MAXWELL'S EQUATIONS MODELING OF BIOLOGICAL TISSUE OPTICS FOR IMPROVING EARLY ST

这个子项目是许多研究子项目中利用 资源由NIH/NCRR资助的中心拨款提供。子项目和 调查员(PI)可能从NIH的另一个来源获得了主要资金， 并因此可以在其他清晰的条目中表示。列出的机构是 该中心不一定是调查人员的机构。 关键词： 麦克斯韦方程，组织光学，相干后向散射，随机介质，早期癌症检测，上皮组织，结肠癌 摘要： 该项目致力于开发计算方法来模拟和分析光在生物组织中的传播和散射。数值研究基于两种相关算法：(1)时域有限差分(FDTD)方法，它能够以纳米空间分辨率求解全矢量Maxwell方程，用于生物组织与生物组织的光学相互作用；(2)伪谱时域(PSTD)技术，这是FDTD方法的最新技术进步，它允许空间采样接近奈奎斯特速率，从而能够在宏观尺度上模拟光学与组织的相互作用。我们的具体建模工作旨在了解最近观察到的低相干光后向散射现象的物理学，这对于改善上皮组织，特别是结肠的早期癌症检测具有重要的前景。目前，涉及光子扩散和输运的近似模型由于不能处理近场和衰减场以及偏振而提供了不充分的物理基础。通过求解基本的全矢量Maxwell方程建立对低相干光后向散射的严格物理理解，可能会导致开发能够加速检测上皮组织癌前状态的优化临床仪器和程序。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Keywords: Maxwell's equations, tissue optics, coherent backscattering, random media, early stage cancer detection, epithelial tissues, colon cancer Abstract: This project addresses the development of computational methodologies to model and analyze optical propagation within, and scattering by, biological tissues. The numerical investigation is based on two related algorithms: (1) the finite-difference time-domain (FDTD) method, which enables solving the full-vector Maxwells equations for optical interactions with biological tissues with nanometer spatial resolution; and (2) the pseudospectral time-domain (PSTD) technique, a recent technical advance of the FDTD method which allows spatial sampling approaching the Nyquist rate, and therefore enables modeling optical-tissue interactions at macroscopic scales. Our specific modeling efforts are aimed at understanding the physics of the recently observed phenomenon of low-coherence optical backscattering, which has significant promise for improving early-stage cancer detection in epithelial tissues, especially the colon. At present, approximate models involving photon diffusion and transport provide an inadequate physics basis because of their inability to treat near and evanescent fields and polarization. Establishment of a rigorous physical understanding of low-coherence optical backscattering by solving the underlying full-vector Maxwells equations could lead to the development of optimized clinical instruments and procedures capable of accelerated detection of precancerous conditions in epithelial tissues.