A sensitivity analysis of laser thermotherapy efficacy in lung cancer treatment to the temperature dependence of thermal properties

Laser interstitial thermotherapy has shown potential in the treatment of inoperable lung cancers, which make up 70-80 % of all cases, thanks to the possibility of real-time ultrasound guidance, a fine introducer needle, and faster recovery after the procedure. To plan a laser ablation session through numerical modeling, the sensitivity analysis of the input parameters is necessary since simplifying the influential parameters could lead to a different treatment outcome.The purpose of this study is to determine the sensitivity of laser-induced ablated volume, an indicator of therapy efficacy, with regard to the temperature dependence of thermal properties in the clinical power ranges (i.e., between 2 W and 5 W at the wavelength of 1064 nm) for lung tissue. According to the results, the difference between ablated volumes derived from constant and temperature-dependent thermal properties grows with increasing power, reaching 17.5% and 60.3% under ex vivo and in vivo conditions at 5 W, respectively. As the blood perfusion rate strongly affects the thermal effects in tissue, the temperature dependency of this parameter cannot be ignored. The assumption of constant thermal properties is valid for ex vivo planning by acceptable error when the laser power is set at a low level, e.g., ~ 2% at 2 W and ~ 6% at 3 W.Clinical Relevance - The methods and results of this study set the basis for defining the accurate pre-planning of laser-induced thermotherapy of lung cancer.