Numerical modeling of heat distribution during laser tissue interaction

Abstract

Since the invention of Laser, it has been extensively used for various medical purposes. So, some fundamental aspects of laser-tissue interaction is discussed, that includes how fluence rate varies with varying optical parameters, and how temperature distribution occurs within the tissue based on this fluence rate. In all laser-tissue interactions, it is imperative to know the tissue temperature, which is usually achieved by inserting temperature probes into tissue, but can also be calculated by a model for the heating and heat distribution in tissue. This work discusses the optical and thermal properties of laser-tissue interaction. For this, a semi-infinite model has been proposed to study optical and thermal properties of biological tissues, and optical and thermal studies have been done based on the model. Monte-Carlo simulation technique has been used to calculate the fluence rate in a laser-irradiated tissue and further, by using the fluence rate distribution profile, the heat distribution has been calculated. It has been found that, for lower anisotropic coefficient as depth of the laser-tissue interaction site increases, fluence rate also increases and simultaneously Tmax is also higher. But, the same is not true for the higher anisotropic coefficient and instead of increasing Tmax, it has been found to be decreasing. So, depending on the type of tissue to be influenced, the depth and optical parameters can be manipulated so as to achieve the desired laser-tissue interaction result with high precision.