ICU · Environmental emergencies
Radiation Injury
Also known as Acute radiation syndrome · ARS · Radiation sickness · Hematopoietic subsyndrome · GI subsyndrome · Neurovascular subsyndrome · Cutaneous radiation syndrome · Radiation emergency · Deterministic tissue reaction · Stochastic radiation effect · Internal contamination / radionuclide incorporation
The acute radiation syndrome (ARS) is the illness caused by a high dose of whole-body ionising radiation delivered over a short time, producing three dose-dependent subsyndromes: the HEMATOPOIETIC (1-2 Gy, bone-marrow suppression, pancytopenia, infection and bleeding), the GASTROINTESTINAL (6-8 Gy, mucosal sloughing, fluid loss and sepsis) and the NEUROVASCULAR (above 30 Gy, cerebral oedema, seizures, coma, cardiovascular collapse). It evolves through four classical phases — prodromal, latent, manifest illness, and recovery or death. Radiation injury is best understood through two effect categories: DETERMINISTIC (tissue reactions with a dose THRESHOLD and severity that rises with dose — e.g. skin erythema 2 Gy, cataracts 0.5 Gy, bone-marrow suppression 1 Gy, GI syndrome 6-8 Gy, neurovascular syndrome above 30 Gy) and STOCHASTIC (cancer and heritable effects with NO threshold where PROBABILITY, not severity, rises with cumulative dose). The four radiation types behave very differently as hazards: ALPHA (stopped by paper/dead skin — an internal hazard only if inhaled/ingested), BETA (penetrates a few mm — causes skin burns), GAMMA and X-RAY (highly penetrating — a whole-body external hazard) and NEUTRON (penetrating and induces secondary radioactivity). Management is built on five pillars: (1) scene safety and external DECONTAMINATION (removing clothing removes ~90% of external contamination), (2) supportive ICU care with irradiated blood products, (3) cytokines (G-CSF / GM-CSF / pegfilgrastim) to accelerate neutrophil recovery, (4) treatment of internal contamination with specific countermeasures (Ca/Zn-DTPA for plutonium and transuranics, Prussian blue for caesium-137 and thallium, potassium iodide for radioactive iodine) and (5) haematopoietic stem-cell transplant for the most severe, irreversible marrow injury.
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Red flags
- The TIME TO VOMITING is the single best bedside dose estimator: vomiting within 1 hour of exposure implies a very high (often fatal) dose above 6 Gy; vomiting after 2 hours implies a lower dose. The earlier the vomiting, the higher the dose and the worse the prognosis
- Removing contaminated clothing removes ~90% of external contamination — do this FIRST, before any decontamination wash or patient transfer. Staff must wear appropriate PPE and use time, distance and shielding principles
- Do NOT scrub contaminated skin — skin damage increases radionuclide absorption. Wash gently with soap and water, bag all clothing and wash-water as radioactive waste
- The LATENT phase is deceptive — the patient looks well while the bone marrow and gut are failing. Serial absolute lymphocyte counts (the Andrews lymphocyte-depletion nomogram) estimate whole-body dose; lymphocytes below 1.0 x10^9/L at 24 hours implies a severe (above 4 Gy) exposure
- All transfusions in ARS must be IRRADIATED and LEUKODEUCED to prevent transfusion-associated graft-versus-host disease (TA-GvHD) and CMV transmission — the immunocompromised marrow cannot reject donor lymphocytes
- Start G-CSF / GM-CSF EARLY (within 24-72 hours), do not wait for manifest neutropenia — early cytokines reduce the depth and duration of neutropenia and the risk of neutropenic sepsis
- Internal contamination requires a SPECIFIC countermeasure matched to the radionuclide: Ca/Zn-DTPA for plutonium/americium/curium (transuranics), Prussian blue for caesium-137 and thallium, potassium iodide for radioactive iodine (most effective if given within 4 hours, little benefit after 24 hours)
- Potassium iodide does NOT protect against caesium (Chernobyl) or any radionuclide other than iodine — giving KI after a Cs-137 or non-iodine release is ineffective and creates a false sense of protection
- Whole-body dose above 8-10 Gy with irreversible marrow failure and a suitable donor is an indication for haematopoietic stem-cell transplant; dose above 10-12 Gy with refractory GI-toxicity carries near-100% mortality and transplant is futile
- DETERMINISTIC effects have a threshold (severity rises with dose, e.g. skin erythema, cataract, marrow suppression); STOCHASTIC effects have NO threshold (cancer — probability, not severity, rises with cumulative dose). Both have exam-favourite 'threshold or not?' questions
- Alpha radiation cannot penetrate intact skin and is essentially harmless externally, but inhaled/ingested alpha emitters (e.g. polonium-210, plutonium, radium) are among the most carcinogenic substances known — alpha is an INTERNAL hazard only
Meet the patient
A 38-year-old sterilisation-plant technician is brought in three hours after leaning over a damaged cobalt-60 source. He vomited once at ninety minutes, has watery diarrhoea, and looks frightened but well. The nurse wants to send him to the ward. His baseline lymphocyte count was normal; you already drew another tube.[1]
The trap is standing in front of you. He looks well because he is in the latent phase — the deceptive interval where prodromal symptoms settle while the marrow and gut are silently failing. The single most important number you will collect over the next 72 hours is the absolute lymphocyte count, and the single most important question for the examiner is whether you can estimate his whole-body dose at the bedside.[3]
References9ShowHide
- [1]Benderitter M, Arnautou P, Bartels C, et al. European Approach for Acute Radiation Syndrome's Management Facing Radiological and Nuclear Threats: A Call for Arms Disaster Med Public Health Prep, 2025.PMID 41234135
- [2]Dainiak N, Akashi M, Chao N, et al. Cytokine use in the hematopoietic subsyndrome of acute radiation syndrome (H-ARS): implications for the role of cytokines in a mass casualty radiologic/nuclear (R/N) emergency J Radiol Prot, 2026.PMID 41678840
- [3]Waselenko JK, MacVittie TJ, Blakely WF, Pesik N, Wiley AL, Dickerson WE, et al. Medical management of the acute radiation syndrome: recommendations of the Strategic National Stockpile Radiation Working Group Ann Intern Med, 2004.PMID 15197022
- [4]Dent RA Management of Casualties from Radiation Events Eur Burn J, 2023.PMID 39600027
- [5]Kazzi Z, Buzzell J, et al. Emergency department management of patients internally contaminated with radioactive material Emerg Med Clin North Am, 2015.PMID 25455668
- [6]Sakamoto-Hojo ET Lessons from the accident with (137)Cesium in Goiania, Brazil: Contributions to biological dosimetry in case of human exposure to ionizing radiation Mutat Res Genet Toxicol Environ Mutagen, 2018.PMID 30389165
- [7]Farina R, Brandão-Mello CE, Oliveira AR Medical aspects of 137Cs decorporation: the Goiania radiological accident Health Phys, 1991.PMID 1983984
- [8]Reiners C, et al. High-dose radiation exposure and hypothyroidism: aetiology, prevention and replacement therapy J Radiol Prot, 2021.PMID 34547726
- [9]Palmer JL, et al. Development of a combined radiation and burn injury model J Burn Care Res, 2011.PMID 21233728