Management of Radiation Exposure

Introduction

Radiation is perhaps one of the most feared yet misunderstood phenomena in the history of humankind. The Cold War created an ever-present undercurrent of nuclear anxiety which continues in many forms to this day. Current events demonstrate the ending of the Cold War has not erased the threat of a nuclear attack.

This chapter provides an overview of radiation injuries and associated management as well as the unique considerations applicable to the treatment of casualties of radiation events.

Types of Radiation

The type of radiation event influences the nature of the exposure (e.g., nonionizing versus ionizing radiation), types of ionizing particles (e.g., alpha particles, beta particles, neutrons) and/or x-ray or gamma rays.

Nonionizing radiation causes damage to cells through direct transfer of thermal energy (e.g., sunburn) and does not penetrate human tissue. Therefore, nonionizing radiation poses no risk of contamination, and is easily shielded by sunscreens, sunglasses, and clothing. Examples of nonionizing radiation include radio waves, microwaves, infrared light, and the visible portion of the electromagnetic spectrum into the ultraviolet (UV) light range.

Conversely, ionizing radiation has very short wavelengths, and includes higher frequency UV radiation, X-rays, gamma rays, and particulate ionizing radiation (e.g., alpha particles, beta particles, neutrons).  The different types of ionizing radiation exposure cause distinct injury. Particularly concerning are X-ray and gamma radiation since they cause local injury and acute radiation syndrome (ARS).1

Units of Measurement

Radiation can be measured in multiple ways. The activity is the amount of radiation emitted by the radioactive material. Exposure is the amount of radiation traveling through the air. The amount of energy absorbed by tissue is known as the absorbed dose, or dose rate. Dose rate also refers to the amount of radiation delivered per unit time. Finally, the biological effect of the radiation is known as the dose equivalent or effective dose.

There are multiple units used to measure each of the above characteristics. The International System of Units (SI) is now preferred.  

Table 1: Radiation Units of Measurement

For reference, a chest x-ray is about 0.02mSv and a CT scan of the chest is 6mSv. Acute radiation syndrome develops at about 500mSv and 5 Sv is frequently fatal.²

Principles of Radiation Safety

Protection from radiation is accomplished by the principles of distance, time, and shielding. Maximizing the distance from the exposure source is the most effective protective strategy.

As the formula indicates, the quantity or intensity (X) is inversely proportional to distance² from the source. Thus, distancing oneself from the source of radiation exponentially decreases the amount of exposure.

The health effects of radiation exposure are cumulative. Whether a person spends an hour next to a radioactive source or six periods of ten minutes, the total effect is the same. Minimizing exposure time is key to reducing risk.

Shielding is an important principle of radiation safety. Alpha particles can be stopped by a sheet of paper or a layer of skin, beta particles by less than one inch of plastic, and gamma rays by inches to feet of concrete or an inch of lead. Understanding the type of radiation exposure is important when determining the amount of shielding required.³

Types of Exposure

The concepts of external and internal contamination are key to understanding risk to the patient and healthcare provider. Radioactive substances that are on the patient is a type of external contamination and are typically of minimal concern. However, the clinical effects can be severe if the radioactive debris becomes integrated into the body via ingestion, inhalation, or absorption. Respiratory protection is of utmost importance when caring for a patient contaminated with radioactive material, particularly at the scene of the event.

When radiation passes through a person they have been irradiated, such as during a CT scan. Depending on the dose, this may cause health effects for the patient but will not make the patient a danger to others.

Table 2: Types of Radiation Exposure

Types of Radiation Events

Potential exposure events include, but are not limited to, a radiologic dispersal device, nuclear reactor incidents, and nuclear detonation. The type of event affects the likelihood of seeing concomitant injuries.

A radiologic dispersal device, colloquially known as a dirty bomb, is the use of conventional explosives to spread radioactive material. The primary effect is psychological as the population fears they have been exposed to radiation. In 1987 the opening of a radiotherapy capsule in Goiania, Brazil led to 249 people becoming contaminated with radiation. Yet, over 112,000 people went to the local stadium for medical screening.⁴ In addition to the wounded from the conventional explosive component, the “worried well” could easily overwhelm local emergency services. Given the dispersal of radiation across a wide area, the actual effect of radiation is likely quite small. Radioactive debris does pose a risk if ingested, and so all emergency responders working in the affected area should wear respirators for protection.

