Study On Alkali Metal Based Tumor Minimally Invasive Ablation Therapy

Traditional hyperthermia techniques based on radiofrequency, microwave, ultrasound and laser often encounter a common bottleneck. That is, they will inevitably cause thermal damage to the healthy tissues along the path heat energy is transmitted to the tumor. In addition, the complex operation and high cost also limit their application. To resolve these problems, this thesis is dedicated to establish a new therapy, the alkali metal ablation for localized killing of tumors via exothermic chemical reaction. Theoretical and experimental investigations were performed on several typical issues raised from the new modality.Aiming for a comprehensive understanding the mechanisms of the alkali metal ablation, the thermal effect, chemical effect and cavity effect during ablation process were evaluated based on multiple experiments, respectively. Dynamic parameters related with the cell damage rate were obtained. Further more, the temperature response of the activiation free energy at different situations were given to reveal damage reaction direction and the rate based on transtsion state theory.Following the analysis of chemical reaction between alkali metal and water, it was proposed that exothermic rate mainly depends on the water diffusion flux. A heat release equation of alkali metal was established. In addition, the reaction production OH- diffusion characteristics were simultaneously performed both in experiments and theoretical analysis. Through a combination between heat transfer and reaction diffusion equation, a heat and mass transfer model is established and studied.Considering the limitation on heat damage function to describe the alkali metal damage, a multi-factor coupling model was proposed to estimate the injury of tissue subject to alkali metal ablation based on entropy production theory. And the relationship between entropy production and damage degree was originally established. In order to quantify the damage scope, a three-dimensional imaging reconstruction method to presisly refect shape and size of ablation area was built, which provides a useful tool to quantify the ablation dose.Statistic animal experiments were performed to comprare anti-tumor effect among chemical ablation, hyperthermia and alkali metal on mice implanted with EMT6 breast tumor, and the infrared thermography was introduced as an effective imaging tool for administration and evaluation of alkali metal ablation therapy. Endosomatic temperature field reconstruction method utilizing surface infrared imaging data was developed by conjugate gradient method. A liquid alkali metal ablation system was also set up, and tissue pathological changes after ablation and the relationship between injection quantity and ablation area were investigated.Considering that the effect of large blood vessel may lead to thermal under-dosage in most conventional thermal ablation, the cool effect of large vessel during alkali metal ablation was also studied, and effects of the parameters such as blood diameter and velocity on temperature distribution were clarified.This thesis is expected to establish a low cost mean of minimally invasive treatment of tumors. Further efforts on conresponding bioheat and mass transfer are of great significance to promote effective clinical application of the new ablaion method.