Fig. 4From: Comprehensive SPECT/CT system characterization and calibration for 177Lu quantitative SPECT (QSPECT) with dead-time correctionPlanar sensitivity (observed primary photons count rate per activity) as a function of activity (a), of photopeak count rate (187–229 keV; b) or 6-window wide-spectrum count rate (18–680 keV; c). The dotted line indicates the upper limit of the usable range. Data is shown for each detector separately, and averagedBack to article page