Radiation is any form of energy propagated as rays, waves, or energetic particles that travel (radiate) from their source. Radiation can travel through the air or through a material medium (CISAC, 2002).
There are five primary types of radiation:
Radiation types vary in their size, charge, ability to travel, and ability to penetrate objects. These variations affect their uses, their current and future effects, what materials effectively shield against them, the parts of the body they can potentially damage, and the exposure restrictions mandated by the government (ORISE, 2017).
Radioactive materials are composed of atoms that are unstable. An unstable atom gives off its excess energy until it becomes stable. The energy emitted is radiation. The process by which an atom changes from an unstable state to a more stable state by emitting radiation is called radioactive decay or radioactivity (CISAC, 2002).
Radiation is often divided into ionizing and non-ionizing radiation. Radiation that has enough energy to move atoms in a molecule or cause them to vibrate, but not enough to change them chemically, is referred to as non-ionizing radiation. Examples of this kind of radiation are radio waves and visible light (CISAC, 2002).
Radiation that falls within the ionizing radiation range (alpha and beta particles and gamma rays) has enough energy to break the bonds that tie electrons into the atoms or molecules that make up ordinary substances. This is the type that people usually think of as “radiation” when dealing with nuclear dangers. Ironically, this is also the type of radiation that is used for medical treatment and in many manufacturing processes (CISAC, 2002; ORISE, 2015).
Compared with other types of radiation that may be absorbed, ionizing radiation deposits a large amount of energy into a small area. All ionizing radiation is capable, directly or indirectly, of removing electrons from most molecules. This property of ionizing radiation lies at the root of both its usefulness and its dangers (CISAC, 2002).
Radiation cannot be detected by the human senses. A radiologic survey conducted with specialized equipment is the only way to confirm the presence of radiation. If a terrorist event involves the use of radioactive material, both patient exposure and contamination must be assessed.
Exposure occurs when a person is near a radiation source. People exposed to a source of radiation can suffer radiation illness if the dose is high enough, but they do not become radioactive. For example, an x-ray machine is a source of radiation exposure, yet a person does not become radioactive or pose a risk to others following a chest x-ray (CDC, 2014g).
When scientists measure radiation, they use different terms depending on whether they are discussing radiation coming from a radioactive source, the radiation dose absorbed by a person, or the risk that a person will suffer health effects (biological risk) from exposure.
Most scientists in the international community measure radiation using the Système International d’Unités (SI), a uniform system of weights and measures that evolved from the metric system. In the United States, however, the conventional system of measurement is still widely used.
Different units of measure are chosen depending on what aspect of radiation is being measured. For example, the amount of radiation being given off, or emitted, by a radioactive material is measured using the conventional unit curie (Ci), named for the famed scientist Marie Curie, or the SI unit becquerel (Bq).
The radiation dose absorbed by a person (the amount of energy deposited in human tissue by radiation) is measured using the conventional unit rad or the SI unit gray (Gy). The biologic risk of exposure to radiation (the risk that a person will suffer health effects from an exposure to radiation) is measured using the conventional unit rem or the SI unit sievert (Sv) (CDC, 2014i).
The only non-test deployment of nuclear weapons was the 1945 dropping of the atomic bombs on Hiroshima and Nagasaki, Japan, near the end of World War II. Those at the center of impact were killed immediately by thermal and shock forces as well as intense radiation poisoning. Others at varying distances from the bomb’s center were injured and died later. Still others are alive today, but many of them have suffered from the latent effects of radiation exposure. Patterns of aftereffects are known, as are the patterns of radiation illness and injury that follow closely upon exposure. Understanding these patterns will aid in diagnosis and treatment of radiation-induced injury or illness.
Radioactive contamination and radiation exposure could occur if radioactive materials are released into the environment as the result of an accident, an event in nature, or an act of terrorism. Such a release could expose people and contaminate their surroundings and personal property (CDC, 2014f).
Radiation exposure occurs when all or part of the body absorbs penetrating ionizing radiation from an external radiation source. Exposure from an external source stops when a person leaves the area of the source, the source is shielded completely, or the process causing exposure ceases. During exposure, the body may absorb radiation, or it may pass completely through the body. This is similar to what happens during an ordinary chest x-ray. An individual who has been exposed in this way is not radioactive and can be treated like any other patient (ORISE, 2015; CDC, 2014f; REMM, 2016).
Radiation exposure also occurs after internal contamination, ie, when a radioactive material is ingested, inhaled, or absorbed into the bloodstream. This kind of exposure stops only if the radionuclide is eliminated from the body, with or without treatment (REMM, 2016).
An individual exposed only to an external source of radiation, is NOT radioactive or contaminated and may be approached without risk, just as is the case following a chest x-ray or CT scan (REMM, 2016).
Radiation from external exposure alone is either absorbed without the body becoming radioactive, or it can pass through the body completely. Therefore, if a person is scanned with a radiation survey monitor after external exposure alone, the device will not register radiation above the background level (REMM, 2016).
Contamination results when a radioisotope (as gas, liquid, or solid) is released into the environment and then ingested, inhaled, or deposited on the body surface. External contamination results when radioactive material is deposited on skin, hair, eyes, or other external structures, much like mud or dust. External contamination stops when the material is removed by shedding contaminated clothes and/or completely washing off the contamination (REMM, 2016a).
