Guidance for Radiation Accident Management

Introduction

Basics of Radiation

Detection

Measurement

Safety Around Radiation Sources

Types of Radiation Exposure

Managing Radiation Emergencies

Manage radiation emergencies

Guidance for Hospital Medical Management

Managing Emergency Care || Radiation Injury || Acute Radiation Syndrome || Internal Contamination


Radiation Injury

Exposure to high levels of penetrating radiation can involve the whole body (uniformly or nonuniformly), a significant portion of the body, or a small, localized part. The exposure can be acute, protracted, or fractionated over time.

Local Injury

Most radiation injuries are "local" injuries, frequently involving the hands. These local injuries seldom cause the classical signs and symptoms of the acute radiation syndrome.

Consider local radiation injury in the differential diagnosis if the patient presents with a skin lesion without a history of chemical or thermal burn, insect bite, or history of skin disease or allergy. If the patient gives a history of possible radiation exposure (such as from a radiography source, X-ray device, or accelerator) or a history of finding and handling an unknown metallic object, note the presence of any of the following: erythema, blistering, dry or wet desquamation, epilation, ulceration. Local injuries to the skin evolve very slowly over time and symptoms may not manifest for days to weeks after exposure.

Conventional wound management is usually ineffective in these cases. Consultation with experts regarding definitive diagnosis, tissue dose, treatment, and prognosis is recommended.

Acute Radiation Syndrome

Acute radiation syndrome (ARS) is an acute illness caused by irradiation of the whole body (or a significant portion of it). It follows a somewhat predictable course and is characterized by signs and symptoms which are manifestations of cellular deficiencies and the reactions of various cells, tissues, and organ systems to ionizing radiation.

Immediate, overt manifestations of the acute radiation syndrome require a large (i.e., hundreds of rem, usually whole-body) dose of penetrating radiation delivered over a short period of time. Penetrating radiation comes from a radioactive source or machine that emits gamma rays, X-rays, or neutrons. The signs and symptoms of this syndrome are non-specific and may be indistinguishable from those of other injuries or illness.

The ARS is characterized by four distinct phases: a prodromal period, a latent period, a period of illness, and one of recovery or death. During the prodromal period patients might experience loss of appetite, nausea, vomiting, fatigue, and diarrhea; after extremely high doses, additional symptoms such as fever, prostration, respiratory distress, and hyperexcitability can occur. However, all of these symptoms usually disappear in a day or two, and a symptom-free, latent period follows, varying in length depending upon the size of the radiation dose. A period of overt illness follows, and can be characterized by infection, electrolyte imbalance, diarrhea, bleeding, cardiovascular collapse, and sometimes short periods of unconsciousness. Death or a period of recovery follows the period of overt illness.

In general, the higher the dose the greater the severity of early effects and the greater the possibility of late effects.

Depending on dose, the following syndromes can be manifest:

  • Hematopoietic syndrome - characterized by deficiencies of WBC,   lymphocytes and platelets, with immunodeficiency, increased infectious complications, bleeding, anemia, and impaired wound healing.
  • Gastrointestinal syndrome - characterized by loss of cells lining intestinal crypts and loss of mucosal barrier, with alterations in intestinal motility, fluid and electrolyte loss with vomiting and diarrhea, loss of normal intestinal bacteria, sepsis, and damage to the intestinal microcirculation, along with the hematopoietic syndrome.
  • Cerebrovascular/Central Nervous System syndrome - primarily associated with effects on the vasculature and resultant fluid shifts. Signs and symptoms include vomiting and diarrhea within minutes of exposure, confusion, disorientation, cerebral edema, hypotension, and hyperpyrexia. Fatal in short time.
  • Skin syndrome - can occur with other syndromes; characterized by loss of epidermis (and possibly dermis) with "radiation burns."

Initial Emergency Management:

  • If trauma is present, treat.
  • If external contaminants are present, decontaminate.

Diagnosis:

  • History of exposure - consider acute radiation syndrome in the differential diagnosis if there is:
  • a history of a known or possible radiation exposure (for example, entering an irradiation chamber when the source is unshielded)
  • a history of proximity to an unknown (usually metallic) object with a history of nausea and vomiting, especially if n/v are unexplained by other causes
  • a tendency to bleed (epistaxis, gingival bleeding, petechiae) and/or respiratory infection with neutropenia, lymphopenia, and thrombocytopenia, with history of nausea and vomiting two to three weeks previously
  • epilation, with a history of nausea and vomiting two to three weeks previously
  • Symptom - type of symptom, time of onset, severity, and frequency.
  • Clinical lab - STAT CBC with differential. Repeat in 4-6 hours, then every 6 to 8 hours for 24 to 48 hours. Look for a drop in the absolute lymphocyte count if the exposure was recent (see diagram). If the initial WBC and platelet counts are abnormally low, consider the possibility of exposure a few days to weeks earlier.


