浅表组织后向散射检测中偏振门的蒙特卡罗研究

已有实验表明偏振门和斜入射技术能有效地抑止深层散射光子,实现浅表组织光学特性的检测。采用蒙特卡罗方法,分析了斜入射、偏振门的特性,研究了组织光学参量和入射角等参量对平均探测深度的影响。结果表明,组织的各向异性因子和入射角对平均探测深度影响较大。当各向异性因子较小(小于0.8)或者入射角较大(大于1.4 rad)时,组织的平均探测深度能满足小于2倍平均自由程的要求。偏振门和斜入射技术均可使探测光子经历的散射次数和探测深度有明显减小,因此,结合偏振门和斜入射技术能够更有效地分辨来自浅层的信号光,抑止来自深层的背景光。

Monte Carlo Simulation of Polarization Gating for Superficial Tissue Detection

Previous studies have demonstrated that the techniques of polarization and oblique incidence can effectively suppress the scattered light from deep layer,thus providing feasible methods to detect optical properties of superficial tissue.Monte Carlo simulation is used to study their mechanism.The effects of optical properties and incident angle on detection depth are investigated respectively.It is found that anisotropy factor and incident angle affects the detection depth much.While for the cases of small anisotropy(<0.8) or large incident angle(>1.4 rad),detection depth can be constrained in the depth of less than 2 fold of mean free path.The techniques of polarization and oblique incidence can effectively reduce scattering times and penetration depth of detected photons,which indicates that it can effectively differentiate signal from superficial tissue and remove background signal from underlying tissue through combining these two techniques.