近紅外光擴散光學斷層掃瞄是一種非侵入式且無輻射性的新型生醫影像技術，主要提供組織內光學係數分佈的功能性影像。本論文的研究目的為發展頻域近紅外光擴散光學斷層掃瞄系統及數據校正方法，以期能為臨床上的腫瘤診斷提供有用之工具。量測系統為一單臂式旋轉機構用以擷取調變光穿過組織後的光強度及相位資訊。擷取的資料在進行影像重建之前必須經過適當的校正。我們使用的校正方式是以已知光學係數之均質假體做為基準，將量測與模擬結果作比較，藉此估算量測系統造成的資訊偏移。經由雙積分球系統量測假體材料(人造脂質,India ink)的光學係數在不同濃度下的線性變化，並求得製作所需真實光學係數之假體之配方。我們針對校正後之數據相對於模擬數據的誤差進行分析。結果顯示使用不同均質假體做為校正基準校正後之量測數據與模擬數據間會有不同程度的誤差。非均質假體之影像重建結果亦將在本論文中呈現並討論目前系統的量測極限。 Near-infrared diffuse optical tomography is a new non-invasive and non-radiation biomedical imaging technique that provides functional image of optical properties distribution within objective tissues. The purpose of this thesis is to develop frequency-domain (FD) NIR-DOT system and the corresponding calibration method. We expected that FD NIR-DOT would become a useful tool for clinical tumor diagnosis. FD NIR-DOT measurement system is constructed based on a single-armed rotating scanning device. Intensity and phase delay information of intensity modulated light propagates through the objective tissue are acquired. For image reconstruction, acquired data (intensity and phase delay) must be calibrated properly in order to eliminate systematic offsets. We introduced a calibration method involving one complete characterized homogeneous phantom measurement and forward simulation. Double integrating sphere system was applied to determine absorption coefficient and reduced scattering coefficient of different concentrations of tissue-mimicking phantom contents (fat emulsions and India ink). According to the linear relationship between optical properties and concentration of phantom contents, phantoms with exact optical properties can be prepared. We analyzed the relative error between the calibrated data and the computed ones. Reconstructed images of two heterogeneous phantom cases are demonstrated that reveal the limitation of the current NIR-DOT imaging system.
