Antimatter in Medicine

Antimatter sounds exotic, but your body makes it every day. Potassium-40 in bananas and your own muscles occasionally emits a positron during radioactive decay, and that positron annihilates with a nearby electron almost instantly.

PET scans turn this into medicine. Doctors inject a radioactive tracer into your bloodstream. As it decays, it emits positrons that annihilate with electrons in your tissue, producing pairs of gamma rays. Detectors around your body catch those pairs and trace them back to their origin, mapping your metabolic activity. Cancer cells glow brightly because they burn more sugar than healthy tissue.