Physics - CT Generation Scanners

Third Generation Scanners

- Continuously rotating fan beam scanning - Fan beam geometry - continuous 360 degree rotation around patient - path traced is circle, not semicircular like 1st and 2nd gen

Sixth Generation Scanners

- Dual source CT scanners - x2 x-ray tubes (off set by 90 degrees) - 2 sets of detectors - designed for cardiac CT (greater temporal resolution)

Fifth Generation Scanners

- Electron beam CT scanner - developed primarily for high speed CT scanning - no longer in use (replaced by volume scanning) - goal was to produce high resolution images of moving organs

Seventh Generation Scanners

- Flat panel volume CT - detectors are wide area flat panels (high volume coverage)

Second Generation Scanners

- Rectilinear multiple pencil beam scanning - Fan beam geometry - translate-rotate scanning; rotates in larger increments than 1st gen; repeated for 180 degrees - linear detector array (30 detectors)

First Generation Scanners

- Rectilinear pencil beam scanning - Parallel beam geometry - translate-rotate scanning motion at 1 degree at a time; repeated for 180 degrees

Fourth Generation Scanners

- Wide fan beam - continuous 360 degree rotation around patient - stationary circular detector array

Spiral Scanners

- based on 3rd gen geometry - made possible due to slip-ring technology (allows for continuous rotation of gantry) - spiral scanners acquire data while the table is moving.

Multiple-Slice Scanners

- based on multiple rows of detectors - when multiple detector arrays are used, the collimator spacing is wider - started with dual row/dual slice, now have up to 256 slice CT scanners - cone beam geometry