title: How accurate is size-specific dose estimate in pediatric body CT examinations?
abstract: BACKGROUND
  Size-specific dose estimate is gaining increased acceptance as the preferred index of CT dose in children. However it was developed based on non-clinical data.
  
  
  OBJECTIVE
  To compare the accuracy of size-specific dose estimate (SSDE) based on geometric and body weight measures in pediatric chest and abdomen CT scans, versus the more accurate [Formula: see text] (mean SSDE based on water-equivalent diameter).
  
  
  METHODS
  We retrospectively identified 50 consecutive children (age <18 years) who underwent chest CT examination and 50 children who underwent abdomen CT. We measured anteroposterior diameter (DAP) and lateral diameter (DLAT) at the central slice (of scan length) of each patient and calculated DAP+LAT (anteroposterior diameter plus lateral diameter) and DED (effective diameter) for each patient. We calculated the following in each child: (1) SSDEs based on DAP, DLAT, DAP+LAT, DED, and body weight, and (2) SSDE based on software calculation of mean water-equivalent diameter ([Formula: see text] adopted standard within our study). We used intraclass correlation coefficient (ICC) and Bland-Altman analysis to compare agreement between the SSDEs and [Formula: see text].
  
  
  RESULTS
  Gender and age distribution were similar between chest and abdomen CT groups; mean body weight was 37 kg for both groups, with ranges of 6-130 kg (chest) and 8-107 kg (abdomen). SSDEs had very strong agreement (ICC>0.9) with [Formula: see text]. SSDEs based on DLAT had 95% limits of agreement of up to 43% with [Formula: see text]. SSDEs based on other parameters (body weight, DAP, DAP+LAT, DED) had 95% limits of agreement of up to 25%.
  
  
  CONCLUSIONS
  Differences between SSDEs calculated using various indications of patient size (geometric indices and patient weight) and the more accurate [Formula: see text] calculated using proprietary software were generally small, with the possible exception for lateral diameter, and provide acceptable dose estimates for body CT in children.
authors.affiliation: Department of Radiology, Riley Hospital for Children, 705 Riley Drive, Room 1053, Indianapolis, IN, 46202, USA. bkarmazy@iupui.edu.|Department of Radiology and Imaging Sciences, Indiana University School of Medicine, Indianapolis, IN, USA. bkarmazy@iupui.edu.
authors.forename: Boaz
authors.initials: B
authors.lastname: Karmazyn
authors.affiliation: Department of Radiation Oncology, Indiana University School of Medicine, Indianapolis, IN, USA.
authors.forename: Huisi
authors.initials: H
authors.lastname: Ai
authors.affiliation: CT Clinical Science, Philips Healthcare, Highland Heights, OH, USA.
authors.forename: Paul
authors.initials: P
authors.lastname: Klahr
authors.affiliation: Department of Biostatistics, Indiana University School of Medicine, Indianapolis, IN, USA.
authors.forename: Fangqian
authors.initials: F
authors.lastname: Ouyang
authors.affiliation: Department of Radiology and Imaging Sciences, Indiana University School of Medicine, Indianapolis, IN, USA.
authors.forename: S Gregory
authors.initials: SG
authors.lastname: Jennings
mesh_terms: D000293:Adolescent; D001835:Body Weight; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D011829:Radiation Dosage; D011860:Radiography, Abdominal; D013902:Radiography, Thoracic; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed
keywords: Abdomen; Chest; Children; Computed tomography dose index volume; Size-specific dose estimate