Knowra Positron emission tomography Positron emission tomography Positron emission tomography (PET) is a medical imaging technique that maps tracer distribution by detecting paired gamma rays from positron–electron annihilation.
Positron emission : A radioactive decay process in which a proton becomes a neutron and emits a positron and a neutrino. PET tracers emit positrons through this radioactive decay.
Radiopharmaceutical : A medicinal formulation containing a radioactive isotope for diagnosis or therapy. PET imaging agents are radiopharmaceuticals selected to trace biological processes.
Oncology : The branch of medicine concerned with the prevention, diagnosis, and treatment of cancer. PET helps detect, stage, and monitor cancers through tracer uptake patterns.
Single-photon emission computed tomography : A nuclear medicine imaging method that detects individual gamma photons emitted directly by radioactive tracers. SPECT uses single emitted photons, whereas PET detects photon pairs from positron annihilation.
Standardized uptake value : A normalized measure of radiotracer concentration in tissue, commonly used in PET interpretation. SUV makes tracer uptake easier to compare across regions and scans, with important methodological limits.
Positron–electron annihilation : A process in which a positron and an electron interact, converting their mass primarily into two gamma-ray photons. The paired photons detected by PET arise when tracer-emitted positrons annihilate with electrons.
Fluorine-18 : A radioactive isotope of fluorine that decays by positron emission and has a half-life of about 110 minutes. It labels widely used PET tracers, including fluorodeoxyglucose.
Neurology : The branch of medicine concerned with disorders of the nervous system. Brain PET can assess metabolism, neurotransmitter systems, and selected neurological diseases.
Computed tomography : An imaging method that reconstructs cross-sectional anatomy from measurements of X-ray transmission. CT maps X-ray attenuation rather than the distribution of radioactive tracers.
Attenuation correction : A method for correcting imaging data for signal loss as radiation passes through absorbing material. Without correction, tissue absorption distorts PET estimates of tracer concentration.
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