Bun (hairstyle) Bun (hairstyle) A bun is a type of hairstyle wherein the hair is pulled back from the face, twisted or plaited, and wrapped in a circular coil around itself, typically on top or back of the head or just above the neck. A bun can be secured with a hair tie, barrette, bobby pins, one or more hair sticks, a hairnet, or a pen or pencil. Hair may also be wrapped around a piece called a "rat". Alternatively, hair bun inserts, or sometimes rolled up socks, may also be used to create donut-shaped buns. Buns may be tightly gathered, or
Commonly used gamma-emitting isotopes into a tumor such as a breast tumor, and the tumor is irradiated by gamma ray photons from the wire. At the end of the treatment the wire is removed. A rare but notable gamma source is sodium-24, this has a very short half-life but it emits photons with very high energies (>2 MeV). It could be used for radiography of thick steel objects if the radiography occurred close to the point of production. In common with Co-60 and Ir-192 it is formed by the neutron activation of the commonly found stable isotope. Americium-241 has been used as a source