Occupational Dose and Dose Limits: Experience in a Large Multisite Hospital System

The Nuclear Regulatory Commission (NRC) has recently proposed changes that reduce the occupational dose limits for lens dose equivalent (LDE), embryo/fetus dose, and administrative control levels (ACLs) related to deep dose equivalent (DDE). This study collected occupational dose data from a large hospital system and determined how proposed NRC regulatory changes may affect worker and hospital workflow.

Radiation badge data were collected for 1,305 workers, from between 2013 and 2014, and 180 pregnancies, from between 2009 and 2014. Median values for LDE, DDE, and embryo/fetus dose were determined. Current and proposed NRC regulations were applied, and the percentage of workers exceeding regulatory limits/ACLs was recorded. Fisher's exact test was applied to determine if physicians were disproportionately affected by dose regulations.

Median doses were one to two orders of magnitude lower than current annual dose limits prescribed by the NRC. Proposed NRC regulations significantly increased the percentage of workers who exceeded limits and ACLs. Interventional radiologists, pain medicine physicians, and cardiologists working in catheter laboratories were most affected by LDE limits and DDE ACLs. Nuclear medicine technologists were most affected by embryo/fetus limits. Physicians were disproportionately affected by regulations (odds ratio 26.86; P < .0001).

Proposed NRC regulatory changes will cause a small increase in the number of workers who exceed ACLs and limits. Physicians and pregnant nuclear medicine workers are most affected and may need to alter their workloads. Practical difficulties in implementing cumulative dose tracking, and use of an LDE shielding factor, should be considered.