Radiation sickness

Pronunciation

RAY-dee-AY-shun SIK-nes

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Radiation Sickness

Definition

Serious illness caused by being exposed to high doses of certain types of radiation, usually over a short period of time.

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Death by haematopoietic syndrome of radiation sickness- influence of medical care

Types of radation

There are two main types of radiation: nonionizing and ionizing.

• Nonionizing radiation comes in the form of light, radio waves, microwaves and radar. These forms usually don't cause tissue damage.
• Ionizing radiation causes immediate effects on human tissue. X-rays, gamma rays, and particle bombardment (neutron beam, electron beam, protons, mesons, and others) give off ionizing radiation. This type of radiation is used for medical testing and treatment. It is also used in industrial and manufacturing purposes, weapons and weapons development, and more.

Acute and Chronic

• Radiation sickness results when humans are exposed to very large doses of ionizing radiation.
• Radiation exposure can occur as a single large exposure when it is called acute or over time as many small exposures spread over time when it is called chronic

Accidental or iatrogenic

Radiation exposure may be accidental or intentional as in radiation therapy for cancer treatment.

Acute radiation syndrome

• Radiation sickness is generally associated with acute exposure and has a characteristic set of symptoms that appear in an orderly fashion. Chronic exposure is usually associated with delayed medical problems such as cancer and premature aging, which may happen over a long period of time.

Causes

Radiation exposure can happen in many ways:

• Accidental exposure to high doses of radiation, such as radiation from a nuclear power plant accident.
• Exposure to excessive radiation for medical treatments.

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Chernobyl radiation map

Acute Radiation Syndrome (ARS)

• The radiation dose must be large (i.e., greater than 0.7 Gray (Gy)1, 2 or 70 rads).
• Mild symptoms may be observed with doses as low as 0.3 Gy or 30 rads.
• The dose usually must be external ( i.e., the source of radiation is outside of the patient’s body).
• Radioactive materials deposited inside the body have produced some ARS effects only in extremely rare cases.
• The radiation must be penetrating (i.e., able to reach the internal organs).
• High energy X-rays, gamma rays, and neutrons are penetrating radiations.
• The entire body (or a significant portion of it) must have received the dose3.
• Most radiation injuries are local, frequently involving the hands, and these local injuries seldom cause classical signs of ARS.

The dose must have been delivered in a short time (usually a matter of minutes).

Fractional doses

Fractionated doses are often used in radiation therapy. These are large total doses delivered in small daily amounts over a period of time. Fractionated doses are less effective at inducing ARS than a single dose of the same magnitude.

Stages of ARS

Acute-Radiation-Cell-Survival

The four stages of ARS are:

1. Prodromal stage (N-V-D stage): The classic symptoms for this stage are nausea, vomiting, as well as anorexia and possibly diarrhea (depending on dose), which occur from minutes to days following exposure. The symptoms may last (episodically) for minutes up to several days.
2. Latent stage: In this stage, the patient looks and feels generally healthy for a few hours or even up to a few weeks.
3. Manifest illness stage: In this stage the symptoms depend on the specific syndrome (see Table 1) and last from hours up to several months.
4. Recovery or death: Most patients who do not recover will die within several months of exposure. The recovery process lasts from several weeks up to two years.

ARS syndromes

1. Bone marrow syndrome (sometimes referred to as hematopoietic syndrome) the full syndrome will usually occur with a dose between 0.7 and 10 Gy (70 – 1000 rads) though mild symptoms may occur as low as 0.3 Gy or 30 rads4. The survival rate of patients with this syndrome decreases with increasing dose. The primary cause of death is the destruction of the bone marrow, resulting in infection and hemorrhage.

1. Gastrointestinal (GI) syndrome: the full syndrome will usually occur with a dose greater than approximately 10 Gy (1000 rads) although some symptoms may occur as low as 6 Gy or 600 rads. Survival is extremely unlikely with this syndrome. Destructive and irreparable changes in the GI tract and bone marrow usually cause infection, dehydration, and electrolyte imbalance. Death usually occurs within 2 weeks.

