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The threat of a terror attack employing nuclear or radiation-related devices is unequivocal in the twenty-first century. Such an attack would certainly have the potential to cause unique and devastating medical and psychological effects that would require prompt action by members of the medical community. This chapter outlines the most probable scenarios for an attack involving radiation as well as the medical principles for handling such threats.
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Potential terrorist incidents with radiologic consequences may be considered in two major categories. The first is the use of radiologic dispersal devices. Such devices disseminate radioactive material purposefully and without nuclear detonation. An attack with a goal of radiologic dispersal could take place through use of conventional explosives with incorporated radionuclides (“dirty bombs”), one or more fixed nuclear facilities, or nuclear-powered surface vessels or submarines. Other means could include detonation of malfunctioning nuclear weapons with no nuclear yield (nuclear “duds”) and installation of radionuclides in food or water. The second and less probable scenario is the actual use of nuclear weapons. Each scenario poses its own specific medical threats, including “conventional” blast or thermal injury, introduction to a radiation field, and exposure to either external or internal contamination from a radioactive explosion.
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TYPES OF RADIOISOTOPIC RADIATION
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Atomic isotopes with uneven numbers of protons and/or neutrons are typically unstable; such isotopes discharge particles or energy to matter as they move to stability, a process that is defined as radiation. Mass-containing particles, including alpha particles, electrons, and/or neutrons, may be transferred during this process (alpha radiation, beta radiation, and neutron radiation, respectively); alternatively, the transfer may consist only of energy in the form of a gamma ray. Alpha (α) radiation consists of heavy, positively charged particles, each of which contains two protons and two neutrons. Alpha particles usually are emitted from isotopes that have an atomic number of ≥82, such as uranium and plutonium. Due to their large size, alpha particles have limited penetrating power. Fine obstacles such as cloth and human skin usually can stop these particles from penetrating into the body. Thus they represent a small risk from external exposure. If they are somehow internalized, however, alpha particles can cause significant damage to human cells that are in their immediate proximity.
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Beta (β) radiation consists of electrons, which are small, light, negatively charged particles (about 1/2000 the mass of a neutron or proton). Electrons can travel only a short, finite distance in tissue, with the precise distance depending on their energy. Exposure to beta particles is common in many radiation accidents. Radioactive iodine released in nuclear plant accidents is the best-known form of beta radiation. Plastic layers and clothing can stop most beta particles, and their penetration is generally measured at a few millimeters. A large quantum of energy delivered via beta particles to the basal stratum of the skin can cause a burn that is similar to a thermal burn ...