Introduction to Radiologic Technology Practice Test 2026 - Free Radiologic Technology Practice Questions and Study Guide

Positron Emission Tomography stands for PET, a functional imaging method that uses a radiotracer labeled with a positron-emitting isotope. When the tracer decays, a positron meets an electron and they annihilate, producing two gamma photons of 511 keV that shoot off in nearly opposite directions. The scanner detects these coincident photons with a ring of detectors, and the data are reconstructed to show where the tracer is concentrated, reflecting tissue metabolism rather than structure alone. This is why PET is so valuable for observing metabolic activity in cancers, brain disorders, and heart disease, often using tracers like fluorodeoxyglucose to highlight areas of high glucose uptake.

The other terms don’t fit PET’s mechanism: Proton Emission Tomography would imply detecting protons, which isn’t used clinically; Photon Emission Tomography would suggest single-photon imaging rather than the coincident detection PET relies on; Particle Emission Tomography is not a standard clinical modality.