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 (Williams, 2020). There are five primary types of radiation:
- Alpha particles
- Beta particles
- Gamma rays
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 (CDC 2020 f,g; 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 (NTI, 2015d).
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 (Williams, 2020).
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 (Williams, 2020; ORISE, 2017).
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 (Williams, 2020).
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 themselves. 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 (Kotora, 2015). When nuclear medicine is used however, a patient may be considered to emit some radiation upon others and must be careful to not share eating utensils or even the same bathroom for a period of time.
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 and not metric is still widely used.
Different units of measurements 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 is the amount of energy deposited in human tissue by radiation and is measured using the conventional unit rad or the SI unit gray (Gy). The biologic risk of exposure to radiation is the risk that a person will suffer health effects from an exposure to radiation and is measured using the conventional unit rem or the SI unit sievert (Sv) (NTI, 2021; Williams, 2020).
Types of Radiation Injury
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. Because of the huge populations that were affected, we now have identified patterns of aftereffects, which 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 (Williams, 2020).
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, 2017; REMM, 2017).
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, 2017).
Radiation exposure also occurs after internal contamination, 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, 2017).
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, 2017).
Contamination: External or Internal
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, 2017).
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, 2017).
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, (e.g., thyroid, lungs, kidneys, bones/bone marrow, or liver/spleen) resulting in exposure at that site. Medical countermeasures called decorporation agents or other procedures such as diuresis may be needed to remove radioisotopes that have been incorporated into tissues. Patients who have received radioactive substances for diagnostic procedures should be taught to drink 1 t 2 liters of water after the procedure to help eliminate the radioisotope. Toxic effects of radioisotopes may be due to their chemical and/or radiologic properties (REMM, 2017).
Acute Radiation Syndrome (ARS)
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, 2018d). 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, 2018d).
Basic issues of ARS that may modify how symptoms present include:
- Time of exposure, distance from radioactive source, and duration of exposure.
- Patients may present individually if exposed to radioactive sources that are hidden in the community.
- Symptoms can be immediate or delayed, mild or severe, based on radiation dose.
- Nausea and vomiting may occur minutes to days after exposure.
- Early onset of vomiting followed by symptoms of bone marrow suppression, gastrointestinal destruction, and/or cardiovascular/CNS effects are indicative of acute illness.
- Depending on the stage of illness, a patient may be asymptomatic. (CDC, 2018d)
The required conditions for ARS are:
- The radiation dose must be large (> 0.7 Gy, or >70 rads).
- The dose usually must be external.
- The radiation must be penetrating (able to reach the internal organs).
- The entire body (or a significant portion of it) must have received the dose.
- The dose must have been delivered in a short time (usually a matter of minutes). (CDC, 2018d)
The three classic ARS syndromes are:
- Bone marrow syndrome (hematopoietic syndrome)
- Gastrointestinal syndrome
- Cardiovascular (CV)/central nervous system (CNS) syndrome (CDC, 2018d)
The four stages of ARS are:
- Prodromal stage (N-V-D stage): Classic symptoms are nausea, vomiting, and diarrhea. Anorexia generally follows depending on dose of exposure. The symptoms may begin from minutes to days following exposure and last episodically from minutes to several days.
- Latent stage: The patient looks and feels generally healthy, for a few hours to a few weeks.
- Manifest illness stage: The symptoms depend on the specific syndrome and last from hours to several months.
- Recovery or death: Most patients who do not recover will die within several months of exposure. The recovery process lasts from several weeks to 2 years (CDC, 2018d).
Cutaneous Radiation Syndrome (CRS)
The concept of cutaneous radiation syndrome (CRS) was introduced in recent years to describe the complex pathologic syndrome that results from acute radiation exposure to the skin.
ARS is usually accompanied by some skin damage. It is 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, 2018d).
The concern about nuclear agents is similar to radiation exposure and is addressed with the same protocols. The difference is the agent, which is a nuclear radiation. Although nuclear weapons have been the fodder for many Hollywood movies as having potential to cause the greatest impact of public health, it is less common because it requires advanced knowledge and technology.
The great concern, however, is if the nuclear weapons contain biological agents that could be disseminated to huge, populated areas, killing thousands of humans as well as livestock (SNHD, 2020). A Kg of viable anthrax could kill as many as Hiroshima size weapon. Although anthrax can be treated with cipro and doxycycline, prophylactic medications have a limited shelf life and limitations in supplies is real. Stockpiling these medications is impossible.
Protecting Staff and Patients
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. An example of a common protection is having staff who work in the radiology department wear tags that indicate daily and weekly radiation exposure. If they exceed the limit, they are pulled from working directly with the radiation machines to prevent additional radiation exposure until their total exposure decreases to acceptable levels. The department most regulated in any hospital is the radiology department.
Hospitals and other agencies are expected to have mass casualty strategies in place, and all appropriate staff should be trained in proper procedures and use of equipment. OSHA provides many resources for establishing triage areas and managing mass casualties (OSHA, 2005, latest).
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, 2018c).
The CDC staff protection guidelines include the following for an ad hoc triage area:
- Base it on your hospital’s disaster plan and the anticipated number of casualties.
