A New Model for Estimation of Individual Blood Flow Effect during Multimode Thermal Therapy of Tumor.

An accurate temperate control is the key during multimode thermal therapy of tumor. However, the tumor tissue temperature is greatly influenced by local blood flow changes of individuals. A simple but effective method is proposed for estimation of the local blood flow and its impact on the ablation boundary temperature. The proposed model is focused on the tumor domain, namely the targeted treatment region. In the natural thawing process post tumor freezing during the therapy, the main energy transferring to the tumor tissue comes from the blood flow of the surrounding normal tissue on the tumor boundary. By fitting the rewarming temperature measured in the tissue, the inversed problem is solved by the model to calculate the boundary convection condition and thus to predict the corresponding blood perfusion rate. The model is validated by the animal experimental data. The calculated blood perfusion rates are within the published range, but differ individually. The results prove that the new model and the estimated personalized convection coefficient can better predict the tissue temperature distribution during the therapy.Clinical Relevance-The model estimates the local blood flows around the tumor of individuals and the influence on heat transfer process. It can be used to better predict and control the temperature on the tumor boundary during the therapy that is critical to the therapeutic effect. The model also greatly cuts down the calculation time which facilitates the possibility of intraoperative real time monitoring.