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Positron emission is mediated by the weak force. The positron is a type of beta particle (β +), the other beta particle being the electron (β −) emitted from the β − decay of a nucleus. An example of positron emission (β + decay) is shown with magnesium-23 decaying into sodium-23: 23 12 Mg → 23 11 Na + e + + ν e
The two types of beta decay are known as beta minus and beta plus.In beta minus (β −) decay, a neutron is converted to a proton, and the process creates an electron and an electron antineutrino; while in beta plus (β +) decay, a proton is converted to a neutron and the process creates a positron and an electron neutrino. β + decay is also known as positron emission.
Positron emission tomography (PET) [1] is a functional imaging technique that uses radioactive substances known as radiotracers to visualize and measure changes in metabolic processes, and in other physiological activities including blood flow, regional chemical composition, and absorption. Different tracers are used for various imaging ...
Positron emission tomography–computed tomography (better known as PET-CT or PET/CT) is a nuclear medicine technique which combines, in a single gantry, a positron emission tomography (PET) scanner and an x-ray computed tomography (CT) scanner, to acquire sequential images from both devices in the same session, which are combined into a single superposed (co-registered) image.
After a radioactive atom in a material undergoes a β + decay (positron emission), the resulting high-energy positron slows down by colliding with atoms, and eventually annihilates with one of the many electrons in the material. It may however first form positronium before the annihilation event.
The gamma emission of gallium-67 is imaged by a gamma camera, while the positron emission of gallium-68 is imaged by positron emission tomography (PET). Gallium salts like gallium citrate and gallium nitrate may be used. The form of salt is not important, since it is the freely dissolved gallium ion Ga 3+ which is active. [1]
Potassium-40 undergoes four different types of radioactive decay, including all three main types of beta decay: electron emission (β −) to 40 Ca with a decay energy of 1.31 MeV at 89.6% probability, positron emission (β + to 40 Ar at 0.001% probability, [1] electron capture (EC) to 40 Ar * followed by a gamma decay emitting a photon [Note 1 ...
bosons are verified mediators of neutrino absorption and emission. During these processes, the W ± boson charge induces electron or positron emission or absorption, thus causing nuclear transmutation. The Z boson mediates the transfer of momentum, spin and energy when neutrinos scatter elastically from matter (a process which conserves charge).