RADIATION BASICS
Anxiety and fear associated with radiation emergencies is often out of proportion to the degree of radiation-induced health effects.

Radiation and radiation injury are complex; however, two important concepts facilitate understanding: radioisotopes and ionization The first, radioisotopes (also called isotopes or radionuclides are the physical substances which release ionizing radiation as they decay. These radioisotopes can be toxic on their own without consideration to their radioactivity (or ability to release ionizing radiation). Radioisotopes can be found in any physical state (solid, powder, liquid, vapor, gas, even salts or other compounds). The second concept to understand is ionizing radiation. This is the “irradiation” portion of radioisotopes. Ionizing radiation is the invisible dose of energy that causes biological damage. This damage only occurs when exposed to a radioisotope.2

Four potential sources of radiation injury are:

1. Irradiation (no contamination, similar to an x-ray exposure).
2. External contamination (a radioisotope physically present on the patient that may also be irradiating the patient).
3. Internal contamination (a radioisotope has been inhaled, ingested, or injected into the patient: the radioisotope may also be irradiating the patient internally).
4. Incorporation (uptake of the radioisotope into the cells or tissue: in addition to the potentially heavy metal poisoning, the radioisotope is irradiating the patient internally).

Ionizing radiation is radiation that has enough energy to detach electrons from atoms, creating ions. Ions are atoms that have a positive or negative charge. There are five types of ionizing radiation: alpha, beta, gamma, neutron, and x-ray.3,4 Details of the sources and properties can be found in Table 1. All of these types of radiation can cause clinically significant impacts to a casualty. Clinical effects are determined by isotope, route of exposure, length of time exposed, and strength of and distance from the radiation source.5

Exposure to ionizing radiation can occur from natural and artificial sources. Of greatest concern to healthcare providers is release of ionizing radiation from artificial sources. These include industrial radiography, diagnostic and therapeutic clinical sources, nefarious use as part of a radiological exposure device (RED), radiological dispersal device (RDD), or through nuclear weapon detonation. Table 2 discusses potential radiological and nuclear weapons which can be used to expose a population to ionizing radiation.6,7

Isotopes are two or more forms of the same element that contain a varying number of neutrons. Commonly used isotopes are divided into four categories of concern:

1. The University Five (C14, P32, I125, I131, and Cf252) are used in laboratories and for medical care.
2. The Industrial Three (Ir192, Cs137, and Co60) are found in industrial radiography sources and are prime for terrorist use due to ease of access and the high energy emitted.
3. The Military Five (H3, U235, U238, Pu239, and Am241) are used in making nuclear weapons.
4. Fission products are radioactive decay products released after a nuclear detonation or power plant accident.

Table 1. Properties and clinical effects of ionizing radiation
Table 2. Radiology and nuclear devices

RADIOLOGICAL UNITS

The unit of exposure, the amount of energy deposited in tissue from being irradiated by a source, and the biological effects from being irradiated are described by three different units of measure. Both conventional and SI units of measure are regularly used. The unit of exposure is the Roentgen or Coulomb per kilogram. Deterministic clinical effects from absorbed dose are described in RAD or Gray. Equivalent dose from different types of radiation is described in REM or Sievert.9,10 Determining equivalent dose applies to stochastic effects and is dependent on type of ionizing radiation.

In the immediate aftermath of an incident, healthcare providers will see radiation exposure measured in Roentgen (R) when using detectors and discussion of Acute Radiation Syndrome (ARS) and Cutaneous Radiation Syndrome (CRS), based on dose received in RAD and Gray. This information is summarized in Table 3. It is extremely important to confirm the unit the detector utilizes, particularly the prefix as milli (m) and micro (µ) are often confused or even omitted when relaying dose and/or dose rate.

Table 3. Units of radiation measurement

CLINICAL INDEX OF SUSPICION

While there are no cases for radiation exposure in the DoDTR – military providers must have a clinical index of suspicion for radiation weapons on the future battlefield. The first step is management is identification and to recognize the risk of radiation weapons and RAD injury in the Area of Operations (AOR). Some patients will present immediately with a burn that was not from a flame or obvious exposure if they were close to the radiation source. The main factors that result in clinical manifestations are time of exposure, distance from source, and any shielding. Other symptoms are relatively non-specific. The severity and onset of symptoms depends on the dose received. The clinical syndromes are described in more detail later in this CPG – but clinicians may be the first to identify the use of radiation weapons based on casualties with the below (non-specific) findings.

