Microwave Ablation Antenna Choke Assembly Impedance Matching
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Solution Overview
Problem
Existing microwave ablation antenna designs lack optimal impedance matching and spherical ablation shape, leading to inefficient energy delivery and potential tissue damage during tumor treatment.
Innovation Solution
The design incorporates a choke assembly with dielectric and conductive elements to enhance impedance matching and achieve a more spherical ablation pattern, featuring a coaxial conductor assembly with a choke dielectric element, first and second choke conductors, and a dielectric fluid to improve energy transfer and minimize reflected power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional dipole antenna is used for microwave ablation, then the antenna can be inserted into tissue for treatment, but the impedance matching is suboptimal and the ablation shape is not spherical
Solution Approach 1:
The antenna is divided into distinct functional segments: a dipole radiating portion for microwave emission, a choke assembly with separate first and second choke conductors for impedance matching, and a dielectric layer for field confinement. This segmentation allows each component to be optimized independently for its specific function, achieving both spherical ablation and proper impedance matching simultaneously.
Solution Approach 2:
A dielectric layer is introduced as an intermediary between the conductive elements and the surrounding tissue. This dielectric medium serves multiple functions: it confines the microwave field to produce a spherical ablation pattern, provides electrical insulation, and contributes to impedance matching. The choke assembly acts as an intermediary structure that transforms the impedance characteristics between the feed line and the radiating elements.
2Productivity
If microwave energy is delivered into tissue using conventional antennas, then tissue ablation occurs, but power is reflected back into the microwave source due to impedance mismatch
Solution Approach 1:
The choke assembly functions as an impedance-matching network that provides electromagnetic feedback between the feed line and the radiating elements. The first and second choke conductors, positioned at specific locations along the dielectric layer, create resonant conditions that cancel reflected waves and transfer maximum power to the tissue, minimizing energy loss to reflection.
Solution Approach 2:
The impedance characteristics of the antenna system are optimized by carefully controlling geometric parameters: the length and position of the choke conductors, the thickness and material properties of the dielectric layer, and the spacing between radiating elements. These parameter adjustments transform the impedance profile to achieve optimal power transfer and minimize reflected power across the operating frequency range.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The improved design achieves better impedance matching and a spherical ablation shape, enhancing the efficiency of microwave energy delivery to tissues and reducing damage to adjacent tissue, allowing for effective treatment of various body tissues with consistent results.
Implementation Method 1
a dielectric layer arranged radially outwardly of the inner conductor and extending along the inner conductor
Implementation Method 2
an elongate coaxial conductor assembly for connection to a source of microwave energy
Implementation Method 3
delivering a controlled amount of microwave energy into the tumour
Implementation Method 4
ablate the targeted tissue by delivering a controlled amount of microwave energy into the tumour
Implementation Method 5
it is desirable for the antenna assembly to be impedance matched with the microwave energy generator
Data Source
AI summary
A microwave ablation antenna assembly includes an elongate body that extends from a first end to a second end thereof, and which defines therein a hollow inner volume and a longitudinal axis of the antenna. The ablation antenna assembly includes an applicator tip portion mounted on the second end of the elongate body, an elongate coaxial conductor assembly for connection to a source of microwave energy, a dipole tip portion that extends from the feed point of the coaxial conductor assembly towards the applicator tip, and a choke assembly with first and second choke conductors.