Fig. 4
From: Performance assessment of the 2 γpositronium imaging with the total-body PET scanners
Registration efficiency (taking into account the geometrical acceptance, probability of gamma quanta registration in the plastic scintillator and J-PET resolution) as a function of applied threshold for the cases of prompt gamma (dashed line), two back-to-back 511 keV photons (dotted line), and two photons simultaneously with the prompt gamma with energy loss higher than 400 keV (solid line)