Annihilation Coincidence Detection
Annihilation Coincidence Detection
Annihilation Coincidence Detection
Annihilation Coincidence Detection is a Basic Principles of Which Imaging?
[A] MRI
[B] CAT Scan
[C] PET Scan
[D] Angiogram
Annihilation Coincidence Detection
Mechanism
- When a positron undergoes mutual annihilation with a negative electron, their rest masses are converted into a pair of annihilation photons
- The photons have identical energies (511 keV) and are emitted simultaneously, in 180-degree opposing directions, usually within a few tenths of a mm to a few mm of the location where the positron was emitted, depending on the energy and range of the positrons.
- Near-simultaneous detection of the two annihilation photons allows PET to localize their origin along a line between the two detectors, without the use of absorptive collimators.
- This mechanism is called annihilation coincidence detection (ACD).
