利用漫反射光譜及螢光光譜進行仿體強度分佈之分析

Using Diffuse Reflectance Spectroscopy and Fluorescence Spectroscopy to Analyze the Intensity Distribution on Phantom

蘇鈺惠(Yu-Hui Su)

指導教授 ： 宋孔彬

國立臺灣大學/電機資訊學院/生醫電子與資訊學研究所/碩士(2013年)

https://doi.org/10.6342/NTU.2013.02208

摘要

病變發展過程中，組織內自體螢光物質如煙酰胺腺嘌呤二核苷酸(Reduced nicotinamide adenine dinucleotide)、黃素腺嘌呤二核苷酸(Flavin adenine dinucleotide)、膠原蛋白(collagen)等因為病理結構及代謝不同，而使得其放出自體螢光強度改變，可望藉由此資訊判別癌前病變組織及正常組織。然而由於組織內散射及吸收的特性，使得量測到的螢光強度受影響且光譜變形，於分析上較為困難。本研究建立雙層組織模型，假設組織包含鱗狀上皮細胞(squamous epithelium)及下層基底層(stroma)，以及設計光纖角度並且利用多根偵測光纖分析光譜於空間上的資訊，進而使得光纖具有深度選擇偵測能力。利用施光偉同學所建構之高光譜影像系統量測仿體漫反射光譜及螢光光譜強度分佈，並藉由反向漫反射光譜擬合工具萃取仿體的吸收係數及散射係數，期望未來能運用於量測人體組織之螢光光譜，將萃取出的光學參數套用於蒙地卡羅演算法分析量測到的自體螢光光譜，使其還原成組織內生性螢光光譜(intrinsic fluorescence spectroscopy)，為臨床光譜診斷工具開發的評估。於漫反射仿體實驗之設計，利用聚苯乙烯小球(polystyrene)及血紅蛋白製作單層仿體及雙層仿體。本研究於漫反射仿體量測實驗分別利用垂直光纖及斜角光纖量測，並評估兩者之靈敏度及光學參數萃取的準確度。液態仿體量測結果，兩種光纖量測實驗光譜與理論光譜於400nm-700nm整體方均根誤差約為7%以內，顯示移動式高光譜影像系統量測漫反射光譜是可靠且穩定；雙層仿體漫反射量測結果：垂直光纖量測於450nm-700nm波段實驗與理論方均根誤差約為6%；利用資料庫萃取仿體光學參數誤差約25%，以反向光譜擬合工具萃取光學參數誤差皆在15%以內。斜角光纖量測雙層仿體漫反射光譜之結果，於450nm-700nm實驗與理論方均根誤差為14%，利用資料庫萃取光學參數整體平均誤差約23%。顯示雖斜角光纖量測漫反射光譜誤差約為垂直光纖的兩倍，然利用資料庫萃取光學參數的整體結果略佳，表示斜角光纖可能對於光學參數的變化較為靈敏。此外，本研究利用蒙地卡羅演算法模擬螢光的過程，並量測仿體螢光光譜，評估模擬方法與實驗上擬合的準確度。於仿體設計上，利用小球及Rhodamine B為材料，利用405nm雷射作為激發光源。本研究液態仿體其實驗值與理論值結果於放光波段方均根誤差約10%，表示此模擬方法能作為螢光光譜擬合工具。

關鍵字

漫反射光譜 ； 螢光光譜 ； 蒙地卡羅 ； 上皮組織 ； 仿體

並列摘要

During the development and progression of neoplasia, research have shown that there are changes in the concentration of fluorophores in precancer tissue such as reduced nicotinamide adenine dinucleotide(NADH), flavin adenine dinucleotide(FAD), collagen, etc. However, the measured autofluorescence spectrum would be distorted due to scattering and absorption in tissue, resulting in the difficulties in analyzing the information. Therefore, there is necessary to extract intrinsic fluorescence spectrum (IFS) from turbid media. To extract IFS accurately, optical parameters extraction from tissue are needed to input the numerical model.
The objectives of this research are to establish 2-layer tissue model, utilizing the design of fiber probe to measure intensity distribution of diffuse reflectance spectrum (DRS) and fluorescence spectrum (FS) from phantoms with a custom-built portable hyperspectral image system (PHI system), and to validate the stability of the PHI system and the accuracy of Monte Carlo method as a spectral curve-fitting tool. In order to evaluate the potential of developing diagnostic tool, we tried to extract the μa and μs of the phantoms from an inverse curve-fitting tool and estimated its accuracy.
Experimental studies were first carried out on DRS of single and double layer phantoms that contained polystyrene and hemoglobin. Besides, we’ve measured DRS of phantom with normal and oblique probe, so that we could evaluate the performance of sensitivity and accuracy on these two fibers.
In order to extract the optical parameters of phantoms, we used data table and inverse iterative scaling Monte Carlo (sMC) as inverse curve-fitting tools respectively. Results of DRS of single layer phantoms show that the RMSE are within 7% at 400nm-700nm from normal probe and oblique probe measurement. Results show the RMSE% of DRS on double layer phantoms at 450nm-700nm are 6%. The error% of optical parameters extraction from date table are about 25%, and error are within 15% from inverse iterative sMC. The RMSE% of DRS measurement on 2-layer phantom with oblique probe is 14% at 450nm-700nm, and error of parameters extraction are about 23%, which shows oblique probe may be more sensitive with the changes of optical parameters.
For FS experiment, we chose polystyrene and rhodamine B as scatter and fluorophore for phantoms. The excitation source is 405nm laser. Results show the RMSE% between experiment and theory is about 10% for liquid phantom measurement.

並列關鍵字

Diffuse reflectance spectrum ； Fluorescence spectrum ； Monte Carlo ； epithelial tissue ； phantom

參考文獻

[28] 涂文福, "燃煤發電廠中排煙脫硫之不透光率研究," 2012.

[23] 陳俊宇, "利用高光譜影像系統量測組織仿體光學參數以及血紅素濃度," July, 2010.

[33] 陳錫勳, "利用斜角光纖定量雙層組織的光學參數," July, 2012.

[37] A. Welch, C. Gardner, R. Richards-Kortum, E. Chan, G. Criswell, J. Pfefer, and S. Warren, "Propagation of fluorescent light," Lasers in surgery and medicine, vol. 21, pp. 166-178, 1997.

[1] D. W. Felsher, "Cancer revoked: oncogenes as therapeutic targets," Nat Rev Cancer, vol. 3, pp. 375-80, May 2003.