Positron Emission Tomography (PET)

Sugar with positron-emitting Fluorine-19 (110 minute halflife).
Can be formed, eg, by the reaction [ F-19 + gamma -> F-18 + neutron ] .

Emitted positron encounters an electron and annihilates.
Two counter-propagating 511 Mev gamma rays are detected simultaneously.

Lung PET scan overlayed on CT scan