Learning objectives
Describe how a radioactive tracer is taken up by the tissue under study, and explain why positron emission tomography (PET) needs a tracer that emits positrons (β⁺ decay).
Explain annihilation of a particle with its antiparticle, applying conservation of mass–energy and of momentum.
Explain why electron–positron annihilation gives two gamma-ray photons moving in opposite directions, and calculate the energy of each photon.
Describe how a ring of detectors records the two gamma photons from each annihilation and uses their arrival times to locate it, building up a map of where the tracer has collected.
Continue with a revision plan
These learning objectives are available to everyone. Sign in with an eligible plan to read the full note and worked examples.