Positron Emission Tomography (PET) Teaching Series

Lines of response

Annihilation (simple)

Event detection

LOR/coincidence determination

LOR determination

Equipment confounds to LOR determination

BGO 25% energy resolution

Count loss vs. activity in FOV

Equipment confounds to LOR determination

Ideal events

Event positioning: phototube gains

Equipment confounds to LOR determination

What we want to detect ...(coincidences)

Coincidence window

Prompt events

Unwanted events

Multiple events

Random events

Randoms correction

True events

Positron & photon confounds to LOR determination

Positron & photon confounds to LOR determination

Positron range

Positron range

Annihilation

Scatter

Effects of scatter

Effects of scatter

Energy window / scatter fraction

Modeled scatter correction

Problems in the real world

Attenuation … photons lost