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研究生： 施柏全
Po-Chan Shih
論文名稱： 移動式電阻抗斷層攝影術量測系統設計
Design of the Movable Electrical Impedance Tomography System
指導教授： 鍾鴻源
Hung-Yuan Chung
口試委員:
學位類別： 碩士
Master
系所名稱： 資訊電機學院 - 電機工程學系
Department of Electrical Engineering
畢業學年度： 93
語文別： 中文
論文頁數： 91
中文關鍵詞： 電阻抗斷層攝影術 、移動式電阻抗斷層攝影術 、人機介面 、影像重建 、有限元素法 、牛頓拉夫遜法 、鎖相
外文關鍵詞： MEIT, GUI, image reconstruction, finite element method, Newton Raphson, lock in, electrical impedance tomography
相關次數： 點閱：15  下載：0 
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    • 本篇論文之目的，在於設計移動式電阻抗斷層攝影術量測系統(MEIT)配合有限元素法以及修正式牛頓拉夫遜法，估算生物組織內部的阻抗分佈情形。MEIT系統設計包括資料擷取系統、馬達控制驅動電路、穩壓器、定電流源、解調器、電極選用、以及電極的配置等；軟體部分則是以Labview 圖控軟體設計人機介面(GUI)，GUI中包括自動量測介面、手動測試量測介面以及馬達驅動測試介面。
    MEIT系統的特色是改善目前EIT系統在量測時因電極數目過多且無法在增加電極數目的狀況下，以移動電極的方式來提高電極的數目，並進一步提昇阻抗影像的品質。實驗的結果中得知，雖然由固定式量測所建立的6組個別影像可以估測出待測物體的位置，並且可觀察出待測物因電極轉動所產生不同像素值的變化，但是個別影像卻受到雜訊的影響使得影像的清晰度不高，因此本研究將6組個別影像重新做平均合成，或利用此6組數據再建立更高解析度之圖形，可得知經由合成後的影像清晰度會大幅提高，並同時消除雜訊在影像中的影響。
    雖然MEIT系統尚在研究發展的階段，然而重新合成後的影像可發現，影像中的清晰度已經明顯的提高且待測物位置也能清楚地指出，擴展電極數所合成之影像更可明確的看出影像位置。因此，驗證出利用移動式電極擴展量測資料到高品質的阻抗影像圖形是可行的。

    In this paper, the principal purpose is to develop a novel imaging system, which is named Movable Electrical Impedance Tomography (MEIT). The MEIT system estimates the distribution of the internal conductance of the tissue by the finite element methods (FEM) and the modified Newton-Raphson. The Design of the MEIT system contains of the data collection system, the stepping motor circuit, the voltage control current source (VCCS), and the electrodes configuration. For part of the software, the Graphical User Interface (GUI) which is developed by Labview, consists of automatic measurement, manual measurement and motor test interfaces.
    In order to improve the resolution of image from the traditional EIT system which was limited by the number of electrodes, the MEIT system can obtain more amount of measuring data after moving the electrodes. Although the reconstruction results show that the six individual images constructed by the static electrodes could detect the position of the object approximately, some of the individual images were perturbed by the noise. So the MEIT system synthesizes the six individual images to a combined image and high-resolution image. These new images display clearly an imaging object and the eliminated noise simultaneously.
    Although the MEIT system is still under development, the combined images could indicate the position of object obviously. Therefore, the MEIT system provides a feasibility to reconstruct a high quality impedance image by moving electrodes.

