Abstract: We present a new coax-fed interstitial antenna for generating directional heating patterns during microwave ablation. The antenna comprises a base-fed monopole wherein, a portion of the outer conductor is extended to create a reflector that directs the fields toward the opposing direction. Schematic cross sections of five antenna designs for theoretical evaluation of the treatment effectiveness a antenna design and tissue parameters considerations for an microwave ablation results with three diffe diameters microwave ablation antenna design and lication theoretical evaluation of the treatment effectiveness a.

• Slot Antenna For Microwave Ablation Procedure
• Slot Antenna For Microwave Ablation Without

Slot Antenna For Microwave Ablation Procedure

Abstract

Microwave ablation is a technique used in treating hepatocellular carcinoma, especially in cases where surgical removal is impossible. In the present study we are investigating the effects of design characteristics of a coaxial slot antenna (single- versus double-slot, slot-to-tip distance and slot size) on the ablation zone characteristics (dimensions and shape). The specific absorption rate field and the temperature rises are calculated for a variety of application times and powers. A plateau in the ablation zone dimensions in healthy and cirrhotic liver models is predicted, but not in malignant ones. It is found that the value of the perfusion rate (which is different for each clinical case) is of crucial importance in order to correctly estimate the ablation zone. An underestimation of dimensions is expected, if higher perfusion rates are used (i.e., values for healthy tissue rather than malignant). In contrast, an exact determination of the values of relative permittivity and conductivity is less significant for predicting the ablation zone.

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General scientific summary Microwave ablation (MWA) is a novel, minimally invasive, thermal-based technique used in treating hepatocellular carcinoma. In this study we present clinically relevant numerical models, aimed to quantify the characteristics (dimensions and shape) of the ablation zones. Such information can aid in patient-specific pre-treatment planning. Coaxial antennas of different designs (single- vs double-slot, various slot-to-tip distances and slot sizes) were modelled and their performance was compared. Double-slot antennas in the range of about 10 mm were found efficient. Regarding modelling the tissue, we showed that the value of perfusion rate (which is different for each clinical case) determines the behaviour of the ablation zone. Its correct evaluation is of crucial importance to estimate the extent of heating. As a step to close the gap between experimental and theoretical studies, we showed that an underestimation of dimensions is expected when higher perfusion rates (as such of healthy rather than malignant liver) are considered.

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Abstract

This paper presents a multi-slot coaxial antenna with a pi impedance matching network for liver tumor ablation. A multi-slot radiating probe was optimized by using the modified genetic algorithm to produce a near-spherical heating zone with significantly increased possibility of conformal treatment. A pi impedance matching network was designed to match the feeding transmission line and antenna without increasing antenna size. The reflection coefficient, ablation zone shape, specific absorption rate, and temperature were determined by a finite element electromagnetic simulation using COMSOL. Experimental validations were designed to evaluate the proposed antenna. Both simulation and experimental results show that the proposed antenna has the ability for liver tumor ablation, which offers faster heating rates in the heating center and more localized heating distribution than the conventional single-slot antenna.

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