CE Article: Radiation Injury, Burns and Illness: A Review of Best Practices

Objectives

• Discuss classifications of radiation
• Review contamination vs. irradiation
• Outline scene safety, general patient assessment and triage
• Review decontamination procedures
• Outline patient surge management protocols

Injuries involving radiation sources and radioactive reactions are rare. Nevertheless, they can be catastrophic for the patient while simultaneously exposing the first responder to great risk.¹ This work will focus on radiation-related injuries as well as thermal burns produced by nuclear reactions. It will also address radiation injuries that may have burn injury characteristics.²

What Is Radiation?

Inherently unstable atomic structures are termed radioactive due to their natural tendency to release excess energy or mass to attain states of greater molecular stability. These emissions are called radiation. Radiation is emitted from its source and subsequently travels through substance, space or a combination of the two.

There are two classifications of radiation: ionizing and nonionizing. While ionizing radiation poses the greater danger, both ionizing and nonionizing radiation pose an injury risk. There are four subclassifications of ionizing radiation (see Figure 1).³

Radioactive forms of elements are called radionuclides. There are more than 60 radionuclides found naturally in the environment, while others are human-produced. Radionuclides are commonly grouped into three categories.⁴ Although quantitatively the smallest category, the human-produced sources will be the focus of this work due to the significant role they play in determining radiation-associated injury.

The term irradiation, often referred to as exposure, is used to describe a situation where the human body is subjected to penetrating radiation emitted from radioactive materials or a radiation-generating device.⁵ Contamination occurs when radioactive materials are deposited on body surfaces such as skin. This condition is specifically referred to as external contamination. If radioactive materials enter the body (e.g., through inhalation, ingestion, absorption or direct entry via wounds), internal contamination occurs.

Exposure to radioactive materials is not an absolute indication that an individual was also contaminated. For contamination to occur, the material must be physically present on or in the body. This is an important differentiation because the risk of contamination determines the need for personal protective equipment. The presence of contamination and identity of the contaminating radionuclide should be determined as soon as feasible, preferably prior to patient transport. However, lifesaving medical care should not be delayed due solely to contamination concerns.

Nonionizing radiation—Radiation is a general term that simply refers to the emission of energy in the form of waves or particles. Because radio waves, microwaves and ultraviolet radiation are all types of radiation, “radiation-emitting devices” include common sources of daily exposure such as cell phone towers and microwave ovens (Figure 2). These types of radiation, as well as others, are called nonionizing because they lack the energy necessary to remove an electron from a target atom. While most significant clinical injuries are caused by ionizing radiation, in certain circumstances nonionizing radiation can also have biological effects.

Ionizing radiation—An atom consists of a nucleus of positively charged protons and uncharged neutrons orbited by a cloud of negatively charged electrons. In an electrically stable atom, the positive and negative charges cancel each other out, resulting in a neutrally charged atom. On impact, ionizing radiation has enough enrgy to strip an orbiting electron from an atom. The remaining atom then becomes positively charged since the lost electron carried a negative charge. As a result, ionizing radiation poses a significant biologic threat because of its potential to physically alter the structure and charge structure of atoms or molecules.

Subclassifications of ionizing radiation—Both alpha and beta radiation are particulate in nature. X-rays and gamma radiation are electromagnetic (not particulate). Gamma rays and x-rays behave identically, so they will be considered as one. Neutrons are usually emitted when there is a criticality or nuclear detonation and from a few radionuclides.

Alpha particles have minimal penetration capability and as a general rule do not penetrate the outer dead layer of human skin. Alpha particles can be shielded by items such as a piece of notebook paper. Because alpha particles do not pose a major external threat to humans, alpha emitters are considered a hazard only when taken into the body.

Beta particles are moderately penetrating (up to about a millimeter in tissue) and can typically be shielded by materials such as aluminum foil or several sheets of notebook paper. Because of their penetration range, beta particles can be an external hazard to the skin and lens of the eye. If internalized, the radiation dose to the target organ must also be considered.

