CAIE A-Level Physics A2 24.3.4 That in Pet Scanning Positrons Emitted By the Decay of the Tracer Questions
Practise explaining how positron-electron annihilation in a PET tracer produces two opposing gamma photons, converting particle mass into detectable gamma-ray energy.
Syllabus
2028–2030
Course
Physics 9702
Level
A2
Exam points
explain how positron-electron annihilation in PET converts particle mass into gamma-ray energy
explain why two gamma photons travel in opposite directions and are detected outside the body
CAIE A-Level Physics A2 24.3.4 That in Pet Scanning Positrons Emitted By the Decay of the Tracer Questions question 1
[Maximum number: 2]
Fluorine-18 (918F) is a radioactive nuclide that is used as a tracer in positron emission tomography (PET scanning). Fluorine-18 decays to a nuclide of oxygen ( O ) according to
918F⟶PQX+8RO.
Explain how the radioactive decay of fluorine-18 results in the emission from the body of the gamma-ray photons that are detected during a PET scan.
positrons (emitted in the decay) and electrons annihilate mass of particles becomes energy of gamma photons