Radiological Exposure Devices (REDs)

Radiological Exposure Devices (REDs) = Hidden Sealed Radioactive Source

  • Definition of Radiological Exposure Device
  • Causes exposure (Animations) but NOT usually contamination
  • Example: hiding a hidden radioactive source on a subway or in a sports arena, where people would unknowingly receive radiation exposure (See Figure 1)
  • Dose from exposure and specific effect on people would depend on
    • Source properties: isotope, activity, amount
    • Proximity of each person to the source
    • Length of time people were in proximity to the source
    • Whether a person's whole body or only a portion of the body received exposure

    Figure 1. Hidden Sealed Radioactive Source (Radiological Exposure Device) in Train Car

    150 Ci Iridium-192 Source Under Seat

    Hidden sealed radioactive source in metro car: 150 Ci iridium source under seat Replay animation

    Ci = Curie; R = Roentgen; Γ constant = 4.69 R-cm2/mCi-hr.

    Note: This graphic describes radiation exposure rate (in air) in units of R/Hr. For gamma radiation, this is roughly equivalent to a radiation absorbed dose rate in units of cGy/hour, which must also take into account any shielding present, e.g., material in the seats in this example.

  1. Responding to an RDD / RED Emergency: the HHS Playbook, guidance for executive decision makers within the Department of Health and Human Services (HHS) in the event of an actual radiological terrorist attack in a U.S. city. (HHS/ASPR, April 2010)
  2. Radiation Exposure Device information sheet for the general public (HHS/CDC)
  3. The Regulation and Use of Radioisotopes in Today’s World (PDF - 1.1 MB) (NRC, April 2020)
  4. Radiological Sources of Potential Exposure and/or Contamination (PDF - 3.1 MB) (US Army Public Health Center, TG-238, January 2020)
    • This document provides details about radioisotopes of potential concern and where they are used. It updates the TG-238 document from 1999.

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