title: Body Size-Specific Organ and Effective Doses of Chest CT Screening Examinations of the National Lung Screening Trial.
abstract: OBJECTIVE
  We calculated body size-specific organ and effective doses for 23,734 participants in the National Lung Screening Trial (NLST) using a CT dose calculator.
  
  
  METHODS
  We collected participant-specific technical parameters of 23,734 participants who underwent CT in the clinical trial. For each participant, we calculated two sets of organ doses using two methods. First, we computed body size-specific organ and effective doses using the National Cancer Institute CT (NCICT) dosimetry program, which is based on dose coefficients derived from a library of body size-dependent adult male and female computational phantoms. We then recalculated organ and effective doses using dose coefficients from reference size phantoms for all examinations to investigate potential errors caused by the lack of body size consideration in the dose calculations.
  
  
  RESULTS
  The underweight participants (body mass index [BMI; weight in kilograms divided by the square of height in meters] < 18.5) received 1.3-fold greater lung dose (median, 4.93 mGy) than the obese participants (BMI > 30) (3.90 mGy). Thyroid doses were approximately 1.3- to 1.6-fold greater than the lung doses (6.3-6.5 mGy). The reference phantom-based dose calculation underestimates the body size-specific lung dose by up to 50% for the underweight participants and overestimates that value by up to 200% for the overweight participants. The median effective dose ranges from 2.01 mSv in obese participants to 2.80 mSv in underweight participants.
  
  
  CONCLUSIONS
  Body size-specific organ and effective doses were computed for 23,734 NLST participants who underwent low-dose CT screening. The use of reference size phantoms can lead to significant errors in organ dose estimates when body size is not considered in the dose assessment.
authors.affiliation: 1 Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, 9609 Medical Center Dr, Rm 7E448, MSC 9778, Rockville, MD 20850.
authors.forename: Choonsik
authors.initials: C
authors.lastname: Lee
authors.affiliation: 2 Department of Radiology, Henry Ford Health System, Detroit, MI.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Flynn
authors.affiliation: 3 Department of Radiology, Brigham and Women's Hospital, Boston, MA.
authors.forename: Phillip F
authors.initials: PF
authors.lastname: Judy
authors.affiliation: 4 Department of Imaging Physics, University of Texas MD Anderson Cancer Center, Houston, TX.
authors.forename: Dianna D
authors.initials: DD
authors.lastname: Cody
authors.affiliation: 5 J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Gainesville, FL.
authors.forename: Wesley E
authors.initials: WE
authors.lastname: Bolch
authors.affiliation: 6 System Radiology, Marshfield Clinic Health System, Marshfield, WI.
authors.forename: Randell L
authors.initials: RL
authors.lastname: Kruger
mesh_terms: D000368:Aged; D049628:Body Size; D005260:Female; D006801:Humans; D008175:Lung Neoplasms / Q000000981:diagnostic imaging* / Q000453:epidemiology; D008297:Male; D008403:Mass Screening; D008875:Middle Aged; D009929:Organ Size; D019047:Phantoms, Imaging; D011829:Radiation Dosage; D013902:Radiography, Thoracic / Q000379:methods*; D012907:Smoking / Q000453:epidemiology; D014057:Tomography, X-Ray Computed / Q000379:methods*; D014481:United States / Q000453:epidemiology
keywords: National Lung Screening Trial; body size; effective dose; low-dose CT; organ dose