Nausea, vomiting, diarrhea, fever, and transient skin erythema characterize the prodromal phase, which may last minutes to days. The patient may then appear well for a few hours, or even a few weeks during the latent phase, which is characterized by silent cell and tissue destruction. This destruction is later manifested clinically as one or more of three syndromes: 1) hematopoietic (H-ARS), 2) gastrointestinal (GI-ARS), 3) neurologic (N-ARS). Death can occur within days for gastrointestinal and neurologic but may not occur for weeks for hematopoietic.14,17-18

Without treatment, the LD50/60 for ionizing radiation is about 4 Gy. With appropriate intervention and treatment, the dose goes up to about 6 Gy. Experience from those who receive even higher doses suggest that with aggressive resuscitation and critical care, survival can be extended by months. This factor can lead to the eventual need to evacuate these casualties.14