Which stage of Acute Radiation Syndrome is characterized by an immediate response?

The prodromal stage of Acute Radiation Syndrome is characterized by an immediate response following exposure to a significant dose of radiation. This stage occurs within hours of radiation exposure and typically presents with a variety of symptoms such as nausea, vomiting, diarrhea, and fatigue. These symptoms arise from the rapid turnover of cells in the gastrointestinal tract and the central nervous system, which are highly sensitive to radiation.

In contrast, the latent stage follows the prodromal period and is marked by a temporary improvement in symptoms, even though damage is still occurring at the cellular level. The recovery stage, on the other hand, involves the body beginning to heal and recover from the effects of radiation, which may take days to weeks depending on the severity of the exposure. The manifest illness stage is where more severe symptoms becomes evident due to the full impact of the radiation on the body's systems, often leading to serious health outcomes. Thus, the prodromal stage is crucial in understanding how the body immediately reacts to radiation injuries.