Microwave Applicator Calibration Using Tissue Permittivity
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Solution Overview
Problem
Current calibration methods for microwave applicators used in treating malignant tissue are complex and do not allow for precise determination of the dielectric properties of surrounding tissue, leading to insufficient or effort-intensive identification of malignant tissue contours.
Innovation Solution
A device that calibrates the microwave applicator using reflection signals from at least two predetermined environments with known permittivities and automatically measures healthy tissue to achieve relative calibration, enabling detection of permittivity jumps between healthy and malignant tissue, allowing for precise positioning of the applicator.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If separate calibration units or material standards are used for calibrating the microwave applicator, then calibration can be performed, but the calibration process becomes very complex and requires multiple predetermined materials with known permittivities
Solution Approach 1:
The patent extracts the calibration function from separate complex calibration units and material standards, and integrates it directly into the microwave applicator. The applicator now performs calibration measurements autonomously by utilizing the tissue itself as the calibration medium, eliminating the need for external calibration devices and multiple predetermined materials.
Solution Approach 2:
The microwave applicator performs self-calibration by using the tissue surrounding it as the calibration medium. The system automatically measures the complex permittivity of the tissue and uses this information to calibrate itself, without requiring external calibration units or manual intervention with multiple standards.
2Measurement precision
If traditional calibration methods with look up tables are used, then calibration can be performed, but adjustments to specific tissue are still required and results cannot be used immediately
Solution Approach 1:
The system performs preliminary calibration measurements on the specific tissue before treatment begins. By measuring the actual complex permittivity of the patient's tissue in advance, the system prepares the calibration data specific to that tissue, eliminating the need for subsequent adjustments using generic look up tables during the treatment procedure.
Solution Approach 2:
The system changes from using fixed, pre-determined permittivity values from look up tables to dynamically measuring and using the actual complex permittivity parameters of the specific patient's tissue. This allows immediate use of the calibration results without requiring adjustments to match specific tissue characteristics.
3Measurement precision
If imaging methods are used to determine applicator position, then position can be determined, but precise demarcation between malignant and healthy tissue cannot be achieved
Solution Approach 1:
The system detects changes in the dielectric properties (complex permittivity) of the tissue, which act as a characteristic signature differentiating healthy from malignant tissue. By measuring the real and imaginary parts of the permittivity, the system can precisely demarcate tissue boundaries and identify tissue types based on their unique electromagnetic characteristics.
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 approach significantly improves the precision of determining the edge of malignant tissue, enabling more accurate treatment and continuous monitoring of microwave treatment by using healthy tissue for calibration, thus enhancing the contrast between healthy and malignant tissue.
Implementation Method 1
a microwave applicator (200) suitable for treating tissue by means of a microwave treatment
Implementation Method 2
determine reflection signals from an environment of the microwave applicator
Implementation Method 3
Healthy and malignant tissue differ in their dielectric properties, such as the (complex-valued) permittivity, with a jump in permittivity between 15 and 30% being to be expected at the transition
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
The invention relates to an apparatus (100) for calibrating a microwave applicator (200) for treating tissue (300), comprising: a control device (110) for controlling calibration signals, which are to be applied to the microwave applicator (200) for calibration; a device (120) for determining an environment (51, 52, 350) of the microwave applicator (200); and an evaluating unit (130). According to the invention, the evaluating unit is designed to determine reflection signals (Γη) from the environment (51, 52, 350) of the microwave applicator (200) associated with the applying of the calibrating signals and to carry out the calibration of the microwave applicator (200) based on measurements at at least two predetermined environments having known permittivity (εη) and based on a measurement in an environment having healthy tissue (350), wherein the measurement on the healthy tissue (350) automatically occurs upon a determination by the device (120).