The Effects of Dielectric & Thermal Property Functions on the Thermal Response during the Focused Microwave Ablation Treatment in the Liver Cancer Model: Numerical Investigation

Wutipong Preechaphonkul1

Phadungsak Rattanadecho1,Email 

Center of Excellence in Electromagnetic Energy Utilization in Engineering (CEEE), Department of Mechanical Engineering, Faculty of Engineering, Thammasat University (Rangsit Campus), Pathumthani 12120, Thailand.
 

Abstract

Microwave ablation (MWA) is a minimally invasive cancer treatment technique using microwave power to create thermal damage in the local malignant tumor by using a microwave antenna. In the previous literature, there are investigated some property sensitivity but used by supposed values and supposed situations. So, this study has investigated the sensitivity of property functions based on a realistic situation that is a different point from the literature, which considered sensitivity by supposed value. This study investigated the effect of widely properties model types on the thermal response of liver tissue during the MWA treatment process. The mathematical models are developed coupled with electromagnetic wave propagation, bioheat, and Arrhenius damage equations to describe the specific absorption rate (SAR) and temperature distribution in the tissue during MWA process. In particular, the results calculated from models with different property model types are investigated and demonstrated with the same conditions, as well as the experimental results from previous work in order to show the validity of the numerical results. This study presented the sensitivity of the individual property functions as the relative permittivity, electrical conductivity, blood perfusion rate, thermal conductivity, and specific heat capacity of the liver tissue to indicate the high property functions that should be considered as a function depending on the temperature. The results show that the difference in SAR and temperature distribution area appears within the liver when using different model types in the same conditions. The electrical conductivity is the most impact function. However, the difference between the various models can be observed when tissue temperature exceeds 60 ºC, and it is clearly observed when tissue temperature exceeds 100 ºC. The main reason for the difference is that some functions consider the effect of tissue evaporation during the ablation process, but some properties are not considered.

The Effects of Dielectric & Thermal Property Functions on the Thermal Response during the Focused Microwave Ablation Treatment in the Liver Cancer Model: Numerical Investigation