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U.S. Department of Health & Human Services
Radiation Emergency Medical Management (REMM)

Hidden Sealed Radioactive Source (Radiological Exposure Device) in Train Car - Illustration
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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.