- Establish a contaminated area and a clean area separated by a buffer zone.
- Remove your contaminated outer garments when leaving the contaminated area.
- Have your body surveyed with a radiation meter when exiting a contaminated area. (CDC 2018c)
Use standard precautions to protect staff:
- Follow standard guidelines for protection from microbiologic contamination.
- Surgical masks should be adequate.
- N-95 masks, if available, are recommended.
- Survey hands and clothing at frequent intervals with a radiation meter.
- Due to fetal sensitivity to radiation, assign pregnant staff to other duties. (CDC, 2018c)
Protective Clothing for 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). Additional protective clothing includes wearing radiation-blocking lead aprons, which are commonly used in catherization labs.
PPE in Radiation Emergencies
In a radiation emergency, the choice of appropriate personal protective equipment (PPE) depends on:
- Response role and specific tasks
- Risk of contamination
PPE can protect against:
- External contamination
- Internal contamination via inhalation, ingestion, absorption through open wounds
- Other physical hazards (e.g., debris, fire/heat, chemicals)
PPE cannot protect against:
- Exposure from high energy—highly penetrating forms of ionizing radiation associated with most radiation emergencies
- Note that lead aprons worn in diagnostic radiology do not provide sufficient shielding against these kinds of radiation.
- PPE should include a personal radiation dosimeter whenever there is concern about exposure to penetrating ionizing radiation.
- Direct-reading personal radiation dosimeters may be used to monitor radiation dose and can help workers stay within recommended Dose Limits for Emergency Workers.
- Direct-reading dosimeters should be worn so that a worker can easily see the read-out and/or hear warning alarms.
- Recommended respiratory PPE includes a full-face piece air purifying respirator with a P-100 or High Efficiency Particulate Air (HEPA) filter.
- Other respiratory protective equipment (e.g., a simple surgical face mask, N-95 respirators), non-fit tested respirators, or ad hoc respiratory protection do not deliver appropriate or sufficient respiratory protection.
- Environmental testing and hazard assessment by a safety professional can help identify hazards and risk levels and direct choices.
More detailed information about forms of PPE and their efficacy is available from the Radiation Emergency Medical Management website (https://www.remm.nlm.gov/radiation_ppe.htm#emergencies).
Decontamination Guidelines for Patients
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 and doffing protective clothing or equipment.
Guidelines to complete a correct survey of radiation for any patient including the following for using a radiation meter:
- Perform surveys using consistent technique and trained personnel.
- Note exceptionally large amounts of surface or embedded radioactive material.
- Handle radioactive objects with forceps and store in lead containers.
- Record location and level of any contamination found.
- Remove patient clothing:
- Carefully cut clothing and roll it away from the face to contain the contamination.
- Double-bag clothing using radioactive hazardous waste guidelines, label, and save as evidence.
- Repeat patient survey and record level. (REMM 2017)
Cleanse contaminated areas:
- Wash wounds first with saline or water.
- If facial contamination is present, flush eyes, nose, and ears, and rinse mouth.
- Gently cleanse intact skin with soap and water, starting outside the contaminated area and washing inward.
- Do not irritate or abrade the skin.
- Resurvey and note levels.
- Repeat washing until survey indicates radiation level is no more than twice background or the level remains unchanged.
- Cover wounds with waterproof dressing.
- Dispose of wastewater through normal channels.
- For mass casualties, consider establishing separate shower areas for ambulatory and non-ambulatory patients. (REMM, 2017.)
Management of deceased:
- If exposed to a lethal dose of radiation without contamination, a patient is not radioactive, and no special precautions are needed.
- Special precautions may be necessary for contaminated deceased. (NTI, 2021)
Initial Evaluation and Treatment
Treat vomiting and then complete a 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):
- Supportive care in a clean environment (e.g., burn unit)
- Prevention and treatment of infections
- Stimulation of hematopoiesis by use of growth factors
- Stem cell transfusions or platelet transfusions (if platelet count is < 100,000)
- 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. (CDC, 2018c)
Government guidance for radiation management is clustered in the website of the Oak Ridge Institute for Science and Education (https://orise.orau.gov/resources/reacts/guide/hospital-medical-management.html).
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:
- Assessment may include analysis of urine, blood, and fecal samples or whole-body counts. Consult with radiation experts.
- Radiation experts may recommend early administration of radionuclide-specific decorporation agents such as Prussian blue, DTPA, or bicarbonate.
- Gastric lavage, antacids, and cathartics assist in clearing ingested contaminants. (CDC, 2018c)
Medical Management: Countermeasures
During a radiological or nuclear emergency, radioactive materials may be released into the air and then breathed into the lungs, or may get into the body through open wounds. Radioactive materials can also contaminate the local food supply and enter the body through eating or drinking. This is called internal contamination.
The sooner internal contamination is removed from the body, the fewer and less severe the health effects will be. Small amounts of internal contamination may not need treatment.
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:
- Potassium Iodide (KI)
- Prussian Blue
- DTPA (Diethylenetriamine pentaacetate)
- Neupogen (CDC, 2018d)
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 be members of the response team and available in a 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.
Provide radiation exposure fact sheets 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.