Osaka University, Medical Beam Physics Laboratory, Graduate School of Engineering, 2-1-A14 Yamadaoka, Suita, Osaka 565-0871, Japan.
J Biomed Opt. 2011 May;16(5):058003. doi: 10.1117/1.3581111.
Photodynamic therapy (PDT) efficacy depends on the amount of light distribution within the tissue. However, conventional PDT does not consider the laser irradiation dose during PDT. The optical properties of biological tissues (absorption coefficient μ(a), reduced scattering coefficient μ's), anisotropy factor g, refractive index, etc.) help us to recognize light propagation through the tissue. The goal of this paper is to acquire the knowledge of the light propagation within tissue during and after PDT with the optical property of PDT-performed mouse tumor tissue. The optical properties of mouse tumor tissues were evaluated using a double integrating sphere setup and the algorithm based on the inverse Monte Carlo method in the wavelength range from 350 to 1000 nm. During PDT, the μ(a) and μ's were not changed after 1 and 5 min of irradiation. After PDT, the μ's in the wavelength range from 600 to 1000 nm increased with the passage of time. For seven days after PDT, the μ's increased by 1.7 to 2.0 times, which results in the optical penetration depth decreased by 1.4 to 1.8 times. To ensure an effective procedure, the adjustment of laser parameters for the decreasing penetration depth is recommended for the re-irradiation of PDT.
光动力疗法（PDT）的疗效取决于组织内的光分布量。然而，传统的 PDT 并不考虑 PDT 期间的激光辐照剂量。生物组织的光学特性（吸收系数μ(a)、散射系数μ's 的减少、各向异性因子 g、折射率等）有助于我们识别光在组织中的传播。本文的目的是获取在 PDT 期间和之后通过 PDT 执行的小鼠肿瘤组织的光学特性在组织内传播的知识。使用双积分球装置和基于逆蒙特卡罗方法的算法在 350 到 1000nm 的波长范围内评估了小鼠肿瘤组织的光学特性。在 PDT 期间，在照射 1 和 5 分钟后，μ(a)和μ's 没有变化。在 PDT 之后，在 600 到 1000nm 的波长范围内的 μ's 随着时间的推移而增加。在 PDT 后七天，μ's 增加了 1.7 到 2.0 倍，这导致光学穿透深度减少了 1.4 到 1.8 倍。为了确保有效的治疗过程，建议调整激光参数以适应穿透深度的减少，以便对 PDT 进行再照射。
