title: Calculation of Organ Doses for a Large Number of Patients Undergoing CT Examinations.
abstract: OBJECTIVE
  The objective of our study was to develop an automated calculation method to provide organ dose assessment for a large cohort of pediatric and adult patients undergoing CT examinations.
  
  
  METHODS
  We adopted two dose libraries that were previously published: the volume CT dose index-normalized organ dose library and the tube current-exposure time product (100 mAs)-normalized weighted CT dose index library. We developed an algorithm to calculate organ doses using the two dose libraries and the CT parameters available from DICOM data. We calculated organ doses for pediatric (n = 2499) and adult (n = 2043) CT examinations randomly selected from four health care systems in the United States and compared the adult organ doses with the values calculated from the ImPACT calculator.
  
  
  RESULTS
  The median brain dose was 20 mGy (pediatric) and 24 mGy (adult), and the brain dose was greater than 40 mGy for 11% (pediatric) and 18% (adult) of the head CT studies. Both the National Cancer Institute (NCI) and ImPACT methods provided similar organ doses (median discrepancy < 20%) for all organs except the organs located close to the scanning boundaries. The visual comparisons of scanning coverage and phantom anatomies revealed that the NCI method, which is based on realistic computational phantoms, provides more accurate organ doses than the ImPACT method.
  
  
  CONCLUSIONS
  The automated organ dose calculation method developed in this study reduces the time needed to calculate doses for a large number of patients. We have successfully used this method for a variety of CT-related studies including retrospective epidemiologic studies and CT dose trend analysis studies.
authors.affiliation: 1 Space Radiation Analysis Group, National Aeronautics and Space Administration, Johnson Space Center, Houston, TX.
authors.forename: Amir
authors.initials: A
authors.lastname: Bahadori
authors.affiliation: 2 Department of Public Health Sciences, Division of Biostatistics, School of Medicine, University of California, Davis, CA.
authors.forename: Diana
authors.initials: D
authors.lastname: Miglioretti
authors.affiliation: 3 Department of Radiology, Marshfield Clinic and Research Foundation, Marshfield, WI.
authors.forename: Randell
authors.initials: R
authors.lastname: Kruger
authors.affiliation: 4 Department of Radiology and Center for Health Services Research, Henry Ford Health System, Detroit, MI.
authors.forename: Michael
authors.initials: M
authors.lastname: Flynn
authors.affiliation: 5 Center for Health Research, Kaiser Permanente Northwest, Portland, OR.
authors.forename: Sheila
authors.initials: S
authors.lastname: Weinmann
authors.affiliation: 6 Departments of Radiology and Biomedical Imaging, Epidemiology and Biostatistics, Obstetrics, and Gynecology and Reproductive Sciences, University of California, San Francisco, CA.
authors.forename: Rebecca
authors.initials: R
authors.lastname: Smith-Bindman
authors.affiliation: 7 Division of Cancer Epidemiology and Genetics, Radiation Epidemiology Branch, National Cancer Institute, National Institutes of Health, 9609 Medical Center Dr, Rockville, MD 20850.
authors.forename: Choonsik
authors.initials: C
authors.lastname: Lee
mesh_terms: D000465:Algorithms; D001331:Automation; D005260:Female; D006801:Humans; D008297:Male; D009010:Monte Carlo Method; D019047:Phantoms, Imaging; D011829:Radiation Dosage; D011874:Radiometry / Q000379:methods*; D014057:Tomography, X-Ray Computed; D014481:United States
keywords: CT; Monte Carlo simulations; dosimetry; informatics; phantom