Shanshool Alaa Sabeeh, Lazareva Ekaterina Nikolaevna, Hamdy Omnia, Tuchin Valery Victorovich
Science Medical Center, Saratov State University, 410012 Saratov, Russia.
Laboratory of Laser Molecular Imaging and Machine Learning, Tomsk State University, 634050 Tomsk, Russia.
Materials (Basel). 2022 Aug 18;15(16):5696. doi: 10.3390/ma15165696.
The accurate estimation of skin and skull optical properties over a wide wavelength range of laser radiation has great importance in optogenetics and other related applications. In the present work, using the Kubelka-Munk model, finite-element solution of the diffusion equation, inverse adding-doubling (IAD), and Monte-Carlo simulation, we estimated the refractive index, absorption and scattering coefficients, penetration depth, and the optical fluence distribution in rabbit head tissues ex vivo, after dividing the heads into three types of tissues with an average thickness of skin of 1.1 mm, skull of 1 mm, and brain of 3 mm. The total diffuse reflectance and transmittance were measured using a single integrating sphere optical setup for laser radiation of 532, 660, 785, and 980 nm. The calculated optical properties were then applied to the diffusion equation to compute the optical fluence rate distribution at the boundary of the samples using the finite element method. Monte-Carlo simulation was implemented for estimating the optical fluence distribution through a model containing the three tissue layers. The scattering coefficient decreased at longer wavelengths, leading to an increase in optical fluence inside the tissue samples, indicating a higher penetration depth, especially at 980 nm. In general, the obtained results show good agreement with relevant literature.
在广泛的激光辐射波长范围内准确估计皮肤和颅骨的光学特性在光遗传学及其他相关应用中具有重要意义。在本研究中，我们使用库贝尔卡 - 蒙克模型、扩散方程的有限元解、逆倍增法（IAD）和蒙特卡罗模拟，在将兔头分为平均厚度为1.1毫米的皮肤、1毫米的颅骨和3毫米的脑三种组织类型后，对离体兔头组织的折射率、吸收和散射系数、穿透深度以及光通量分布进行了估计。使用单积分球光学装置测量了532、660、785和980纳米激光辐射的总漫反射率和透射率。然后将计算得到的光学特性应用于扩散方程，使用有限元方法计算样品边界处的光通量率分布。通过包含三层组织的模型进行蒙特卡罗模拟以估计光通量分布。散射系数在较长波长处降低，导致组织样品内部的光通量增加，表明穿透深度更大，尤其是在980纳米处。总体而言，所得结果与相关文献显示出良好的一致性。
