Xu Kuangyi, Arbab M Hassan
Department of Biomedical Engineering, State University of New York at Stony Brook, Stony Brook, New York 11794, USA.
Biomed Opt Express. 2024 Mar 13;15(4):2328-2342. doi: 10.1364/BOE.515623. eCollection 2024 Apr 1.
Many promising biomedical applications have been proposed for terahertz (THz) spectroscopy and diagnostic imaging techniques. Polarimetric imaging systems are generally useful for enhancing imaging contrasts, yet the interplay between THz polarization changes and the random discrete structures in biological samples is not well understood. In this work, we performed Monte Carlo simulations of the propagation of polarized THz waves in skin and adipose tissues based on the Mie scattering from intrinsic structures, such as hair follicles or sweat glands. We show that the polarimetric contrasts are distinctly affected by concentration, size and dielectric properties of the scatterers, as well as the frequency and polarization of the incident THz waves. We describe the experimental requirements for observing and extracting these polarimetric signals due to the low energy and small angular spread of the back-scattered THz radiation. We analyzed the spatially integrated Mueller matrices of samples in the normal-incidence back-scattering geometry. We show that the frequency-dependent degree of polarization (DOP) can be used to infer the concentrations and dielectric contents of the scattering structures. Our modeling approach can be used to inform the design of the imaging modalities and the interpretation of the spectroscopic data in future terahertz biomedical imaging applications.
太赫兹（THz）光谱和诊断成像技术已经被提出用于许多有前景的生物医学应用。偏振成像系统通常有助于增强成像对比度，然而太赫兹偏振变化与生物样品中随机离散结构之间的相互作用尚未得到很好的理解。在这项工作中，我们基于毛囊或汗腺等固有结构的米氏散射，对偏振太赫兹波在皮肤和脂肪组织中的传播进行了蒙特卡罗模拟。我们表明，偏振对比度明显受到散射体的浓度、大小和介电特性以及入射太赫兹波的频率和偏振的影响。由于后向散射太赫兹辐射的能量低且角扩散小，我们描述了观察和提取这些偏振信号的实验要求。我们分析了正入射后向散射几何结构中样品的空间积分穆勒矩阵。我们表明，频率相关的偏振度（DOP）可用于推断散射结构的浓度和介电含量。我们的建模方法可用于为未来太赫兹生物医学成像应用中的成像模式设计和光谱数据解释提供信息。
