Study on the Effect of Micro-Vessels on Ablation Effect in Laser Interstitial Brain Tissue Thermal Therapy Based on PID Temperature Control

Laser interstitial thermal therapy (LITT) is an emerging clinical treatment for deep brain tumors, which is safe, minimally invasive, and effective. This paper established a three-dimensional model based on the LITT heat transfer model, including brain tissue, laser fiber, and straight tube vessels. Combining the PID control equation, diffuse approximation equation, Pennes heat transfer equation, and Murray's law, the effect of micro-vessel radius and distance between vessels and fiber on the ablation temperature field during laser ablation was investigated by using COMSOL finite element software. The results showed that at a constant distance of 1 mm between the vessel and the fiber, the vessels with a radius of 0.1-0.2 mm could be completely coagulated, the vessels with a radius of 0.3-0.6 mm had cooling and directional effects on temperature distribution and thermal damage, and the vessels with a radius of 0.7-1.0 mm had cooling effects on the ablation temperature. When the vessel-fiber spacing was raised by 2 mm, 0.3-0.4 mm, vasculature had a directional influence on the temperature field; when the vessel-fiber spacing was raised by 3 mm, only 0.3 mm vessels had a directional effect on the temperature field. The range of temperature field impacted by blood flow diminishes as the distance between the optical fiber and the blood artery grows. The ablation zone eventually tends to be left and right symmetrical. In this study, we simulated the LITT ablation temperature field model influenced by tiny vessels based on PID control. We initially classified the vessels, which provided some guidance for accurate prediction and helped the accuracy of preoperative planning.