Optical Tissue Temperature Sensing for Surgical Switch-Off Control
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Solution Overview
Problem
Current methods for measuring tissue temperature during high-frequency surgery are imprecise, leading to potential overheating of instruments and thermal damage to surrounding tissue, as well as inadequate sealing of blood vessels due to reliance on indirect temperature measurements and tissue impedance changes.
Innovation Solution
A method and device for precise tissue temperature measurement using optical reflectance spectroscopy in the NIR range to determine the absorption spectrum of tissue components like water and collagen, allowing direct calculation of tissue temperature for real-time control of thermal processes, with a shutdown criterion based on the SP parameter to prevent overheating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If indirect temperature measurement methods (tissue impedance changes) are used, then the device complexity is reduced, but the measurement precision deteriorates
Solution Approach 1:
The patent replaces indirect electrical impedance-based temperature measurement with direct optical measurement using reflectance spectroscopy. Light sources emit light that interacts with tissue chromophores (water, hemoglobin, melanin), and detectors measure the reflected light intensity to directly calculate tissue temperature based on temperature-dependent optical absorption properties, eliminating the need for complex impedance-to-temperature conversion models
Solution Approach 2:
The patent utilizes the temperature-dependent change in optical absorption parameters of tissue chromophores. As tissue temperature changes, the absorption spectra of water, hemoglobin, and melanin change predictably. By monitoring these spectral parameter changes in the reflectance signal, the system directly determines tissue temperature with high precision without requiring complex measurement systems
2Reliability
If real-time temperature monitoring is implemented, then the reliability of vessel sealing is improved, but the device complexity increases
Solution Approach 1:
The optical measurement system serves multiple functions: it measures tissue temperature, monitors tissue composition changes during sealing, and provides feedback for real-time power adjustment. The same light sources and detectors used for temperature measurement also detect tissue optical properties that indicate sealing progress, eliminating the need for separate monitoring systems
Solution Approach 2:
The system implements real-time feedback control by continuously measuring tissue temperature through reflectance spectroscopy and automatically adjusting the high-frequency power delivery. When the tissue reaches the target temperature range for effective sealing (typically 60-80°C), the system reduces or stops power delivery, ensuring reliable vessel sealing while preventing overheating and thermal damage to surrounding tissues
3Measurement precision
If direct optical measurement is used, then the measurement precision is improved, but the ease of operation deteriorates
Solution Approach 1:
The system performs automatic temperature calculation and sealing control without requiring manual intervention. The processor automatically analyzes the reflectance spectral data, calculates tissue temperature based on chromophore absorption characteristics, and adjusts power delivery parameters in real-time, making the complex optical measurement process transparent to the user and maintaining ease of operation
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
Enables accurate, real-time temperature monitoring and control of thermal processes, preventing overheating and ensuring effective sealing by directly measuring tissue temperature at the electrode site, reducing thermal damage and ensuring reliable vessel sealing.
Implementation Method 1
measuring the remission of the light with a remission spectrum from the tissue... calculating an absorption spectrum of the tissue by comparing the illumination spectrum with the remission spectrum
Implementation Method 2
receiving the remission of the light with a remission spectrum from the tissue
Implementation Method 3
high-frequency alternating current is passed through the human body or a body part to specifically cauterize (coagulate) or cut (electrotomy) tissue through the resulting heat
Data Source
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AI summary
The invention relates to a method for determining a switch-off time of a medical instrument, comprising the following steps: measuring the duration for which the temperature of a tissue is above 85° Celcius, preferably over 95° Celcius; calculating, preferably online, the average temperature from the first time it reaches 85° Celcius, preferably 95° Celcius; measuring and/or calculating the energy input until the temperature reaches 85° Celsius, preferably 95° Celcius and preferably below 110° Celcius, preferably below 100° Celcius; calculating a parameter SP that links said results and switches off the medical instrument at a predetermined value. The invention also relates to a medical instrument and an application and a storage medium according to the associated claims.