Internal contamination results when radioactive material is taken into the body via inhalation or ingestion or open wounds. Internal deposition of radioisotopes in organs results in local exposure at that location. Internal contamination continues until the radioactive material decays, is flushed from the body by natural processes, or is removed by medical countermeasures (REMM, 2016a).
After inhalation, ingestion, or wound contamination, small radioisotope particles may be transported via blood or lymphatics into cells, tissues, and organs. Isotopes can be alpha-, beta-, or gamma-emitting. Radioisotopes can be incorporated into one or more organs specific for that isotope, (eg, thyroid, lungs, kidneys, bones/bone marrow, or liver/spleen) resulting in exposure at that site. Medical countermeasures called decorporation agents or other procedures (eg, diuresis) may be needed to remove radioisotopes that have been incorporated into tissues. Toxic effects of radioisotopes may be due to their chemical and/or radiological properties (REMM, 2016b).
Acute radiation syndrome (ARS)—sometimes known as radiation toxicity or radiation sickness—is an acute illness caused by irradiation of the entire body, or most of the body, by a high dose of penetrating radiation in a very short period of time (usually a matter of minutes) (CDC, 2017e). The most probable terrorist events, such as a dirty bomb attack, will likely generate low levels of radiation exposure. If ARS cases are seen, it is likely that casualty numbers will be small (CDC, 2014g).
Basic symptomatic issues of ARS include:
The required conditions for ARS are:
The three classic ARS syndromes are:
The four stages of ARS are:
The concept of cutaneous radiation syndrome (CRS) was introduced in recent years to describe the complex pathological syndrome that results from acute radiation exposure to the skin.
ARS usually will be accompanied by some skin damage. It is also possible to receive a damaging dose to the skin without symptoms of ARS, especially with acute exposures to beta radiation or X-rays. Sometimes this occurs when radioactive materials contaminate a patient’s skin or clothes.
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 (CDC, 2017e).
The CDC has established general guidelines for managing patients and protecting staff in the event of radiation exposure. These guidelines are specifically designed for small-scale incidents not resulting from a large or nuclear device.
Hospitals and other agencies are also expected to have mass casualty strategies in place, and all appropriate staff should be trained in proper procedures and use of equipment. Many resources are available for establishing triage areas and managing mass casualties (OSHA, 2005).
According to the CDC, addressing contamination issues should not delay treatment of life-threatening injuries. It is highly unlikely that the levels of radioactivity associated with a contaminated patient would pose a significant health risk to care providers. In certain rare instances, the presence of imbedded radioactive fragments or large amounts of external contamination may require expedited decontamination, thus it is recommended to include in-house radiation professionals on the response team (CDC, 2014g). The CDC staff protection guidelines include the following.
Establish an ad hoc triage area:
Use standard precautions to protect staff:
The purpose of protective clothing is to keep bare skin and personal clothing free of external contamination. Paper coveralls, cloth coveralls, and surgical garb are all appropriate protective clothing. Because most people are not used to working in extra layers of clothing they should be monitored for heat stress. “Standard issue particulate protective masks (respirators) afford excellent protection from inhalation and ingestion of most radioactive material” (ORISE, 2017).
PPE in Radiation Emergencies
More detailed information about forms of PPE and their efficacy is available from the Radiation Emergency Medical Management website: http://www.remm.nlm.gov/radiation_ppe.htm.
The CDC offers the following guidelines for managing patients who are believed to have been contaminated either externally or internally with radiation. Before beginning treatment, staff should be sure to take care in following their agency’s guidelines for donning protective clothing or equipment.
Survey the patient with a radiation meter:
Remove patient clothing:
Cleanse contaminated areas:
Management of deceased:
Treat vomiting, and repeat CBC analysis, with special attention to the lymphocyte count, every 2 to 3 hours for the first 8 to 12 hours after exposure (and every 4 to 6 hours for the following 2 to 3 days). Precisely record all clinical symptoms, particularly nausea, vomiting, diarrhea, and itching, reddening, or blistering of the skin. Be sure to include time of onset.
Note and record areas of erythema. If possible, take color photographs of suspected radiation skin damage. Consider tissue and blood typing as well as initiation of viral prophylaxis. Promptly consult with radiation, hematology, and radiotherapy experts about dosimetry, prognosis, and treatment options. Call the Radiation Emergency Assistance Center to record the incident in the Radiation Accident Registry System (see numbers under Resources at the end of this course).
After consultation, begin the following treatment (as indicated):
Consider internal contamination if high survey readings persist following decontamination. Internal contamination generally does not cause early symptoms. Nose or mouth contamination may indicate inhalation or ingestion.
To check for internal contamination:
Treating internal contamination:
Some medical treatments are available for limiting or removing internal contamination depending on the type of radioactive material involved. Medical professionals will determine if any of the following treatments are needed:
In urban areas, hundreds to thousands may seek care. Most will self-refer to the nearest hospital. While many may need decontamination, others may seek radiologic screening even though not contaminated. Many simply seek reassurance. Mental health professionals should always be members of the response team and available in any first-receiver facility to provide such support.
When evaluating patients, healthcare workers need to understand that psychogenic symptoms, such as nausea or vomiting, may manifest. Keep in mind that vomiting due to radiation exposure is usually recurrent rather than episodic.
Have radiation exposure fact sheets available for patients and families and remember that pregnant patients require special counseling. It is likely that separate areas for radiation screening and counseling will be needed for patients with minimal risk of exposure or injury (CDC, n.d.).