Validation of a comprehensive analytical model for photothermal therapy planning in a layered medium with gold nanoparticles

Photothermal therapy (PTT) is a minimally invasive alternative to conventional surgery and can provide faster recovery times as well as reduction in complication rates. Successfully targeting of gold nanoparticles to the tumor increases its light absorption leading to more important temperature rise in the tumor than surrounding tissue. Hence, it is possible to heat tumor with a minimal damage to the surrounding tissue only if the appropriate laser parameters are employed. In this study, our purpose is to develop a simulation tool capable of determining temperature rise and duration in the tissue for therapy planning. This simulation tool is based on a new analytical approach which models laser-induced temperature in a two-layered medium mimicking concentric tumor and its surrounding healthy tissue. First, the diffusion equation is used to model the light propagation in tissue and then a comprehensive solution is derived by obtaining a special Greens’ function. Next, the Pennes' bioheat equation is analytically solved for a source term defined as the product of local optical absorption and the solution of the diffusion equation. Our approach is validated by comparing the spatiotemporal temperature distribution obtained by our method, finite element method, and experimental studies, respectively. The obtained results are in very good agreement with an average R-squared of 0.953. This analytical approach can provide a suitable and fast platform for modeling laser-induced temperature distribution for thermal therapy applications.