title: Childhood exposure to ionizing radiation from computed tomography imaging in Nova Scotia.
abstract: BACKGROUND
  Examining radiation dose in the paediatric population is particularly important due to the vulnerability of paediatric patients (increased radiosensitive tissues and postexposure life-years) and risk for future radiogenic malignancy.
  
  
  OBJECTIVE
  To evaluate trends in paediatric computed tomography (CT) use and ionizing radiation exposure using population-based data from Nova Scotia.
  
  
  METHODS
  A retrospective, population-based cohort study of CT use in patients <20 years of age, from January 1, 2004 to December 31, 2011, was performed in Nova Scotia. CT examination data were retrieved from a provincial imaging repository. Trends in CT use were described, and both annual and cumulative effective dose exposures were calculated.
  
  
  RESULTS
  In total, 29,452 CT events, involving up to 22,867 individuals were retrieved. Overall annual paediatric CT examination rates remained static (range 17.4 to 18.8 per 1000 per year). However, use in children <10 years of age decreased by >50% (P<0.001); this was counterbalanced by a steady increase among 15- to 19-year-olds (P<0.0001). Overall, 15.4% of scanned patients underwent ≥2 examinations, of which 58 patients (1.6%) exceeded 50 mSv of exposure.
  
  
  CONCLUSIONS
  Despite a static rate in CT imaging among the entire cohort, children <15 years of age and, particularly, those <10 years of age displayed marked reductions in CT use. This may reflect increased awareness of campaigns emphasizing judicious CT use, revised clinical practice guidelines and increased availability of alternative modalities. A small subgroup demonstrated high-dose exposure (>50 mSv), and rates in individuals >15 years of age steadily increased, suggesting further exposure reduction efforts are necessary.
authors.affiliation: Department of Paediatrics, Dalhousie University; IWK Health Centre;
authors.forename: Mark
authors.initials: M
authors.lastname: Inman
authors.affiliation: Department of Paediatrics, Dalhousie University; IWK Health Centre;
authors.forename: Anthony
authors.initials: A
authors.lastname: Otley
authors.affiliation: Department of Paediatrics, Population Cancer Research Program, Dalhousie University, Halifax, Nova Scotia; School of Population and Public Health, University of British Columbia, Vancouver, British Columbia;
authors.forename: Trevor
authors.initials: T
authors.lastname: Dummer
authors.affiliation: Population Cancer Research Program, Dalhousie University, Halifax, Nova Scotia.
authors.forename: Yunsong
authors.initials: Y
authors.lastname: Cui
authors.affiliation: Department of Diagnostic Radiology, Dalhousie University, Halifax, Nova Scotia.
authors.forename: Matthias H
authors.initials: MH
authors.lastname: Schmidt
authors.affiliation: Departments of Medicine and Paediatrics, Population Cancer Resarch Program, Dalhousie University, Halifax, Nova Scotia.
authors.forename: Louise
authors.initials: L
authors.lastname: Parker
keywords: Cancer; Computed tomography; Ionizing radiation; Paediatrics; Risk