Transcript IMAGE ARTIFACTS - Montgomery College

IMAGE
ARTIFACTS
What is an ARTIFACT
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Any irregularity on
an image that is not
caused by the proper
shadowing of tissue
by the primary beam.
• an undesirable
optical density on
radiograph
How are they produced?
•Exposure
•Processing
•Handling & Storage
ARTIFACT FROM EXPOSURE
Associated with conducting Exam
• Equipment
Incorrect film screen match or poor contact
Warped or dirty cassettes
Grid misalignment
• Patient
preparation or instruction (motion)
positioning errors
technical errors
ARTIFACTS FROM
PROCESSING
Pressure marks from transport of film
produced during processing and will
usually appear with a higher OD
• Roller Marks
• Dirty Rollers
• Chemical Fog
• Wet-Pressure Sensitization
ROLLER MARK
• Guide Shoes-mark on leading or trailing
edge of film, found parallel to the film
travel direction. Caused by improper
positioned guide shoes or spring shoes
• pi lines- 3.1416 inch intervals
dirt and chemical stains
DIRTY ROLLERS
• Emulsion Pickoff
• Gelatin buildupsludge
• Can appear as sharp
positive or negative
optical density on
film
CHEMICAL FOG
Improper or Inadequate
processing chemistry
• Chemical Fog- uniform dull
grey
– Dichoic Stain- 2 colors
yellow, green, blue, purple
• Curtain Effect-chemistry
running up trailing edge or
down leading edge
WET PRESSURE
SENSITIZATION
• Developer tank
• Irregular or dirty rollers
• Small circular increased optical density
HYPO RETENTION
• Hypo - fixing agent
ammonium
thiosulfate
• Improper washing
• Yellowish
discoloration to
stored
radiograph
HANDLING & STORAGE
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Radiation and Light fog
Rough Handling- kink marks
Static
Hypo retention
Kinks
Scratches
ARTIFACTS FROM
RADIATION AND LIGHT FOG
• Light leaks
• Safelight
• Radiation
• Heat/humidity
below 68 degrees
40 to 60 % humidity
HANDLING
Before or After processing
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Kink marks
Scratches
Fingerprints
Darkroom
environment
clean dry surfaces
STATIC
Electron buildup on emulsion
Low humidity
• Crown
• Tree
• Smudge
CASSETTE BASED FILMLESS ARTIFACTS
Digital Radiography and PACS pg 90-98
1. IMAGING PLATE ARTIFACTS
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CRACKS –AREAS OF LUCENCY
Adhesive tape residue
Static causing hair to adhere to plate
Backscatter
CASSETTE BASED FILMLESS ARTIFACTS
Digital Radiography and PACS
2.
PLATE READER ARTIFACTS
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Extraneous line patterns caused by electronics
White lines (horizontal) dirt on light guide of reader
Loading of more than one IP into a cassete=double
exposure artifact
Grid orientation so that grid lines are parallel to the
plate reader’s laser scan = moire pattern. (Grids
should be high frequency and grid lines need to run
perpendicular to the laser scan line
CASSETTE BASED FILMLESS ARTIFACTS
Digital Radiography and PACS
3. Printer Artifacts
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Fine white lines from debris on mirror in printer
4. Operator ARTIFACTS
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Insufficient collimation = incorrect exposure
range (S) reading
Backward cassette
Underexposure = quantum mottle
DR Processing Artifacts
• Electronic rather than chemical
• Artifacts caused by interference with
electronic components
CR Handling and Storage Artifacts
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Debris on image receptor
Discoloration of fluorescent screens
Fogging
“ghost images”
“dead” detector images
Cassetteless Artifacts
Digital Radiography and PACS pg 108
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Conversion from x-ray to digital is very fast
Potential for signal loss
Electronic noise – most typical of artifact
Rapid exposures can cause lose of
signal=reduction of image quality