Patterns of Early Lymphocyte Response in Relation to Dose graphic

Figure. Classical Andrews lymphocyte depletion curves and accompanying clinical severity ranges. According to the data presented in this paper, curse 1-4 correspond roughly to the following whole-body doses: curve 1 - 3.1 Gy; curve 2 - 4.4 Gy; curve 3 - 5.6 Gy; curve 4 - 7.1 Gy.
From Goans, Ronald E., Holloway, Elizabeth C., Berger, Mary Ellen, and Ricks, Robert C. "Early Dose Assessment Following Severe Radiation Accidents," Health Physics 72(4): 1997.

 

Acute Radiation Syndrome: Dose Less Than 2 Gy (200 rad)

Nausea and vomiting due to radiation are seldom experienced unless the exposure has been at least 0.75 to 1 Gy (75-100 rads) of penetrating gamma or X-rays and it has occurred within a matter of a few hours or less. The prospective patient who has been asymptomatic within the past 24 hours will most certainly have had less than 0.75 Gy of whole-body exposure. Hospitalization generally will be unnecessary if the dose has been less than 2 Gy (200 rads).

Management of ARS (dose <2 Gy):

  • Close observation and frequent CBC with differential.
  • Outpatient management may be appropriate.
  • Provide instructions regarding home care.

Acute Radiation Syndrome: Dose Greater Than 2 Gy (200 rad)

Signs and symptoms become increasingly severe with dose.

Hematopoietic Syndrome:

  • The prodromal phase - nausea, vomiting and anorexia within a few hours at the higher dose levels, or after 6 to 12 hours at the lower dose levels. Lasts 24 to 48 hours, after which time the patient is asymptomatic and may feel well. The absolute lymphocyte count will fall; a stress response of WBC may be present.
  • The latent phase - lasts a few days to as long as 2 to 3 weeks at the lower dose levels. The patient is asymptomatic but CBCs will show characteristic changes in the blood elements, with lymphocyte depression and gradual decrease in neutrophil and platelet counts.
  • A bone marrow depression phase requires sophisticated treatment.  Infection and hemorrhage could occur when white cell and platelet counts become critically low.
  • The recovery phase - stem cells in the bone marrow are never completely eradicated at 2 to 10 Gy (200 to 1000 rads); some may replicate and eventually produce sufficient blood elements. Supportive therapy is required.

Gastrointestinal Syndrome:

  • Over 10 Gy (1000 rads) - this syndrome is distinguishable from the hematopoietic syndrome by the immediate, prompt and profuse onset of nausea, vomiting and diarrhea, followed by a short latent period. GI symptoms recur and lead to marked dehydration, and vascular effects. The GI mucosa becomes increasingly atrophic, and massive amounts of plasma are lost to the intestine. Massive denuding of the GI tract and accompanying septicemia and dehydration can occur. If the patient survives long enough, depression of the hematopoietic system occurs and complicates the clinical course.

Cardiovascular Syndrome:

  • Over 30 Gy (3000 rads), an extremely high dose, to the whole-body. Always fatal, there is immediate nausea, vomiting, anorexia and prostration, and irreversible hypotension; blood pressure will be markedly unstable. Within hours after exposure, the victim will be listless, drowsy, tremulous, convulsive, and ataxic. Death most likely will occur within a matter of days.

Management of Acute Radiation Syndrome (Dose >2 Gy)

Initial management:

  • Vomiting - use selective blocking of serotonin 5-HT3 receptors or use 5-HT3 receptor antagonists.
  • Consider initiating viral prophylaxis.
  • Consider tissue, blood typing.
  • Treat trauma.
  • Consider prompt consultation with hematologist and radiation experts, re: dosimetry and prognosis, use of colony stimulating factors, stem cell transfusion, and other treatment options.
  • Draw blood for chromosome analysis; use heparinized tube.
  • Note areas of erythema and record on body chart. If possible, take photographs.

Begin, as indicated:

  • SUPPORTIVE CARE in a CLEAN environment (reverse isolation).
  • Prevention and treatment of infections.
  • Stimulation of hematopoiesis (use of growth factors, i.e., GCSF, GMCSF, interleukin 11).
  • Stem cell transfusions: cord blood, peripheral blood, or bone marrow. Platelet transfusions if bleeding occurs or if platelet count too low.
  • Psychological support.
  • Observe carefully for erythema (document locations), hair loss, skin injury, mucositis, parotitis, weight loss, and/or FEVER.
  • Consultation with experts in radiation accident management is encouraged.
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