title: Diagnostic reference levels from the ACR CT Accreditation Program.
abstract: OBJECTIVE
  The aim of this study was to assess the distribution of CT dose index (CTDI) values reported by sites undergoing ACR CT accreditation between 2002 and 2004.
  
  
  METHODS
  Weighted CTDI (CTDI(w)) values were measured and reported by sites applying for ACR CT accreditation, and the percentage of scanners with values above the 2002 ACR diagnostic reference levels (DRLs) was determined. Acquisition parameters for a site's adult head, adult abdominal, and pediatric abdominal examinations were used to calculate volume CTDI (CTDI(vol)), and the average and standard deviation were calculated by year. Histogram analysis was performed to determine 75th and 90th percentiles of CTDI(vol).
  
  
  RESULTS
  Between September 2002 and December 2004, 829 scanners underwent the accreditation process. Volume CTDI values (average ± SD) for 2002, 2003, 2004, and 2002 to 2004, respectively, were 66.7 ± 23.5, 58.5 ± 17.5, 55.8 ± 15.7, and 59.1 ± 18.6 mGy for adult head examinations; 18.7 ± 8.0, 19.2 ± 8.6, 17.0 ± 7.6, and 18.4 ± 8.3 for adult abdominal examinations; and 17.2 ± 9.7, 15.9 ± 8.6, 14.0 ± 7.0, and 15.5 ± 8.4 for pediatric abdominal examinations. For 2004 data, 23.8%, 2.3%, and 6.9% of sites reported doses above the 2002 CTDI(w) reference levels, compared with 49.6%, 4.7%, and 15% for 2002 data for adult head, adult abdominal, and pediatric abdominal examinations, respectively. Seventy-fifth percentiles of CTDI(vol) were 76.8 mGy (adult head, 2002 only), 22.2 mGy (adult abdominal), and 20.0 mGy (pediatric abdominal).
  
  
  CONCLUSIONS
  From 2002 to 2004, average CTDI(vol) values decreased by 10.9, 1.7, and 3.2 mGy for adult head, adult abdominal, and pediatric abdominal examinations. Effective January 1, 2008, the ACR program implemented United States-specific diagnostic reference levels of 75, 25, and 20 mGy, respectively, for the CTDI(vol) of routine adult head, adult abdominal, and pediatric abdominal CT scans.
authors: Mayo Clinic, Rochester, Minnesota 55905, USA. mccollough.cynthia@mayo.edu
authors: Cynthia
authors: C
authors: McCollough
authors: Theresa
authors: T
authors: Branham
authors: Vince
authors: V
authors: Herlihy
authors: Mythreyi
authors: M
authors: Bhargavan
authors: Lavonne
authors: L
authors: Robbins
authors: Krista
authors: K
authors: Bush
authors: Michael
authors: M
authors: McNitt-Gray
authors: J Thomas
authors: JT
authors: Payne
authors: Tom
authors: T
authors: Ruckdeschel
authors: Doug
authors: D
authors: Pfeiffer
authors: Dianna
authors: D
authors: Cody
authors: Robert
authors: R
authors: Zeman
mesh_terms: D000005:Abdomen / Q000528:radiation effects; D000068:Accreditation / Q000458:organization & administration*; D000328:Adult; D000367:Age Factors; D002648:Child; D002675:Child, Preschool; D005069:Evaluation Studies as Topic; D005260:Female; D006257:Head / Q000000981:diagnostic imaging; D006801:Humans; D008297:Male; D015397:Program Evaluation; D011829:Radiation Dosage; D011835:Radiation Protection / Q000592:standards*; D011860:Radiography, Abdominal / Q000592:standards; D011874:Radiometry / Q000592:standards*; D012016:Reference Values; D015203:Reproducibility of Results; D012189:Retrospective Studies; D018570:Risk Assessment; D017751:Safety Management; D012955:Societies, Medical / Q000592:standards; D014481:United States