Positron emission, also known as beta plus decay, is a type of radioactive decay in which a proton within the nucleus of an atom turns into a neutron, releasing a positron and a neutrino. Some synonyms for positron emission include beta plus decay, electron capture, and positron decay. These terms refer to different types of radioactive decay, but all involve changes in the number of protons and neutrons in the nucleus of an atom. Positron emission is commonly used in medical imaging techniques such as PET scans, which use positron-emitting isotopes to track the movement of molecules in the body.