Radiation Incidents and Emergency Preparedness - RAD363-60

Radiation Incidents and Emergency Preparedness

by Lynn Slepski, RN, PhD, CCNS and Richard Stilp, RN, MA, CHSP
RAD363-60
(4.5 / 464 ratings )

This course is credentialed for:
Radiologic Technology (0.75 CE Credit)


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Radiation emergencies are one of the least understood healthcare emergencies and, therefore, one of the most frightening.1 You can’t see, smell or touch radiation.1 Most healthcare workers believe they are unprepared to handle a radiological incident. A mass casualty incident from radiation is likely to generate large numbers of frightened people, or “worried well,” who may require decontamination.1,2,3
 
Definitions
 
Ionized Radiation. Ionizing radiation is radiation with enough energy so that during an interaction with an atom, it can remove tightly bound electrons from the orbit of an atom, causing the atom to become charged or ionized. Ionizing radiation occurs in two forms — waves or particles.1
 
Incorporation. The uptake of radioactive materials by body cells, tissues and target organs, such as bone, liver, thyroid or kidney.2
 
Unstable. An unstable nucleus is one that undergoes change when the nucleus gives off a subatomic particle, or a burst of energy, or both. A nucleus that gives off a particle or energy is said to undergo radioactive decay.2 
 
Fission. Also called nuclear fission is the splitting of the nucleus of an atom into nuclei of lighter atoms, accompanied by the release of energy.3
 
Fusion. Also called nuclear fusion is a thermonuclear reaction in which nuclei of light atoms join to form nuclei of heavier atoms.3
 
Radiation Overview
 
Radiation is energy that can be characterized as waves or particles trying to become stable. Radioactive materials contain energized atoms that are unstable and release energy. This energy may damage certain critical cellular structures and cause a cell to malfunction or die. It may also interact with water molecules in the body to create unstable, hyperoxide molecules that cause further damage.
 
Characteristics of Ionizing Radiation1 
Type
Characteristic
Shielding
Risk
Alpha particles
Much larger than beta particles and are positively charged ionizing radiation
 
Capable of being propelled several centimeters off of the source but can be carried by wind and may be inhaled or ingested causing sickness
 
Will not penetrate the dead layer of skin
 
 
Thin layer of paper or clothing
 
Superficial layers of skin
 
Negligible external hazard. Internal contamination causes incorporation resulting in tissue damage.
Beta particles
An extremely small particle
 
Is propelled from inches to many feet through air but, like an alpha particle can be carried in the wind.
 
Moderately penetrating in other materials
 
Can penetrate human skin to the layer where new skin cells are produced
 
 
 
Sheet of aluminum foil
If allowed to remain on the skin for a long period of time, may cause skin injury and can be inhaled or ingested causing incorporation and resulting in tissue injury.
 
Beta-emitting contaminants may be harmful if deposited internally.
Gamma rays and photons contained in X-rays
Uncharged electromagnetic radiation
 
Highly energetic
 
Travel many feet in air and many inches in human tissue, readily penetrating most materials
Thick layers of dense material, such as lead, tungsten, steel and concrete. Clothing and turnout gear provide little shielding from Gamma and X-ray radiation.
Readily penetrates most materials. Constitutes both an external and internal hazard to humans
Neutrons
Emitted at the time of a nuclear detonation
 
Neutrons travel many feet in concrete and thousands of feet in air, penetrating most materials
Thick layers of shielding material, such as concrete
Significant
 
Time, distance and shielding directly affect survivability.
 
 
Units of Measurement for Radiation
 
There are four different but interrelated units for measuring radioactivity, exposure, absorbed dose, and dose equivalent.4 These can be remembered by the mnemonic R-E-A-D:
Radioactivity refers to the amount of ionizing radiation released by a material. Whether it emits alpha or beta particles, gamma rays, X-rays or neutrons, a quantity of radioactive material is expressed in terms of its radioactivity (or simply its activity), which represents how many atoms in the material decay in a given time. The units of measure for radioactivity are the curie (Ci) and becquerel (Bq).
  • Exposure describes the amount of radiation traveling through the air. Many radiation monitors measure exposure. The units for exposure are the roentgen (R) and coulomb/kilogram (C/kg).
  • Absorbed dose describes the amount of radiation absorbed by an object or person (that is, the amount of energy that radioactive sources deposit in materials through which they pass). The units for absorbed dose are the radiation absorbed dose (rad) and gray (Gy).
  • Dose equivalent (or effective dose) combines the amount of radiation absorbed and the medical effects of that type of radiation. For beta and gamma radiation, the dose equivalent is the same as the absorbed dose. By contrast, the dose equivalent is larger than the absorbed dose for alpha and neutron radiation, because these types of radiation are more damaging to the human body. Units for dose equivalent are the roentgen equivalent man (rem) and sievert (Sv), and biological dose equivalents are commonly measured in 1/1000th of a rem (known as a millirem or mrem). For comparison purposes, one sievert equals 100 rem.
 
