Diagnostic reference levels from the ACR CT accreditation program

Cynthia McCollough, Theresa Branham, Vince Herlihy, Mythreyi Bhargavan, Lavonne Robbins, Krista Bush, Michael McNitt-Gray, J. Thomas Payne, Tom Ruckdeschel, Doug Pfeiffer, Dianna Cody, Robert Zeman

Research output: Contribution to journalArticlepeer-review

60 Scopus citations


Purpose: 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 (CTDIw) 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 CTDIvol. 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 CTDIw 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 CTDIvol 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 CTDIvol 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 CTDIvol of routine adult head, adult abdominal, and pediatric abdominal CT scans.

Original languageEnglish (US)
Pages (from-to)795-803
Number of pages9
JournalJournal of the American College of Radiology
Issue number11
StatePublished - Nov 2011


  • ACR accreditation
  • CT dose
  • diagnostic reference levels

ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging


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