Lecture Notes on Artifacts and Errors in CR (Computed Radiography)

Key Terms and Errors

Ghosting Error (Ghost Image)

• Definition: An error with erasing the CR plate.
• Cause: Occurs when the CR plate does not erase fully due to issues with the bright white light used for erasing.
• Example: A previous image (e.g., a lead marker) appears faintly on a new exposure, resembling a double image.
• Solution: Repeat the exposure and consider erasing the plate twice, especially after large exposures using higher technical factors.

Roller Malfunction Error

• Description: Appears as a clear line due to roller malfunction in the CR processor.
• Cause: Occurs when the imaging plate is under the scanning beam longer than necessary due to faulty rollers.
• Example: Bright areas or lines through the anatomy, possibly requiring a repeat scan.

Moire Pattern (Wave-like Pattern)

• Description: Wave-like grid lines appear on the image.
• Cause: Error with the CR grids and laser scanning, parallel to the grid lines.
• Solution: Recognize and correct CR grid errors to avoid the moire effect.

General Information on Artifacts

Maintenance and Cleaning

• Cassettes and Imaging Plates: Should be cleaned regularly; technologist's responsibility.
  • Dust and Scratches: Easily collect dust; scratches can appear as bright white lines through anatomy.
  • Cleaning: Use vendor-specified solutions and clean after each patient for infection control.
• Hinge Issues: Check hinges if there are alerts indicating plate insertion errors.

Infection Control

• Best Practices: Use protective bags for cassettes, clean after each use, and avoid pouring cleaning solutions into the cassette.

Advantages of CR over Film

• No Need for Dark Room: Eliminated the need for processing chemicals.
• Speed and Efficiency: Faster processing with PACS (Picture Archiving and Communication System).
• Lower Patient Dose: Allows for lower techniques compared to film.
• Reduced Repeats: Fewer repeats due to under or overexposure, thanks to computer applications and processing capabilities.

Disadvantages: Dose Creep

• Definition: A tendency to increase radiation exposure over time for quality images.
• Prevention: Monitor exposure index numbers and understand the target range for each equipment set.

These notes cover the common CR artifacts, their causes, preventive measures, and the pros and cons of CR technology.