Construction and verification of portable hyper-spectral imaging system

本研究主旨為建構一移動式高光譜顯微影像系統，並結合影像光纖束所提供的空間分布訊號以進行不同距離下之漫反射光譜以及螢光光譜資訊，再透過漫反射光譜擬合工具進行組織光學參數之萃取，以期可應用於臨床研究之量測系統。 本研究使用兩種不同形式之影像光纖束，分別為斜角及平口光纖束，可應用於淺層及較深層組織之訊號量測；本系統利用自製設計之鉻材質衰減片以消除光源光纖對於漫反射及螢光訊號量測的影響，並結合電動遮光器以切換選擇不同之入射光源，以進行漫反射和螢光訊號量測模式的切換；在不同距離下的漫反射訊號分析則採用兩種分析模式，一為沿影像光纖束中心軸由光源光纖向外圈選圓形區域(Region of interest, ROI)之分析模式，另一則為由光源光纖為中心，向外圈選同心圓環進行漫反射訊號分析。 本系統以驗證後之縮放式蒙地卡羅順向模擬光譜進行組織漫反射光譜校正，目前採用由光源光纖向外圈選同心圓環之SDS分析模式，並以兩種不同尺寸之單層擬組織散射源(polystyrene)進行量測校正比對，目前於SDS = 400、600、800 μm 之偵測光纖束下其校正之絕對誤差率平均值已可達到6%以內的水準，由此可知本系統之漫反射光譜量測已達到相當程度的準確率，目前亦已針對正常人體口腔黏膜組織進行量測並使用反向模型擬合工具萃取出組織光學參數。預計本系統未來可直接應用於雙層仿體、活體組織的實際量測，期能以反向擬合工具進行準確之光學參數萃取及光學參數資料庫比對、血氧濃度和血紅素濃度之資訊定量。 在螢光量測的部分，未來將會針對合適之激發-放出對(Excitation-emission matrix, EEM)的資訊，以選取應用的激發光源以及螢光濾片。本系統最終目標為成為一穩定的移動式臨床量測系統，並能提供癌前病變診斷的資訊。The gist of this research is to construct a portable hyper-spectral imaging (HSI) system. This system utilizes imaging fiber bundle as a detection probe to gathering spatially-resolved diffuse reflectance (DRS) and fluorescence signals. And we use DRS fitting tools to extract tissue optical parameters: scattering/absorption coefficients, hemoglobin concentration, and tissue thickness. The system has two types of fiber probe: oblique and perpendicular probes. These probes can be applied to obtain optical signals from superficial and deeper tissue layers. The system integrates motorized electronic shutters and broadband/UV light sources to switch DRS and fluorescence measurements. And the system uses self-made chromium (Cr) attenuation filter to eliminate the specular reflection from the surface of imaging fiber bundles. In the signal analysis, we designed two analysis modes: 1.choosing circular region of interests (ROI) from source fiber to outside detection fibers along the center of imaging fiber bundles; 2.selecting concentric ROI from source fiber to outside. We used verified scaling Monte Carlo (MC) forward simulation spectrum to calibrate practical DRS spectrum data. At this study, we measured and compared two different sizes of scattering phantoms (polystyrene). The averages of calibration error achieved to 6.02% or below at SDS = 400、600、800 μ"m" . It shows that the portable system possesses proper performance in DRS measurements. And this study shows the DRS results of normal human oral mucous tissues, including experimental spectra and extracted optical parameters by calibration and inverse fitting tools. Based on standard calibration protocols and fitting tools, we expect to use this portable system to execute DRS measurements of double layer phantom and live tissues, to extract precise optical parameters from measured data by inverse simulation spectrum, and to quantify the contents of hemoglobin and blood oxygen saturation. For the fluorescence measurements, our research team will search for enough information of fluorescence excitation-emission matrix (EEM) to choose proper light source and filters for uses. The final aim is to establish a stable and portable optical system for clinical diagnosis