Numerical simulation of electromagnetic heating process of biological tissue via time-fractional Cattaneo transfer equation.

In order to simulate the heat transfer in the process of hyperthermia, one-dimensional time-fractional Cattaneo heat transfer equation (TFHE) is established. Based on TFHE, the heat transfer model is solved by using finite difference method, because a single layer of biological tissue in vitro is irradiated by electromagnetic energy. The effect of power parameters (energy flux density P0, tissue attenuation coefficient h) and equation parameters (relaxation time τq and fractional order ß) on the prediction of temperature simulated by TFHE were studied. Furthermore, comparative studies on TFHE, Pennes and CV are performed and evaluated. In the heating process, because of the existence of relaxation time τq, the temperature response of TFHE and CV are later than Pennes, leading to the lower temperature prediction of TFHE and CV than that of Pennes. The shorter the time is, the higher the energy is, and the more obvious the difference is.

Analysis to a critical state of thermal field in microwave ablation of liver cancer influenced by large vessels.

To study the effect of large blood vessels on the temperature field in invasive microwave ablation, a finite element method was applied based on the convective-type boundary condition on the interface between tissues and blood flow. Whether a large blood vessel is outside of or involved in the lesion area will affect the 54 degrees C effective therapeutic area in different critical conditions. This paper drew the function diagraph on the distance between blood vessel and antenna with the diameter of the blood vessel and put forward the concept of effective therapy radius. It can be used to study the influence of large vessels on the external boundary of the coagulation area and can be used as a theoretical basis to help to decide whether to occlude the large vessels before microwave ablation therapy.