100 years of Personal Badge Radiation Doses in a Cohort of U.S. Radiologic Technologists: Expanded and Updated Reconstruction, 1916–2020

The U.S. Radiologic Technologists (USRT) study investigates cancer and other serious disease risks associated with low-dose occupational radiation exposure. The previous dose system (URDS13) for the full cohort was based on badge dose records through 1997, three self-reported questionnaires administered between 1983 and 2005, and historical estimates from the literature. In this article, we describe an extended (23 additional calendar years, 1998-2020), updated and enhanced dosimetry system for the USRT cohort (URDS25). We incorporated 1,156,584 newly acquired annual badge dose readings (1977-2020) obtained by integrating annual summary data (1977-2011) and monthly badge reading data (2004-2020), bringing the total to 1,416,420 annual badge dose readings (1960-2020) for 81,885 technologists. To enhance the individualization of dose estimates, we also utilized detailed work history and protection practice data from the fourth survey, administered in 2012-2013, along with supplementary work history modules for technologists who performed nuclear medicine and assisted with fluoroscopically guided interventional procedures. Based on all badge readings and work history data collected to date, we re-evaluated the URDS13 badge dose estimates prior to 1997 and reconstructed the estimates from 1998 to 2020, resulting in a total of 3.27 million estimated annual badge doses for 110,374 technologists for the years 1916-2020. Each annual badge dose was reconstructed as a probability distribution using Monte Carlo simulation, generating 1,000 realizations to account for uncertainty in the true dose. Compared to the previous version (URDS13, 1916-1997), this update (URDS25, 1916-2020) resulted in a slight increase in the mean cumulative dose estimates for the entire cohort, from 76 mSv (median: 47 mSv; range: 0.19-3,000 mSv) to 79 mSv (median: 48 mSv; range: 0.12-3,000 mSv), and a mean absolute change of the individual cumulative dose estimates of 26% per technologist. Organ absorbed doses will also be updated based on these revised badge dose estimates and detailed, self-reported work history information and, along with updated follow-up data, will be used in future dose-response analyses to more precisely investigate radiation-associated cancer and non-cancer disease risks.