Endoscope Oxygen Saturation Calculation via Multi-Wavelength Segmentation
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Solution Overview
Problem
Existing endoscope systems face challenges in accurately calculating oxygen saturation when the observation target is contaminated with dirt such as colored mucus, as it affects the signal ratio used for calculation, leading to reduced accuracy.
Innovation Solution
An endoscope system that acquires image signals across multiple wavelength bands, including a first band where light absorption changes with oxygen saturation, a second band where absorption changes with blood volume, a third band with minimal absorption changes for oxygen saturation, and a fourth band with an isosbestic point, allowing for accurate oxygen saturation calculation using signal ratios and correlation tables.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If signal light in blue wavelength band is used to calculate oxygen saturation, then oxygen saturation can be calculated, but accuracy is reduced when yellow dye (bilirubin or stercobilin) is present in mucus
Solution Approach 1:
The patent segments the measurement process into multiple wavelength band measurements. Instead of using a single blue wavelength band, the system divides measurements into at least two wavelength bands: one where yellow dye absorption is significant and another where it is minimal. This segmentation allows the system to differentiate between absorption by blood hemoglobin and absorption by yellow dye, thereby resolving the contradiction between obtaining oxygen saturation measurement and avoiding interference from yellow dye.
Solution Approach 2:
The patent changes the measurement parameters by selecting different wavelength bands for measurement. The system varies the wavelength parameter to find regions where yellow dye absorption is minimal while still maintaining sensitivity to oxygen saturation changes. This parameter change approach allows the system to bypass the harmful absorption effect of yellow dye in the blue wavelength band.
2Measurement precision
If multiple wavelength bands are measured to account for contamination, then oxygen saturation accuracy is maintained, but device complexity increases
Solution Approach 1:
The patent applies multi-functionality by designing the light source and detection system to handle multiple wavelength bands within a single integrated measurement device. The system uses a broadband light source that can emit multiple wavelength bands and a detection system that can simultaneously or sequentially measure reflections across these bands. This universal approach allows the complex multi-wavelength measurement to be performed by a single multi-functional device rather than requiring separate specialized devices for each wavelength band.
Solution Approach 2:
The patent employs periodic action by alternately emitting light at different wavelength bands in a time-sequential manner. Instead of requiring all wavelength measurements to occur simultaneously, the system periodically switches between different wavelength bands, measuring the reflected light at each band in sequence. This periodic measurement approach reduces the complexity of simultaneous multi-wavelength detection while still gathering all necessary data for accurate oxygen saturation calculation.
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 oxygen saturation calculation even with contamination, by considering the presence and amount of residue and colored mucus, and provides a warning notification for severe contamination, improving diagnostic accuracy.
Implementation Method 1
first signal light and second signal light having different wavelength bands and different absorption coefficients for oxygenated hemoglobin and reduced hemoglobin are alternately emitted to blood vessels in the mucous membrane
Implementation Method 2
reflected light beams of the first and second signal light beams are detected by a sensor located at the distal end of the endoscope
Data Source
AI summary
The endoscope system includes: an image signal acquisition unit acquiring B1 image signal corresponding to blue narrow band where the amount of light absorption changes according to the oxygen saturation of blood hemoglobin, G2 image signal corresponding to green wavelength band where the amount of light absorption changes according to a blood volume of an observation target, R2 image signal corresponding to red wavelength band where a change in the amount of light absorption with respect to the oxygen saturation or the blood volume is small compared with the B1 and G2 image signal, and B2 image signal corresponding to a wavelength band, a difference between a center wavelength of the wavelength band and a center wavelength of the blue narrow band being 20 to 100 nm; and an oxygen saturation calculation unit calculating the oxygen saturation based on the B1, G2, R3, and B2 image signal.