Numerically verified parametric modeling of CO2 laser-induced bioheat transfer in superficial skin tumors using COMSOL Multiphysics

Laser irradiation represents a highly precise method for delivering thermal energy to superficial cancer cells while minimizing injury to surrounding healthy tissue. Mathematical modeling of laser–tissue interaction is essential for treatment planning and outcome prediction. This study presents a comprehensive numerical simulation of heat distribution during CO2 laser-induced thermal therapy for superficial tumors using COMSOL Multiphysics. The novelty of this work lies in the integration of a multilayered skin geometry with a tumor-specific domain to perform a detailed parametric analysis of critical treatment variables. A 2D cross-sectional skin model consisting of the epidermis, dermis, and subcutaneous layers was constructed, with a circular tumor spanning the dermal and upper subcutaneous layers. Heat transfer was modeled using Pennes’ bioheat equation coupled with a laser heat source described by the Beer–Lambert absorption model. The effects of blood perfusion, optical absorption, laser intensity, exposure duration, and tumor geometry were evaluated through a controlled parametric sensitivity analysis. The simulation demonstrates that optimized laser parameters can selectively raise tumor temperature to the therapeutic hyperthermia range (42–45 °C) and achieve localized temperature elevation above commonly reported thermal injury thresholds. For instance, under an intensity of 3 W/cm2 applied for 50 s, the tumor center reached a peak temperature of ∼48.2 °C, while surrounding healthy tissue remained below 40 °C. This study focuses on the CO2 laser due to its well-established thermal interaction profile, predictable spatiotemporal heat diffusion profile, and clinical relevance for superficial tumor therapy. Other laser systems will be investigated in future work. The model underscores the critical role of parameter optimization, particularly laser intensity and exposure time, in enhancing the efficacy and safety of laser-based tumor therapy, providing a valuable framework for preclinical treatment planning.