title: Variability in Radiation Dose From Repeat Identical CT Examinations: Longitudinal Analysis of 2851 Patients Undergoing 12,635 Thoracoabdominal CT Scans in an Academic Health System.
abstract: OBJECTIVE
  The purpose of this study was to conduct longitudinal analyses of radiation dose data from adult patients undergoing clinically indicated, repeat identical thoracoabdominal CT examinations.
  
  
  METHODS
  Radiation dose data were electronically collected from 2851 subjects undergoing 12,635 repeat identical CT scans (mean number of scans per patient, 4.8; range, 2-33) in one health system. Included CT protocols were chest-abdomen-pelvis with contrast administration (n = 4621 CT studies of 1064 patients), abdomen-pelvis with contrast administration (n = 876 CT studies of 261 patients), renal stone (n = 1053 CT studies of 380 patients), and chest (n = 6085 CT studies of 1146 patients) without contrast administration. A radiation-tracking software infrastructure was adopted to extract data from DICOM headers in PACS. Size-specific dose estimate (SSDE) was calculated.
  
  
  RESULTS
  A trend was observed toward global reduction in SSDE values with all protocols investigated (chest-abdomen-pelvis slope, -1.78; abdomen-pelvis slope, -0.82; renal stone slope, -0.83; chest slope, -0.47; p < 0.001 for all comparisons). The intraindividual analyses of radiation dose distribution showed widespread variability in SSDE values across the four protocols investigated (chest-abdomen-pelvis mean coefficient of variance, 14.02 mGy; abdomen-pelvis mean coefficient of variance, 10.26 mGy; renal stone mean coefficient of variance, 34.18 mGy; chest mean coefficient of variance, 6.74 mGy).
  
  
  CONCLUSIONS
  Although there is a trend toward global reduction in radiation doses, this study showed widespread variability in the radiation dose that each patient undergoing identical repeat thoracoabdominal CT protocols absorbs. These data may provide a foundation for the future development of best-practice guidelines for patient-specific radiation dose monitoring.
authors.affiliation: 1 Department of Radiology, University of Washington School of Medicine, Box 357115, 1959 NE Pacific St, Seattle, WA 98195.|2 Department of Radiology, Duke University Medical Center, Durham, NC.
authors.forename: Achille
authors.initials: A
authors.lastname: Mileto
authors.forename: Rendon C
authors.initials: RC
authors.lastname: Nelson
authors.forename: Douglas G
authors.initials: DG
authors.lastname: Larson
authors.forename: Ehsan
authors.initials: E
authors.lastname: Samei
authors.forename: Joshua M
authors.initials: JM
authors.lastname: Wilson
authors.forename: Olav
authors.initials: O
authors.lastname: Christianson
authors.forename: Daniele
authors.initials: D
authors.lastname: Marin
authors.affiliation: 2 Department of Radiology, Duke University Medical Center, Durham, NC.|3 Department of Radiology, University Hospital of Basel, Basel, Switzerland.
authors.forename: Daniel T
authors.initials: DT
authors.lastname: Boll
mesh_terms: D000046:Academic Medical Centers / Q000706:statistics & numerical data*; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D009657:North Carolina / Q000453:epidemiology; D011829:Radiation Dosage; D000069079:Radiation Exposure / Q000706:statistics & numerical data*; D011860:Radiography, Abdominal / Q000706:statistics & numerical data*; D013902:Radiography, Thoracic / Q000706:statistics & numerical data*; D011874:Radiometry / Q000706:statistics & numerical data; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000706:statistics & numerical data*; D055815:Young Adult
keywords: CT; longitudinal analysis; radiation dose; size-specific dose estimate; variability