Gamma rays and x-rays are highly energetic and penetrating and thus require dense materials, such as lead, to shield them. While gamma and x-rays differ in origin, they pose the same hazard. The main hazard typically associated with these radiations is external irradiation.

Neutron radiation is not commonly encountered. This is the only type of radiation that can make something else radioactive. This process is referred to as neutron activation.

Contamination vs. Irradiation

It is important to differentiate between irradiation and contamination. Irradiation (exposure) occurs when an individual is or has been in the presence of radioactive materials. One does not have to come into contact with radioactive materials to be exposed to radiation. Contamination occurs when the radioactive material itself is measurably present in or on a person. An irradiated but uncontaminated patient poses no direct threat to the responder, transport vehicle or receiving facility.⁶

The atomic number, or number of protons in an atom, determines the elemental nature. Uranium, for example, always has 92 protons in the nucleus. The only difference between the uranium-235 atom and the uranium-238 atom is the latter has three more neutrons in the nucleus than the former. It is the neutron-to-proton ratio in the nucleus that determines whether an isotope (same number of protons, different number of neutrons) is radioactive. As a result, treatment methodologies for internal contamination are largely based on the chemistry of the element itself, rather than of a particular radioisotope.

A contaminated patient, by definition, is taking radioactive material with them, so care must be taken to minimize the spread of contaminant during treatment and transport. Methods to prevent the spread of contamination can include basic but critical maneuvers such as clothing removal or simply covering the patient with a sheet during transport. Turnout gear, surgical clothing and even paper coveralls can all potentially be adequate PPE for contamination events.

Scene Safety, General Assessment and Triage

If prearrival information suggests the involvement of a radiation source or a radiation-emitting ydevice, it is critical to follow local protocols for approaching the scene. Standard PPE does not protect a wearer from exposure to penetrating radiation; PPE only mitigates contamination. Potential radiation contamination threats can be managed with many of the same basic principles commonly employed for more common responses to hazardous materials. Effective methods of limiting radiation exposure include limiting time spent in the area of the radiation source, identifying the source location and maintaining a safe distance from it, and the creation of effective shielding between the responders, patients and source.

General clinical assessment—Life-, limb- and vision-saving medical care is the priority and should not be delayed for decontamination of radioactive materials. The order of decontamination should be 1) wounds, 2) facial orifices and 3) intact skin.⁶

Acute radiation syndrome (ARS) is not contagious. (Note that the phrase radiation sickness once used describe the symptoms associated with ARS is no longer used in the scientific literature.) The risk to the responder is limited and primarily focused on the initial source that may have been at the scene where the patient was injured.

For radiation exposure, an initial assessment must include measuring and reporting the time lapse between exposure and time to emesis (TE; Figure 8).⁷ The latent onset or absence of nausea and vomiting is associated with a greater likelihood of survival. (TE is a good indicator but not a sole determinant and requires more testing.⁷) In addition to TE, other potential signs/symptoms include the onset and intensity of a headache, evaluated body core temperature (hyperthermia/hypothermia), diarrhea, neurological/cognitive deficits and hypotension.

Assessment of the skin should start with a determination of whether there is involvement of a radiation source, a thermal source or both. If it is determined that a patient has been exposed to a radiation source, assessment should include the nature of the source as well as an estimation of absorbed dose. Depending on the dose received, local radiation injury (LRI) can manifest itself as epilation, erythema, desquamation, ulceration or even frank necrosis. Time to onset is an important dose-dependent phenomenon and can be helpful in estimating exposure magnitude. In some cases it may take weeks or even months to express a given radiation injury. If a radiation-associated injury is readily apparent and a thermal source is known to be involved, a thermal burn injury should be suspected and managed as such. (For details regarding the estimation of early internal and external dose magnitude, see Figure 4.)⁸

Patients presenting with burn injuries should be triaged to a burn center if possible, or to a trauma center if a burn center is not immediately available. With LRI/ARS, while a burn center is also a typical destination for wound management, a health physicist should be involved as soon as possible to begin dose assessment to help inform medical management.