In the event of a nuclear reactor incident it is advisable to communicate with the plant operator to coordinate the best response. Modern nuclear power plants are generally quite safe. The most recent incident was in 2011 at the Fukushima Daiichi Nuclear Power Plant in Japan and resulted in no deaths or cases of radiation sickness.⁵

Detonation of a nuclear device is the most feared event. The initial injuries including blindness, burns, and trauma from the blast wave and projectiles. Gamma waves can cause severe irradiation. Highly radioactive debris is ejected into the atmosphere and will fall to the earth over the next several days.

The Clinical Presentation of Radiation Injury

Patients that receive a sufficient dose of radiation to a large portion of their body may develop acute radiation syndrome (ARS).

There are classically four stages of ARS:

There are three typical ARS syndromes that develop during manifest illness. Bone marrow is the most radiosensitive so this syndrome develops first, followed by the GI and CNS subtypes.⁶

Cutaneous Radiation Injury (CRI)

Cutaneous radiation injury (CRI) may occur in conjunction with ARS, or it can occur alone if the radiation was concentrated to a specific area of the body. Similarly to ARS, there is a prodromal, latent, manifest illness, and recovery phase. The prodromal phase includes erythema and itching. Within days to weeks the manifest illness phase occurs and is characterized by recurrence of erythema, edema, and may include ulceration and necrosis.⁷

Management of Radiation Injuries

Ideally, healthcare facilities should have a medical response plan for a nuclear or radiologic emergency as part of an all-hazards emergency management plan which can be referenced during radiologic events. In facilities with limited in-house radiation safety resources, it is recommended that those facilities reach out to a central resource to be connected with radiation safety subject matter experts for additional support. A process should be identified to access chelating agents to help managing internal contamination. For example, diethylenetriaminepentaacetic acid (DTPA) can be used for decorporation of radioactive plutonium, americium, and uranium.⁸

Preparation and Staff Safety

A separate triage and separate decontamination zone should be established outside the clean parts of the facility. If a separate decontamination zone is not feasible, facilities receiving casualties should have a separate area to care for patients following a radiation incident.  The contaminated area should be physically separated from the clean area by well marked signage. A buffer zone should be designated between the contaminated and clean areas to help prevent the spread of radioactive material. All unnecessary equipment should be removed from the contaminated area.  Unless patients have undergone a radiologic survey and decontamination prior to arrival at the receiving facility, assume all patients are contaminated.

Protective clothing should be worn by medical facility staff and include surgical scrubs, zip up coveralls (gown if not available), surgical cap, mask, booties, and eye protection. Two layers of surgical gloves are ideal, taping the inner set of gloves to the surgical gown. Respirators are most critical for rescue personnel, but should also be worn by healthcare personnel if there is any chance of patient contamination. Dosimeters should be worn by each staff member since the body senses cannot detect radiation.  Staff should only be committed to the contaminated area when needed, and should be rotated frequently to minimize exposure time. Absolutely no eating or drinking should be allowed in the contaminated area and bathroom use should occur prior to entering.

Depending on the available resources, additional equipment can help identify and contain the spread of radiation contamination which includes the Geiger-Mueller (GM) survey meter and ionization chamber survey meters. The GM survey meter detects alpha, beta, and gamma radiation and can rapidly identify the presence of contamination while the ionization chamber survey meters can be used to determine the safe amount of time that staff can stay in close proximity to a patient who has significant contamination before they need to be relieved by another individual.⁹

Patient Decontamination

When patients arrive following a radioactive exposure, the priority is patient stabilization.  Patients with immediately life-threatening conditions should be brought directly to the resuscitation area prior to radiologic survey and decontamination. Conversely, stable patients should be decontaminated (in a separate decontamination area if that exists) before the patient is brought into the clean area of the healthcare facility.

