Welch A J, Pearce J A, Diller K R, Yoon G, Cheong W F
Department of Electric and Computer Engineering, University of Texas, Austin 78712.
J Biomech Eng. 1989 Feb;111(1):62-8. doi: 10.1115/1.3168341.
Many medical applications involving lasers rely upon the generation of heat within the tissue for the desired therapeutic effect. Determination of the absorbed light energy in tissue is difficult in many cases. Although UV wavelengths of the excimer laser and 10.6 microns wavelength of the CO2 laser are absorbed within the first 20 microns of soft tissue, visible and near infrared wavelengths are scattered as well as absorbed. Typically, multiple scattering is a significant factor in the distribution of light in tissue and the resulting heat source term. An improved model is presented for estimating heat generation due to the absorption of a collimated (axisymmetric) laser beam and scattered light at each point r and z in tissue. Heat generated within tissue is a function of the laser power, the shape and size of the incident beam and the optical properties of the tissue at the irradiation wavelength. Key to the calculation of heat source strength is accurate estimation of the light distribution. Methods for experimentally determining the optical parameters of tissue are discussed in the context of the improved model.
许多涉及激光的医学应用都依赖于在组织内产生热量来达到预期的治疗效果。在很多情况下，确定组织中吸收的光能是困难的。尽管准分子激光的紫外波长和二氧化碳激光的10.6微米波长在软组织的前20微米内被吸收，但可见光和近红外波长会发生散射以及吸收。通常，多次散射是光在组织中分布以及产生的热源项的一个重要因素。本文提出了一个改进模型，用于估计由于在组织中每个点r和z处准直（轴对称）激光束的吸收和散射光而产生的热量。组织内产生的热量是激光功率、入射光束的形状和大小以及组织在照射波长下的光学特性的函数。热源强度计算的关键是准确估计光分布。在改进模型的背景下讨论了实验确定组织光学参数的方法。