Injuries that are immediately apparent will be collateral, such as heat from a blast or blunt-force trauma from a concussion.⁹ Treat collateral injuries as indicated.

Determine the exposure type: external irradiation, external contamination with radioactive material, or internal contamination with radioactive material. Determine exposure (generally measured in grays, abbreviated Gy). Information may be available from those on-site who have appropriate monitoring equipment. Do not delay transport to acquire this information.

Assessment of burns from a radiation source—Exposure to high-intensity ionizing radiation can itself cause a burn injury. The literature describes this particular type of burn injury as LRI or cutaneous radiation syndrome (CRS).^6,7,10 Nevertheless, visible burns produced by ionizing radiation should serve as a critical signal that patient evaluation should include an assessment for ARS.

Cutaneous exposure doses of 3 grays or more may result in skin changes, although development may be delayed as long as two weeks following an event. Generally thermal burns may be distinguished from LRI because thermal burns often can be visually identified immediately. For sequential images of an LRI taken as the injury developed over time, see Figure 3.¹¹ These images are reproduced from a report by the International Atomic Energy Agency entitled “The Radiological Accident in Gilan” and are widely used to demonstrate an LRI.

Localized radiation injury (also known as a radiation burn) is caused by exposure to ionizing radiation. Note that this patient found the 185-GBq Ir-192 source and placed it in his shirt pocket. The photo on the left reveals the early expression of injury. This patient also showed early signs of ARS. The photo on the right is the same patient with the same injury as it progressed, reflecting the actual damage caused by the radioactive source. The patient survived the injury.¹¹

Assessment of ARS—Any patient presenting with a radiation burn injury, LRI or who suffers known exposure to a significant radiation source should be evaluated for development of ARS. ARS can develop following either partial or complete irradiation to the body. The organ systems most impacted include those manifesting either the highest rates of cellular turnover (e.g., gastrointestinal, hematopoietic) or the least resilience to injury (e.g., neurovascular).

General treatment—Although it is unlikely EMS services will be involved in an isolated LRI/ARS event, the underlying principle remains the provision of supportive care and management of injuries to the skin with clean and dry dressings. Supportive care may include intravenous fluid infusion (lactated Ringer’s is generally preferred over 0.9% sodium chloride solution, but either isotonic fluid is acceptable) and airway management to include oxygen as indicated.^12,13 A preferred hospital destination is one that routinely manages cancer patients (i.e., has experience with radiation therapy) or, when available, a facility in the Radiation Injury Treatment Network (RITN).¹⁰

The ideal clinical setting that supports the complex management of ARS patients is a hospital with available treatments that include blood products, nutritional and laboratory support, intravenous fluids, antibiotics, mechanical ventilation and even critical care. With adequate supportive medical care, the LD50 (lethal dose where 50% of the population will die) can be extended from approximately 4 Gy to approximately 6 Gy. (Without medical care, the LD50 is 3.5–4.0 Gy; a nonsurvivable whole-body dose is generally considered greater than 10 Gy.) In some severe cases, optimal care for a patient with ARS may require a stem cell transplant.

Decontamination

Patients with known or suspected radioactive exposure should be decontaminated, with particular attention paid to skin injuries and open wounds. Interventions indicated from primary assessment findings should not be delayed for extensive decontamination efforts.

Decontamination should include:

• Removal of clothing (bag and label with personal identification; when possible deliver this with the patient to the hospital, as it can be quite valuable in determining the source of the radiation);
• Bagging and labeling discarded dressings, bandages, cleaning materials and clothes;
• Whenever possible, take the steps necessary to minimize contaminants in transport vehicles and receiving healthcare facilities.