1. Cardiovascular (CV)/ Central Nervous System (CNS) syndrome: the full syndrome will usually occur with a dose greater than approximately 50 Gy (5000 rads) although some symptoms may occur as low as 20 Gy or 2000 rads. Death occurs within 3 days. Death likely is due to collapse of the circulatory system as well as increased pressure in the confining cranial vault as the result of increased fluid content caused by edema, vasculitis, and meningitis.

Cutaneous Radiation Syndrome (CRS)

Fluoroscopy burn

When the basal cell layer of the skin is damaged by radiation, inflammation, erythema, and dry or moist desquamation can occur. Also, hair follicles may be damaged, causing epilation. Within a few hours after irradiation, a transient and inconsistent erythema (associated with itching) can occur. Then, a latent phase may occur and last from a few days up to several weeks, when intense reddening, blistering, and ulceration of the irradiated site are visible.

In most cases, healing occurs by regenerative means; however, very large skin doses can cause permanent hair loss, damaged sebaceous and sweat glands, atrophy, fibrosis, decreased or increased skin pigmentation, and ulceration or necrosis of the exposed tissue.

Symptoms

Symptoms of radiation sickness usually occur right after exposure but they may happen over time, and they may come and go.

Nausea and vomiting, diarrhea, headache, dizziness, weakness, fatigue, bleeding, hair loss, swelling, itching, and redness of the skin, and other skin problems.

Radiation therapy for cancer

Diagnosis

• The diagnosis of ARS can be difficult to make because ARS causes no unique disease.
• Depending on the dose, the prodromal stage may not occur for hours or days after exposure, or the patient may already be in the latent stage by the time they receive treatment, in which case the patient may appear and feel well when first assessed.
• If a patient received more than 0.05 Gy (5 rads) and three or four CBCs are taken within 8 to 12 hours of the exposure, a quick estimate of the dose can be made (see Ricks, et. al. for details).
• If these initial blood counts are not taken, the dose can still be estimated by using CBC results over the first few days.
• It would be best to have radiation dosimetrists conduct the dose assessment, if possible.
• If a patient is known to have been or suspected of having been exposed to a large radiation dose, draw blood for CBC analysis with special attention to the lymphocyte count, every 2 to 3 hours during the first 8 hours after exposure (and every 4 to 6 hours for the next 2 days). Observe the patient during this time for symptoms and consult with radiation experts before ruling out ARS.
• If no radiation exposure is initially suspected, you may consider ARS in the differential diagnosis if a history exists of nausea and vomiting that is unexplained by other causes.
• Other indications are bleeding, epilation, or white blood count (WBC) and platelet counts abnormally low a few days or weeks after unexplained nausea and vomiting.
• Consider CBC and chromosome analysis and consultation with radiation experts to confirm diagnosis.

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Radiation Dose Ranges

Treatment

Radiation pneumonitis

Treat vomiting5, and repeat CBC analysis, with special attention to the lymphocyte count, every 2 to 3 hours for the first 8 to 12 hours following exposure (and every 4 to 6 hours for the following 2 or 3 days).

Sequential changes in absolute lymphocyte counts over time are demonstrated below in the Andrews Lymphocyte Nomogram (see Figure 1). Precisely record all clinical symptoms, particularly nausea, vomiting, diarrhea, and itching, reddening or blistering of the skin. Be sure to include time of onset.

• supportive care in a clean environment (if available, the use of a burn unit may be quite effective)
• prevention and treatment of infections
• stimulation of hematopoiesis by use of growth factors
• stem cell transfusions or platelet transfusions (if platelet count is too low)
• psychological support
• careful observation for erythema (document locations), hair loss, skin injury, mucositis, parotitis, weight loss, or fever
• confirmation of initial dose estimate using chromosome aberration cytogenetic bioassay when possible. Although resource intensive, this is the best method of dose assessment following acute exposures.
• consultation with experts in radiation accident management

Risk of death

Very large doses of radiation may cause death.

Other names

Also called acute radiation sickness, acute radiation syndrome, radiation poisoning, and radiation sickness syndrome.

Radiation sickness Resources
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