Journal of Research in Medical Sciences1735-199517720120515The relationship between occupational radiation exposure and thyroid nodules69776977ENAtoosaAdibiAssosiate Professor, Department of Radiology, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran. a_adibi@med.mui.ac.irAfshinRezazadeSilvaHovsepianRazieKoohiMohsenHosseini2011031920110809BACKGROUND: Considering that thyroid nodules and thyroid cancer occur more frequently in people exposed chronically to radiation, the aim of this study was to evaluate the prevalence of thyroid nodules in a population occupationally exposed to radiation, in the hospitals of Isfahan.METHODS: In this case control study the prevalence of thyroid nodules in radiation exposed workers was determined by ultrasonography which was performed by a radiologist. The results were compared with the results of another study among the adult population of Isfahan city which were selected by Cluster – random sampling method. The two studied groups were matched according to sex and age.RESULTS: The studied population in case and control groups was 124 and 471 respectively. The prevalence of thyroid nodule in the case and control groups was 22.6% and 24.6% respectively (p > 0.05). Thyroid nodule was more prevalent in females in the control group but there was no difference between the females and males of the case group (p > 0.05).The number of thyroid nodules (single or multiple) and calcification were not different for the two groups (p > 0.05). Moreover, the echo pattern of thyroid nodules for hypoechogenicity was not different in the two groups (p > 0.05).CONCLUSIONS: In our study, there was no correlation between occupational chronic exposure to a low dose of radiation and the risk of developing thyroid nodules. Further studies with a larger sample size and the consideration of different doses of radiation, in accordance with the iodine status and thyroid function are necessary. KEYWORDS: Thyroid Nodule, Radiation, Occupational Exposure, Ultrasonography