Image reconstruction in CT fluoroscopy

Image reconstruction in CT fluoroscopy requires the computer to provide very fast reconstructions of images in order to provide immediate and accurate spatial and anatomical feedback during a procedure. This is achieved by:

  • use of a small reconstruction matrix – e.g. 256 x 256 (compared with conventional 512 x 512 matrix)
  • arithmetic and logical operations performed in parallel in the array processor
  • speed enhanced by high-speed internal buses
  • reconstruction limited to a circular area
  • no corrections made for beam hardening or other artefacts
  • modified reconstruction algorithms

CT fluoroscopy uses a partial (or incremental) reconstruction technique, which means that data from the last 360 degree set is reconstructed and displayed after every N° (30°/45°/60°) of tube motion. A frame rate of 6-12 frames per second is generally used. The delay between each image displayed depends on frame rate and N°. For example, for 60 degree updates and 6 frames per second, the image is updated every 0.17 seconds (compared with conventional fluoroscopy which is around 25 frames per second). Because of this, a relatively high level of noise will be apparent in soft tissues.

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rID: 62861
Section: Physics
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