What dose category indicates central nervous system syndrome?

Central nervous system syndrome, also referred to as acute radiation syndrome affecting the central nervous system, is associated with exposure to very high doses of ionizing radiation. The threshold for this syndrome typically begins at doses greater than 5000 Rad. At this level of exposure, the effects on the central nervous system can be severe and immediate, leading to symptoms like confusion, loss of consciousness, and other neurological disturbances.

Doses in the ranges of 1000-5000 Rad are generally associated with gastrointestinal syndrome or more severe hematological effects, rather than direct central nervous system damage. Lower doses, such as 200-1000 Rad and 0-200 Rad, are typically not sufficient to induce significant symptoms, and instead, they might lead to milder forms of acute radiation syndrome, focusing more on blood and tissue damage without central nervous system implications.

Thus, only doses greater than 5000 Rad are recognized for their direct and severe impact on the central nervous system, which solidifies why this option is indicated as the correct answer.