Endoscope Light-Adjusting Circuit for Blood Vessel Contrast
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Solution Overview
Problem
Conventional endoscope systems face challenges in clearly visualizing blood vessels, particularly thick ones deep within the mucous membrane, during procedures like endoscopic submucosal dissection, due to limitations in light absorption and scattering characteristics, which can lead to inadequate contrast and increased risk of bleeding.
Innovation Solution
The endoscope apparatus employs a narrow-band light observation mode using a rotating filter to irradiate specific wavelength bands, such as around 600 nm and 630 nm, which are optimally absorbed and scattered by hemoglobin, enhancing contrast and visibility of blood vessels, and adjusts light levels based on calculated luminance values to optimize image clarity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional white light or broad-spectrum light is used for illumination, then the illumination intensity is sufficient, but the contrast and visibility of blood vessels deep in the mucous membrane is poor
Solution Approach 1:
The broad-spectrum light is segmented into multiple narrow wavelength bands using a rotating filter wheel with bandpass filters. Each wavelength band (e.g., 405nm, 480nm, 530nm, 585nm, 630nm, 680nm) is sequentially applied to illuminate the tissue, allowing selective enhancement of blood vessel visibility at different depths while maintaining sufficient illumination intensity through optimized filter transmission characteristics.
Solution Approach 2:
The spectral parameters of the illumination light are changed by switching between different narrow wavelength bands. This enables optimization of light-tissue interaction at each wavelength to enhance the absorption contrast of hemoglobin in blood vessels while compensating for light attenuation at depth, thereby improving visibility without requiring excessive overall illumination intensity.
2Loss of information
If multiple wavelength bands are used to improve blood vessel visualization, then the contrast and depth penetration are enhanced, but the device complexity increases
Solution Approach 1:
A single rotating filter wheel assembly serves multiple functions: it sequentially provides multiple narrow wavelength bands for different imaging depths and contrasts, acts as a wavelength multiplexer, and integrates bandpass filtering and illumination control in one component. This multi-functional design achieves enhanced blood vessel visualization across multiple wavelength bands while minimizing the number of separate optical components required.
Solution Approach 2:
The rotating filter wheel implements periodic switching between different wavelength bands, with each band being applied in sequential time intervals. This periodic action allows the system to capture multiple wavelength-specific images over time, enhancing blood vessel visibility through spectral differentiation while using a simple mechanical rotation mechanism rather than complex simultaneous multi-wavelength optics.
3Loss of information
If narrow wavelength bands are used to enhance blood vessel contrast, then the selectivity and depth resolution are improved, but the light amount reaching deep tissue is reduced
Solution Approach 1:
The system applies multiple narrow wavelength bands sequentially, with each band providing partial contribution to the overall blood vessel visualization. By combining the information from multiple wavelength bands (each optimized for specific absorption characteristics of hemoglobin), the system achieves superior contrast and depth resolution that exceeds what any single wavelength band could provide, compensating for the reduced light amount in each individual band.
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 allows for clear visualization of blood vessels, reducing the risk of bleeding by providing high contrast images of vessels up to 2 mm deep, facilitating safer and more precise surgical procedures without the need for medical agents like indocyanine green.
Implementation Method 1
a first luminance value based on a signal with a first wavelength band that is a narrow band and a second luminance value based on a signal with a second wavelength band that is a narrow band between a wavelength band providing a maximal value and a wavelength band providing a minimal value in a light absorption characteristic of hemoglobin
Implementation Method 2
an image pickup section that picks up an image of return light from the subject based on the irradiation by the illumination section
Data Source
AI summary
An endoscope apparatus includes a light source apparatus, and a light-adjusting circuit. The light-adjusting circuit, based on a first image signal with a first wavelength band having a peak wavelength of a spectral characteristic and a second image signal with a second wavelength band having a peak wavelength of a spectral characteristic providing a value lower than that of the first image signal in the absorption characteristic and providing a suppressed scattering characteristic of the body tissue between a wavelength band providing a maximal value and a wavelength band for a minimal value in an absorption characteristic of a body tissue of a subject, provides a weight larger than that of the second image signal to the first image signal to calculate a light adjustment signal for adjusting a light amount in a light source apparatus and outputs the light adjustment signal.