Rubidium-82 is used for positron emission tomography. It is used in positron emission tomography. EEG has also been combined with positron emission tomography. Radioactive verapamil can be used for measuring P-gp function with positron emission tomography. C is one of the isotopes often used in positron emission tomography. Cu is used in Cu-PTSM as a radioactive tracer for positron emission tomography. Nitrogen-13 (N) is a radioisotope of nitrogen used in positron emission tomography (PET). Nuclei which decay by positron emission may also decay by electron capture. The increased photo-fraction is important for some applications such as positron emission tomography. When a positron collides with an electron, annihilation occurs. Examples are charged particle beams, an electron cloud in a Penning trap and positron plasmas. It consists of an antiproton with a positron. It predicts electron spin and led Dirac to predict the existence of the positron. Maximum energy of positron emission is at 1.9 MeV. Rb is a positron and gamma emitter.