shape, size, position and motion state of the object in the test sink, such as the number, shape, size, position and motion state of the object. Using COMSOL, a two-dimensional lung physical simulation model with prior information is constructed, and the sensitivity matrix is calculated with MATLAB programming. In the volunteers' chest, the.4. is used to calculate the sensitivity matrix. The cavity carries on the data collection, obtains the two-dimensional electrical impedance image of the lung breathing process through the conjugate gradient algorithm. The imaging quality is good.5. is carried out on the 3D electrical impedance imaging experiment on the tank model. The physical simulation model of the three dimensional tank is constructed by using the COMSOL software, and the working mode of the quasi angle excitation and the same layer adjacent measurement is adopted, and the MA is combined with the model. A new sensitivity matrix is obtained by TLAB programming. Three-dimensional data acquisition and static and dynamic imaging are carried out on two layers of electrodes on the test sink. The imaging results accurately reflect the number, shape, size, position, motion state, height, etc. of the target object in the test sink for 3D electrical impedance data acquisition of the.6. body respiration process. The two layers of 32 electrocardio electrodes were pasted evenly on the periphery of the volunteers' chest, and the boundary voltage of the respiratory process was collected under the working mode of quasi diagonal excitation and the adjacent measurement of the same layer. The system is the improvement of the EIT system and the performance of the system, the evaluation of lung function and the breathing process. The bedside monitoring and the help of the doctor to make the correct diagnosis of the disease provide an effective solution. Finally, on the basis of the summary of the research work, some suggestions for improvement are also put forward.

【學(xué)位授予單位】：天津科技大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2016
【分類號(hào)】：TP391.41

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