ABSTRACT
This chapter describes the clinically relevant physical and other factors that influence the intensity of radiation-induced emesis during the acute radiation syndrome, and briefly reviews clinically used antiemetics. The human emetic response to radiation has been described primarily for X-ray and γ-photons, which are both considered electromagnetic radiation and indirectly ionizing. Head-only radiation therapy involves irradiation primarily of the brain and various head and neck structures with megavoltage X-rays to treat tumors. The neural effects of brain irradiation that cause emesis may be direct, indirect, or both. Radiation-induced emesis is totally suppressed during this incapacitation, but returns when the animal recovers. The psychological state probably influences the incidence of radiation-induced emesis. Domperidone, another dopamine receptor antagonist, was tested as an antiemetic for radiation-induced emesis in humans only once. The radiation-induced hypomotility will also alter the intestinal bacterial flora, which could act as a toxic trigger.
