近光源下基于稳态空间分辨漫反射测量的光学参数反构

在各种生物医学诊断和治疗的过程中，准确计算组织的光学参数有着重要的意义．在大约化反照率及大检测距离下，通常使用漫射近似理论来描述光子在生物组织中的传输；而在低约化反照率或小检测距离下，学者们研究了多种其他的传输模型，如PN近似以及混合漫射近似等．针对在大约化反照率范围（0．50～0．99）以及小检测距离（0．4～8．0mm）下，使用6种光子传输模型（单点源和双点源模型下的漫射近似、混合漫射近似和P3近似），研究了准确反构吸收系数和约化散射系数的方法．通过对模拟数据的非线性拟合及误差分析，发展了一种在5个不同约化反照率区间使用不同传输模型的联合反构方法，并给出了相应的最佳正向模型和误差范围．

Derivation of Optical Properties from Steady-State Spatially Resolved Diffuse Reflectance Measurement at Small Source-Detector Separations

Accurate determination of the optical properties of tissue is very important in a variety of diagnostic and therapeutic procedures. Optical diffusion theory is frequently used as the forward model, which is commonly appli- cable in large reduced albedo and source-detector separations （SDSs）. Several other methods, such as PN approxima- tion and hybrid diffuse approximation, have been published for describing the photon transfer in media with low re- duced albedo or small SDSs. In this paper, researchers investigated the methods for accurate determination of absorp- tion coefficient and reduced scattering coefficient at large reduced albedo range（from 0.50 to 0.99）and small SDSs （from 0.4 mm to 8 mm） based on six theoretical models （diffuse approximation, hybrid diffuse approximation, P3 approximation of both one point and two point sources）. Nonlinear fitting to the Monte Carlo simulation, a joint method is devised to derive optical properties in five intervals of reduced albedo for the steady-state spatially resolved diffuse reflectance measurement. For every interval, efforts have been made to give the best theoretical derivation model and the corresponding derivation error range in deriving absorption coefficient and reduced scattering coefficient.