Positron Emission Tomography (PET Scan)
A 3D nuclear medicine imaging technique detecting pairs of 511 keV gamma photons emitted during positron annihilation to map metabolic activity.
Governing formula
Coincidence Detection of 180° Back-to-Back 511 keV Gamma Photons
SI unit
MBq (Activity) & Standardized Uptake Value (SUV)
In depth
Administers positron-emitting radiotracers (like Fluorine-18 FDG). Emitted positrons travel ~1 mm before annihilating with tissue electrons, creating two collinear 511 keV gamma photons detected in coincidence by a surrounding detector ring.
Examples in the real world
18F-FDG PET scans locating metastatic cancer tumors by mapping abnormally high glucose metabolic rates.