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Characterization of Biological Tissues by Polarization Analysis of diffused light

通过漫射光偏振分析表征生物组织

基本信息

批准号：
16500303
负责人：
FUJII Mamiko
金额：
$ 2.05万
依托单位：
Sophia University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2004
资助国家：
日本
起止时间：
2004 至 2005
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-16500303/
关键词：
2D polarization measurement of back scattered ligh scattering pattern back scattering Monte Carlo method intra cellular structure tissue structure モンテカルロシミュレーション

项目摘要

The scattering properties of a tissue depend on the cell size, cell constituents and cell structure ; therefore, the measurement of scattering light can be useful for tissue characterization, metabolism monitoring and so on. In particular, backscattering is very sensitive to both the size of the subcellular structure and the polarization state. The conventional method employed to study the scattering from biological material involves goniophotometric measurement ; however, the sample for this method should be very thin. Because biological tissues have very strong scattering properties and incident polarized beam becomes diffusive light while passing through very short path.This project aims to propose new method to obtain the 2D angular pattern of polarized backscattering light from small volume of turbid media such as living tissue without pretreatment. The system derives a single scattering component that has a specific angular distribution pattern depending on the constituents and s … More tructures of the scattering substances. We attempt to detect the angular distribution of the backscattered light by using a 2D imaging sensor. We developed a Monte Carlo simulation to estimate the photon propagation behavior of our experimental system. This simulation employed Mie scattering phase function and the results were normalized with incident beam power. The simulation results showed that the characteristic patterns, which contain information on the scattering particles and medium, are due to the scattering phenomenon that occurs only in a very small volume around the incident point. Moreover, the reduced scattering coefficient μs' served as a suitable index for estimating the influence of diffusive multiple scattering on the 2D pattern. The small pinhole system enables the suppression of the diffusive multiple scattering; therefore, the angular distribution of the informative single scattering component can be observed as a 2D image by using our system. We developed a basic experimental system that could obtain the 2D angular pattern of backscattering, and preliminary experiments using suspensions of polystyrene sphere in water were performed. We verified that the proposed system could obtain the 2D angular pattern of backscattered polarized light from even high scattering materials, with a μs' value of 1 mm^<-1>, which was equivalent to that obtained from biological materials. However, difference of intensity due to polarization direction was not clear compare to the predictions by the simulation. The reason of this discrepancy remains unsolved yet. In order to apply our method for tissue characterization, the experimental system should be improved further and new approaches to relate the 2D patterns of angular distribution to the tissue structure and constituents are required. Less

组织的散射特性取决于细胞大小、细胞成分和细胞结构；因此，散射光的测量可用于组织表征、代谢监测等。特别是，反向散射对亚细胞结构的大小和偏振态都非常敏感。研究生物材料散射的传统方法包括测角光度测量。然而，该方法的样品应该非常薄。由于生物组织具有很强的散射特性，入射偏振光束在通过很短的路径时会变成漫射光。该项目旨在提出一种新方法，无需预处理即可从小体积的浑浊介质（例如活体组织）中获得偏振后向散射光的二维角图案。该系统根据散射物质的成分和结构得出具有特定角分布模式的单个散射分量。我们尝试使用 2D 成像传感器来检测反向散射光的角度分布。我们开发了蒙特卡罗模拟来估计我们实验系统的光子传播行为。该模拟采用米氏散射相位函数，并用入射光束功率对结果进行归一化。模拟结果表明，包含散射粒子和介质信息的特征图案是由于仅在入射点周围很小的体积内发生的散射现象造成的。此外，降低的散射系数μs'可作为估计扩散多重散射对二维图案影响的合适指标。小针孔系统可抑制扩散多重散射；因此，使用我们的系统可以将信息丰富的单散射分量的角度分布观察为二维图像。我们开发了一个可以获得反向散射二维角图案的基本实验系统，并使用聚苯乙烯球在水中的悬浮液进行了初步实验。我们验证了所提出的系统甚至可以从高散射材料中获得反向散射偏振光的2D角图案，μs'值为1mm^<-1>，这与从生物材料中获得的相同。然而，与模拟的预测相比，由于偏振方向引起的强度差异并不明显。造成这种差异的原因尚未解决。为了应用我们的组织表征方法，应该进一步改进实验系统，并且需要新的方法将角度分布的二维图案与组织结构和成分联系起来。较少的