Imaging for Physicists

Scatter Fraction  Fraction of the total coincidences recorded in the photopeak window that have been scattered  Sources of scattering ● Scattering within the object containing the radionuclide

● Scattering off the gantry components (lead septa/side shields) ● Scattering within the detectors

 Scatter fraction can be reduced by ● TOF

● Usage of a powerful iterative reconstruction method ● Shielding of scattered photons by septa and endshiels ● Small coincidence window ● Good energy resolution

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ESTRO Teaching Course Advanced Imaging: PET – Basic Principles