title: Radiation dose for routine clinical adult brain CT: Variability on different scanners at one institution.
abstract: OBJECTIVE
  The purpose of this study was to determine, using an anthropomorphic phantom, whether patients are subject to variable radiation doses based on scanner assignment for routine CT of the brain.
  
  
  METHODS
  Twenty metal oxide semiconductor field effect transistor dosimeters were placed in the brain of a male anthropomorphic phantom scanned three times with a routine clinical brain CT protocol on four scanners from one manufacturer in four configurations and on one 64-MDCT scanner from another manufacturer. Absorbed organ doses were measured for skin, cranium, brain, lens of the eye, mandible, and thyroid. Effective dose was calculated on the basis of the dose-length product recorded on each scanner.
  
  
  RESULTS
  Organ dose ranges were as follows: cranium, 2.57-3.47 cGy; brain, 2.34-3.78 cGy; lens, 2.51-5.03 cGy; mandible 0.17-0.48 cGy; and thyroid, 0.03-0.28 cGy. Statistically significant differences between scanners with respect to dose were recorded for brain and lens (p < 0.05). Absorbed doses were lowest on the single-detector scanner. In the comparison of MDCT scanners, the highest doses were found on the 4-MDCT scanner and the dual-source 64-MDCT scanner not capable of gantry tilt. Effective dose ranged from 1.22 to 1.86 mSv.
  
  
  CONCLUSIONS
  According to the phantom data, patients are subject to different organ doses in the lens and brain depending on scanner assignment. At our institution with existing protocols, absorbed doses at brain CT are lowest with the single-detector CT scanner, followed by MDCT scanners capable of gantry tilt. On scanners without gantry tilt, CT of the brain should be performed with careful head positioning and shielding of the orbits. These precautions are especially true for patients who need repeated scanning and for pediatric patients.
authors.affiliation: Department of Radiology, Duke University Medical Center, Durham, NC 27710, USA. jaffe002@mc.duke.edu
authors.forename: Tracy A
authors.initials: TA
authors.lastname: Jaffe
authors.forename: Jenny K
authors.initials: JK
authors.lastname: Hoang
authors.forename: Terry T
authors.initials: TT
authors.lastname: Yoshizumi
authors.forename: Greta
authors.initials: G
authors.lastname: Toncheva
authors.forename: Carolyn
authors.initials: C
authors.lastname: Lowry
authors.forename: Carl
authors.initials: C
authors.lastname: Ravin
mesh_terms: D000328:Adult; D001822:Body Burden; D001921:Brain / Q000000981:diagnostic imaging*; D002648:Child; D004867:Equipment Design; D019544:Equipment Failure Analysis; D006801:Humans; D008297:Male; D019047:Phantoms, Imaging; D011829:Radiation Dosage; D011874:Radiometry / Q000706:statistics & numerical data*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000295:instrumentation* / Q000706:statistics & numerical data*