Thermal damage analysis of sub-surface soft tissue sarcoma for Indocyanine Green mediated photothermal cancer therapy

•Thermal damage of sub-surface tumors during photothermal therapy was evaluated using Lattice Boltzmann method.•Simulations were validated using optical properties mimicking tumor-tissue phantoms.•Various ICG distributions (Uniform, Intravenous and Intratumoral) within tumor were considered to mimic the distributions in real tumors.•Deeper tumors took more irradiation duration for complete thermal damage than shallower tumors. Photothermal therapy is a minimal invasive technique to treat tumors situated near the skin or other light accessible organs. Here, a photothermal agent is delivered to tumor either intratumorally or intravenously and the tumor is irradiated with near infrared (NIR) radiation to generate heat for thermal damage of tumor. In this paper, thermal damage of soft tissue sarcoma, a type of sub-surface forearm tumor, is evaluated for photothermal therapy using numerical simulations. Indocyanine green (ICG) is used as photothermal agent and the effect of various spatial distributions and doses of ICG for sub surface tumors located at various depths (3-6 mm) were investigated. Further, numerical simulation is validated experimentally through tumor-tissue mimicking phantoms. Computations were performed in MATLAB software using Lattice Boltzmann method and validated through experiments using tumor-tissue mimicking phantoms. Results show that the thermal damage region (damage parameter (Ω) of magnitude 4.6) was enlarged on increasing the concentration of ICG while it got shrunk for the deeper tumors. Computations reveal that ICG concentration of 50μg/ml is optimum, for intravenous distribution, for photothermal therapy with minimal damage to surrounding tissue. It is found that irradiation duration of more than 900s is required to achieve the complete damage of tumor. For the case of deeper tumors, about 1200s of exposure is required, at irradiation intensity of 0.25W/cm2. This study provides a numerical approach to determine therapeutic parameters and demonstrates the thermal damage for subsurface tumors through ICG mediated photothermal therapy by proper selection of therapeutic parameters.