#### Key Symptoms of Acute Radiation Syndrome (ARS) aka ‘Radiation Sickness’

1. Prodromal Stage will occur minutes to days after the radiation exposure

- Nausea and vomiting
- Diarrhea
- Fatigue and weakness
- Anorexia (loss of appetite)
- Headache

2. Latent Stage will occur hours to weeks after the radiation exposure

- Temporary improvement or stabilization of symptoms
- Patients may feel relatively well

3. Manifest Illness Stage occur weeks to months after the radiation exposure

- Hematopoietic Syndrome: Decreased white blood cell count, increased risk of infections, bleeding, and anemia
- Gastrointestinal Syndrome: Severe nausea, vomiting, diarrhea, dehydration, and electrolyte imbalance
- Cardiovascular/Central Nervous System Syndrome: Confusion, dizziness, hypotension, and potentially seizures or coma (at very high doses)
- Skin Damage: Redness, blistering, ulceration, and hair loss

Providers at deployed MTFs should be able to identify these patients if not initially because of the risk/threat of injury than through MTF PI events and clinical case reviews. Given the non-specific nature of these presentations, providers must have an index of suspicion for the clinical manifestations of radiation sickness

DECONTAMINATION CONSIDERATIONS

Lifesaving medical care takes priority over radiological decontamination efforts. Mettler, 2002

In the case of managing casualties in a known radiation hot zone: there is no documented case of medical personnel receiving a clinically significant dose while performing lifesaving interventions on a contaminated casualty. Medical personnel are extremely unlikely to receive a medically significant acute radiation dose when providing patient care to casualties with radioactive debris in wounds from an RDD (radiologic dispersal device).4,11 That being said, providers should shield themselves and wear appropriate PPE.

The physical state of the radioisotope will determine the best method of decontamination. If the patient has only been exposed to ionizing radiation, DECON IS NOT REQUIRED.

Personal Protective Equipment (PPE) should be selected such that eyes, nose, mouth, hair, and all exposed skin is covered. Respiratory protection should consist of a N95 or P100 mask. Double gloves and disposable apron or overgarment with long sleeves are sufficient skin coverage for personnel performing decontamination.5,12 While operating in a tactical or field setting, Mission-Oriented Protective Posture (MOPP) level 4 may be downgraded to mask and gloves in order to provide respiratory and dermal protection (See Appendix A for descriptions of levels of PPE). While full PPE changes may not be feasible when moving from casualty to casualty, frequent glove changes are recommended. During decontamination, the casualty should wear an N95 or P100 mask (or remain in their tactical respirator) to minimize inhalation of any aerosolized radioactive particles. Open wounds should be considered contaminated and irrigated using clean or sterile water and subsequently covered to prevent recontamination. If surgical debridement of radioactive shrapnel is required, consider utilizing x-ray (lead) aprons as PPE for the surgical team, or drape over the patient, when not actively operating. This will reduce any dose received by the providers.

Dry decontamination consists of removing all clothing, equipment, and personal effects from the casualty, and this step alone removes about 90% of external contamination from exposure to radioactive solids or liquids. Further dry decontamination involves brushing the skin to remove loose epithelial cells and/or using lint rollers or masking tape to remove contamination.6,13 Use of non-ethanol containing baby or wet wipes would be adequate to remove contaminants on skin and should be used in a motion that wipes away from the face and open wounds.

Wet decontamination consists of water and mild soap to remove contamination on the patient’s skin. Self-showering for ambulatory patients can be employed for large numbers of casualties. Avoid irritating the skin with aggressive abrasions and avoid contaminated fluid from entering the mouth/nose or wounds. If available, use indoor facilities for wet decontamination in temperatures below 65°F/18°C. If these facilities are unavailable, use of dry decontamination materials is recommended to prevent hypothermia.

Decontamination should be confirmed with appropriate radiological monitoring equipment utilized by personnel familiar with their use (See Appendix B). The goal for decontamination is to reduce external contamination to a level less than two times the background level, however, levels can be over two times without significant health risk to others.

