Effect of roughness in nondiffusive regions within diffusive media
Effect of roughness in nondiffusive regions within diffusive media
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DOI：
10.1364/josaa.18.000940
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发表时间：
2001-04-01
影响因子：
1.9
通讯作者：
Arridge, SR
中科院分区：
文献类型：
--
作者：
Ripoll, J;Nieto-Vesperinas, M;Arridge, SR
最近，研究表明，扩散介质中的透明区域可以通过新型边界条件在扩散近似中准确建模[J. Opt. Sec. Am. A 17，1671（2000）]或其近似值[Phys.Med.Biol.41，767（1996）; Med.Phys.27，252（2000）]。这可以直接应用于光在脑组织中传播的研究，在脑组织中存在清晰的区域，特别是在颅骨下的脑脊液（CSF）层中。在这项工作中，我们提出的效果，在非扩散区域的边界粗糙度上测得的平均强度，因为，在实践中，CSF层是相当粗糙。同样的结论可以推广到任何包围着粗糙的非扩散区域的扩散介质。我们将证明与数值计算的粗糙度统计的接口（虽然不是他们的实际配置文件）必须是已知的先验正确预测的平均强度的形状。我们发现，随着粗糙度的增加，非扩散区域的影响逐渐减小，直到它消失，从而产生类似于一个完全扩散区域的数据。我们还提出了一个数值研究的漫射光散射的存在下，扩散和非扩散区域和两者之间的相互作用，表明当非扩散区域是粗糙的，由两个区域产生的空间强度分布可以他非常相似。(C)2001年美国光学学会。
Recently it has been shown that clear regions within diffusive media can be accurately modeled within the diffusion approximation by means of a novel boundary condition [J. Opt. Sec. Am. A 17, 1671 (2000)] or by an approximation to it [Phys. Med. Biol. 41, 767 (1996); Med. Phys. 27, 252 (2000)]. This can be directly applied to the study of light propagation in brain tissue, in which there exist clear regions, and in particular in the cerebrospinal fluid (CSF) layer under the skull. In this work we present the effect that roughness in the boundary of nondiffusive regions has on the measured average intensity, since, in practice, the CSF layer is quite rough. The same conclusions can be extended to any diffusive medium that encloses rough nondiffusive regions. We will demonstrate with numerical calculations that the roughness statistics of the interfaces (although not their actual profiles) must be known a priori to correctly predict the shape of the average intensity. We show that as the roughness increases, the effect of the nondiffusive region diminishes until it disappears, thus yielding data similar to those of a fully diffusive region. We also present a numerical study of the diffuse light scattered in the presence of both diffusive and nondiffusive regions and the interaction between the two, showing that when the nondiffusive region is rough, the spatial-intensity distribution produced by the two regions can he very similar. (C) 2001 Optical Society of America.