How does positron emission tomography work?

Positron emission tomography (PET) works by detecting gamma rays emitted from positron-emitting radioactive tracers.

PET is a medical imaging technique that uses radioactive tracers to visualize metabolic activity in the body. The tracer is injected into the patient, and as it decays, it emits positrons. When a positron collides with an electron in the body, they annihilate each other, releasing two gamma rays in opposite directions. These gamma rays are detected by a ring of detectors surrounding the patient, and their location is used to create a 3D image of the tracer's distribution in the body.

The detectors in a PET scanner are typically made of scintillating crystals, which emit light when struck by gamma rays. This light is detected by photomultiplier tubes, which amplify the signal and convert it into an electrical signal that can be processed by a computer. The computer then uses algorithms to reconstruct the 3D image of the tracer's distribution in the body.

PET is particularly useful for imaging metabolic processes, such as glucose uptake in cancer cells. It can also be used to diagnose neurological disorders, such as Alzheimer's disease, by visualizing the distribution of specific neurotransmitters in the brain. PET has revolutionized medical imaging and has become an essential tool in the diagnosis and treatment of many diseases.