Dual-mode Microwave Applicator for Tissue Ablation and Permittivity Sensing
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Solution Overview
Problem
Conventional microwave ablation systems face challenges in accurately localizing and positioning the applicator within the tumor, and in distinguishing between malignant and healthy tissue based on dielectric properties.
Innovation Solution
A dual-mode microwave applicator with a coaxial line and a metal sleeve, featuring a slot at a specific distance from the tip, allowing for both ablation and sensing modes. The control unit manages the applicator to generate standing waves for treatment and use reflection signals to detect tissue type.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional microwave applicators are used for ablation, then tissue treatment can be performed, but accurate localization and positioning of the applicator in the center of the tumor is difficult
Solution Approach 1:
The applicator integrates both ablation and sensing functions into a single device. The same coaxial structure with slot and metal sleeve serves dual purposes: delivering microwave energy for ablation and detecting tissue permittivity for positioning and tumor boundary detection, eliminating the need for separate sensing devices
Solution Approach 2:
The sensing mode provides real-time feedback about the applicator's position and tissue boundaries by detecting permittivity changes. This feedback enables the system to automatically adjust or alert the operator when the applicator is properly positioned or when tumor boundaries are approached
2Measurement precision
If imaging techniques are used to determine applicator position, then location information can be obtained, but it is difficult to determine the exact line between malignant and healthy tissue
Solution Approach 1:
The system replaces external imaging techniques with an intrinsic sensing mechanism. The coaxial line with slot and metal sleeve directly interacts with the tissue to detect permittivity changes, providing real-time electrical property measurements that directly reveal tissue boundaries without relying on external imaging equipment
Solution Approach 2:
The system detects tissue boundaries by monitoring changes in the complex permittivity parameter. The transition from healthy to malignant tissue causes a measurable jump in permittivity (15-30%), which the sensing mode detects to precisely locate tissue boundaries
3Reliability
If a single-mode applicator is used, then the device structure is simple, but combining treatment with reliable monitoring is insufficient
Solution Approach 1:
The applicator integrates both ablation and sensing functions into a single device. The same coaxial structure with slot and metal sleeve serves dual purposes: delivering microwave energy for ablation and detecting tissue permittivity for positioning and tumor boundary detection, eliminating the need for separate sensing devices
Solution Approach 2:
The sensing and ablation functions are merged into a single integrated system. The control unit manages both modes, and the same physical structure performs both detection and treatment, ensuring that monitoring and treatment are coordinated and reliable
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 dual-mode applicator achieves a strong increase in efficiency for microwave treatment and high sensitivity in determining complex permittivity values, enabling accurate differentiation between healthy and malignant tissues.
Implementation Method 1
during the ablation mode microwave radiation is applied
Implementation Method 2
Healthy and malignant tissues differ in their dielectric properties such as (complex-valued) permittivity
Implementation Method 3
The control unit is configured, in the application mode, to generate a standing wave of predetermined frequency in the coaxial line
Data Source
Figure 1A~1B
Figure 2
Figure 3A~3B
AI summary
A dual-mode microwave applicator for treating tissue comprises a control unit (no), a rod-shaped element (210), a coaxial line (213, 214), and a metal sleeve (216). The control unit (110) is configured to control the applicator in an application mode and a sensing mode, wherein during the application mode microwave radiation is applied and during the sensing mode tumorous tissue is detected. The rod-shaped element (210) comprises a tip (217). The coaxial line (213, 214) is formed in the rod-shaped element to relay microwaves to the tip (217) for treatment of the tissue, wherein the coaxial line comprises an inner conductor (213) and an outer conductor (214), the outer conductor (214) including a slot (215) of a slot length (l3) formed at a slot distance (l4) from the tip (217). The metal sleeve (216) at a sleeve distance (l2) from the slot (215). Values of the lengths and distances are set as follows: the sleeve distance (l2) is about 0.55 mm, the slot length (l3) is about 1.75 mm, and the slot distance (l4) is about 7.7 mm, wherein a tolerance region is ±0.5 mm or ±50% of the set values.