The radiologic technologists' health study in South Korea: study design and baseline results

To describe the study design, methods, and baseline results of a prospective cohort of radiologic technologists which we have initiated in South Korea. The cohort participants were enrolled through a self-administered questionnaire survey administered from April 2012 to May 2013. Survey data were linked with radiation dosimetry, a cancer registry, and health insurance data by personal identification numbers. A nationwide representative survey was also conducted using a stratified random sampling design with face-to-face interviews. A total of 12,387 radiologic technologists were enrolled, which accounted for approximately 63 % of all diagnostic radiologic technologists working in South Korea. For nationwide survey, 585 workers were interviewed using the detailed questionnaire, and buccal cells were also collected by scraping the inside of the cheek. The majority of study subjects were under 50-year-old and male workers. The average annual effective dose of radiation declined both men (from 2.75 to 1.43 mSv) and women (from 1.34 to 0.95 mSv) over the period of 1996-2011. A total of 99 cancers (66 cancers in men and 33 in women) were reported from 1992 to 2010. The standardized incidence ratio of all cancer combined was significantly lower in men (SIR = 0.75, 95 % CI 0.58-0.96) than general population, but the ratios for thyroid cancer were significantly higher than expected among both men and women. This cohort provides comprehensive information on work activities and health status of diagnostic radiologic technologists. In addition, the nationwide representative sample provides unique opportunities compared with previous radiologic technologist studies.