Microwave Ablation Antenna Switching for Accurate Tissue Thermometry
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing ablation systems, particularly those using microwave energy, face challenges in accurately measuring tissue temperature at depth due to variations in antenna construction and interference issues, leading to inconsistent results and potential damage to adjacent tissues.
Innovation Solution
A microwave ablation system with a catheter incorporating a main antenna for energy emission and a reference termination for temperature measurement, integrated with a Dicke switch for alternating energy emission and temperature sensing, and a processor for calculating target tissue temperature and lesion volume, while accounting for environmental and reference termination heating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single antenna is used for both microwave energy emission and temperature measurement, then device complexity is reduced, but temperature measurement precision deteriorates due to antenna construction variations and interference
Solution Approach 1:
The catheter is divided into functionally distinct segments: a separate microwave antenna for energy emission and a separate radiometer antenna for temperature measurement. This segmentation allows each component to be optimized for its specific function without interference, resolving the contradiction between device simplicity and measurement precision.
Solution Approach 2:
A radiometer is introduced as an intermediary device to measure temperature passively by detecting microwave radiation emitted by heated tissue, rather than using the ablation antenna itself for measurement. This intermediary approach enables accurate temperature monitoring without compromising the ablation function or adding excessive complexity.
2Productivity
If microwave energy is continuously emitted to ablate target tissue, then ablation efficacy is improved, but temperature measurement accuracy deteriorates due to heating of the antenna and surrounding environment
Solution Approach 1:
The system alternates between microwave energy emission phases and temperature measurement phases in a periodic cycle. During measurement phases, microwave emission is temporarily suspended to allow accurate radiometric temperature sensing without interference from antenna heating or environmental heating caused by continuous energy emission.
Solution Approach 2:
Temperature measurement is performed preliminarily before each microwave energy emission cycle to establish a baseline, and again after emission to monitor temperature changes. This preliminary and post-action measurement approach ensures accurate temperature data is captured at critical moments without continuous emission interfering with measurements.
3Loss of information
If radiometry is used for temperature measurement during ablation, then temperature feedback is improved, but reliability deteriorates due to variations in antenna construction and interference issues
Solution Approach 1:
The system measures multiple radiometric parameters including brightness temperature, antenna temperature, and environmental temperature, and uses these changing parameters over time to calculate accurate target tissue temperature. By monitoring parameter changes rather than relying on a single static measurement, the system compensates for variations in antenna construction and environmental interference, improving both feedback quality and measurement reliability.
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
Provides accurate temperature feedback and lesion volume estimation, ensuring safe and efficacious ablation by maintaining target tissue temperature within a predetermined threshold and preventing overheating.
Implementation Method 1
a main antenna disposed at the distal region of the catheter to emit energy to ablate the target tissue
Implementation Method 2
microwave energy for ablation
Implementation Method 3
measure a radiometer temperature generated as a result of the energy emission
Implementation Method 4
The cooling sleeve may be coupled to a source of coolant and to permit the coolant to flow over the main antenna and the reference termination, thereby cooling the main antenna and the reference termination
Data Source
Figure 1
Figure 2
Figure 3
AI summary
An exemplary ablation system is provided. The system is designed for safe and efficacious energy delivery into tissue by, for example, emitting energy in a controlled, repeatable manner that allows for feedback and energy emission titration based on sensed parameters (e.g., tissue temperature) measured during ablation. The system may include a switching antenna for both heating of target tissue and radiometry to monitor the temperature of the heated tissue. For example, the switching antenna may include a monopole formed by proximal and distal radiating elements, such that the proximal radiating element includes a short to defeat a choke action of the proximal radiating element. The system further includes a processor for calculating the temperature of the target tissue and estimating volume of the ablation lesion based on the target tissue temperature.