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Color Imaging in
Endoscopy and Laparoscopy
May. 08. 2013Olympus Medical Systems Corp.
Hiroyuki Homma
No data copy / No data transfer permitted2 2013/5/15
Outline1. Introduction - Endoscopy Imaging Systems 2. Factors that affect color in endoscopic
imaging 3. White light endoscopy4. Narrow band imaging (NBI)5. Color management6. Summary & Area for practical improvement
第 章
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Introduction: Endoscopy imaging systems
2Chap.1
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Basic types of Endoscopes:
Fiberscope
Rigid Telescope
Videoscope
Direct Viewing – Optical Image
Video Endoscopes – Displayed on Monitor
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Self Contained Endoscopes
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Battery-powered, portable endoscope
Capsule endoscope
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Video Imaging System
Monitor
Light Source
Video Processor
Recording device Rigid Telescope
+ External Camera
RigidVideo Endoscope
FlexibleVideo Endoscope
Fiberoptic
Flexible Endoscope+ External Camera
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Thoracic
Gastroenterology
Intubation
Bronchoscopy
General Surgery
ENT
UrologyOrthopedics
ENT
Esophagoscopy
Gynecology
GynecologyUrology
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Factors that affect color in endoscopic imaging
2Chap.2
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Factors affecting color
Illumination system:Light source Endoscope
Observation system:Optical System
(direct viewing endoscopes)Image Sensor
(video endoscopes)Video processorMonitor
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Illumination System
LIGHT SOURCE
Light Guide(Fiber optic bundle)
Simplified model of illumination system
Lamp
ENDOSCOPE
TissueFilter
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Illumination System
Light guide bundleLamp
Characteristics of Light Guide Bundle
Different types of illumination systems have different color characteristics
Characteristics of the Lamp
Filter
Xenon Lamp
Halogen Lamp
LED
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Direct Viewing EndoscopesSimplified model of observation system
Rod Lens Telescope
Fiberscope
Spectral transmissionof a series of rod lenses
Spectral transmission of image guide fibers
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Video Endoscopes
Image sensor in distal end
Image sensor in proximal end
Color Characteristicsof Image Sensor
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Video Monitor
Observation Monitor
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White Light Endoscopy
2Chap.3
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Basic images for clinical examinationUsers are looking for ‘natural’ looking colorIdentifying abnormal tissue & targeting a biopsy
Gastroenterological endoscopy
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Narrow Band Imaging (NBI)
2Chap.4
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Human Tongue: Image varies with wavelength
415nm 445nm 500nm 540nm 600nm
400 450 500 550 600 nm
Narrow Band Imaging (NBI)
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Structure of Vessels in Human Tongue
415nm 445nm 500nm 540nm 600nm
Narrow Band Imaging (NBI)
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540 nmIllumination
415 nmIllumination
White Light NBIClinical images courtesy of Roy Soetikno, MD
NBI Filter
Narrow-Band Illumination
Narrow Band Imaging (NBI)
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White Light NBI
Clinical images courtesy of Tonya Kaltenbach, MD & Roy Soetikno, MD
NBI enhances microvasculature and surface morphology
Narrow Band Imaging (NBI)
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Color management
2Chap.5
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Color Management
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Things that cannot be (easily) changed:
Color temperature of various types of lamps (xenon vs. halogen)Light sources change their color output as their lamps ageColor transmission characteristics of glass and fiberoptic bundles
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Color Management
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Factors under the control of the manufacturer:
Manufacturing variations from device to deviceProvision of an “auto white-balance” featureAttempt to produce the most “natural” color
possible given the constraints of customer requirements, even with low-cost, battery-powered, portable systems.
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Color Management
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Factors NOT under the control of the manufacturer:
Users mix components from various manufacturers
Users adjust the controls on the monitor to their own liking
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Color Management
Due to the nature of endoscopy, the level of tissue illumination is often very uneven. Illumination follows an inverse square law.Color varies with brightness.
Brightness varies inversely by the square of the distance Clinical image courtesy of Roy Soetikno, MD
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Therefore, even if an endoscope provided accurate color reproduction under ideal test conditions, actual tissue color will vary constantly during live endoscopy.
Endoscopic photo of test card with uniform color
Color Management
Clinical image courtesy of Roy Soetikno, MD
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Prior to the mid 1980’s gastroenterologists were accustomed to seeing the reddish-yellow images produced by fiber optic instruments with halogen light sources.When video endoscopes were introduced, the new technology allowed for image color similar to viewing under sunlight (i.e., higher color temperature). However, users complained that the video image did not appear to be “natural”and requested that the video endoscope’s color be adjusted to match the fiberscope’s image.
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Color Fidelity
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Color FidelityIn the 1990s, laparoscopy was quickly and widely adopted. Initially, laparoscopic image color was designed to be similar to that of open surgery under operating room lights.
Original pictureOriginal picture
Yellowish colorYellowish color Reddish colorReddish color29
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The goal is not to realize the precise color reproduction equivalent to the color seen under sunlight.
The monitor and video processor can be adjusted to match the user’s own color preferences.
The important point for endoscopic color imaging is to provide the specific image information that the user wants to see.
Color Fidelity
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Summary & Area for practical improvement
2Chap.6
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Summary
There are many different types of endoscopesEndoscopic systems can be complexThe color of the endoscopic image is affected by the source of illumination, the physical components of the endoscope, the method of observation, and the video monitor.Many of the factors which affect color cannot be changed. Others are uncontrolled.However, the current level of color across the broad spectrum of endoscopes appears to be acceptable to end users.
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No data copy / No data transfer permitted
Area for practical improvementWhile endoscopists generally focus on real-time imaging, image documentation is gradually becoming more important.As PACS systems and electronic medical record (EMR) systems become more integrated, there is a need for a standard format & common method of sharing and archiving color endoscopic images.In the area of filing system, for example, extended file format with color parameters for displaying images would be practical improvement.
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