以近紅外光動態傳播影像分析生物組織特性

Tissue Characterization by the Dynamic Propagation of Near-Infrared

黃敏菁(MIN-JING HUANG)

指導教授 ： 蔡正倫

中原大學/工學院/醫學工程研究所/碩士(2006年)

https://doi.org/10.6840/cycu200600122

摘要

光在散射物質內的遷移是決定生醫光學應用的基本現象之一，對其發生過程的了解越多，就越知道如何操控以便獲得較好測量結果，而研究光遷移過程的方法之ㄧ就是直接觀察光的動態擴散傳播現象。
在此研究中建立了一套小型化的低同調光干涉儀用來從介質側面觀察光子的擴散傳播，實驗所使用的光源有655nm 以及780nm兩種波長。所擷取的影像也分別使用了光斑點對比以及可見度兩種影像處理方式來做處理，而可見度影像的訊號強度比斑點對比的訊號約大了一倍，而此訊號的產生來源主要是光斑隨著時間而晃動，產生了亮度改變。經過空間濾波平滑化之後的影像，可更明顯看出光在動態擴散時的分布輪廓，而光分布影像的亮度截面也提供了用以研究光隨著時間經過而散射的重要資訊。
光動態擴散量測明確顯示了紅光比近紅外光在塑膠以及生物組織內都有較強的散射特性，與蒙地卡羅模擬(Monte Carlo Simulation)之結果比較，找出各樣本之光學參數。

關鍵字

可見度 ； 光斑點對比 ； 低同調光干涉儀 ； 光傳播

並列摘要

Photon migration in scattering media is one of the basic phenomena that determine the applications of biomedical optics. The more we understand its process, the better we can manipulate it to obtain better measurement. One way to study the photon migration process is to direct observe the dynamic diffusive propagation of light.
In this study, a compact low coherence time-gating interferometer was set up to observe the lateral image of photon diffusive propagation. Both 650nm and 780nm light sources were used in this study. The interference images were processed by using speckle contrast and visibility methods to acquire the photon distribution within a specific time period. The results show that the intensity of visibility is about twice the magnitude of speckle contrast. The variation of speckle intensity in time is the major source of signal. The filtered speckle contrast images provide smoother profile of diffusing light distribution. The cross-section of light distribution image also showed useful information for studying the time-resolved behavior of light scattering.
The dynamic propagation measurement clearly showed that opaque plastic and biological tissues all have stronger scattering property for red light near infrared. The Monte Carlo simulation also showed results similar to the measurements.

並列關鍵字

Speckle contr ； Low coherence interferometer ； Visibility

參考文獻

7. Eiji Okada and David T. Delpy “Near-infrared light propagation in an adult

11. Charles A. Thompson, Kevin J. Webb and Andrew M. Weiner,” Diffusive media

2. J. David Briers and Sián Webster ”Laser speckle contrast analysis (LASCA):

A nonscanning, full-field technique for monitoring capillary blood flow,”

Doppler and time-varying speckle: a reconciliation,” Opt. Soc. Am. A Vol.