I was told that the PET in PET scans used to image the brain stands for Positron Emission Tomography. Aren’t positrons antimatter? What’s the deal?
Yes, positrons are anti electrons. Emission tomography relies on measuring radiation emitted from radioactive chemicals injected into the subject. Short lived isotopes are used to limit the patients exposure to radiation. The biologically interesting isotopes [sup]11[/sup]C,[sup]15[/sup]O,[sup]13[/sup]N,[sup]18[/sup]F emit positrons when they decay. They also all have half-lives of between two minutes and two hours.
EET, or electron emission tomography, would likely be used more often if there were more short lived isotopes that emitted electrons.