Radiation exposure from a radiological/nuclear incident, including accidents, acts of terrorism, and nuclear reactor events could result in mass casualties and expose victims to substantial doses of ionizing radiation. These events create challenges for initial responders to effectively triage casualties and assess radiological exposures, further complicated by biological radiation absorption characteristics. Depending on the absorbed dose, the biological intensity and onset/latency of Acute Radiation Syndromes (ARS) and Delayed Effects of Acute Radiation Exposure (DEARE) vary. ARS follows a deterministic path whereby dose effects have distinct clinical outcomes. Therefore, early detection of the extent of radiation injury is critical to ensure timely administration of countermeasures and proper allocation of the available resources necessary to save lives.
Studies have identified a panel of candidate radio-responsive serum proteins and messenger RNAs in peripheral blood; however, tests that measure these responses do not appear robust across a broad dose range and their sensitivity, accuracy, and rapidity are not adequate for use in triage for a mass casualty event. Inherent issues such as the depletion of lymphocytes, differences in DNA damage response, and gene variation in stress response sensitivity confound normalization and radiation dose reconstruction readings from these messenger RNA panels.
Current approaches for radiation biodosimetry rely on clinical symptoms, evaluation of lymphocyte depletion kinetics, as well as dicentric chromosome assay (DCA) assessment. Unfortunately, the DCA requires processing in a specialized laboratory and a three to four-day analysis time. Patients who receive high doses of radiation usually require management decisions well before DCA results are available. With limited national laboratory capacity and a small but critical window to begin patient treatment, a biodosimetry solution capable of overcoming these challenges in the initial phase of a large-scale incident is vital to emergency preparedness.