Dehghani Hamid, Brooksby Ben, Vishwanath Karthik, Pogue Brian W, Paulsen Keith D
Thayer School of Engineering, Dartmouth College, Hanover, New Hampshire 03755, USA.
Phys Med Biol. 2003 Aug 21;48(16):2713-27. doi: 10.1088/0031-9155/48/16/310.
Near-infrared (NIR) tomography is a technique used to measure light propagation through tissue and generate images of internal optical property distributions from boundary measurements. Most popular applications have concentrated on female breast imaging, neonatal and adult head imaging, as well as muscle and small animal studies. In most instances a highly scattering medium with a homogeneous refractive index is assumed throughout the imaging domain. Using these assumptions, it is possible to simplify the model to the diffusion approximation. However, biological tissue contains regions of varying optical absorption and scatter, as well as varying refractive index. In this work, we introduce an internal boundary constraint in the finite element method approach to modelling light propagation through tissue that accounts for regions of different refractive indices. We have compared the results to data from a Monte Carlo simulation and show that for a simple two-layered slab model of varying refractive index, the phase of the measured reflectance data is significantly altered by the variation in internal refractive index, whereas the amplitude data are affected only slightly.
近红外（NIR）层析成像技术用于测量光在组织中的传播，并根据边界测量生成内部光学特性分布的图像。最常见的应用集中在女性乳房成像、新生儿和成人头部成像以及肌肉和小动物研究。在大多数情况下，假设在整个成像区域内是具有均匀折射率的高散射介质。基于这些假设，可以将模型简化为扩散近似。然而，生物组织包含具有不同光吸收和散射以及不同折射率的区域。在这项工作中，我们在有限元方法中引入了一个内部边界约束，用于对光在组织中的传播进行建模，该约束考虑了不同折射率的区域。我们将结果与蒙特卡罗模拟的数据进行了比较，结果表明，对于一个简单的具有不同折射率的两层平板模型，内部折射率的变化会显著改变测量反射率数据的相位，而幅度数据仅受到轻微影响。
