Display and artifacts
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| What are the acceptable ways to divide the CR plate to make multiple exposures? | Vertical split - 2 images;
Horizontal split - 2 images:
Quarter split - 4 images
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| Name the types of exposure artifacts. | *Motion
*patient artifacts
*improper positioning/clipped anatomy
*quantum mottle
*double exposure (CR)
*grid lines/cutoff
*moire effect
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| What is DICOM? | Digital Imaging and Communications in Medicine -
international standard to transmit, store, retrieve, print, process, and display medical imaging information
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| What is HL7? | Health Level 7 -
a comprehensive framework and related standard for the exchange, integration, sharing and retrieval of electronic health information
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| What does SMPTE stand for? | Society of Motion Picture and Television Engineers
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| What does AAPM stand for? | American Association of Physicists in Medicine
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| What does NEMA stand for? | National Electronics Manufacturer's Association
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| How is QC of electronic display devices performed? | using a SMPTE or AAPM TG18-QC test pattern
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| What does a Display Test Pattern evaluate? | First, clean the screen.
*Geometric distortion
*general image quality
*Luminance
*Spatial Resolution
*Ambient Light
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| What is geometric distortion? | involves verification all lines/borders in pattern are visible, straight and centered within active area of display device.
No DISTORTION is present in viewing area
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| What is general image quality? | involves evaluating overall appearance of pattern - look for dropped pixels (no brightness, appears as a dark space that doesn't change location w/diff images)
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| What is luminance? | verification all 16 luminance patches are distinctly visible from adjacent patches
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| What is resolution? | All letters and numbers are visible
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| What is ambient light and what is standard? | measure illuminance in area where primary reading takes place and ensure it doesn't exceed 4.5foot candles/50lux
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| Are you able to visually identify a monitor test pattern? | Papp p191-194
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| Describe procedure for QC displays? Papp p 187-188 | a- max luminance (luminance response) ;
e - luminance dependencies - viewing angle
f - spatial/geometric distortion
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| What is maximum luminance ? | (luminance dependencies) - relationship between display luminance and input values from standard display systems (test pattern)
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| What is luminance dependency? | viewing angle between observer and center of display - no less than 80' for LED screen
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| What is spatial/geometric distortion in QC of displays? | verify that pattern lines are recorded accurately - straight lines, perfect squares/circles
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| What is low contrast resolution of QC displays? | verify contrast patterns are visible both in white and black squares; verify proper contrast balance available within image
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| What is spatial resolution ? | Note any differences in visibility of test patterns between horizontal and vertical lines
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| What is grayscale uniformity? | uniformly gray across entire display
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| What is display artifacts? | verify no streaks, lines or dark/light patches; look for small black dots (dropped pixels)
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| What is display reflection? | verify all light coming from display surface has been generated by display device only and no reflected light
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| Which display is best luminance (brightness)? | Plasma; however, we will probably see LCD/CRTs due to cost
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| What is reject and repeat analysis program (RAP)? | systematic process of cataloging rejected images and determine the nature of error to eliminate or minimize going forward.
REJECT -
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| What are the advantages of RAP? | increased department efficiency; decreased department cost; decrease patient dose (most important)
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| What is an artifact? | any irregularity on an image that is not caused by proper shadowing of tissue by primary x-ray beam;
undesirable optical density or blemish on radiograph
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| Why do CR artifacts require special attention ? | b/c may be produced by CR system itself; users not using proper image techniques or selecting appropriate imaging protocols
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| Why is using a grid so important in CR? | because the IP is very sensitive to scattered radiation
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| Why should a technologist be concerned about artifacts? | artifacts can obscure important anatomy; picture looks bad; cannot be corrected by any image processing algorithm
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| List some Image Plate artifacts. Papp p 137-139 | Phantom image artifact - not properly erased prior to exp;
foreign objects - dirt/debris cause light colored specks;
Phosphor wear - friction removes part of PSP crystal from IP
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| What are digital radiography artifacts? | positioning errors;
collimation errors;
backscatter radiation;
LUT selection/histogram
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| are you familiar with appropriate collimation when making more than one exposure on a CR plate? | four symmetrical borders; can do three; must be symmetrical and even number of patterns (1,2,4) no more than 4 per plate
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| Describe exposure artifacts. | *motion - involuntary/voluntary
*patient artifacts - removable/not removable
*improper positioning or anatomy
*quantum mottle
*double exposure (CR plates)
*grid lines/cutoff (angel hair pasta)
*Moire effect (Nyquist frequency)
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| Describe CR / DR artifacts | *Heat Blur - CR
*Improper image brightness (incorrect algorithm)
*Electronic noise
*Quantum mottle
*Phantom image
*Scatter
*Dbl exposure
*Foreign Objects
*Dropped pixel
*Halo artifacts
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| What is heat blur? | occurs when plate gets too hot; considered operator error
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| What is Improper image brightness? | incorrect algorithm
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| What is electronic noise? |
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Created by:
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