What is Acute Radiation Syndrome?
Acute Radiation Syndrome (ARS) is the medical term for the damage occurring to the body after exposure to large amount of radiation within a short period of time (24 hours). The amount of damage and the type of damage to the body depends on the dose and amount of radiation absorbed by the body. Acute radiation syndrome is a rare, but serious and usually a life threatening condition. Acute radiation syndrome refers to the acute medical problems, which the patient experiences within 24 hours of exposure to extremely high or lethal doses of radiation.
Other names for Acute Radiation Syndrome are: Acute Radiation Sickness, Radiation Sickness, Radiation Poisoning and Radiation Toxicity.
Low-dose exposure to radiation, such as occurring during imaging tests like x-ray, MRI scan or CT scan do not cause acute radiation syndrome.
In acute radiation syndrome, there is damage to DNA and other important molecular structures, which causes cellular degradation in the tissues. The ability of cells to divide normally gets affected and produces a host of symptoms, which can be experienced within one to two hours after the exposure. These symptoms can be present for many months after the exposure.
Onset of the symptoms and the type of symptoms depends on the radiation exposure. If the patient has had comparatively smaller doses of radiation exposure then he/she will experience gastrointestinal symptoms, such as nausea and vomiting. Other than this, symptoms include decrease in blood counts, increased tendency to infection and bleeding. If the patient has had exposure to relatively larger doses then he/she will experience neurological symptoms leading to death.
Treatment of acute radiation syndrome consists of supportive therapy with blood transfusions, antibiotics to combat infection. In serious cases, aggressive treatments need to be done, which includes bone marrow transfusions.
Causes of Acute Radiation Syndrome
The energy discharged from atoms is known as Radiation, which can be either in the form of a wave or a minute particle of matter. Exposure to a high dose of radiation, which can occur in an industrial accident, will cause Acute Radiation Syndrome. Immediate medical attention should be sought if there are been overexposure to radiation.
Some of the possible sources of exposure to high-dose radiation are:
- An attack on a nuclear industrial facility.
- An accident at a nuclear industrial facility.
- Detonation of a traditional explosive device, which disperses radioactive material.
- Detonation of a standard nuclear weapon.
- Detonation of a small radioactive device.
In acute radiation syndrome, the high-energy radiation destroys or damages some specific cells in the body leading to this condition. Parts of the body, which are most vulnerable to the high dose radiation, are cells that line the gastrointestinal tract and the cells, which produce bone marrow.
Signs & Symptoms of Acute Radiation Syndrome
The severity of symptoms occurring in Acute Radiation Syndrome depends on the amount of radiation absorbed by the patient. The amount of radiation absorbed in turn depends on the dose or the strength of the radiation and the distance between the source of radiation and the patient.
Symptoms of Acute Radiation Syndrome also depend on the type of radiation exposure for example if a part of the body has been exposed or if the complete body has been exposed to the radiation. The sensitivity of the affected tissues also determines the intensity of the symptoms of Acute Radiation Syndrome. As mentioned before, the bone marrow and the gastrointestinal system are extremely sensitive to radiation.
Duration of Exposure & the Absorbed Dose of Radiation: The dose of radiation that is absorbed by the body is measured in gray (Gy). The diagnostic imaging tests such as an x-ray only use small amount of radiation, which is usually below 0.1 Gy and that too the radiation is focused on small amount of tissue or organs.
Symptoms of Acute Radiation Syndrome appear when the complete body receives and absorbs a radiation dose of a minimum of 1 Gy. The greater the radiation exposure, the more severe and rapid are the symptoms of acute radiation exposure. Radiation doses that are greater than 10 Gy towards the complete body usually are not treatable and will ultimately lead to death in a couple of days to a couple of weeks, depends on the amount of exposure and the intensity of the radiation.
Initial Signs & Symptoms of Acute Radiation Syndrome
Nausea and vomiting comprise of the initial signs and symptoms of acute radiation syndrome, which is treatable. Other initial symptoms consist of fatigue, headaches, fever and skin reddening. The time passed between the radiation exposure and the development of the symptoms indicates the amount of radiation, which the patient has absorbed. Patient suffering from acute radiation syndrome and having recovered from it are at a high risk for developing leukemia or cancer later on. The patient can also experience short-term as well as long-term mental health problems, such as grief and fear about.
After the initial symptoms, the patient will have a brief period where there are no symptoms, which is then followed by development of new and more-serious symptoms.
The symptoms of Acute Radiation Syndrome are divided into three groups and the initial symptoms may or may not appear in these. Acute Radiation Syndrome consists of the following sub syndromes:
Hematopoietic Syndrome: In this category of acute radiation syndrome, there is a drastic decrease in the blood cells resulting in aplastic anemia. There is drop in the white blood cells also, which causes infections, the low platelets causes bleeding and the low red blood cells result in anemia. Burns and trauma occurring from a bomb blast get more complicated by the poor wound healing occurring because of hematopoietic syndrome. This also results in increased mortality.
