composition radiation quality radiation beam composition http://orcid.org/0000-0002-5111-7263 The types and characteristics of particles or waves that make up the radiation produced or emitted by a radiation source for use in a particular exposure context or protocol. The source may be artificial as in a particle accelerator or natural, in a controlled environment, such as a collimated beam from a radioactive isotope. beam composition https://orcid.org/0000-0001-9227-0670