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Original Investigation
June 2017

Optimizing Radiation Doses for Computed Tomography Across InstitutionsDose Auditing and Best Practices

Author Affiliations
  • 1Department of Epidemiology and Biostatistics, University of California, San Francisco
  • 2Department of Radiology, University of California, San Francisco
  • 3Department of Radiology, University of California, San Diego
  • 4Department of Public Health Sciences, UC Davis, and Kaiser Permanente Washington Health Research Institute, Kaiser Foundation Health Plan of Washington
  • 5Department of Radiology, University of California, Irvine
  • 6Department of Radiology, University of California, Los Angeles
JAMA Intern Med. 2017;177(6):810-817. doi:10.1001/jamainternmed.2017.0445
Key Points

Question  Does auditing and sharing of best practice across institutions lead to optimization of radiation dose in computed tomographic scans?

Findings  In this study, after auditing and sharing of best practices the mean effective dose for chest and abdominal CT decreased by 19% and 25%, respectively, with the percentage of CT scans exceeding benchmarks decreasing by 48% and 54%, respectively. Mean effective dose in head CT scans varied less following auditing and sharing best practices, with some institutions increasing and some decreasing mean head CT doses.

Meaning  Sharing best practices on CT dose optimization with professionals from different institutions can lower radiation doses and potentially improve practice.


Importance  Radiation doses for computed tomography (CT) vary substantially across institutions.

Objective  To assess the impact of institutional-level audit and collaborative efforts to share best practices on CT radiation doses across 5 University of California (UC) medical centers.

Design, Setting, and Participants  In this before/after interventional study, we prospectively collected radiation dose metrics on all diagnostic CT examinations performed between October 1, 2013, and December 31, 2014, at 5 medical centers. Using data from January to March (baseline), we created audit reports detailing the distribution of radiation dose metrics for chest, abdomen, and head CT scans. In April, we shared reports with the medical centers and invited radiology professionals from the centers to a 1.5-day in-person meeting to review reports and share best practices.

Main Outcomes and Measures  We calculated changes in mean effective dose 12 weeks before and after the audits and meeting, excluding a 12-week implementation period when medical centers could make changes. We compared proportions of examinations exceeding previously published benchmarks at baseline and following the audit and meeting, and calculated changes in proportion of examinations exceeding benchmarks.

Results  Of 158 274 diagnostic CT scans performed in the study period, 29 594 CT scans were performed in the 3 months before and 32 839 CT scans were performed 12 to 24 weeks after the audit and meeting. Reductions in mean effective dose were considerable for chest and abdomen. Mean effective dose for chest CT decreased from 13.2 to 10.7 mSv (18.9% reduction; 95% CI, 18.0%-19.8%). Reductions at individual medical centers ranged from 3.8% to 23.5%. The mean effective dose for abdominal CT decreased from 20.0 to 15.0 mSv (25.0% reduction; 95% CI, 24.3%-25.8%). Reductions at individual medical centers ranged from 10.8% to 34.7%. The number of CT scans that had an effective dose measurement that exceeded benchmarks was reduced considerably by 48% and 54% for chest and abdomen, respectively. After the audit and meeting, head CT doses varied less, although some institutions increased and some decreased mean head CT doses and the proportion above benchmarks.

Conclusions and Relevance  Reviewing institutional doses and sharing dose-optimization best practices resulted in lower radiation doses for chest and abdominal CT and more consistent doses for head CT.