Gastrointestinal Syndrome: This occurs after the patient has absorbed doses of around 7 to 30 Gy. Symptoms produced of this type of acute radiation syndrome consist of nausea, vomiting, abdominal pain and appetite loss. If the patient has vomiting in this time, then it indicates that there has been exposure of the complete body to radiation above 4 Gy. Aggressive treatment with bone marrow transplant is needed to prevent death with this dose. The patient dies more from infection in the body than gastrointestinal problems.
Neurovascular Syndrome: This type of acute radiation syndrome is seen when the patient has absorbed radiation doses more than 30 Gy. Patient experiences neurological symptoms, which consist of headache, dizziness and decreased/altered level of consciousness. All these symptoms are experienced within a few minutes to a few hours without any vomiting. This condition is very serious and life threatening.
Diagnosis of Acute Radiation Syndrome
When a patient comes forward after experiencing probable or known exposure to a high dose radiation caused due to attack or accident, then the doctor undertakes a number of steps for determining the dose or amount of the radiation that is absorbed. This is important to predict the severity of the Acute Radiation Syndrome and to decide the type of treatment to be done and determine the prognosis and likelihood of the patient’s survival.
The following information is needed to determine the absorbed dose:
Details about the known exposure, such as duration of exposure and the distance from the source of radiation are asked of the patient. This information will help in determining the severity of acute radiation syndrome.
Blood tests done over the period of next several days help in identifying any decrease in the blood cells and in detecting any abnormal changes in the DNA of the blood cells. These aspects indicate the degree of damage to the bone marrow, which further depends on the level of the absorbed radiation dose.
Vomiting and other initial symptoms, which occur after the radiation exposure, especially the onset of vomiting after the time of exposure, is a reasonably accurate measure for determining the amount of the radiation absorbed. The shorter the duration before the onset of vomiting and the exposure, the higher is the radiation dose. The timing and the severity of other symptoms also help in determining the absorbed radiation dose.
Survey meter is a device, which helps in determining the location of radioactive particles in the body.
Dosimeter is a device, which helps in measuring the absorbed dose of radiation; however, only if this device was also exposed to the same radiation as the patient.
It is also important to indentify the type of radiation exposure, such as whether it was an attack or a radioactive accident to determine the treatment for acute radiation syndrome.
Treatment for Acute Radiation Syndrome
Treatment for Acute Radiation Syndrome consists of supportive treatment, treating fatal injuries such as burns, alleviating symptoms including pain and preventing further radioactive contamination. The treatment steps for Acute Radiation Syndrome comprise of the following:
Decontamination: This consists of removing as much external radioactive particles as possible. The shoes and clothing need to be removed. This eliminates around 90 % of external contamination. Gently washing the skin with soap and water also helps in removing radiation particles from the skin. Decontamination helps in preventing additional distribution of radioactive materials and also decreases the risk of internal contamination from ingestion, inhalation or open wounds.
Granulocyte Colony-Stimulating Factor (G-CSF): Treatment for damaged bone marrow consists of using granulocyte colony-stimulating factor G-CSF, which is a protein that promotes the growth of white blood cells and helps in countering the effect of radiation on the bone marrow. Medications, which contain this protein include sargramostim, filgrastim and pegfilgrastim. These medicines help in increasing the production of white blood cells, which in turn will help in prevention of infections. In case of severe damage to the bone marrow, aggressive treatment is done, which includes transfusions of red blood cells or platelets.
Supportive Treatment: Supportive treatment for acute radiation syndrome includes antibiotics, painkillers, intravenous fluids etc. Supportive treatment is done to treat bacterial infections, fever, burns, dehydration, headache, nausea, vomiting, diarrhea and also includes end-of-life care.
Psychological Care: Patient who has absorbed increased doses of radiation that are greater than 10 Gy have very less chance of recovering. Death can occur in a couple of days to couple of weeks. Such patients will be given medications for controlling nausea, pain, vomiting and diarrhea. Psychological care helps a lot for such patients.
Treatment for Internal Contamination
There are some treatments, which help in reducing the damage caused by radioactive particles to the internal organs. These treatments are done only if the patient has been exposed to a particular type of radiation and include:
Prussian Blue (Radiogardase): This is a type of dye which attaches to radioactive elements known as thallium and cesium, which are then excreted from the body via feces. Treatment with Prussian Blue increases elimination of the radioactive particles and also cuts down the amount of radiation which the cells can absorb.
Potassium Iodide: This is a nonradioactive form of iodine. Iodine is important for proper functioning of the thyroid gland and for this reason, the thyroid gland becomes a target for iodine. If there is internal contamination with radioiodine then the thyroid absorbs radioiodine and treatment with potassium iodide helps in filling the gaps in the thyroid to prevent absorption of radioiodine. The radioiodine is gradually excreted via urine from the body. Potassium iodide is most effective when taken within 24 hours after the exposure.
Diethylenetriaminepentaacetic Acid (DTPA): This is a substance, which binds to metals including particles of radioactive elements such as curium, americium and plutonium and these radioactive particles are ejected from the body via urine resulting in decreased absorption of radiation by the body.