A thermal-FSI framework for optimizing laser treatment of skin disorders

Dermatological disorders such as neurofibromatosis type 1 (von Recklinghausen disease) and hemangiomas significantly impair patient quality of life. Laser therapy presents a promising alternative to invasive surgical procedures, although optimizing its thermal and mechanical safety remains a significant challenge. This study develops a multiphysics model of laser-irradiated skin tissue affected by neurofibromatosis, using a 975 nm diode laser, selected for its superior penetration depth within the therapeutic optical window. A fully coupled thermal fluid-structure interaction (FSI) model is implemented using the Arbitrary Lagrangian-Eulerian (ALE) formulation. Light transport is modeled via the diffusion approximation to the radiative transport equation, accounting for tissue scattering and absorption. The bioheat equation and hyperelastic constitutive models (Ogden and Yeoh) are applied to predict tissue temperature and deformation. Simulation results indicate that laser parameters can be tuned to maintain intra-tissue pressure below 817 kPa while inducing therapeutic thermal gradients, minimizing scarring risks. These findings offer a quantitative framework to optimize laser settings for safer and more effective treatment of dermatological lesions.