The Armed Forces Radiobiology Research Institute recommends radiological decontamination be very similar to chemical decontamination.⁷ The key differences include that chemical decontamination is an emergency, while radiological decontamination is not. Furthermore, for certain chemicals the aim is neutralization, while with radiological decontamination the aim is physical removal of the contaminants. Since this is not an emergency, containment is a reasonable strategy until the patient can be appropriately decontaminated. A wet decontamination (showering) may actually spread contamination and worsen the situation. Nevertheless, if there are multiple contaminants present (in addition to a radiation source), local procedures and best care practices may dictate the need for wet decontamination as well.

If wet decontamination is indicated, take care not to abrade or otherwise breach intact skin.⁶ A conventional process for wet decontamination employs rinsing affected patients with copious amounts of warm or cool water (not cold or hot). This may include the use of a commercial decontamination shower, fire department booster hose, hand line (minimal pressure) or other realistic and safe means to facilitate access.

Mass Casualty Triage and Patient Surges

A triage table (Figure 4) has been included to reflect combined burn, trauma and radiation injury when the surge of patients exceeds local resources. Surge capacity reflects a situational balance of available staff, space and supplies to meet the needs of a surge of patients.¹⁴ For radiation and burn disasters, the ultimate goal is to reach a surge equilibrium.^15,16 This is accomplished through a combination of balancing local resources with the effective and efficient transport of patients to available tiers of specialized centers. A rational flow of patients helps achieve the critical balance between staff, space and supplies with the new and ongoing needs of the incoming surge.

Radiation sources can be commonly found in many hospital and industrial settings. Industrial uses of radiation can range from instrumentation required to measure the density of soil being compacted during road construction to radioactive sources used for the nondestructive testing of materials (some of these can be highly radioactive). Nuclear power relies on the maintenance of a chain reaction, or a criticality, that produces heat as a product of the nuclear reaction. This energy is used to heat water and produce steam that drives turbines and generates electricity.

Two major events involving nuclear power plants have occurred over the last three decades, including following the Japan earthquake and tsunami of 2011^17–19 and at the Chernobyl nuclear power plant in 1986.^18,20,21 Both events resulted in major uncontrolled releases of radiation with significant impact to the environment in the immediate area of the plants and a long-term threat to the area surrounding. While the Fukushima release was substantial, the release at Chernobyl produced a catastrophic environmental impact, significant death toll and long-term health effects to tens of thousands of residents evacuated from the area.

According to a report published in 2004 by FEMA, the greatest foreseeable risk of a mass-casualty event is associated with radiation injury and centers on terrorism and military action. Scenarios outlined in that text include the use of a “radiologic dispersal device (RDD; commonly referred to as a dirty bomb) or a radiological exposure device (RED; placement of radioactive materials in locations with the purpose of generating human exposures) and the detonation of a military-grade nuclear weapon.”^22,23 For more information regarding improvised nuclear devices, refer to the CDC information referenced here.²⁴

Dirty bombs include anything that disperses radioactive material through conventional explosives or other (non-nuclear) means. Examples include a crop-dusting airplane, a building’s ventilation system or wrapping radioactive material around a common explosive device (such as dynamite) with the ensuing explosion distributing it in the blast wave.

A radiation exposure device relies on placing radioactive material in a location for the purpose of exposing a person or persons without their knowledge. An example would be if a terrorist placed a source commonly used in industry (e.g., a soil density probe or cancer treatment source used for brachytherapy) under a seat on public transportation.

Nuclear (atomic) weapons include highly enriched material and range from very small to very large. For more information regarding improvised nuclear devices, refer to the CDC information referenced here.²⁴

