Fig. 3
Ratio of trues count-rate over the injected dose at scan time from 942 clinical 18F-FDG exams during a 900-day period. The spread in the data is likely due to physiologic factors such as the size of the patient (attenuation/scatter fraction) and the radioactivity amount voided by the patient. Overall, the close-to-flat trend indicates good scanner performance stability over time.