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IMAGE ARTIFACTS

IMAGE ARTIFACTS. What is an ARTIFACT. 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.

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IMAGE ARTIFACTS

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  1. IMAGE ARTIFACTS

  2. What is an ARTIFACT • 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

  3. How are they produced? • Exposure • Processing • Handling & Storage

  4. 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

  5. ARTIFACTS FROM PROCESSING Pressure marks from transport of film produced during processing and will usually appear with ahigher OD • Roller Marks • Dirty Rollers • Chemical Fog • Wet-Pressure Sensitization

  6. 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

  7. DIRTY ROLLERS • Emulsion Pickoff • Gelatin buildup- sludge • Can appear as sharp positive or negative optical density on film

  8. 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

  9. WET PRESSURE SENSITIZATION • Developer tank • Irregular or dirty rollers • Small circular increased optical density

  10. HYPO RETENTION • Hypo - fixing agent ammonium thiosulfate • Improper washing • Yellowish discoloration to stored radiograph

  11. HANDLING & STORAGE • Radiation and Light fog • Rough Handling- kink marks • Static • Hypo retention • Kinks • Scratches

  12. ARTIFACTS FROM RADIATION AND LIGHT FOG • Light leaks • Safelight • Radiation • Heat/humidity below 68 degrees 40 to 60 % humidity

  13. HANDLING Before or After processing • Kink marks • Scratches • Fingerprints • Darkroom environment clean dry surfaces

  14. STATIC Electron buildup on emulsion Low humidity • Crown • Tree • Smudge

  15. CASSETTE BASED FILMLESS ARTIFACTSDigital Radiography and PACS pg 90-98 • IMAGING PLATE ARTIFACTS • CRACKS –AREAS OF LUCENCY • Adhesive tape residue • Static causing hair to adhere to plate • Backscatter

  16. CASSETTE BASED FILMLESS ARTIFACTSDigital Radiography and PACS • PLATE READER ARTIFACTS • 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

  17. CASSETTE BASED FILMLESS ARTIFACTSDigital Radiography and PACS • Printer Artifacts • Fine white lines from debris on mirror in printer • Operator ARTIFACTS • Insufficient collimation = incorrect exposure range (S) reading • Backward cassette • Underexposure = quantum mottle

  18. DR Processing Artifacts • Electronic rather than chemical • Artifacts caused by interference with electronic components

  19. CR Handling and Storage Artifacts • Debris on image receptor • Discoloration of fluorescent screens • Fogging • “ghost images” • “dead” detector images

  20. Cassetteless ArtifactsDigital Radiography and PACS pg 108 • 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

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