title: Optimization of eight-element multi-detector row helical CT technology for evaluation of the abdomen.
abstract: OBJECTIVE
  To evaluate protocols for abdominal imaging with an eight-element multi-detector row computed tomographic (CT) scanner.
  
  
  METHODS
  An eight-element helical CT scanner was used to acquire data in two phantoms with four-element (pitch, 0.75 and 1.5; section thickness, 1.25, 2.5, and 5.0 mm) and eight-element (pitch, 0.625, 0.875, 1.35 and 1.675; section thickness, 1.25 and 2.5 mm) protocols. One phantom was used for low-contrast detectability and streak artifact; the other, for high-contrast performance. Protocols included near constant radiation dose (140 kV and varied tube current, confirmed by using the above protocols to scan a dedicated radiation dose phantom). Data were analyzed by three blinded readers for streak artifacts, contrast-to-noise ratio, and z-axis resolution (contrast-transfer function). Statistical analysis included studentized range tests.
  
  
  RESULTS
  Contrast-to-noise ratios for four and eight elements were not consistently different. Qualitative evaluation for streak artifacts revealed fewer artifacts for all eight-element 1.25-mm-thick section protocols, as compared with eight-element 2.5-mm protocols. All eight-element 2.5-mm protocols except that with 27.0 mm per rotation had fewer streak artifacts than did four-element protocols (P =.02-.04). Contrast-transfer functions along the z axis for eight-element protocols were better than those for four-element protocols, demonstrating improved z-axis resolution (P <.05).
  
  
  CONCLUSIONS
  Images acquired at eight sections per rotation demonstrated no sacrifice of contrast-to-noise ratio, improved z-axis resolution, and fewer streak artifacts, even when radiation dose was similar to that for four-element CT.
authors.affiliation: Department of Radiology, Duke University Medical Center, Erwin Rd, Rm 1531, Box 3808, Durham, NC 27710, USA.
authors.forename: Ashok K
authors.initials: AK
authors.lastname: Gupta
authors.forename: Rendon C
authors.initials: RC
authors.lastname: Nelson
authors.forename: G Allan
authors.initials: GA
authors.lastname: Johnson
authors.forename: Erik K
authors.initials: EK
authors.lastname: Paulson
authors.forename: David M
authors.initials: DM
authors.lastname: Delong
authors.forename: Terry T
authors.initials: TT
authors.lastname: Yoshizumi
mesh_terms: D016477:Artifacts; D006801:Humans; D019047:Phantoms, Imaging; D011829:Radiation Dosage; D011860:Radiography, Abdominal / Q000379:methods*; D015898:Tomography Scanners, X-Ray Computed; D036542:Tomography, Spiral Computed / Q000379:methods