Dual-slot antennas for microwave tissue heating: parametric design analysis and experimental validation

Area of Science:

• Biomedical Engineering
• Electromagnetics
• Medical Devices

Background:

• Microwave ablation is a minimally invasive technique for tumor treatment.
• Conventional antennas often produce elongated ablation zones, which may not match tumor geometry.
• Optimizing antenna design is crucial for improving ablation efficacy and patient outcomes.

Purpose of the Study:

• To design and validate an efficient dual-slot coaxial microwave ablation antenna.
• To achieve an approximately spherical heating pattern for better tumor targeting.
• To match the ablation geometry to typical abdominal and pulmonary tumor shapes.

Main Methods:

• Utilized finite-element electromagnetic simulations to analyze dual-slot antenna geometry variations.
• Employed a two-term sigmoidal objective function to optimize antenna design based on reflection coefficient and heat generation aspect ratio.
• Fabricated the optimal antenna and validated its performance using ex vivo bovine liver tissue and numerical models.

Main Results:

• The optimal dual-slot antenna geometry featured specific proximal and distal slot widths and separation.
• Demonstrated an active choking mechanism focusing heating to the antenna tip.
• Achieved a dual-band resonance with a low reflection coefficient (-20.9 dB) near 2.45 GHz.
• Produced larger diameter (35 mm vs. 31 mm) and shorter length (49 mm vs. 60 mm) ablation zones compared to a conventional monopole antenna.

Conclusions:

• Dual-slot antennas effectively produce more spherical ablation zones with low reflection coefficients.
• The improved heating pattern is achieved without increasing antenna diameter.
• Further clinical evaluation of this dual-slot antenna for microwave ablation is recommended.