    目錄 頁次 中文摘要 英文摘要 致謝 目錄 I 圖目錄 IV 表目錄 VII 第一章 緒論 1.1 電阻抗斷層攝影系統之背景與原理 1 1.2 生物組織之電阻抗特性 4 1.3 電阻抗斷層攝影系統之文獻回顧 7 1.4 研究目的 11 第二章 移動式系統組成之設計與量測原理 2.1 移動式電阻抗量測原理 13 2.2 穩壓器設計 17 2.3 電壓控制電流源設計 18 2.4 資料擷取系統設計 22 2.5 馬達驅動電路設計 24 2.5.1 步進馬達原理 24 2.5.2 步進馬達驅動電路 25 2.5.3 步進馬達激磁順序 26 2.6 量測訊號解調設計 27 2.6.1 RMS解調設計 27 2.6.2 Lock-in解調設計 28 2.7 改善量測偏壓 30 第三章 電阻抗斷層攝影之影像重建 3.1 介紹 32 3.2 阻抗型態定義 32 3.3 影像重建問題 33 3.3.1 正向問題 34 3.3.2 反向問題 35 3.4 影像重建方法 35 3.4.1 正向問題解 36 3.4.2 反向問題解 41 第四章 MEIT系統控制介面設計 4.1 介面軟體與資料擷取卡之介紹 44 4.1.1 介面軟體介紹 44 4.1.2 資料擷取卡介紹 45 4.2 圖控式介面設計 47 第五章 系統測試與實驗結果 5.1 系統測試 52 5.1.1 數位控制電路訊號測試 53 5.1.2 步進馬達電路訊號測試 54 5.1.3 電流注入-電壓量測訊號測試 55 5.1.4 電極測試 56 5.2 實驗結果 59 5.2.1 網格建立方式 60 5.2.2 阻抗影像重建 62 第六章 結論與展望 6.1 結論 82 6.2 硬體之未來發展 82 參考文獻 84 論文著作 91 圖目錄 頁次 圖1-1 電阻抗斷層攝影流程圖 1 圖1-2 4電極量測示意圖 2 圖1-3 生物組織之電路等效模型 7 圖1-4 TS2000 量測儀器 10 圖1-5 論文架構 12 圖2-1 MEIT系統方塊圖 13 圖2-2 圓盤與電極設計圖 15 圖2-3 步進馬達帶動圓盤位移方式以及電極數目 16 圖2-4 穩壓器電路設計 17 圖2-5 定電流負載浮接法 19 圖2-6 有源電橋法 20 圖2-7 三運算放大器組成之定電流源電路 21 圖2-8 Howland 定電流電路 22 圖2-9 EIT資料擷取架構圖 23 圖2-10 共模回授電路設計 24 圖2-11 步進馬達驅動電路 26 圖2-12 MEIT系統解調流程 27 圖2-13 鎖相解調放大電路 28 圖2-14 濾除直流影響之主動放大電路 31 圖3-1 重建影像之正向問題與反向問題解 34 圖3-2 影像重建方法的處理流程 36 圖3-3 建立量測區域模型 37 圖3-4 經由Negten軟體網格化圖示 38 圖3-5 電壓電流量測對應方式 40 圖3-6 牛頓-拉夫遜原理 42 圖4-1 Labview圖控式介面設計 45 圖4-2 Labview語言描述程式 45 圖4-3 NI DAQ-6025E卡對外的溝通介面 46 圖4-4 主要測試介面 48 圖4-5 手動測試介面 49 圖4-6 馬達測試介面 49 圖4-7 主要量測與手動測試介面流程 50 圖4-8 馬達測試介面流程圖 51 圖5-1 MEIT完整電路實體圖 52 圖5-2 數位控制電路 53 圖5-3 測試介面量測電壓訊號測試 53 圖5-4 步進馬達正轉激磁測試 54 圖5-5 碳、銅電極之電壓量測訊號測試 57 圖5-6 待測物量測實體架構圖 59 圖5-7 介面-硬體操作之顯像流程 60 圖5-8 網格建立流程圖 61 圖5-9 假體網格分佈與電極位置(紅色標記) 62 圖5-10 影像重建流程 63 圖5-11 比較銅電極於絕緣體解調量測之個別影像 64 圖5-12 比較銅電極於絕緣體解調量測之合成影像 65 圖5-13 比較銅電極於絕緣體解調量測之48電極影像重建 65 圖5-14 比較碳電極於絕緣體解調量測之個別影像 65 圖5-15 比較碳電極於絕緣體解調量測之合成影像 66 圖5-16 比較碳電極於絕緣體解調量測之48電極影像重建 66 圖5-17 絕緣體、導體量測實體圖 66 圖5-18 應用碳電極於金屬導體上量測之個別影像重建 67 圖5-19 應用碳電極於金屬導體上量測之合成影像重建 68 圖5-20 應用碳電極於金屬導體上量測之48電極影像重建 69 圖5-21 應用碳電極於絕緣體上量測之個別影像重建 70 圖5-22 應用碳電極於絕緣體上量測之合成影像重建 71 圖5-23 應用碳電極於絕緣體上量測之48電極影像重建 72 圖5-24 應用銅電極於金屬導體上量測之個別電極影像重建 73 圖5-25 應用銅電極於金屬導體上量測之合成電極影像重建 74 圖5-26 應用銅電極於金屬導體上量測之48電極影像重建 75 圖5-27 應用銅電極於絕緣體上量測之個別影像重建 76 圖5-28 應用銅電極於絕緣體上量測之合成影像重建 77 圖5-29 應用銅電極於絕緣體上量測之48電極影像重建 78 圖5-30 導體、絕緣體置於碳電極位置1、5之影像重建 80 圖5-31 絕緣體、導體置於碳電極位置3、5、7之影像重建 81 表目錄 頁次 表1-1 哺乳動物的組織電阻率分佈 6 表1-2 Sheffield 阻抗量測系統發展史 9 表1-3 EIT相關儀器裝置參考目錄 11 表2-1 一般EIT量測與移動式EIT比較 14 表2-2 2相激磁順序圖 27 表4-1 NI DAQ-6025E 卡 規格表 47 表5-1 MEIT 系統規格表 53 表5-2 數位電路控制訊號 53 表5-3 定電流誤差比 56 表5-4 銅、碳電極對應誤差比 58

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