Author: Mallika Singh, MD

Editor: Jonathan Kobles, MD

Background

Unintentional or intentional exposure to radiological material represents a potential threat to human health on the individual to mass-casualty scale. Radioactive sources include medical isotopes, fuel rods, generators, and other industrial sources. Due to their availability, iridium-192, Cesium-137, and Cobalt-60 are often viewed as the substances posing the greatest threat for intentional radiation exposure. Despite the rarity of radiation exposure, it is important to remain well-versed in the triage and treatment of these patients.

Sources of Radiation

  • Cosmic: Radiation generated by the sun and stars.
  • Internal: Radiation that is present in living organisms (e.g., from 40K and 14C isotopes), or administered intentionally for internally present in living organisms (e.g., from 40K and 14C isotopes) or administered intentionally for internal radiotherapy (brachytherapy).
  • Terrestrial: Radiation that emanates from natural earth sources.

Types of Exposure

  • Contamination: A radioactive substance may cover an object (e.g., through spills, intentional dispersal) or can reside internally following ingestion, inhalation, or wounds.
  • Incorporation: When a radio-nuclide is taken up by tissue.

Units of Measurement

  • Rem & Sieverts measure relative biological damage to a body (equivalent dosimetry), accounting for the type(s) of exposure and particle; 1 Sv = 100 rem.

Exposure Levels

  • Exposure levels are typically unavailable in real-time due to the requirement of source and patient sampling and modeling.
  • Individual medical exposures tend not to be significant; however, patients with conditions requiring repeat imaging throughout their lifetime (especially from a young age) or those who are victims of poly-trauma or medical illness requiring frequent imaging have a higher risk of lifetime malignancy.

 

    • 10-Hour Flight: 0.03 mSv
    • Chest Xray: 0.1 mSv
    • CT Head: 2 mSv
    • A Year on Earth: 3 mSv
    • CT Abdomen/Pelvis: 10mSv
    • 201Tl cardiac stress test: 40.7 mSv
    • Lethal Dose (LD50/60): 3500 to 4500 msv

Decontamination

  • Protection from ionizing radiation rests upon the principles of maximizing shielding and distance while minimizing the time of exposure.
  • Once a radioactive threat is identified, prior to caring for patients, all staff should don appropriate personal protective equipment: disposable scrubs with taped seams, waterproof shoe covers, bouffant, masks, goggles, and a dosimeter.
  • Patients should be assessed with a Geiger counter prior to decontamination.
  • Patients should be externally decontaminated by carefully removing all clothing and belongings and washing the body with soap and water. Contaminated hair can be removed by clipping or scissors (but not shaving).
  • Geiger counter measurements and decontamination procedures are repeated until radioactivity measures below two times the baseline radiation of the natural environment.
  • Decontamination considerations should be made in climates with cold temperatures and for EMS personnel entering the hospital with patients without on-scene decontamination.

Triage and Patient Evaluation

  • Triage should be based on conventional trauma needs. Decontamination should not take precedence over ABCs and management of a traumatic injury.
    • It is highly unlikely that radioactivity from a contaminated patient would pose a health risk to treating healthcare personnel.
  • Because most radiation injuries are not immediately life-threatening, patients with isolated radiation injuries will not require immediate attention in mass casualty events.
    •   Patients should be triaged based on the severity of acute traumatic injuries and medical symptoms.
  • Patients presenting following environmental exposures should prompt preparation of mass casualty alogrithms and treatment pathways.
  • When collecting HPI information, focus on the timing and onset of Acute Radiation Syndrome symptoms, including: nausea, vomiting, bloody diarrhea, confusion, loss of consciousness, or fever.
  • On physical examination, assess for cutaneous skin lesions, petechiae, papilledema, focal neurologic deficits, and/or abdominal tenderness.
  • It is recommended that all surgical procedures be performed within 36 hours of exposure due to the possibility of developing anemia, thrombocytopenia, immunosuppression, and GI bleeding.

Acute Radiation Syndrome

Acute radiation syndrome requires the fulfillment of multiple conditions.

    • The dose must be external to the body.
    • The radiation must be of penetrating quality: high energy x-rays, gamma rays, and/or neutrons.
    • The entire body or a significant portion must have been exposed.
    • The dose must have been delivered over a short period of time.
    • The radiation dose must be large, greater than 700 mSv.

Prodrome: 0-2 days after exposure. Characterized by anorexia, apathy, nausea, emesis, diarrhea, fever, and headache. The onset of symptoms within 2 hours indicated a potentially lethal exposure. This phase can be mild or absent if exposure is low.

Latent: 2-20 days after exposure. Characterized by a symptom-free period.

Manifest Illness: 21-60 days after exposure. Characterized by organ dysfunction.

Recovery: Months to years after exposure.

  • The only markers of prognosis are absolute lymphocyte count and time to onset of gastrointestinal symptoms from the time of exposure.

Organ Systems

Hematopoietic

  • Bone marrow is the first organ system to show signs of injury through leukopenia and thrombocytopenia.
  • Lymphocyte nadir is seen within 8-30 days after exposure.
  • Mortality results from pancytopenia leading to sepsis and hemorrhage. Thus, supportive care, prophylactic antimicrobials, and neutropenic precautions are important in the management of exposed patients.

