CT Imaging Systems: Operating Console Functions

CT Scanner Console

• The operating console of a CT scanner can have two or three consoles: one for the CT radiologic technologist, one for post-processing images, and one for the physician to view and manipulate images.
• The consoles allow the operator to select imaging technique factors, control the gantry and patient couch movement, and use computer commands for image reconstruction and transfer.

Patient Table or Couch

• The patient table is an essential component of the CT scanner, controlled by the CT computer using precision motors with telemetric feedback for patient positioning and scanning.
• The table can be retracted from the gantry, lowered to sitting height, and moved upward to insert the patient into the bore of the scanner.
• Laser lights provide references for centering the patient in the bore and adjusting their position.

Image Display, Storage, and Communication

• After reconstruction, the CT image is displayed on a television monitor or liquid crystal display in digital form.
• The grayscale image display requires optimization of image fidelity, influenced by luminance, resolution, noise, and dynamic range.
• Resolution is a critical parameter, with display matrices ranging from 64 × 64 to 2048 × 2048.

Windowing

• Windowing is the process of limiting the number of shades of gray in a CT image to optimize viewing by the human eye.
• The grayscale of a CT image is typically limited to a range of (+1000 to −1000), which represents varying shades of gray.
• Windowing is performed by fine-tuning the image on the computer screen to enhance viewing and emphasize various tissues of interest.
• Window width (WW) defines the number of shades of gray presented, controlling image contrast, while window level (WL) defines the center of the CT number range, controlling image brightness.