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).
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