title: [Report on the 89th Scientific Assembly and Annual Meeting of the Radiological Society of North America--balance between the time sensitivity profile and the slice sensitivity profile in multi-slice helical scanning].
abstract: OBJECTIVE
  With multi-slice helical scanning, increasing helical pitch causes changes in the effective slice sensitivity profile and thus in a thickening of the effective slice thickness. However, the increase in helical pitch alters the time sensitivity profile, thereby decreasing the effective scan time. In this paper we report the results of our research concerning the setting of optimum conditions to resolve this issue.
  
  
  METHODS
  The experiment was conducted with a moving phantom. The movement showed a variety of changes.
  
  
  RESULTS
  When the subject was not in motion, increases in helical pitch resulted in deterioration in the image quality of the CT image. However, when the subject was in motion increases in helical pitch improved image quality.
  
  
  CONCLUSIONS
  The general belief until now has been that helical pitch should be decreased in order to improve CT image quality. However, in the case of a moving subject, reduced helical pitch leads to deterioration in the time resolution and thus to a deterioration in the image quality. Through this study we have acquired an understanding of which helical pitch value is optimal in terms of the subject's rate of movement.
authors.affiliation: Central Division of Radiology, Yokkaichi City Hospital.
authors.forename: Masayoshi
authors.initials: M
authors.lastname: Niwa
mesh_terms: D012680:Sensitivity and Specificity; D013995:Time; D036542:Tomography, Spiral Computed