Antenna design for microwave hepatic ablation using an axisymmetric electromagnetic model

John M Bertram,John G Webster,David M Mahvi,Mark C Converse,Deshan Yang

doi:10.1186/1475-925x-5-15

John M Bertram, John G Webster + Show 3 more

Open Access

https://doi.org/10.1186/1475-925x-5-15

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Abstract

BackgroundAn axisymmetric finite element method (FEM) model was employed to demonstrate important techniques used in the design of antennas for hepatic microwave ablation (MWA). To effectively treat deep-seated hepatic tumors, these antennas should produce a highly localized specific absorption rate (SAR) pattern and be efficient radiators at approved generator frequencies.Methods and resultsAs an example, a double slot choked antenna for hepatic MWA was designed and implemented using FEMLAB™ 3.0.DiscussionThis paper emphasizes the importance of factors that can affect simulation accuracy, which include boundary conditions, the dielectric properties of liver tissue, and mesh resolution.

Highlights

Liver cancer is a significant worldwide public health issue
The electric and magnetic fields associated with the time-varying transverse electromagnetic (TEM) wave generated by the microwave source propagating in a coaxial cable in the z-direction was expressed in 2D axially symmetric cylindrical coordinates as
FAixgiaulraend2 radial schematics of a coaxial-based double slot choked antenna designed for hepatic microwave ablation (MWA) Axial and radial schematics of a coaxial-based double slot choked antenna designed for hepatic microwave ablation (MWA)

Summary

Introduction

Liver cancer is a significant worldwide public health issue. The disease has a mortality rate of 100% at 5 years in untreated cases [1] and results in the deaths of more than one million people each year worldwide [2,3,4,5]. Liver cancer can be treated successfully by surgical resection of the malignant tissue, approximately 90% of patients with the disease are ineligible for the procedure due to factors such as insufficient hepatic reserve and the close proximity of tumors to blood vessels [1,6]. One promising alternative for these patients is hepatic microwave ablation (MWA), an experimental procedure in which an antenna is inserted percutaneously or during surgery [7] to induce cell necrosis through the heating of deep-seated tumors. To effectively treat deep-seated hepatic tumors, these antennas should produce a highly localized specific absorption rate (SAR) pattern and be efficient radiators at approved generator frequencies. The FEM model used in this study was adapted from a coaxial slot antenna general model, developed by COMSOL for microwave cancer therapy [22].

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