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Optical Characteristics of Tissue and its Application for Optical CT

组织的光学特性及其在光学CT中的应用

基本信息

批准号：
06680863
负责人：
FUJII Mamiko
金额：
$ 1.28万
依托单位：
Sophia University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1994
资助国家：
日本
起止时间：
1994 至 1995
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-06680863/
关键词：
Back Projection Method Phase Function Monte Carlo Method Absorption Coefficient Scattering Coefficient Absorbance of Hemoglobin Optical CT optical Anisotropic parameter 非等方性パラメータ CT画像強度変調光

项目摘要

In the medical field, optical CT is expected as a safe and portable methos to get functional image of tissue. Therefore in visible and near infrared light region, absorption is caused mostly hemoglobin, and the absorption spectrum of hemoglobin changes due to oxidization. However it is very difficult to distinguish absorption information, because of strong scattering of light in tissue. At first, we estimated optical parameter of tissue sample, second we investigated the photon propagation in scattering medium, and third we estimated CT image.For the estimation of optical parameter, laser beam amplitude-modulated at 100MHz was used as light source, then measured an amplitude ratio and phase between incident beam and transmitted beam through samples of various thickness. From those experiment we evaluated absorption coefficients, scattering coefficients and anisotropic parameters of blood, muscle, fat and the suspension of intralipid. For theoretical analysis computer simulation was car … More ried out by Monte Carlo method based on radiative transport theory. This results agree with results of phantom experiment.To realize optical CT,we set up experimental system using computer controlled CCD camera and light flux from halogen lamp through Fabry-Perot optical filter. We detected scattered light from phantom as back projected data, and reconstructed images. For our research light is considered as perfect scattering in human tissue, so back projected data is regarded as data from near surface of the phantom. From the experiment using the phantom which had absorbing rods in base material of the same scattering coefficient as tissue, the absorption target at less than 3cm below the surface of the phantom could be distinguished. Experiment using hemoglobin solution as absorber shows that the reconstructed image changed with the change of wavelength.We also measured angular distribution of scattered light from blood and hemoglobin solution to estimate optical anisotropic parameter.From our fundamental study, and it is shown that at less than 3cm blow from the surface of tissue it is possible to get CT image by perfect scattering light, however many problems are remained to realize the image of oxygen saturation which utilize absorption characteristics of hemoglobin. Less

在医学领域，光学CT有望成为一种安全、便携的获取组织功能图像的方法。因此在可见光和近红外光区域，吸收主要是血红蛋白引起的，血红蛋白的吸收光谱因氧化而发生变化。然而，由于组织中光的强烈散射，区分吸收信息非常困难。首先，我们估计了组织样本的光学参数，其次我们研究了散射介质中的光子传播，最后我们估计了CT图像。为了估计光学参数，使用100MHz调幅的激光束作为光源，然后通过不同厚度的样本测量入射光束和透射光束之间的振幅比和相位。通过这些实验，我们评估了血液、肌肉、脂肪和脂肪乳悬浮液的吸收系数、散射系数和各向异性参数。理论分析采用基于辐射输运理论的蒙特卡罗方法进行计算机模拟。这一结果与体模实验的结果一致。为了实现光学CT，我们利用计算机控制的CCD相机和卤素灯的光通量通过法布里-珀罗滤光片建立了实验系统。我们检测到来自体模的散射光作为背投影数据，并重建图像。对于我们的研究，光被认为是人体组织中的完美散射，因此背投影数据被视为来自体模近表面的数据。通过使用在与组织具有相同散射系数的基材中具有吸收棒的体模进行的实验，可以区分体模表面以下小于3cm的吸收目标。使用血红蛋白溶液作为吸收体的实验表明，重建图像随着波长的变化而变化。我们还测量了血液和血红蛋白溶液的散射光的角分布，以估计光学各向异性参数。我们的基础研究表明，在距组织表面小于3cm的距离处，可以通过完美散射光获得CT图像，但要实现氧气的图像仍然存在许多问题利用血红蛋白吸收特性的饱和度。较少的