Fig. 4

Linear relationship between activity and count rates for the Siemens ECAM (2006) (a), Siemens Symbia T2 (2011) (b) and Siemens ECAM 2005 (c) systems. Reference source activity from clinical RAIU measurements at the Franciscus Gasthuis & Vlietland Hospital was obtained with the Siemens ECAM (2005) gamma camera using automatic delineation of ROI without background measurements. Reference source activity from the clinical RAIU measurements at the IJsselland Hospital was obtained with both Siemens ECAM (2006) and Siemens Symbia T2 (2011) gamma cameras using a square box ROI with background measurements. All measurements were performed using a LEHR collimator