Recovery of optical parameters in multiple-layered diffusive media: theory and experiments
Recovery of optical parameters in multiple-layered diffusive media: theory and experiments
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DOI：
10.1364/josaa.18.000821
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发表时间：
2001-04-01
影响因子：
1.9
通讯作者：
Nieto-Vesperinas, M
中科院分区：
文献类型：
--
作者：
Ripoll, J;Ntziachristos, V;Nieto-Vesperinas, M
扩散光子密度波最近已被用来表征扩散介质，并定位和表征隐藏的对象，如肿瘤，在软组织。在实践中，大多数医学感兴趣的生物介质由具有不同光学特性的各种层组成，例如乳房中的脂肪层或皮肤中存在的不同层。此外，大多数实验装置由多层系统组成，其中待表征的介质（即，患者的器官）通常由光漫射板限定。不正确的界面建模可能会引起与从嵌入高度异质组织深处的肿瘤获得的弱信号相当的误差，并导致显著的重建伪影。为了提供一种方法来分析在这些配置中获得的数据，漫射-漫射和漫射-非漫射界面的反射和透射系数的基本表达式。一个比较之间的扩散板和一个普通的电介质板，从而建立板的两个界面之间的限制距离，它们之间的多次反射被认为是重要的。提出了多层（M层）扩散介质的严格公式，并给出了求解任意M层扩散介质的方法。提出的理论是用来表征一个双层介质从传输测量，表明散射系数，μ '（s），和吸收，μ（a），检索具有很高的精度。最后，我们演示了同时检索的mu '（s）和mu（a）。(C)2001年美国光学学会。
Diffuse photon density waves have lately been used both to characterize diffusive media and to locate and characterize hidden objects, such as tumors, in soft tissue. In practice, most biological media of medical interest consist of various layers with different optical properties, such as the fat layer in the breast or the different layers present in the skin. Also, most experimental setups consist of a multilayered system, where the medium to be characterized (i.e., the patient's organ) is usually bounded by optically diffusive plates. Incorrect modeling of interfaces may induce errors comparable to the weak signals obtained from tumors embedded deep in highly heterogeneous tissue and lead to significant reconstruction artifacts. To provide a means to analyze the data acquired in these configurations, the basic expressions for the reflection and transmission coefficients for diffusive-diffusive and diffusive-nondiffusive interfaces are presented. A comparison is made between a diffusive slab and an ordinary dielectric slab, thus establishing the limiting distance between the two interfaces of the slab for multiple reflections between them to be considered important. A rigorous formulation for multiple-layered (M-layered) diffusive media is put forward, and a method for solving any M-layered medium is shown. The theory presented is used to characterize a two-layered medium from transmission measurements, showing that the coefficients of scattering, mu ' (s), and absorption, mu (a), are retrieved with great accuracy. Finally, we demonstrate the simultaneous retrieval of both mu ' (s) and mu (a). (C) 2001 Optical Society of America.