Tissue Temperature Measurement via Diffuse Reflection Spectroscopy
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Solution Overview
Problem
Existing high-frequency surgical techniques face challenges in accurately measuring tissue temperature during thermal processes, leading to potential overheating or insufficient energy input, which can result in thermal damage or hemorrhages, as current methods rely on tissue impedance measurements that are not precise and can be falsified by electrode temperature.
Innovation Solution
A method and device that utilize diffuse reflection spectroscopy to measure tissue temperature by emitting light in the VIS/NIR range, analyzing the absorption spectrum of tissue components like water, collagen, and fat, and calculating temperature based on absorption maxima, allowing for real-time control of energy input and preventing overheating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If tissue impedance measurements are used to infer tissue temperature, then temperature can be indirectly monitored, but the measurement precision deteriorates because electrode temperature falsifies the impedance readings
Solution Approach 1:
The patent introduces an optical intermediary (light) as a mediator between the measurement system and the tissue. Instead of using electrical impedance measurements that are contaminated by electrode temperature, the system uses light absorption spectroscopy where the light interacts with tissue chromophores (water, hemoglobin, melanin) to provide temperature information. The optical path is separated from the heating electrode, eliminating the falsification effect while maintaining measurement reliability.
2Reliability
If high-frequency current is applied to seal vessels, then hemorrhage is stopped and vessels are sealed, but thermal damage occurs due to overheating or insufficient energy control
Solution Approach 1:
The patent implements a feedback control system where optical temperature measurements are continuously monitored during high-frequency vessel sealing. The system measures the absorption spectrum of tissue chromophores, determines temperature from spectral shifts, and uses this information to regulate the high-frequency power delivery. This closed-loop feedback ensures the tissue reaches the optimal sealing temperature range (60-90°C) without exceeding it, preventing thermal damage while ensuring reliable vessel occlusion.
Solution Approach 2:
The patent utilizes parameter changes in the optical absorption spectrum as a function of temperature. Specifically, the absorption maxima of tissue chromophores (particularly water at 1470 nm and hemoglobin) shift with temperature changes. By monitoring these spectral parameter changes, the system can determine tissue temperature in real-time and adjust the high-frequency energy delivery accordingly, enabling precise thermal control during vessel sealing.
3Object-affected harmful factors
If the neutral electrode area is made large to reduce current density, then current density is kept low and burns are prevented, but the device complexity and setup requirements increase
Solution Approach 1:
The patent replaces the mechanical/electrical impedance-based temperature monitoring system with an optical measurement system. The optical probes can be integrated into the bipolar sealing jaws or positioned near the tissue, providing direct temperature feedback without requiring complex neutral electrode configurations. This substitution simplifies the overall system setup by eliminating the need for large neutral electrodes and their associated positioning and contact requirements.
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 precise, real-time measurement of tissue temperature, reducing thermal damage and hemorrhages by ensuring safe sealing of vessels, as the method directly measures tissue temperature without interference from electrode thermal capacity, providing accurate control of thermal processes.
Implementation Method 1
evaluating an absorption spectrum of the tissue by comparing the illumination spectrum to the diffuse reflection spectrum
Implementation Method 2
detecting a position of an absorption maximum of the absorption spectrum of the tissue
Implementation Method 3
receiving the diffuse reflection of the light with a diffuse reflection spectrum from the tissue by at least one detector
Implementation Method 4
calculating a temperature in the tissue by comparing the absorption maximum to at least one reference
Data Source
AI summary
A device and a method for measuring temperature. At least one illumination device emits light with an illumination spectrum into tissue. At least one detector receives the diffuse reflection of the light with a remission spectrum from the tissue. The detector converts the remission spectrum into a detector signal. The detector signal is sent to a computing unit that calculates a remission spectrum from the detector signal. The computing unit calculates an absorption spectrum of the tissue by comparing the illumination spectrum with the remission spectrum, calculates at least one absorption maximum from the absorption spectrum, and calculates a temperature in the tissue by comparing the absorption maximum with at least one reference.