title: [Clinical use of software-controlled x-ray tube modulation with "Smart-Scan" in spiral CT].
abstract: OBJECTIVE
  The modulation of tube current during 360 degree-rotation for equalization of local differences in absorption is able to reduce patient exposure in spiral-CT. The impact on CT investigations of thorax, abdomen and pelvis and the influence of patient geometry within the slice on the decrease of tube current are evaluated.
  
  
  METHODS
  300 spiral-CT's were performed on a HiSpeed Advantage scanner (GE) using a software-triggered modulation of tube current ("Smart-Scan"). The local absorption was measured in the 100 central channels of 2 scoutiviews (lateral and a.p.) and used for anatomical adapted modulation. The reduction of exposure as well as the height and width of the body cross-section were measured in reference slices of 100 thorax, 100 abdomen and 100 pelvis examinations.
  
  
  RESULTS
  The use of "Smart-Scar" enables a decrease of tube current of 7% in thorax, 6% in abdomen and 11% pelvis. There is a significant correlation between the height and width of body cross-section and the reduction of exposure for examinations of thorax and abdomen, but not of the pelvis.
  
  
  CONCLUSIONS
  Independent of patient geometry the clinical use of "Smart-Scan" achieves the pelvis. Anatomical regions with an oval body cross-section show a decrease of x-ray tube current, too.
authors.affiliation: Institut für Klinische Radiologie, Klinikum der Stadt Mannheim, Fakultät für Klinische Medizin Mannheim der Universität Heidelberg.
authors.forename: K J
authors.initials: KJ
authors.lastname: Lehmann
authors.forename: J
authors.initials: J
authors.lastname: Wild
authors.forename: M
authors.initials: M
authors.lastname: Georgi
mesh_terms: D000328:Adult; D000368:Aged; D004867:Equipment Design; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011829:Radiation Dosage; D011874:Radiometry / Q000295:instrumentation*; D014057:Tomography, X-Ray Computed / Q000295:instrumentation*