For practical purposes, 1 R (exposure) = 1 rad (absorbed dose) = 1 rem or 1,000 mrem (dose equivalent).4
 
On average, people living in the U.S. receive about 310 millirem (3.1 millisieverts or mSv) of natural radiation a year. Radon and Thoron gases make up about two-thirds of the natural occurring radiation exposure. Radiation from cosmic, terrestrial and internal radiation account for the rest. In addition to natural radiation, people also receive radiation exposure from man-made sources, such as industrial uses of radiation, CT scans and other medical procedures, and tobacco, fertilizer and other consumer products. This adds another 310 millirems of radiation exposure for an average total of 620 millirems (6.2 millisieverts) per year. All of this is considered “background radiation.”4 
 
Sieverts and rems are units of measure used to describe the biological effect of a radiation dose or how much damage that radiation dose might do to the body (1 Sv = 100 rem).4 The annual occupational exposure allowed by the U.S. Nuclear Regulatory Commission for those who work with and around radioactive materials is 5 rems (0.05 Sv). Dose rates for people should not exceed 0.1 rem (1MSv) in a year above natural background levels.4 The gray is a unit of measure for absorbed dose and reflects the amount of energy deposited into a mass of tissue (1 Gy = 100 rads).
 
Industrial accidents involving nuclear power plants have been rare. In fact, only one major incident has occurred in the U.S and that was in 1979 when Three Mile Island in Harrisburg, Pa., suffered severe damage to the reactor core. Other countries have suffered much worse incidents. In 1986, the Chernobyl nuclear power facility had an accident that destroyed reactor four and was responsible for more than 30 deaths over the next three years. The death toll was from reactor operators and firefighters.5
 
Japan is now recovering from a nuclear crisis after a 9.0-magnitude earthquake and tsunami hit the country in March 2011.6 At the time of the earthquake, 11 reactors at four nuclear plants were operational. As designed, the reactors automatically shut down. The subsequent tsunami disabled the power supply and cooling systems of three nuclear reactors at the Fukushima Daiichi plant, 140 miles north of Tokyo, resulting in nuclear meltdowns of the cores. Radiation leaks in the form of radioactive plumes of airborne particles, and radioactively contaminated water from the cooling vessels rapidly spread, requiring thousands of people within a 30-km (66- mile) zone to first seek shelter in place and later evacuate.6 Within days, trace amounts of cesium, tellurium and iodine 131 and 132 isotopes from the meltdown were detected in Anaheim, Riverside and San Francisco in California and in Seattle, Washington.7 While detected levels of radiation from the Japan incident were well below levels of concern, the accident raised public fears about radiation and the use of nuclear power and pointed out how quickly contamination can spread over large areas.
 
Nuclear power plants aren’t the only possible sources of unexpected radiation releases. Radiation could be used as a weapon of mass destruction (WMD). There are a number of scenarios that could occur that would lead to radiation contamination and mass causalities.8
 
First, would be a criminal or terrorist group obtaining a nuclear weapon from an existing arsenal of a nuclear-armed country. This could occur either as a result of a stolen device or a willing exchange, such as a purchase or exchange for political gain.9 The second would involve a terrorist attack on a nuclear power facility using explosives or an aircraft.10 The third would involve acquiring a sufficient quantity of fissionable materials, such as enriched uranium or plutonium, to build an improvised nuclear device. All of these scenarios are considered to be highly unlikely and a very low threat.11
 
Nuclear devices create a tremendous blast, extreme heat and a significant dose of radiation to people close by (two miles for an improvised nuclear device and more than 50 miles for a kiloton nuclear bomb).11,12 The purchase and transportation of fissionable materials are highly regulated in most countries, which significantly limits their availability.
 
