In a mass casualty event, assign triage categories based on conventional injury. After stabilizing traumatic injuries, and should resources to estimate dose become available, a secondary triage of casualties must occur to account for radiation. Further details for initial dose estimation (biodosimetry) are available in Appendix C. Those with suspected combined injury are moved to the next higher acuity triage category. If someone is suspected of receiving greater than a 6 Gy dose, they are triaged to expectant until more resources become available.14 Table 4 provides an overview of how to update triage categories for radiation. More comprehensive triage tools can be found at https://remm.hhs.gov/triagetool5.htm. As the event progresses and additional resources become available, iterative retriage of all casualties across all triage categories to include expectant, must occur.

In isolated irradiation, the most reliable early clinical indicators of whole-body radiation injury are the time-to-emesis and/or elevated body temperature, which can be seen in the early hours following exposure. When at a Role 3, or a Role 2 with lab capability, the most reliable early laboratory indicator is the lymphocyte depletion rate, which may not be available in 24-48 hours depending on the size of mass casualty and degree of infrastructure damage. While time to emesis is a rapid and inexpensive method for estimating the radiation dose, it should be used with caution because it is imprecise and may lead to very high false positive rate. 15