Radiation detectors and dosimeters produce outputs with various different units. When decontaminating a patient, the detector should display in units of counts per minute (cpm) or counts per second (cps). This provides information on the amount of radioactive material present but does not provide information on the energy being deposited in tissue. The recorded cpm before and after decontamination indicate the effectiveness of the method and whether another iteration of decontamination is necessary.

#### Decontamination Principles for Radiation and Nuclear Exposures

1. Do not delay lifesaving interventions. TCCC principles take priority.

2. Prevent cross-contamination by donning the appropriate PPE (Appendix A).

3. Initial survey should include:

- Confirm radioactive contamination and dose rate if available.
- Identify isotope if appropriate detector is available. (Appendix B)
- Evaluate bulk external contamination (granular, powder, sand).
- Identify radioactive embedded sources (shrapnel) in wounds.

4. Goal of prompt wet or dry external decontamination is to decrease the risk of spreading the contamination and causing internal contamination through inhalation, ingestion, or absorption by avoiding the face/wounds.

5. Remove all clothing and equipment.

6. Cut clothing if needed. Do not rip or tear clothes as this may aerosolize or spread particles. Remove clothing and equipment away from the patient’s face and wounds. Consider the use of a barrier device (i.e. mask) to protect patient from inhalation and ingestion of contamination.

7. Priority order during the decontamination process:

Body orifices

- When irrigating wounds, protect body orifices and surrounding areas from irrigation run off.
- Have patient blow nose to remove contamination after obtaining bilateral nasal swabs with moist cotton swab for isotope identification and estimating level of lung radiation (*note swabs collected >1 hour after contamination may not be reliable and swabs may not be feasible in mass casualty events). Nasal and oral washes are not recommended as this can increase risk of ingesting contaminated material. Further information on nasal swabs can be found at https://remm.hhs.gov/nasalswabwarning.htm

Open wounds and burns

- Protect areas adjacent to wound from irrigation run off by wiping gently away from the wound.
- Use a drape or barrier over wounds during irrigation.
- Treat burns in accordance with the JTS Burn Care CPG.
- Radiological contamination may be present in burned tissues.
- Radioactive particulates identified with detectors should be removed from wounds and followed by wound irrigation.
- Place particulate matter in shielding containers and remove from patient care area.

Intact skin and hair

- Wipe with baby wipes and/or wash with soap and water.
- Gently wipe areas from outside-in to prevent spreading.
- Do not cause abrasions from aggressive rubbing.

Prolonged and aggressive surgical debridement to remove particulate matter is not indicated in a field or deployed setting. The ability to ensure there are no embedded radioactive sources (which is an unlikely event - perhaps onlyfor EOD attempting to render safe an RDD) can provide confidence of limited risk to patient and personnel. The ability to detect dose rate and isotope can provide further data to evaluate health risks.

TRIAGE

In a mass casualty event, assign triage categories based on conventional injury. After stabilizing traumatic injuries, and should resources to estimate dose become available, a secondary triage of casualties must occur to account for radiation. Further details for initial dose estimation (biodosimetry) are available in Appendix C. Those with suspected combined injury are moved to the next higher acuity triage category. If someone is suspected of receiving greater than a 6 Gy dose, they are triaged to expectant until more resources become available.14 Table 4 provides an overview of how to update triage categories for radiation. More comprehensive triage tools can be found at https://remm.hhs.gov/triagetool5.htm. As the event progresses and additional resources become available, iterative retriage of all casualties across all triage categories to include expectant, must occur.

In isolated irradiation, the most reliable early clinical indicators of whole-body radiation injury are the time-to-emesis and/or elevated body temperature, which can be seen in the early hours following exposure. When at a Role 3, or a Role 2 with lab capability, the most reliable early laboratory indicator is the lymphocyte depletion rate, which may not be available in 24-48 hours depending on the size of mass casualty and degree of infrastructure damage. While time to emesis is a rapid and inexpensive method for estimating the radiation dose, it should be used with caution because it is imprecise and may lead to very high false positive rate. 15

Table 4. Outline of how radiation injury dose modifies mechanical trauma and burns.