A FINITE-ELEMENT APPROACH FOR MODELING PHOTON TRANSPORT IN TISSUE
A FINITE-ELEMENT APPROACH FOR MODELING PHOTON TRANSPORT IN TISSUE
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DOI：
10.1118/1.597069
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发表时间：
1993-03-01
期刊：
影响因子：
3.8
通讯作者：
DELPY, DT
中科院分区：
文献类型：
--
作者：
ARRIDGE, SR;SCHWEIGER, M;DELPY, DT
在医学物理学中使用光辐射在治疗和诊断方面很重要。在所有情况下，组织中辐射传播的分析模型对于对程序的有意义解释都是必不可少的。在本文中引入了一个有限元方法（FEM），假设光子传输模型是对辐射传递方程的扩散近似，则在其边界内进行光子通量。给出了特定情况模型的结果：边界通量的计算是由三维函数输入到二维圆圈（相当于无限圆柱中的线源）带有同质散射和均匀散射和吸收特性。这对近红外光谱和成像中感兴趣的时间点扩散函数进行了建模。随着网格的分辨率增加，该系统的分析表达了该系统的分析表达，证明了FEM结果的收敛性。扩散近似通常适用于散射主导的情况，即MU（s）大得多（a）的情况，其他工人的结果将其与替代模型进行了比较。在本文中，证明了与蒙特卡洛方法的高度一致性。 FE方法的主要优势是其速度。它在所有方面都像蒙特卡洛方法一样灵活，此外，它可以在各处产生光子密度，以及边界上的通量。一个缺点是没有手段来得出单个光子历史。
The use of optical radiation in medical physics is important in several fields for both treatment and diagnosis. In all cases an analytic and computable model of the propagation of radiation in tissue is essential for a meaningful interpretation of the procedures. A finite element method (FEM) for deriving photon density inside an object, and photon flux at its boundary, assuming that the photon transport model is the diffusion approximation to the radiative transfer equation, is introduced herein. Results from the model for a particular case are given: the calculation of the boundary flux as a function of time resulting from a delta-function input to a two-dimensional circle (equivalent to a line source in an infinite cylinder) with homogeneous scattering and absorption properties. This models the temporal point spread function of interest in near infrared spectroscopy and imaging. The convergence of the FEM results are demonstrated, as the resolution of the mesh is increased, to the analytical expression for the Green's function for this system. The diffusion approximation is very commonly adopted as appropriate for cases which are scattering dominated, i.e., where mu(s) much greater than mu(a), and results from other workers have compared it to alternative models. In this article a high degree of agreement with a Monte Carlo method is demonstrated. The principle advantage of the FE method is its speed. It is in all ways as flexible as Monte Carlo methods and in addition can produce photon density everywhere, as well as flux on the boundary. One disadvantage is that there is no means of deriving individual photon histories.