title: Optimizing Radiation Doses for Computed Tomography Across Institutions: Dose Auditing and Best Practices.
abstract: Radiation doses for computed tomography (CT) vary substantially across institutions.
  
  
  
  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.
  
  
  
  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.
  
  
  
  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.
  
  
  
  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.
  
  
  
  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.
authors.affiliation: Department of Epidemiology and Biostatistics, University of California, San Francisco.
authors.forename: Joshua
authors.initials: J
authors.lastname: Demb
authors.affiliation: Department of Radiology, University of California, San Francisco.
authors.forename: Philip
authors.initials: P
authors.lastname: Chu
authors.affiliation: Department of Radiology, University of California, San Diego.
authors.forename: Thomas
authors.initials: T
authors.lastname: Nelson
authors.affiliation: Department of Radiology, University of California, San Diego.
authors.forename: David
authors.initials: D
authors.lastname: Hall
authors.affiliation: Department of Public Health Sciences, UC Davis, and Kaiser Permanente Washington Health Research Institute, Kaiser Foundation Health Plan of Washington.
authors.forename: Anthony
authors.initials: A
authors.lastname: Seibert
authors.affiliation: Department of Public Health Sciences, UC Davis, and Kaiser Permanente Washington Health Research Institute, Kaiser Foundation Health Plan of Washington.
authors.forename: Ramit
authors.initials: R
authors.lastname: Lamba
authors.affiliation: Department of Public Health Sciences, UC Davis, and Kaiser Permanente Washington Health Research Institute, Kaiser Foundation Health Plan of Washington.
authors.forename: John
authors.initials: J
authors.lastname: Boone
authors.affiliation: Department of Radiology, University of California, Irvine.
authors.forename: Mayil
authors.initials: M
authors.lastname: Krishnam
authors.affiliation: Department of Radiology, University of California, Los Angeles.
authors.forename: Christopher
authors.initials: C
authors.lastname: Cagnon
authors.affiliation: Department of Radiology, University of California, Los Angeles.
authors.forename: Maryam
authors.initials: M
authors.lastname: Bostani
authors.affiliation: Department of Radiology, University of California, San Francisco.
authors.forename: Robert
authors.initials: R
authors.lastname: Gould
authors.affiliation: Department of Public Health Sciences, UC Davis, and Kaiser Permanente Washington Health Research Institute, Kaiser Foundation Health Plan of Washington.
authors.forename: Diana
authors.initials: D
authors.lastname: Miglioretti
authors.affiliation: Department of Radiology, University of California, San Francisco.
authors.forename: Rebecca
authors.initials: R
authors.lastname: Smith-Bindman
mesh_terms: D002140:California; D004307:Dose-Response Relationship, Radiation; D005260:Female; D006257:Head / Q000000981:diagnostic imaging; D006801:Humans; D008297:Male; D009381:Neoplasms, Radiation-Induced / Q000517:prevention & control; D010388:Pelvis / Q000000981:diagnostic imaging; D011829:Radiation Dosage; D011860:Radiography, Abdominal / Q000592:standards*; D013902:Radiography, Thoracic / Q000592:standards*; D018570:Risk Assessment; D014057:Tomography, X-Ray Computed / Q000009:adverse effects / Q000592:standards*