title: Patient Size-Specific Analysis of Dose Indexes From CT Lung Cancer Screening.
abstract: OBJECTIVE
  The U.S. Centers for Medicare & Medicaid Services (CMS) recently approved the use of low-dose CT for lung cancer screening and described volumetric CT dose index (CTDIvol) requirements. These were based on the National Lung Screening Trial, which used only fixed-tube-current techniques. The aim of this study was to evaluate dose index data from a lung cancer screening program using automatic exposure control (AEC) techniques to ensure compliance with requirements and to correlate dose index values with patient size.
  
  
  METHODS
  CTDIvol, dose-length product (DLP), and body mass index (BMI) data were collected for 563 lung cancer screening examinations performed with AEC between January 1, 2014, through August 31, 2015. CTDIvoland DLP were analyzed according to the patient's BMI classification. Results were compared with the CMS requirement that the CTDIvolfor a standard-sized patient (height, 170 cm; weight, 70 kg) be 3.0 mGy or less, with adjustments for patients of different sizes. For a subset of patients, the average water-equivalent diameter and size-specific dose estimate were estimated.
  
  
  RESULTS
  The average CTDIvolfor a standard-sized patient was 1.8 mGy, which meets CMS requirements. CTDIvolvalues were lower for smaller patients and higher for larger patients. Overall, the mean CTDIvoland DLP were 2.1 mGy and 74 mGy⋅cm, respectively. The size-specific dose estimate for the average water-equivalent diameter (27.5 cm) of the patient subset was 2.6 mGy.
  
  
  CONCLUSIONS
  The screening protocols using AEC resulted in CTDIvolvalues that were compliant with CMS requirements. CTDIvolvalues greater than 3.0 mGy were only observed for overweight or obese patients.
authors.affiliation: 1 Department of Radiological Sciences, Nagoya University Graduate School of Medicine, 1-1-20 Daikominami, Higashi-ku, Nagoya, Aichi 461-8673, Japan.
authors.forename: Keisuke
authors.initials: K
authors.lastname: Fujii
authors.affiliation: 2 Physics and Biology in Medicine Graduate Program, David Geffen School of Medicine, University of California, Los Angeles, CA.
authors.forename: Kyle
authors.initials: K
authors.lastname: McMillan
authors.affiliation: 2 Physics and Biology in Medicine Graduate Program, David Geffen School of Medicine, University of California, Los Angeles, CA.|3 Department of Radiological Sciences, David Geffen School of Medicine, University of California, Los Angeles, CA.
authors.forename: Maryam
authors.initials: M
authors.lastname: Bostani
authors.affiliation: 2 Physics and Biology in Medicine Graduate Program, David Geffen School of Medicine, University of California, Los Angeles, CA.|3 Department of Radiological Sciences, David Geffen School of Medicine, University of California, Los Angeles, CA.
authors.forename: Christopher
authors.initials: C
authors.lastname: Cagnon
authors.affiliation: 2 Physics and Biology in Medicine Graduate Program, David Geffen School of Medicine, University of California, Los Angeles, CA.|3 Department of Radiological Sciences, David Geffen School of Medicine, University of California, Los Angeles, CA.
authors.forename: Michael
authors.initials: M
authors.lastname: McNitt-Gray
mesh_terms: D049628:Body Size; D055088:Early Detection of Cancer / Q000592:standards*; D019983:Guideline Adherence; D006801:Humans; D008175:Lung Neoplasms / Q000000981:diagnostic imaging* / Q000453:epidemiology; D017410:Practice Guidelines as Topic; D015995:Prevalence; D011829:Radiation Dosage; D000069079:Radiation Exposure / Q000032:analysis* / Q000517:prevention & control; D011835:Radiation Protection / Q000592:standards; D011871:Radiology / Q000592:standards; D011874:Radiometry / Q000379:methods / Q000592:standards*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000592:standards*; D014481:United States / Q000453:epidemiology
keywords: low-dose CT; lung cancer screening; volumetric CT dose index