CT head (technique)

CT head technique describes how a CT head is performed.

Technique

The technique for performing a CT of the head depends on the scanner available and fall into two broad camps: 

  • step-and-shoot
  • volumetric acquisition
Step-and-shoot

The tube is angled such that the axis of acquisition is perpendicular to the orbital floor and single shots taken from vertex to foramen magnum. Traditionally, these were 10 mm slices through the cerebrum and 5 mm slices through the base of skull and posterior fossa. 

The angulation of the tube means that dental fillings are much less likely to cause artefact and it is less susceptible to movement artefact.

Volumetric acquisition

When volume acquisition is utilised, the tube and gantry are not angled and a volume dataset is obtained from the vertex to the base of skull.

This allows the creation of multi-planar reconstruction with thick or thin slices using different algorithms.

The ability to create MPRs quickly and easily does result in a significant increase in the number of images to be reviewed and the amount of space required to save them to disc. 

It is not inconceivable to see a CT brain resulting in 3-plane 4 mm soft and 3-plane 1 mm bone reconstructions being sent to PACS with a 3D reformat and even the 0.6 mm overlapping data (to allow reimport into the volume rendering system for future use). We have moved from the traditional 30 images for a CT brain to a mammoth set of data with 1000+ images.

Related studies

CT examinations
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Article information

rID: 9050
Section: Radiography
Synonyms or Alternate Spellings:

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