Acute radiation syndrome (ARS), also known as radiation sickness or radiation poisoning, is a collection of health effects that are caused by being exposed to high amounts of ionizing radiation in a short period of time. Symptoms can start within an hour of exposure, and can last for several months. Early symptoms are usually nausea, vomiting and loss of appetite. In the following hours or weeks, initial symptoms may appear to improve, before the development of additional symptoms, after which either recovery or death follow.ARS involves a total dose of greater than 0.7 Gy (70 rad), that generally occurs from a source outside the body, delivered within a few minutes. Sources of such radiation can occur accidentally or intentionally. They may involve nuclear reactors, cyclotrons, certain devices used in cancer therapy, nuclear weapons, or radiological weapons. It is generally divided into three types: bone marrow, gastrointestinal, and neurovascular syndrome, with bone marrow syndrome occurring at 0.7 to 10 Gy, and neurovascular syndrome occurring at doses that exceed 50 Gy. The cells that are most affected are generally those that are rapidly dividing. At high doses, this causes DNA damage that may be irreparable. Diagnosis is based on a history of exposure and symptoms. Repeated complete blood counts (CBCs) can indicate the severity of exposure.Treatment of ARS is generally supportive care. This may include blood transfusions, antibiotics, colony-stimulating factors, or stem cell transplant. Radioactive material remaining on the skin or in the stomach should be removed. If radioiodine was inhaled or ingested, potassium iodide is recommended.
Internal contamination protective equipment such as respirators are used to prevent internal deposition as a result of inhalation and ingestion of radioactive material. Dermal protective equipment, which protects against external contamination, provides shielding to prevent radioactive material from being deposited on external structures. While these protective measures do provide a barrier from radioactive material deposition, they do not shield from externally penetrating gamma radiation. This leaves anyone exposed to penetrating gamma rays at high risk of ARS. Naturally, shielding the entire body from high energy gamma radiation is optimal, but the required mass to provide adequate attenuation makes functional movement nearly impossible. In the event of a radiation catastrophe, medical and security personnel need mobile protection equipment in order to safely assist in containment, evacuation, and many other necessary public safety objectives. Research has been done exploring the feasibility of partial body shielding, a radiation protection strategy that provides adequate attenuation to only the most radio-sensitive organs and tissues inside the body. Irreversible stem cell damage in the bone marrow is the first life-threatening effect of intense radiation exposure and therefore one of the most important bodily elements to protect. Due to the regenerative property of hematopoietic stem cells, it is only necessary to protect enough bone marrow to repopulate the exposed areas of the body with the shielded supply. This concept allows for the development of lightweight mobile radiation protection equipment, which provides adequate protection, deferring the onset of ARS to much higher exposure doses.