Numerical study of heat transfer and blood flow in two-layered porous liver tissue during microwave ablation process using single and double slot antenna

Abstract

Microwave ablation (MWA) is a process that uses the heat from microwave energy to kill cancer cells without damaging the surrounding tissue. MWA is emerging as an attractive modality for thermal therapy of large soft tissue targets in short periods of time, making it particularly suitable for ablation of liver cancer. The effectiveness of this technique is related to the temperature achieved during the process, as well as the input microwave power and heating time of treatment. The models of heat and blood flow transport have been used extensively in the study of MWA process and a strong tool for predicting the temperature profile, blood velocity profile and coagulation zone. These models play important role in the optimization of devices and economical way to evaluate new hypothetical designs. Furthermore, they can be used as a guideline for the practical treatment. In this work, the interstitial MWA in two-layered porous liver by single slot microwave coaxial antenna (MCA) and double slot MCA is carried out. A complete mathematical model of MWA of the porous media approach is proposed, which uses transient momentum equations (Brinkman model extended Darcy model) and energy equation coupled with electromagnetic wave propagation equation to describe the specific absorption rate (SAR) profile, temperature profile and blood velocity profile within the porous liver. The coupled nonlinear set of these equations is solved using the axisymmetric finite element method (FEM). The role of transport phenomena in two layers porous media (layers of tumor and normal tissue) for advancing the progress in biomedical applications is investigated numerically. The study aims to understand of the influences of antenna type on the SAR profile, temperature profile and blood velocity profile. In particular, the results calculated from a porous media model are compared with the results calculated from a bioheat model as well as the experimental results from previous work in order to show the validity of the numerical results. The results show that the maximum SAR, temperature and blood velocity appears within the porous liver when using a single slot MCA which is higher than when using a double slot antenna. However, the volumetric SAR, temperature and blood velocity profile within the porous liver when using a double slot MCA provides a wider region in porous liver around the slot MCA and has two hot spot zones which occurs in the vicinity of these double slots.