The photons propagation into non trivial geometry

In this work we tried to create a mathematical model of thermal response of laser irradiated multilayer biological tissue. The tissue has 4 horizontal radial symmetric layers with its own optical-physical characteristics. We used the results of Monte Carlo modeling to describe the propagation of light (laser beams) in tissue and receive the function of heat source after we multiply the density of thermal emission by absorption coefficient. As we usually have radial symmetric laser beams we can use cylindrical coordinates. The solution of the 2D heat conduction equation is based on finite-element theory with using square finite elements. We simulated constant laser fluency and as result there are temperature fields. The analysis of the results represents, that heat does not localize on the surface, but collects inside of the tissue. By varying the boundary condition on the surface and type of laser irradiation we can reach high temperature inside the tissue without formation of necrosis at the same time.