A positron is an anti-electron. They are given off during the breakdown of the nuclei
of specific radioisotopes. A type of radioactive fluorine produced at
TRIUMF for the PET program is a positron emitter. When matter collides with its corresponding
anti-matter, both are annihilated. The result is the release
of pure energy in the form of gamma rays. When a positron meets an electron, the collision produces two gamma
rays having the same energy, but going
in opposite directions. The gamma rays leave the patient's body and are detected by the PET scanner.
The information is then fed into a computer to be
converted into a complex picture of the patient's working brain.
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