title: Radiation dose reduction at MDCT with iterative reconstruction for prenatal diagnosis of skeletal dysplasia: preliminary study using normal fetal specimens.
abstract: OBJECTIVE
  The purpose of this study was to investigate to what degree the radiation dose can be reduced without affecting the ability to evaluate normal fetal bones at MDCT with iterative reconstruction.
  
  
  METHODS
  Fifteen normal fetal specimens immersed in containers (30- and 35-cm diameter) were scanned with a 64-MDCT scanner, with tube voltage of 100 kVp and tube current of 600, 300, 150, 100, and 50 mA. Images were subjected to adaptive statistical iterative reconstruction (ASIR). The fetal dose was measured using glass dosimeters. We calculated the relative ratio of the dose at 600 mA. Image quality was evaluated on maximum-intensity-projection and volume-rendering images. Two radiologists recorded the visualization scores of five regions. Images at 600 mA were considered to be standard.
  
  
  RESULTS
  With the 30-cm-diameter container, the fetal dose was 10.15 mGy (relative ratio, 100%) at a tube current of 600, 51% at 300, 25% at 150, 17% at 100, and 9% at 50 mA. With the 35-cm-diameter container the fetal dose was 10.01 mGy (relative ratio, 100%) at 600, 47% at 300, 24% at 150, 17% at 100, and 8% at 50 mA. Visual evaluation showed that in both containers, with ASIR 90%, there was a statistically significant difference between 50-and 600-mA images (p<0.01) but not between 600-mA images and those acquired at 100, 150, and 300 mA (p=0.08-1.00).
  
  
  CONCLUSIONS
  The fetal radiation dose for the evaluation of normal fetal bones can be reduced by 83% with ASIR 90%.
authors.affiliation: 1 Department of Diagnostic Radiology, Hiroshima University, 1-2-3 Kasumi, Minamiku, Hiroshima 734-8551, Japan.
authors.forename: Chihiro
authors.initials: C
authors.lastname: Tani
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Funama
authors.forename: Chikako
authors.initials: C
authors.lastname: Fujioka
authors.forename: Yuko
authors.initials: Y
authors.lastname: Nakamura
authors.forename: Daisuke
authors.initials: D
authors.lastname: Komoto
authors.forename: Hirohiko
authors.initials: H
authors.lastname: Aoyama
authors.forename: Kazuo
authors.initials: K
authors.lastname: Awai
mesh_terms: D000465:Algorithms; D001848:Bone Diseases, Developmental / Q000000981:diagnostic imaging* / Q000196:embryology*; D002102:Cadaver; D005260:Female; D006801:Humans; D008297:Male; D061330:Multidetector Computed Tomography / Q000379:methods*; D015588:Observer Variation; D010865:Pilot Projects; D011296:Prenatal Diagnosis / Q000379:methods*; D011829:Radiation Dosage; D011835:Radiation Protection / Q000379:methods*; D011856:Radiographic Image Enhancement / Q000379:methods; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D012016:Reference Values; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
keywords: fetal CT; fetal radiation dose; iterative reconstruction; prenatal imaging; skeletal dysplasia