title: [Effect of collimation and pitch on radiation exposure and image quality in spiral CT of the thorax].
abstract: OBJECTIVE
  The aim of the study was to optimize the scan parameters for spiral-CT of the thorax.
  
  
  METHODS
  Using a Somatom AR-SP (Siemens AG, Erlangen) CT-unit, four different scanning protocols (collimation/table feed) were compared: A (5/10), B (10/10), C (10/15), D (10/20). High contrast resolution in the xy-plane and in the z-direction were investigated with special phantoms. Noise levels were measured using a water phantom, the radiation exposure of lung parenchyma was investigated using an Alderson-Rande-Phantom. An anthropoid chest phantom was scanned to compare the image quality of the four protocols.
  
  
  RESULTS
  Protocol A showed the best resolution in the z-direction; the resolution in the xy-plane was equal for all protocols. Image noise in the center of the water phantom was 58 HU for protocol A and 40 HU for the other three. The following equivalent organ dose were measured for lung parenchyma: A 14 mSv, B 29 mSv, C 20 mSv, D 14 mSv.
  
  
  CONCLUSIONS
  Scanning protocols with small collimation and a pitch of 2 are characterised by low radiation exposure and excellent resolution in the z-direction. These parameters seem to be most suitable for lung scanning.
authors.affiliation: Zentralinstitut für Röntgendiagnostik, Universitätsklinikums Essen.
authors.forename: J
authors.initials: J
authors.lastname: Barkhausen
authors.forename: F
authors.initials: F
authors.lastname: Stöblen
authors.forename: R D
authors.initials: RD
authors.lastname: Müller
authors.forename: U
authors.initials: U
authors.lastname: Streubühr
authors.forename: K
authors.initials: K
authors.lastname: Ewen
mesh_terms: D003952:Diagnostic Imaging / Q000592:standards; D006801:Humans; D011785:Quality Assurance, Health Care; D011829:Radiation Dosage; D013902:Radiography, Thoracic; D014057:Tomography, X-Ray Computed