BACKGROUND: The reconstruction of lifetime radiation doses for medical workers 
presents special challenges not commonly encountered for the other worker 
cohorts comprising the Million Worker Study.
METHODS: The selection of approximately 175,000 medical radiation workers relies 
on using estimates of lifetime and annual personal monitoring results collected 
since 1977. Approaches have been created to adjust the monitoring results so 
that mean organ absorbed doses can be estimated.
RESULTS: Changes in medical technology and practices have altered the radiation 
exposure environments to which a worker may have been exposed during their 
career. Other temporal factors include shifts in regulatory requirements that 
influenced the conduct of radiation monitoring and the changes in the measured 
dose quantities.
CONCLUSIONS: The use of leaded aprons during exposure to lower energy X rays 
encountered in fluoroscopically based radiology adds complexity to account for 
the shielding of the organs located in the torso when dosimeters were worn over 
leaded aprons. Estimating doses to unshielded tissues such as the brain and lens 
of the eye become less challenging when dosimeters are worn at the collar above 
the apron. The absence of leaded aprons in the higher energy photon settings 
lead to a more straightforward process of relating dosimeter results to mean 
organ doses.