Contaminated skin and clothing is not a medical emergency as the vast majority of the contamination is eliminated with removal of clothing. When taking off clothing avoid shaking since this may dislodge radiation contamination into the air or back onto the patient.  Following stabilization, patient decontamination should occur and the patient should be surveyed for external contamination with a GM probe that is covered by a clear, waterproof, plastic bag to prevent contamination. The findings should be documented on an anatomic chart.¹⁰ In terms of decontamination, it should occur in the following order: open wounds should be irrigated first followed by decontamination of the face and facial orifices (eyes, nose, mouth, and ears), then the hair, and finally the skin.  Contaminated wounds can lead to rapid incorporation of radioactive substances into the body and are a high priority. The wound should be gently irrigated with lukewarm water or normal saline; vigorous scrubbing should be avoided.  Excision of open wounds is reserved for long-lived radionucleotides, especially alpha-emitting.  The mouth, nose, eyes, and ears require special attention in decontamination because of the potential for more rapid absorption of radioactive material from these sites.¹¹ The eyes and ears should be irrigated while mouth rising and tooth brushing should also occur. Swallowing must not occur to prevent internal contamination.  Hair should be washed using shampoo since this is a likely site for contamination.  Once complete, the rest of the patient can be washed with soap and water working from the periphery to the center. All jewelry should be removed and washed as well. Clothing removed from patients should be labeled, double bagged using polythene bags, and placed in a designated area. If possible, all runoff from the decontamination process should be collected.

Skin decontamination is necessary for external contamination and skin contact with radioactive solids and liquids. The goal for decontamination is to achieve background radiation, but twice background may be considered acceptable. Skin decontamination is not necessary for exposure by irradiation from external sources as these patients are NOT radioactive and thus not a danger to rescuers or healthcare personnel. 

Internally Contaminated Patients

Patients who have internal contamination with radioactive isotopes require more specialized treatment. Internal contamination occurs through inhalation, ingestion, wound/burns in the skin. Urine and feces can be examined for radioisotopes to detect internal contamination. If the radiation incident involved an explosion or fire, inhalation of radioactive material should be assumed.¹² The effective treatment depends on the radionucleotide involved.  In these cases, consultation with specialists in hematology, oncology, and radiation medicine should be considered.

There are some radioactive isotopes that have potential medications which can mitigate internal contamination. Potassium iodine can be taken to block thyroid uptake of radioactive iodine. Potassium iodine is most effective when administered soon after exposure. When administered immediately before and 2, 8, and 24 hours after exposure, potassium iodide prevents 100, 80, 40, and 7 percent, respectively, of the radioiodine deposition.¹³ A single dose provides protection for approximately 24 hours. The treatment with potassium iodide is prioritized by age with infants, children, and pregnant and breastfeeding women given priority due to their heightened risk of thyroid cancer.¹⁴ Prussian blue (ferrihexacyano-ferrate II) can be administered to patients internally contaminated with substances such as cesium-137, rubidium-82, or thallium-201 to prevent recycling of the radioactive substance. Additionally, patients with potential incorporation of the transuranics (eg, plutonium-239 or yttrium-90) can receive calcium or zinc diethylene triamine penta-acetate (DTPA) for chelation.¹⁵

Laboratory Monitoring

Serial lymphocyte counts can be obtained to assist in prognostication of ARS. As they are the first cell line to decrease, trending the lymphocyte count every 4-6 hours for the first 2-3 days and plotting results on the Andrews Lymphocyte Nomogram provides valuable information about the degree of radiation injury sustained.

Treatment of Radiation Syndromes

All patients should receive supportive care in the form hydration and antiemetics. Neutropenia should be treated empirically with broad-spectrum antibiotics. Colony-stimulating factors can be considered in certain patients; consultation with hematology is recommended.

Disposition

For patients whose evaluation found no evidence of radiation injury or contamination, management should be based on the nature and extent of other injuries. Patients can be discharged unless other presenting complaints and/or injuries require further care.

Bodies of the deceased should be placed in a separate morgue, such as a refrigerator trailer. If the bodies cannot be completely decontaminated, they must be buried. Cremation will not destroy nuclear material. 

Emergency Department Approach to the Suspected Radiation Patient

Below is a treatment algorithm created by the Radiation Emergency Assistance Center/Training Site for the use of emergency departments receiving patients with suspected radiation injury.

