From the Department of Emergency Medicine (Lin LW, Wang TL), Shin-Kong Wu Ho-Su Memorial Hospital.

Correspondence to Dr. Tzong-Luen Wang, Department of Emergency Medicine, Shin-Kong Wu Ho-Su Memorial Hospital, 95 Wen Chang Road, Taipei, Taiwan. E-mail M002183@ms.skh.org.tw

 

Radiation incident is rare condition but worldwide, the number of radiation incidents has reached 403 since 1944.¹ They influenced with 133,617 victims, of which 2965 had significant exposures and 120 persons died. Most acute radiation injury is related to nuclear weapons, industrial accidents, nuclear power accidents and radiation therapy. After terrorist attacked on the World Trade Centers on September 11, 2001, the United States and all developed nation had increasing concern about the possibility of nuclear terrorism. The terrorist attack may include dispersal of radioactive substances with or without the use of conventional explosives, attacks on nuclear reactors and detonation of nuclear weapons.² In the United State nuclear attacks are thought easier to manage than bio-chemical terrorism because more then 10,000 persons deal with radiation daily at hospitals, universities, military units, national laboratories and government agencies. Geiger counters or dose-rate meter are available in more than 3,000 hospitals. Emergency personnel can carried these equipments to detect radioactive contamination and use a simple blood test, absolute lymphocyte counts and clinical manifestation of acute radiations symptoms to assess the severity of radiation injuries. In Taiwan we lack of the experience of management of radiation crisis so we required a thorough understanding of radiation syndromes for effective management of radiation casualties.

Most acute radiation injury is related to accidents or radiation therapy. Accidents are sporadic and usually effect small numbers of victims. The first large-scale exposure to radiation has been caused by the detonation of atomic bombs over Japan in World War II. One-hundred and twenty thousands individuals developed acute radiation syndrome. In the Marshall Islands 7,266 natives were exposed to radiation due to errors in judging winds after a nuclear test in the South Pacific in 1954.³ A radiation incident involving a medical Cs-137 source in Brazil resulted in 200 contaminated persons and 4 deaths.⁴ A nuclear accident at the Chernobyl nuclear power station in Russia in 1986 had exposed more than 116,500 persons and resulted in 29 deaths from acute radiation syndrome.⁵

Radiation is energy traveling through the space. Radiation includes electromagnetic emissions and particles.⁶ Ionizing radiation means electromagnetic (X ray and gamma) or particulate (alpha, beta and neutron) radiation capable of producing ions or charged particles. Ionizing radiation comes from unstable atoms that had radioactivity to emit radiation spontaneously.
Gamma and X rays are electromagnetic radiation like light, radio waves and ultraviolet light but they have short-wave, high-frequency and more energy. Gamma and X rays travel many meters in air and several centimeters in human tissue. They penetrate most materials and is called penetrating radiation. Only dense materials like lead shied prevent penetrating radiation. A person exposed to penetrating radiation is not radioactive.
Alpha radiation has 4 neutron masses and +2 charges. It travels only a few centimeters in air and cannot penetrate skin. It can be hazard from inhaled, swallowed, or absorbed through open wounds with alpha-emitting materials. Paper and keratin layer of skin provide protection against for most alpha radiation.
Beta radiation is thru electrons and travels meters in air and up to 8 millimeters into skin. It may be harmful if beta-emitting materials deposited on skin or internally. Beta radiation can be prevented by clothing and turnout gear.
Neutrons possess a large range of energy and variable penetrating ability. The major source of neutrons comes from critical accidents around nuclear power production facilities or nuclear weapons. It had a unique property that a stable atom may absorb a neutron and then become an unstable atom. Metallic object worn or implanted in the affected person and sodium in human body will become radioactive.
Ionizing radiation produces free radicals from water and then disrupts chemical bonds. This causes damage of cellular biochemical systems and DNA. Cellular replication and protein synthesis are further disrupted. If higher radiation dose absorbed damage will overcome the ability of repair. In general rapid replicating cells are vulnerable to radiation, e.g. blood, gut, epithelium, and reproductive cells. Clinically young patients, men and debilitated patients are more susceptible from radiation.

Acute radiation syndrome has somewhat predictable clinical courses.⁷ During prodromal phase nausea, vomiting and fatigue happen. According to absorbed dose its onset begins from 3-6 hours to minutes and last from 24 to 48 hours. Latent phase follows prodromal phase and last up to 2 weeks. In the period bone marrow suppression and gastrointestinal system destruction occur insidiously but the victim is asymptomatic. Clinical illness develops after affected systems loss its function. Depending on absorbed radiation dose it divides to hematopoietic, gastrointestinal and neurovascular syndrome. Death or recovery follows the critical period.
Whole body irradiation dose at < 2 Gy is considered subclinically.^1,2,6-8 No symptoms develop when exposure to < 0.75-1 Gy. At 1- 2 Gy nausea and vomiting occur 3-6 hours later after events and last shorter than 24 hours. Under this exposure radiation victims have no disease.

• Thermal burn lesion without heat or chemical exposure
• A tendency to bleed (epistaxis, gingival bleeding, petechiae)
• Infection with bone marrow suppression (neutropenia, lymphopenia and thrombocytopoenia)
• Epilation                    

(3)     Obtain complete blood count with differential immediately post event. Repeat every 6 hours for 48 hours. Absolute lymphocyte count at 48 hours predicts the exposure radiation dose.²

Medical management for radiation emergency includes triage, emergency care, and definitive care. During triage we focus on immediately life-threatening problems and priority. Emergency care includes decontamination, therapy and diagnosis of radiation and combined injuries. Definitive care provide final disposition and stand care for patients.