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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.

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Presentation on theme: "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."— Presentation transcript:

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 a higher 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 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 ARTIFACTS Digital Radiography and PACS pg IMAGING PLATE ARTIFACTS CRACKS –AREAS OF LUCENCY Adhesive tape residue Static causing hair to adhere to plate Backscatter

16 CASSETTE BASED FILMLESS ARTIFACTS Digital Radiography and PACS 2.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 readers 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 ARTIFACTS Digital Radiography and PACS 3.Printer Artifacts –Fine white lines from debris on mirror in printer 4.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 Artifacts Digital 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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