More than 70 years have passed since atomic weapons were used to bring World War II to an end. A bomb was dropped first on Hiroshima and another just over a week later on Nagasaki. The two bombs decimated the military installations and civilian populations of each of these cities.²⁵ While these two events remain the only known incidents in which atomic weapons have been deployed (outside of controlled and secluded testing sites), information from those events remains relevant today. Modern nuclear technology now utilizes highly enriched materials, and comparatively compact weapons can be built to provide a wide range of explosive capabilities. As a result of modernization, the tens of thousands of burn injuries produced by the thermal energy waves released in the 1945 detonations can now be delivered by a small, concealable, highly enriched nuclear weapon.²⁶

hGray, Sievert, Rem and Rad: Radiation Terminology for EMS

Several key concepts are necessary to assess the biological effects of radiation exposure. Clinically relevant radioactive materials emit ionizing radiation that can transfer energy into tissue. Absorbed dose (or simply dose) is the term used to describe the amount of this energy deposited into tissue. In the United States, the traditional unit of dose measurement is the rad (radiation absorbed dose), which is equal to 100 ergs of energy deposited into 1 gram of material. In contrast, the commonly referenced international unit of dose measurement is the gray (Gy), which is equal to 1 joule of energy deposited into 1 kilogram of tissue. One Gy equals 100 rad; conversely, 1 rad equals 0.01 Gy, or 10 mGy. The Absorbed Dose Conversion Chart reproduced in Figure 5 is from The Medical Aspects of Radiation Incidents.¹⁰

A common way to quantify biological radiation damage and estimate a resultant risk profile is via the terms rem in the U.S. (Roentgen equivalent man) and sievert (Sv) internationally. These units of measurement are referred to as dose equivalents. They are equal to the delivered radiation dose (rad or Gy) multiplied by a dimensionless weighting factor that benchmarks resultant biological damage to a hypothetical exposure from a standard radiation source (usually gamma or x-rays). In other words, the rem is defined as the dosage of a particular radiation type (measured in rad) that will cause the same degree of biologic injury as 1 rad of either gamma or x-rays. The Dose Equivalent/Equivalent Dose Conversion Chart comparing U.S. and international units of measure reproduced in Figure 6 is from The Medical Aspects of Radiation Incidents.¹⁰

Dose Equivalent/Equivalent Dose Conversions

Radioactive materials are quantified differently than many other materials. Instead of using traditional units (e.g., ounces or grams), activity is used. Activity is defined as the number of disintegrations that occur per unit of time (disintegrations per minute, dpm, or disintegrations per second, dps). A disintegration is accompanied by the release of one or more radiation types (e.g., a beta particle or gamma ray). The curie (Ci) is the primary unit of activity in the U.S. and is equal to 3.7 x 10¹⁰ dps or 2.22 x 10¹² dpm. Internationally the becquerel (Bq) is used, where 1 Bq equals 1 dps.

Take care when converting between these units. A small number of curies represents a large amount of activity, whereas a large number of becquerels does not necessarily mean much radioactive material is present. The Activity Conversion Chart comparing U.S. and the international units of measure reproduced in Figure 7 is from The Medical Aspects of Radiation Incidents.¹⁰

So, what does all of this mean? The dose exposure and related effect as well as the time lapse are all included in Figure 8. Key terms used include epilation (the loss of hair—radiation kills fast-growing cells, and hair follicles are some of the fastest), erythema (superficial reddening of the skin, red patches), dry desquamation (scaling and dry sloughing off of skin), wet desquamation (very painful, with skin split open, potentially draining) and deep ulceration/necrosis (dead tissue in the center of a dark, angry-appearing wound that looks infected around the perimeter). The comparative Skin Injury Threshold vs. Acute Doses comparison is found in the Oak Ridge Institute for Science and Education publication Early Internal and External Dose Magnitude Estimation.¹²