Another WMD scenario involves an attack on a nuclear power facility. Although highly unlikely, an attack that accessed the core of a nuclear power plant could trigger a meltdown and release radiation over hundreds of miles. These nuclear power facilities are constructed with reinforced concrete and steel that is designed to sustain a large bomb impact and even a plane crash. In the U.S. these nuclear reactors have generated an estimated 45,000 tons of waste radioactive fuel that is still being stored onsite of each power facility. It is contained in bunkers and tanks and in most cases, not as protected as the reactors are. This waste fuel is still highly radioactive, and an attack that dispersed this radioactive fuel could cause thousands of injuries.10
 
Finally, radiological dispersion devices,8 or dirty bombs, combine an ordinary explosive with a radioactive material. Although there have been no documented cases of a dirty bomb detonation, there was one attempt. In 1995, Chechen rebels placed a dirty bomb that failed to detonate in Moscow’s Izmailovsky Park. The bomb contained cesium 137, and it was discovered and deactivated by local authorities.8
 
The purchase of highly radioactive sources is strictly regulated by federal and state laws. There have been several reported cases of radiologic materials being sold illegally (on the black market), but it’s difficult and dangerous to transport and easily detected when crossing country borders. The following radiation emitters are possible sources of radiation for terrorist use:
  • Cobalt-60 is used for cancer therapy with a half-life of five years.
  • Cesium-137 is used for food irradiation and medical therapy with a half-life of 30 years.
  • Iridium-192 is used for industrial radiography and medical therapy with a half-life of 74 days.
  • Plutonium-238 is used as a power source for satellites with a half-life of 88 years.
  • Strontium-90 is used for radio-thermal generators with a half-life of 29 years.
  • Iodine-131 is used for cancer therapy with a half-life of eight days.
  • Americium-241 is used in smoke detectors with a half-life of 432 years.13
 
While it is unlikely that a dirty bomb would cause mass radiation casualties, detonation of one would likely result in fear and economic disruption.9
 
How Radiation Affects the Body
 
Exposure occurs when all or part of the body is exposed to penetrating radiation. We subject patients to exposures every day when we perform CT scans, provide radiation therapy to cancer patients or use X-rays for diagnostic purposes. The radiation is absorbed or passes through the body. Once removed from the source, the patient is not radioactive and can be treated like any other patient.14
 
Contamination is the presence of radioactive material where it does not belong. It can be a solid, liquid or gas — or even dust particles that float through the air and eventually settle on the ground or some other surface. External contamination is radioactive material on the outside of the body, usually on the skin or on clothing. External contamination can be removed by removing clothing and washing the skin with soap and water.14 Internal contamination involves the deposition of radioactive material inside the body through inhalation, ingestion or penetrating wounds.14
 
In the 1990s, a new way to treat prostate cancer was tested and found to work well in certain patients.15 The new treatment involved implantation of radioactive seeds into the cancerous prostate. These seeds are low-level iodine — 125 or palladium — 103. Typically, 40 to 100 seeds are implanted, and the radiation attacks primarily the cancer cells because they reproduce rapidly. Although these patients are essentially radioactive, they are of little to no danger in typical social settings. Patients are warned to keep children away from sitting on their laps for a period of days.15
 
Incorporation is the uptake of radioactive materials by body cells, tissues and organs, such as in the bone, liver, thyroid or kidney, which causes chemical changes at the cellular level. Incorporation cannot take place unless contamination occurs.14 Cells that replicate rapidly, such as spermatocytes, blood elements and intestinal crypt cells, are sensitive. Lymph tissue and bone marrow are the most radiation-sensitive tissues. The most radiation-sensitive organs are the skin, intestines, kidneys and gonads.11
 
Radiation can affect the body in a number of ways, but harmful health consequences may not be seen for many years.14,16 Effects depend on the amount of radiation absorbed by the body (the dose), the type of radiation, the route of exposures and the length of time a person is exposed. Effects can be mild, such as reddening of the skin, or serious, such as cancer and even death.17
 
Special populations that are more radiation-sensitive include those younger than age 12; pregnant women because of their rapidly growing tissues; people older than age 60 because of declining immune systems and comorbidities; and people with preexisting conditions that may result in immunosuppression, blood loss or infectious complications.18 The human embryo and fetus are particularly sensitive to ionizing radiation, and the health consequences of exposure can be severe, even at radiation doses too low to affect the mother immediately. Consequences can include growth retardation, malformations, impaired brain function and cancer. At higher doses, the health effects depend on dose and the stage of gestation.11,19
 

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