Microwave Ablation Antenna With Internal Reflectors for Angular Control
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Solution Overview
Problem
Existing microwave ablation devices face challenges in achieving small diameters while maintaining sufficient rigidity and control over the angular expanse of energy deposition, particularly when ablating targets near critical structures.
Innovation Solution
The device incorporates elongate cylindrical members laterally disposed from the antenna within a lumen, which reflect and shield electromagnetic energy to control the angular expanse, combined with a synthetic resin material for reduced adhesion and ease of insertion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If directional microwave applicators use reflectors and window structures in the tubular outer wall to control energy deposition pattern, then angular control of energy deposition is improved, but device diameter increases and rigidity decreases
Solution Approach 1:
The patent transitions from controlling energy deposition through the wall thickness (2D surface modification) to using internal cylindrical members positioned within the lumen (3D spatial arrangement). This dimensional shift allows angular control to be achieved through the spatial configuration of internal reflectors rather than external wall structures, enabling smaller device diameters while maintaining directional control capability
Solution Approach 2:
The patent nests cylindrical reflecting members within the lumen of the applicator body, placing one functional element inside another. This nesting approach allows the reflectors to be integrated within the existing device structure without increasing the outer diameter, thereby maintaining small device size while adding directional control functionality
2Measurement precision
If directional microwave applicators use reflectors and window structures in the tubular outer wall to control energy deposition pattern, then angular control of energy deposition is improved, but device rigidity decreases
Solution Approach 1:
By nesting the cylindrical reflecting members within the lumen rather than forming them as part of the outer wall structure, the patent preserves the integrity and rigidity of the outer wall. The internal positioning of reflectors allows them to provide angular control functionality without compromising the structural strength of the device body
Solution Approach 2:
The patent applies the reflecting function locally through discrete cylindrical members positioned at specific locations within the lumen, rather than requiring the entire outer wall to have complex reflective properties. This localized approach maintains the overall structural quality and rigidity of the device while providing directional control where needed
3Quantity of substance
If microwave ablation devices are inserted into the center of targeted tissue with radially outward ablation zone growth, then complete thermal coverage of target volume is achieved, but thermal damage to adjacent non-targeted tissues increases
Solution Approach 1:
The patent employs cylindrical reflecting members that create an asymmetric energy deposition pattern, directing microwave energy preferentially in specific angular directions rather than radially in all directions. This asymmetric configuration allows the ablation zone to be shaped to cover the target volume while minimizing energy deposition in directions toward non-targeted tissues
Solution Approach 2:
The patent applies directional control locally through the strategic positioning of cylindrical reflectors within the lumen, creating zones of enhanced energy deposition toward the target while maintaining reduced energy deposition in other directions. This localized directional control enables selective heating of target tissue while protecting adjacent non-targeted structures
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
This configuration allows for precise tissue ablation with minimized thermal damage to adjacent tissues, enabling smaller device diameters and improved control over the ablation zone, enhancing safety and efficacy in minimally invasive procedures.
Implementation Method 1
Electromagnetic power radiated from the antenna is deposited in the electromagnetic lossy tissue leading to heating via dielectric hysteresis
Implementation Method 2
directional microwave applicators such as those described in U.S. Patent Nos. 7,410,485 and 8,235,981 and U.S. Patent Application Publication No. 2017/0265940 offered the ability to control the energy deposition pattern along the angular expanse through the use of reflectors and/or window structures
Implementation Method 3
These devices were based on coaxial antenna designs and had generally axially symmetric radiation patterns. Generally, there was no control of the energy deposition pattern in the angular expanse
Data Source
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Figure 6a~7
AI summary
An electrosurgical device (10) is provided that is operable to deliver microwave energy within a controlled angular expanse to cause targeted tissue ablation. The device (10) comprises a blocking or reflecting material such as cylindrical members (34) that are laterally spaced from the antenna (20) that is operable to emit the microwave energy. The reflecting material creates regions in and/or surrounding the device into which sensors (51), such as thermocouple wires, may be placed to monitor a condition associated with the device or the patient's body.