Serious illness that occurs when the body receives a high dose of penetrating radiation (that is, able to reach internal organs) over a short period of time (usually minutes). More: The earliest symptoms are nausea, fatigue, vomiting, and diarrhea. Hair loss, bleeding, swelling of the mouth and throat, and general loss of energy may follow. If the exposure has been approximately 10 Gy or more, death may occur within 2 " 4 weeks. For more information, see Center for Disease Control and Prevention’s fact sheet "Acute Radiation Syndrome� at  .
