Radiological Weapons By James M Madsen, MD, MPH, U S.Army Medical Research Institute of Chemical Defense (USAMRICD) Reviewed / Revised Jan 2023 View Patient Education Ionizing radiation and its effects are discussed in detail elsewhere (see Radiation Exposure and Contamination). Mass casualties due to ionizing radiation can result from the detonation of a nuclear (fission) or a thermonuclear (fusion) device, from the contamination of conventional explosives with radioactive material (such a weapon is called a radiation dispersal device, or a dirty bomb), or from placement (eg, under a subway seat) of a concealed point source of radiation.