Directional Microwave Ablation Antenna with Asymmetric Reflector
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Solution Overview
Problem
Conventional microwave ablation devices lack spatial control over energy deposition patterns, particularly in angular expanse, which can lead to incomplete thermal coverage of tumors and unintended heating of adjacent tissues, posing challenges in procedures near critical structures.
Innovation Solution
An electrosurgical device with a transmission line, antenna, and reflector configuration that includes specific dielectric materials and structural geometries to achieve optimal impedance matching, allowing for directional microwave energy emission and controlled ablation zones by adjusting the distance between the antenna and reflector, and utilizing a dielectric material with a higher dielectric constant between the antenna and reflector.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional coaxial antenna designs with axially symmetric radiation patterns are used, then the device structure is simple, but spatial control over energy deposition pattern is limited
Solution Approach 1:
The patent introduces an asymmetric reflector structure positioned at a specific distance from the antenna, which breaks the axially symmetric radiation pattern of conventional coaxial antennas. This asymmetric configuration enables directional control of microwave energy deposition, allowing the ablation zone to be steered toward specific angular regions while maintaining structural simplicity
Solution Approach 2:
The patent adds angular dimension control to the energy deposition pattern by positioning a reflector at a specific distance (d) from the antenna. This creates a three-dimensional control capability where the ablation zone can be shaped and directed in angular space, transforming the conventional one-dimensional radial ablation into a controllable three-dimensional ablation pattern
2Ease of operation
If multiple antennas are operated as a phased-array to steer power deposition, then spatial control is improved, but invasiveness and system complexity increase
Solution Approach 1:
The patent combines the functions of multiple antennas into a single antenna-reflector system. The reflector acts as a passive element that redirects microwave energy to achieve phased-array-like steering capability without requiring multiple active antenna elements, signal generators, or complex phase control electronics, thereby reducing system complexity while maintaining spatial control
Solution Approach 2:
The patent introduces a reflector as an intermediary element between the antenna and the target tissue. This reflector mediates the microwave energy distribution by reflecting and redirecting energy to achieve directional control, eliminating the need for complex multi-antenna phased-array systems while providing similar spatial control capabilities
3Object-affected harmful factors
If fluid installation is used between target site and organs at risk, then heating of non-targeted tissues is minimized, but the procedure becomes more complex
Solution Approach 1:
The patent implements preliminary action by using the asymmetric reflector structure to pre-direct microwave energy toward the target tissue before the energy reaches adjacent organs. This proactive directional control prevents energy from reaching sensitive structures, eliminating the need for protective fluid installation and reducing procedural complexity
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 device achieves precise control over ablation zones, minimizing damage to non-targeted tissues and ensuring thorough tumor coverage, as demonstrated by simulations and experimental data showing optimized reflection coefficients and ablation zone dimensions.
Implementation Method 1
Electromagnetic energy radiated from the antenna is deposited in the electromagnetic lossy tissue leading to heating via dielectric hysteresis
Implementation Method 2
an electrically conductive reflector positioned laterally from the antenna and configured to redirect at least a portion of the microwave energy emitted from the antenna toward a side of the device opposite the reflector
Implementation Method 3
exhibits excellent impedance matching between the antenna and microwave energy transmission line due to the selection of an appropriate dielectric material positioned between the antenna and the reflector
Data Source
AI summary
An electrosurgical device (10) operable to deliver microwave energy to cause targeted tissue ablation is provided. The electrosurgical device (10) comprises an antenna (26), a reflector (30), and a dielectric material (34) disposed therebetween. The selection of the dielectric material (30) and the relative positioning of the antenna (26) and the reflector (30) provide impedance matching between the antenna (26) and a transmission line (12) so as to minimize heating along the length of the device (10) during use.