Non-invasive monitoring method for thermal ablation therapy based on UBE

Non-invasive temperature monitoring is one of the key techniques in the ontological thermal therapy since there is a need for quantitatively determining the progress of therapy and its endpoint. However, the conventional temperature estimation method can not meet the required precision in the clinical application. In order to realize a reliable and effective temperature estimation method, a non-invasive monitoring method based on ultrasonic backscattered energy (UBE) was proposed in this paper. Firstly, the changes of UBE was studied, which was in entire liver tissue, ablation centre and tissue surface during therapy process performed by microwave thermal ablation experiment in vitro porcine liver. Then a new tissue characterization method was proposed, which avoided the problem encountered in quantitatively tracking the rising temperature and reduced the impact of individual differences. The experimental results indicated that the UBE is a suitable parameter for non-invasive temperature estimation in the tumour ablation therapy. The parameter of UBE can presented increase trend in tissue surface and decrease trend in ablation centre regularly. Furthermore, those two trend curves crossed at the temperature ranging from 60°C to 70°C, which is just the temperature of coagulation threshold. That is, it provides a good guidance to control the thermal therapy by tracking the cross point at over 60°C.