Summary

• Exposure to ionizing radiation can be reduced by minimizing the time of exposure, maximizing the distance to the source, and with shielding.
• Radiation safety measures should be designed to limit radiation contamination and exposure of patients, hospital personnel, hospital equipment, and the facility.
• Prioritize life-threatening and serious medical conditions over decontamination efforts.
• Unless they have undergone a radiologic survey and decontamination prior to arrival at the receiving facility, assume all patients are contaminated.
• Preliminary decontamination (e.g., removal of clothing, washing of the victim) should begin prior to entry to the medical facility and can remove 90 to 95% of external contamination and limit additional radiation injury.
• Acute radiation syndrome has a prodromal, latent, manifest illness, and recovery phase
• Acute radiation syndrome puts patients at high risk of hypovolemia, infection, and bleeding
• Serial lymphocyte counts provide prognostication in acute radiation syndrome

Further Reading:

US Centers for Disease Control and Prevention, Acute Radiation Syndrome Fact Sheet for Physicians

https://www.cdc.gov/nceh/radiation/emergencies/pdf/arsphysicianfactsheet.pdf

Oak Ridge Institute For Science and Education, Radiation Emergency Resources

https://orise.orau.gov/index.html

Radiation Emergency Medical Management, US Department of Health and Human Services

https://remm.hhs.gov/

References

1 Radiation emergencies: Acute radiation syndrome: A fact … [Internet]. [cited 2022Mar27]. Available from: https://www.cdc.gov/nceh/radiation/emergencies/pdf/arsphysicianfactsheet.pdf

2  ACR RSNAand. Radiation dose in X-ray and CT exams [Internet]. Radiologyinfo.org. RadiologyInfo.org; 2020 [cited 2022Mar27]. Available from: https://www.radiologyinfo.org/en/info/safety-xray

3 Cone D, Brice JH, Delbridge TR, Myers. Chapter 37: Radiation and radiation injury. In: Emergency medical services: Clinical practice and systems oversight. John Wiley & Sons; 2015. p. 339–47.

4 Executive Summary. In: The radiological accident in goiânia: 1988. Vienna: International Atomic Energy Agency; 1988. p. 2.

5  Chapter 4: Radiological Consequences. In: The Fukushima Daiichi accident. Vienna, Austria: International Atomic Energy Agency; 2015. p. 131–.

6 Walls RM, Hockberger RS, Gausche-Hill M. Chapter 138: Radiation Injuries. In: Rosen’s emergency medicine: Concepts and clinical practice. Philadelphia, PA: Elsevier; 2018. p. 1805–12.

7 A brochure for physicians – CDC [Internet]. [cited 2022Mar27]. Available from: https://www.cdc.gov/nceh/radiation/emergencies/pdf/cri.pdf

8 Radiation Emergency Medical Management [Internet]. REMM. [cited 2022Mar27]. Available from: https://remm.hhs.gov/index.html

9 Bushberg JT, Kroger LA, Hartman MB, Leidholdt EM, Miller KL, Derlet R, et al. Nuclear/radiological terrorism: Emergency department management of Radiation Casualties. The Journal of Emergency Medicine. 2007;32(1):71–85.

10 Procedures for radiation decontamination [Internet]. Procedures for Radiation Decontamination – Radiation Emergency Medical Management. [cited 2022Mar27]. Available from: https://remm.hhs.gov/ext_contamination.htm

11 Radiation emergency assistance center/training site (REAC/TS) [Internet]. Oak Ridge Institute for Science and Education. [cited 2022Mar27]. Available from: https://orise.orau.gov/reacts/index.html

12 Managing Acute Radiation Syndrome (ARS). US Department of Health & Human Services. Radiation Emergency Medical Management. https://remm.hhs.gov/ (Accessed on March 21, 2022).

13 Zanzonico PB, Becker DV. Effects of time of administration and dietary iodine levels on potassium iodide (KI) blockade of thyroid irradiation by 131I from Radioactive Fallout. Health Physics. 2000;78(6):660–7.

14 Linet MS, Kazzi Z, Paulson JA. Pediatric considerations before, during, and after radiological or nuclear emergencies. Pediatrics. 2018;142(6).

15 Guidance for radiation accident management – REAC/TS [Internet]. Oak Ridge Institute for Science and Education. 2022 [cited 2022Mar27]. Available from: https://orise.orau.gov/resources/reacts/guide/index.html

16 Prehospital radiological triage poster [Internet]. [cited 2022Mar27]. Available from: https://orise.orau.gov/resources/reacts/documents/prehospital-radiological-triage-poster.pdf