Important Links and Downloads

• ORISE’s The Medical Aspects of Radiation Incidents provides the basic information needed for medical management of victims of radiation incidents in an easy-to-understand manner and is now available to attendees of REAC/TS courses in pocket guide form. See https://orise.orau.gov/reacts/resources/radiation-accident-management.aspx; for the iBook version, https://itunes.apple.com/us/book/medical-aspects-radiation/id719147859?mt=11.
• Radiation Emergency Medical Management: Guidance on Diagnosis and Treatment for Healthcare Providers, www.remm.nlm.gov/index.html.
• The Wireless Information System for Emergency Responders (WISER) is a system designed to assist first responders in hazardous-materials incidents. WISER provides a range of information on hazardous substances, including identification support, physical characteristics, human health information and containment and suppression advice. There are WISER applications that are free and can be downloaded to most smartphones. See https://wiser.nlm.nih.gov/.
• Many casualties of radiation injury will be salvageable but require outpatient or inpatient care. Recognizing this, the National Marrow Donor Program, U.S. Navy and American Society for Blood and Marrow Transplantation collaboratively developed the Radiation Injury Treatment Network (RITN). Consisting of medical centers with expertise in the management of bone marrow failure, stem cell donor centers and umbilical cord blood banks across the U.S., the RITN provides comprehensive evaluation and treatment for victims of radiation exposure or other marrow-toxic injuries. See www.ritn.net.
• The Medical Management of Radiological Casualties handbook was created by the Armed Forces Radiobiology Research Institute’s Military Medical Operations Department. See www.usuhs.edu/sites/default/files/media/afrri/pdf/4edmmrchandbook.pdf. The AFRRI’s Medical Radiobiology Advisory Team (MRAT) may be reached 24 hours a day to provide further assistance in the event of a radiological/nuclear emergency.
• Produced by the CDC’s Emergency Preparedness and Response section, the Internal Contamination Clinical Reference is an application that estimates reference concentrations of radionuclides in urine. See www.orau.gov/rsb/iccr/.

Conclusion

When injury is potentially associated with a radiation source, the complex and chaotic situation represents a rare and potentially frightening experience that may also present risk for responders. A rational preparation-based approach to any such event must facilitate the safe and comprehensive identification of potential radiation sources, the rapid determination of patient exposures, and the efficient and effective management of resources. This process includes sound triage principles while continuously maintaining the critical steps necessary to mitigate risks to both patients and responders.

