Cooled Microwave Antenna Structure for Spherical Tissue Ablation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional microwave ablation devices generate ellipsoid or teardrop-shaped ablation zones due to factors related to antenna physics, leading to inefficient energy deposition, tissue charring, and back-heating, which limits the ability to create a spherical ablation zone desired by physicians for minimizing collateral damage and optimizing probe placement.
Innovation Solution
The development of an antenna system with a choke mechanism and dielectric property management using CO2 cooling, which prevents back-heating and maintains efficient energy delivery, allowing for the creation of a spherical ablation zone by minimizing tissue charring and dielectric property changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If conventional microwave antennas are used for ablation, then energy can be delivered to tissue, but the ablation zone becomes ellipsoid or teardrop-shaped rather than spherical
Solution Approach 1:
The antenna is divided into multiple radiating elements arranged in a specific geometric configuration (e.g., tetrahedral arrangement of four dipole elements). Each element contributes to the overall spherical radiation pattern, with individual elements being simple dipoles but collectively creating the desired spherical ablation zone shape
Solution Approach 2:
The antenna incorporates a dielectric material with specific permittivity properties positioned around the radiating elements. This dielectric composite structure modifies the electromagnetic field distribution to achieve more uniform spherical energy deposition in the tissue, transforming the conventional ellipsoid pattern into a spherical one
2Temperature
If high power microwave energy is delivered to tissue, then deeper penetration and larger thermal lesions are achieved, but tissue charring and dielectric property changes occur
Solution Approach 1:
The system incorporates real-time monitoring of dielectric properties and impedance changes during ablation. When tissue begins to char or dielectric properties change significantly, the system automatically adjusts power delivery to individual antenna elements, reducing power to areas approaching charring thresholds while maintaining effective heating in less damaged regions
Solution Approach 2:
The antenna system dynamically adjusts the amplitude and phase of microwave signals delivered to each radiating element based on real-time tissue response. This dynamic control allows the ablation zone to expand uniformly in all directions without localized charring, adapting the energy distribution as the ablation progresses and tissue properties change
3Ease of operation
If coaxial fed antenna is used, then current is conducted backwards on the outer conductor surface, but this causes back-heating of surrounding tissue proximal to the antenna
Solution Approach 1:
The harmful back-current conduction path on the outer conductor surface is eliminated by extracting this function from the conventional coaxial structure. The design uses isolated radiating elements with dedicated feed lines or balanced feed structures that prevent current from traveling backwards along an outer conductor, thereby removing the source of back-heating while maintaining effective forward energy delivery to the tissue
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 system enables the generation of spherical ablation zones, reducing collateral damage and providing flexibility in probe placement by maintaining efficient energy deposition and preventing tissue charring, thus optimizing treatment efficacy.
Implementation Method 1
a coolant tube extending within the dielectric tube to convey a coolant to the antenna
Implementation Method 2
the antenna is optimized for spherical field pattern, high power handling, and efficiency
Data Source
AI summary
An energy delivery device is disclosed including a cannula extendable through skin of a patient and an antenna extending from the cannula and operable to deliver energy to tissue of the patient. The antenna includes an outer conductor, a dielectric tube extending within the outer conductor, a conductor extending within the dielectric tube, and a coolant tube extending within the dielectric tube. Coolant is to be supplied through the coolant tube.