Acute radiation syndrome

"Radiation poisoning" redirects here. For other uses, see Radiation poisoning (disambiguation).

Acute radiation syndrome (ARS), also known as radiation sickness or radiation poisoning, is a collection of health effects that occur due to exposure to high levels of ionizing radiation within a short period of time. Symptoms can begin within an hour and may last for several months. Initial symptoms typically include nausea, vomiting, and loss of appetite. This is followed by a period of few symptoms which can last for hours or weeks, and later additional symptoms may develop, leading to either recovery or death.

Cause and Diagnosis

Acute radiation syndrome involves a total dose of greater than 0.7 Gy (70 rads), typically occurring from a source outside the body within minutes. Sources of such radiation can occur accidentally or intentionally, and may involve nuclear reactors, cyclotrons, and certain devices used in cancer therapy. Acute radiation syndrome is generally divided into three types: bone marrow, gastrointestinal, and neurovascular syndrome. Bone marrow syndrome occurs at doses between 0.7 and 10 Gy, while neurovascular syndrome occurs at doses that exceed 50 Gy. The cells that are most affected are generally those that are rapidly dividing. At high doses, this can cause 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 and Prognosis

Treatment of acute radiation syndrome is primarily supportive care. This may include blood transfusions, antibiotics, colony-stimulating factors, or stem cell transplant. If radioactive material remains on the skin or in the stomach, it should be removed. If radioiodine was breathed in or ingested, potassium iodide may be recommended. Complications such as leukemia and other cancers among those who survive are managed as usual. Short-term outcomes depend on the exposure dose.

Epidemiology and History

ARS is generally rare, but a single event can affect a relatively large number of people. Notable cases occurred following the atomic bombing of Hiroshima and Nagasaki and the Chernobyl nuclear power plant disaster. ARS differs from chronic radiation syndrome, which occurs following prolonged exposures to relatively low doses of radiation.

Signs and Symptoms

Radiation sickness

Acute radiation syndrome is classically divided into three main presentations: hematopoietic, gastrointestinal, and neurological/vascular. These syndromes may or may not be preceded by a prodrome. The speed of onset of symptoms is related to radiation exposure, with greater doses resulting in a shorter delay in symptom onset. These presentations presume whole-body exposure and many of them are markers that are not valid if the entire body has not been exposed. Each syndrome requires that the tissue showing the syndrome itself be exposed. Some areas affected are:

1. Hematopoietic. This syndrome is marked by a drop in the number of blood cells, called aplastic anemia. This may result in infections due to a low number of white blood cells, bleeding due to a lack of platelets, and anemia due to too few red blood cells in the circulation. These changes can be detected by blood tests after receiving a whole-body acute dose as low as 0.25 Gy (25 rads), though they might never be felt by the patient if the dose is below 1 Gy (100 rads). Conventional trauma and burns resulting from a bomb blast are complicated by the poor wound healing caused by hematopoietic syndrome, increasing mortality.
2. Gastrointestinal. This syndrome often follows absorbed doses of 6 to 30 Gy (600 to 3,000 rads). The signs and symptoms of this form of radiation injury include nausea, vomiting, loss of appetite, and abdominal pain. Vomiting in this time-frame is a marker for whole-body exposures that are in the fatal range above 4 Gy (400 rads). Without exotic treatment such as bone marrow transplant, death with this dose is common. The death is generally more due to infection than gastrointestinal dysfunction.
3. Neurovascular. This syndrome typically occurs at absorbed doses greater than 30 Gy (3,000 rads), though it may occur at 10 Gy (1,000 rads). It presents with neurological symptoms such as dizziness, headache, or decreased level of consciousness, occurring within minutes to a few hours, and with an absence of vomiting. It is invariably fatal.

Early symptoms of ARS typically include nausea and vomiting, headaches, fatigue, fever, and a short period of skin reddening. These symptoms may occur at radiation doses as low as 0.35 Gy (35 rads). These symptoms are common to many illnesses, and may not, by themselves, indicate acute radiation sickness.

Cause and Diagnosis

Acute radiation syndrome is caused by exposure to high levels of ionizing radiation over a short period of time. The exposure typically occurs from a source outside the body within minutes, and the total dose must be greater than 0.7 Gy (70 rads) to cause ARS. Sources of such radiation can occur accidentally or intentionally, and may involve nuclear reactors, cyclotrons, and certain devices used in cancer therapy.

The cells most affected by ARS are generally those that are rapidly dividing, and high doses of radiation can cause DNA damage that may be irreparable. Diagnosis of ARS is based on a history of exposure and the presence of symptoms. Repeated complete blood counts (CBCs) can indicate the severity of the exposure and help confirm the diagnosis.

Treatment and Prognosis

The treatment of acute radiation syndrome is generally supportive care, which may include blood transfusions, antibiotics, colony-stimulating factors, or stem cell transplants. If radioactive material remains on the skin or in the stomach, it should be removed. If radioiodine was inhaled or ingested, potassium iodide may be recommended to help reduce the risk of thyroid damage.

Complications such as leukemia and other cancers among those who survive ARS are managed as usual. The short-term outcomes of ARS depend on the exposure dose; higher doses generally result in more severe symptoms and a higher risk of death.

Epidemiology and History

ARS is generally rare, but a single event can affect a relatively large number of people. Notable cases of ARS occurred following the atomic bombings of Hiroshima and Nagasaki and the Chernobyl nuclear power plant disaster. ARS differs from chronic radiation syndrome, which occurs following prolonged exposures to relatively low doses of radiation.

In conclusion, acute radiation syndrome is a severe condition caused by exposure to high levels of ionizing radiation over a short period of time. While rare, it has had a significant impact on human history and remains a potential threat in cases of nuclear accidents or intentional exposures. Medical management focuses on supportive care, with the goal of minimizing the short-term and long-term consequences of radiation exposure.

Prevention and Preparedness

Preventing acute radiation syndrome primarily involves reducing the risk of exposure to high levels of ionizing radiation. This can be achieved through proper safety measures and regulatory compliance in industries that use radioactive materials, such as nuclear power plants, research facilities, and medical institutions.

In the event of a radiation emergency, preparedness plans should be in place to protect the public and minimize the risk of ARS. This may include evacuation plans, shelter-in-place procedures, and public education on radiation safety. Government agencies, such as the Centers for Disease Control and Prevention (CDC) and the International Atomic Energy Agency (IAEA), offer guidance on radiation emergency preparedness and response.

Personal protective measures, such as the use of lead aprons or other shielding materials, can be effective in reducing radiation exposure for individuals who work with ionizing radiation sources. Regular monitoring of radiation exposure through the use of dosimeters is also essential for these workers to ensure that their accumulated dose remains within safe limits.

Acute radiation syndrome Resources
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Classification	ICD-10: T66 ICD-9-CM: 990 MeSH: D011832
External resources	MedlinePlus: 000026 eMedicine: article/834015