title: Thyroid shields and neck exposures in cephalometric radiography.
abstract: BACKGROUND
  The thyroid is among the more radiosensitive organs in the body. The goal of this study was twofold: (1) to evaluate age-related changes in what is exposed to ionizing radiation in the neck area, and (2) to assess thyroid shield presence in cephalometric radiographs
  
  
  METHODS
  Cephalometric radiographs at one academic setting were sampled and neck exposure was related to calendar year and patient's gender and age.
  
  
  RESULTS
  In the absence of shields, children have more vertebrae exposed than adults (p < 0.0001) and females have more neck tissue exposed inferior to the hyoid bone than males (p < 0.0001). The hyoid bone-porion distance increased with age (p <0.01). Thyroid shields were visible in 19% of the radiographs and depended strongly on the calendar year during which patient was seen (p-value <0.0001). Compared to adults, children were less likely to wear thyroid shields, particularly between 1973 and 1990 (1.8% versus 7.3% -p-value < 0.05) and between 2001 and 2003 (7.1% versus 42.9% -p-value < 0.05).
  
  
  CONCLUSIONS
  In the absence of a thyroid shield, children have more neck structure exposed to radiation than adults. In agreement with other reports, thyroid shield utilization in this study was low, particularly in children.
authors.affiliation: Department of Dental Public Health Sciences, School of Dentistry University of Washington, Seattle, USA. hujoel@u.washington.edu
authors.forename: Philippe
authors.initials: P
authors.lastname: Hujoel
authors.forename: Lars
authors.initials: L
authors.lastname: Hollender
authors.forename: Anne-Marie
authors.initials: AM
authors.lastname: Bollen
authors.forename: John D
authors.initials: JD
authors.lastname: Young
authors.forename: Joana
authors.initials: J
authors.lastname: Cunha-Cruz
authors.forename: Molly
authors.initials: M
authors.lastname: McGee
authors.forename: Alex
authors.initials: A
authors.lastname: Grosso