权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

Experimental Study on CW Diffuse Reflective Optical CT

连续波漫反射光学CT实验研究

基本信息

批准号：
15300169
负责人：
NAKAYAMA Kiyoshi
金额：
$ 6.34万
依托单位：
Sophia University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2003
资助国家：
日本
起止时间：
2003 至 2005
项目状态：
已结题

项目摘要

This project is a feasibility study on diffuse optical tomography which has 3-D spatial resolution using 2-dimensional CW source-detector arrays on the body surface, aiming at real time imaging of the brain activation minimally contaminated by skin circulation fluctuation. We formulated the forward problem based on the Rytov approximation for the small perturbation of the absorption coefficients in the diffusion equation approximation of the photon migration, and formulated the 3-D tomographic reconstruction using simple regularized Moore-Penrose pseudo inverse. We analyzed the dependencies of the reconstruction error and the spatial resolution on the regularization parameter, the target depth and the reconstruction voxel size. The study showed that the trade-off between the reconstruction error and the spatial resolution does not depend on the voxel size. The simple regularized inverse, however, was found to have strong depth dependencies of the reconstruction sensitivity so that the … More target brain signal in the depth would be easily masked by the unwanted skin circulation signal in the shallow range. We devised the depth-adaptive voxel size method and the depth-adaptive regularization, both of which were shown to be effective to overcome this serious problem. Based on these extensive simulation studies, we clarified trade-offs between spatial resolution, reconstruction noise, reconstruction region of interest and the uniformity of the reconstruction sensitivity etc. To assess the feasibility experimentally, we modified a existing commercial optical topograph, enabling digital data acquisition for the reconstruction, and checked the performance by phantom study. Finally, we designed a practical imaging system with the source-detector system of the existing topograph. The system would visualize the brain activity with the spatial resolution of 1cm in the 4cm X 4cm area of the cerebral cortex assumed at the 1cm depth from the skin surface with the 20 dB suppression of the unwanted skin circulation signal. Less

该项目是一项漫射光学断层扫描的可行性研究，该断层扫描具有 3D 空间分辨率，使用体表上的二维 CW 源探测器阵列，旨在对受皮肤循环波动影响最小的大脑活动进行实时成像。我们基于光子迁移的扩散方程近似中吸收系数的小扰动的 Rytov 近似制定了正演问题，并使用简单的正则化 Moore-Penrose 伪逆制定了 3D 断层扫描重建。我们分析了重建误差和空间分辨率对正则化参数、目标深度和重建体素大小的依赖性。研究表明，重建误差和空间分辨率之间的权衡并不取决于体素大小。然而，人们发现简单的正则逆对重建灵敏度具有很强的深度依赖性，因此深度中的目标大脑信号很容易被浅层中不需要的皮肤循环信号掩盖。我们设计了深度自适应体素尺寸方法和深度自适应正则化，这两种方法都被证明可以有效克服这个严重的问题。基于这些广泛的模拟研究，我们阐明了空间分辨率、重建噪声、重建感兴趣区域和重建灵敏度均匀性等之间的权衡。为了通过实验评估可行性，我们修改了现有的商业光学形貌仪，实现了重建的数字数据采集，并通过模型研究检查了性能。最后，我们利用现有地形图的源探测器系统设计了实用的成像系统。该系统将在距离皮肤表面 1 厘米深度的大脑皮层 4 厘米 X 4 厘米区域中以 1 厘米的空间分辨率可视化大脑活动，并对不需要的皮肤循环信号进行 20 分贝的抑制。较少的