PET and SPECT
PET and SPECT image the distribution of radiotracers to infer biological activity, but use different radionuclide decay and photon-detection principles.
Open interactive lesson & self-check ↗PET and SPECT — specialty learning map
Original conceptual SVG · scalableOriginal overview diagram showing four related domains. This is not a literal anatomy drawing, histologic image or clinical decision rule.
PET physics
Positron emission is followed by annihilation generating two approximately opposite 511-keV photons detected in coincidence.
SPECT physics
A gamma camera detects single photons from suitable radioisotopes, and tomographic reconstruction estimates three-dimensional tracer distribution.
Tracer physiology
Tracer uptake reflects its target and pharmacokinetics; increased signal is not universally specific for malignancy or any single pathology.
Fusion and dosimetry
Hybrid imaging co-registers function with CT or MRI in some systems, while radiopharmaceutical selection and radiation protection require specialist protocols.
Reference and next reading
Explore the original curriculum and publisher-hosted resources for full-depth reading; this note is an original schematic introduction, not an exhaustive chapter.