References

1. Christensen DM, Jenkins MS, Sugarman SL, Glassman ES. Management of ionizing radiation injuries and illnesses, part 1: physics, radiation protection, and radiation instrumentation. J Am Osteopath Assoc, 2014 Mar; 114(3): 189–99.
2. Christensen DM, Iddins CJ, Sugarman SL. Ionizing radiation injuries and illnesses. Emerg Med Clin North Am, 2014; 32(1):245–65.
3. Environmental Protection Agency. Radiation Symbols, www.epa.gov/radiation/understand/symbols.html.
4. Idaho State University. Radiation Information Network’s Radioactivity in Nature, https://www.physics.isu.edu/radinf/natural.htm.
5. Radiation Emergency Assistance Center/Training Site. Basics of Radiation, https://orise.orau.gov/reacts/guide/define.htm.
6. Oak Ridge Institute for Science and Education, Radiation Emergency Assistance Center/Training Site. The Medical Aspects of Radiation Incidents, https://orise.orau.gov/files/reacts/medical-aspects-of-radiation-incidents.pdf.
7. Uniformed Services University of the Health Sciences. Armed Forces Radiobiology Research Institute, https://www.usuhs.edu/afrri/outreach/4thEdition.html.
8. Sugarman SL. The Radiation Emergency Assistance Center/Training Site. Early Internal and External Dose Magnitude Estimation, https://orise.orau.gov/files/reacts/rapid-internal-external-dose-magnitude-estimation.pdf.
9. Kearns RD, et al. Blast Injuries and Burn Care. EMS World, www.emsworld.com/article/10913345.
10. Ross JR, Case C, Confer D, et al. Radiation injury treatment network (RITN): healthcare professionals preparing for a mass casualty radiological or nuclear incident. Int J Radiat Biol, 2011 Aug; 87(8): 748–53.
11. International Atomic Energy Agency. The Radiological Accident in Gilan, www-pub.iaea.org/MTCD/Publications/PDF/Pub1123_scr.pdf.
12. Kearns RD, et al. Thermal Burn Care: A Review of Best Practices. EMS World, www.emsworld.com/ 10839933.
13. American Burn Association. American Burn Association Provider Manual, 2011.
14. Hick JL, Barbera JA, Kelen GD. Refining surge capacity: conventional, contingency, and crisis capacity. Dis Med Public Health Prep, 2009; 3(2 Suppl): S59–67.
15. Kearns RD, Conlon KM, Valenta AL, et al. Disaster planning: the basics of creating a burn mass casualty disaster plan for a burn center. J Burn Care Res, 2014; 35(1): e1–e13.
16. Kearns RD, Cairns BA, Cairns CB. Surge Capacity and Capability. A Review of the History and Where the Science Is Today Regarding Surge Capacity during a Mass Casualty Disaster. Front Public Health, 2014; 2:29.
17. Becker SM. Learning from the 2011 Great East Japan Disaster: insights from a special radiological emergency assistance mission. Biosecur Bioterror, 2011 Dec; 9(4): 394–404.
18. Stalpers LJ, van Dullemen S, Franken NA. [Medical and biological consequences of nuclear disasters.] Nederlands tijdschrift voor geneeskunde, 2012; 156(20): A4394.
19. Sugimoto A, Krull S, Nomura S, Morita T, Tsubokura M. The voice of the most vulnerable: lessons from the nuclear crisis in Fukushima, Japan. Bulletin of the World Health Organization, 2012; 90(8):629–30.
20. Dallas CE. Medical lessons learned from Chernobyl relative to nuclear detonations and failed nuclear reactors. Dis Med Public Health Prep, 2012; 6(4): 330–4.
21. Takamura N, Yamashita S. Lessons from Chernobyl. Fukushima J Med Science, 2011; 57(2): 81–5.
22. FEMA. National Planning Scenarios, 2004, https://www.hsdl.org/?view&did=683091.
23. Howe D, Homeland Security Council. Planning Scenarios: Executive Summaries, www.globalsecurity.org/security/library/report/2004/hsc-planning-scenarios-jul04_exec-sum.pdf.
24. Centers for Disease Control and Prevention. More Information on Types of Radiation Emergencies, https://emergency.cdc.gov/radiation/moretypes.asp.
25. Takada J. [Chernobyl nuclear power plant accident and Tokaimura criticality accident.] Nihon Rinsho, 2012; 70(3): 405–9.
26. Zirkle RA, Walsh TJ, Disraelly DS, Curling CA. A new methodology for estimating nuclear casualties as a function of time. Health Physics, 2011; 101(3): 286–98.

Randy D. Kearns, DHA, MSA, NRP (ret.)—a retired clinical assistant professor at the University of North Carolina, School of Medicine—is chair of healthcare, computer informatics and quantitative studies and an assistant professor of healthcare at the University of Mount Olive’s Tillman School of Business.

Steve Sugarman, MS, CHP, CHCM, is health physics project manager for the Radiation Emergency Assistance Center/Training Site (REAC/TS) at the Oak Ridge Institute for Science and Education, part of Oak Ridge Associated Universities.

Charles B. Cairns, MD, FACEP, FAHA, is dean of the University of Arizona College of Medicine, as well as a professor in the Department of Emergency Medicine and assistant vice president of the Arizona Health Sciences Center.

James. H. Holmes IV, MD, FACS, is director of the WFBMC Burn Center within the Wake Forest University Baptist Health System, and an associate professor of surgery in the General Institute for Regenerative Medicine at the Wake Forest University School of Medicine.

Bruce A. Cairns, MD, FACS, is director of the North Carolina Jaycee Burn Center as well as the faculty chair and John Stackhouse Distinguished Professor of Surgery/Microbiology and Immunology at the University of North Carolina School of Medicine.

Preston B. Rich, MD, MBA, FACS, is a professor of surgery in the Division of Acute Care Surgery at the University of North Carolina School of Medicine, and a firefighter and medical adviser for the Chapel Hill Fire Department.