真皮层参数对OCT中皮肤各层光吸收的影响

Influence of Dermis Properties on Photon Energy Absorption in OCT System

为获取OCT中光子在高散射多层皮肤内传输特性,研究真皮层光学性质对光能量吸收分布的影响.利用蒙特卡罗方法分析准直激光束垂直照射条件下的高散射多层皮肤组织,采取依次改变真皮层的吸收系数μ_α、散射系数μ_s、各向异性因子g等三种典型光学参数的办法,研究了组织内光能量吸收密度A(r,z)随组织厚度z和径向半径r的二维分布和纵向光能量吸收密度A(z)的分布.模拟结果表明:A(r,z)、A(z)分布在层与层的交界处存在明显的分界线,随着μ_α变大,真皮层的光吸收能量的中心半径变大,表皮层和肌肉层的光吸收能量的中心半径都变小;随着μ_s的变大,真皮层和表皮层的光吸收能量的中心半径变大,肌肉层的光吸收能量的中心半径变小;随着g的变大,真皮层和表皮层的光吸收能量的中心半径变小,肌肉层的光吸收能量的中心半径变大.

In order to obtain the characteristics of the OCT photon propagation in the highly scattering multilayer skin, the influence of the optical properties of dermis on light energy absorption and distribution is studied. Monte Carlo method is used to analyze the highly scattering multilayer skin tissue when the collimated laser beam irradiating vertically. By successively changing the absorption coefficient μa, scattering coefficient μs and anisotropy factor g of dermis, the paper studies the two- dimensional distribution of the light energy absorption density A （r, z） in the tissue with the tissue thickness z and the radial radius r and the distribution of the longitudinal light energy absorption density A（z）. The simulation result shows that A（r,z） and A（z） have obvious boundary line at the junction between the layers. With μa increasing, the center radius of light absorption energy A（z） in dermis is becoming greater while the center radii of light absorption energy in epidermis and muscular layer are becoming smaller. With μs increasing, the center radii of light absorption energy in dermis and epidermis layers are becoming greater while the center radius in muscular layer is becoming smaller.With g increasing, the center radii of light absorption energy in dermis and epidermis layers are becoming smaller while the center radius in muscular layer is becoming greater.