Gastrointestinal

  • GI involvement most commonly develops within 5 days of exposure.
  • At doses near 5000 mSv, the destruction of intestinal cells leads to a loss of the mucosal barrier and bleeding.
  • Mortality is caused by dehydration, electrolyte imbalances, bacterial translocation, bowel wall necrosis, and subsequent perforation.

Central Nervous System/Neurovascular

  • Occurs only with substantial irradiation and is universally fatal.
  • Presentation includes the rapid onset of nausea and vomiting followed by confusion, imbalance, fever, hypotension, seizure, coma, and death.

Cutaneous

  • Cutaneous radiation occurs in 4-5 stages: Prodromal, Latent, Manifest Illness,  3rd Wave, and Late effects.
  • Early signs of cutaneous damage include erythema, inflammation, desquamation, pigmentation changes, and epilation. Late signs of damage may include blood vessel injury, chronic edema, pain, ulceration, and blue discoloration. Ultimately, reactions ranging from dermal thinning to recurrent ulcerations, tissue necrosis, and invasive fibrosis may occur.
  • Many of these symptoms may be treated with antihistamines, antibiotics, and corticosteroids. For severe full-thickness burns, early full-thickness skin grafting is a consideration.

Management

  • Emergency department treatment of radiation exposure is prioritized to treat traumatic injuries, burns, and unstable medical conditions, with simultaneous decontamination and sample collection. Patients may be stabilized with fluids, blood products, analgesics, and vasoactive medications.
  • Critical laboratories include a complete blood count with differential, including a lymphocyte count, with reassessments every 2-3 hours within the first 8-12 hours to determine lymphocyte depletion. Blood type and screening/crossmatching supports potential blood product transfusion. HLA typing is preformed early if bone marrow or stem cell transplant is anticipated base on exposure (>2Gy).
  • Take color photographs of areas of suspected cutaneous exposure to monitor stages of cutaneous radiation syndrome.
  • Inpatient treatment will include the management of electrolytes secondary to oral and rectal fluid losses, cytopenias, and cutaneous wounds.
  • Inpatient treatment can be further tailored towards radiation exposure after identification of the offending agent. Examples of exposure specific treatment include:
    • Tritium (3H): treated with adequate hydration
    • Radioactive Iodine: treated with Potassium Iodide
    • Radioactive Cesium & Thallium: treated with Prussian Blue
    • Americium, Curium, and Plutonium: treated with DPTA (Diethylenetriamine Pentaacetate)
    • Radioactive Strontium: treated with Aluminum Phosphate (AlPO4) gel to bind Sr in the gut
    • Colony-stimulating factors can be used to produce more white blood cells (e.g., filgrastim, sargramostim) and platelets (e.g., romiplostim) to prevent infection from neutropenia and are given early if required.

References:

  1. American Cancer Society. Understanding Radiation Risk from Imaging Tests. https://www.cancer.org/treatment/understanding-your-diagnosis/tests/understanding-radiation-risk-from-imaging-tests.html#:~:text=A%20single%20chest%20x%2Dray,background%20exposure%20over%207%20weeks.
  2. Chandler, David L. “Explained: Rad, REM, Sieverts, Becquerels.” MIT News | Massachusetts Institute of Technology, https://news.mit.edu/2011/explained-radioactivity-0328.
  3. Centers for Disease Control and Prevention, Centers for Disease Control and Prevention. Radiation Emergencies. 6 Aug. 2021, https://www.cdc.gov/nceh/radiation/emergencies/.
  4. Hryhorczuk D, Theobald JL. Radiation injuries. Emergency Medicine: Concepts and Clinical Practice. 9th ed. Philadelphia, PA: Elsevier; 2018:(Ch) 138.
  5. “Ionizing Radiation Injuries and Illnesses: Ensuring Patient Safety and Self-Preservation.” EmDOCs.net – Emergency Medicine Education, 7 Apr. 2017, http://www.emdocs.net/ionizing-radiation-injuries-illnesses-ensuring-patient-safety-self-preservation/.
  6. Lopez AM, Stephani JA. Radiation injuries. Tintinalli’s Emergency Medicine: A Comprehensive Study Guide. 8th ed. New York, NY: McGraw-Hill; 2012:51–57.
  7. OlympicHealthPhysics. “How to Use a Geiger Counter.” YouTube, 21 November 2022, https://www.youtube.com/watch?v=_ydgmg4gbkU&ab_channel=OlympicHealthPhysics.
  8. “Radiation Emergencies.” Centers for Disease Control and Prevention, Centers for Disease Control and Prevention, 6 Aug. 2021, https://www.cdc.gov/nceh/radiation/emergencies/.
  9. Shen, J, et al. “Chapter: Radiation Injury and Emergency Medicine.” IntechOpen, IntechOpen, 21 Dec. 2020, https://www.intechopen.com/chapters/61433.
  10. Shen, J, et al. “Chapter: Radiation Injury and Emergency Medicine.” IntechOpen, IntechOpen, 21 Dec. 2020, https://www.intechopen.com/chapters/74507.
  11. Tsujiguchi, T., Suzuki, Y., Sakamoto, M. et al. Simulation study on radiation exposure of emergency medical responders from radioactively contaminated patients. Sci Rep 11, 6162 (2021). https://doi.org/10.1038/s41598-021-85635-2
  12. World Health Organization. National stockpiles for radiological and nuclear emergencies: policy advice. Geneva: World Health Organization; 2023