title: The relationship between occupational radiation exposure and thyroid nodules.
abstract: BACKGROUND
  Considering that thyroid nodules and thyroid cancer occur more frequently in people chronically exposed to radiation, the aim of this study was to evaluate the prevalence of thyroid nodules in a population occupationally exposed to radiation in hospitals of Isfahan, Iran.
  
  
  METHODS
  In this case-control study, the prevalence of thyroid nodules in staff members occupationally exposed to radiation was determined by ultrasonography. The results were compared with the results of another study among the adult population of Isfahan which selected by cluster random sampling method. The 2 studied groups were matched according to sex and age.
  
  
  RESULTS
  The case and control groups included 124 and 471 persons, respectively. The prevalence of thyroid nodules in the case and control groups was 22.6% and 24.6%, respectively (p > 0.05). Although thyroid nodules were significantly more prevalent in females in the control group, no such difference was observed between females and males of the case group (p > 0.05). The number of thyroid nodules (single or multiple) and calcification were not different between the two groups (p > 0.05). In addition, hypoechogenicity of thyroid nodules was not different between the two groups for (p > 0.05).
  
  
  CONCLUSIONS
  In our study, there was not any correlation between chronic occupational exposure to low dose of radiation and the risk of developing thyroid nodules. Further studies with larger sample sizes, at different doses of radiation, and considering iodine status and thyroid function are thus required.
authors.affiliation: Associate Professor, Department of Radiology, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran.
authors.forename: Atoosa
authors.initials: A
authors.lastname: Adibi
authors.forename: Afshin
authors.initials: A
authors.lastname: Rezazade
authors.forename: Silva
authors.initials: S
authors.lastname: Hovsepian
authors.forename: Razie
authors.initials: R
authors.lastname: Koohi
authors.forename: Mohsen
authors.initials: M
authors.lastname: Hosseini
keywords: Occupational Exposure; Radiation; Thyroid Nodule; Ultrasonography