rubidium-82 generator yield and efficiency for pet perfusion imaging: comparison of two clinical systems

Strontium-82/rubidium-82 (82sr/82rb) generators are used widely for positron emission tomography (pet) imaging of myocardial perfusion. in this study, the 82rb isotope yield and production efficiency of two fda-approved 82sr/82rb generators were compared. n = 515 sequential daily quality assurance (qa) reports from 9 cardiogen-82® and 9 ruby-fill® generators were reviewed over a period of 2 years. a series of test elutions was performed at different flow-rates on the ruby-fill® system to determine an empirical correction-factor used to convert cardiogen-82® daily qa values of 82rb activity (dose-calibrator ‘maximum’ of 50 ml elution at 50 ml·min−1) to ruby-fill® equivalent values (integrated ‘total’ of 35 ml elution at 20 ml·min−1). the generator yield (82rb) and production efficiency (82rb yield/82sr parent activity) were measured and compared after this conversion to a common scale. at the start of clinical use, the system reported 82rb activity from daily qa was lower for cardiogen-82® vs ruby-fill® (2.3 ± 0.2 vs 3.0 ± 0.2 gbq, p < 0.001) despite having similar 82sr activity. dose-calibrator ‘maximum’ (cardiogen-82®) values were found to under-estimate the integrated ‘total’ (ruby-fill®) activity by ~ 24% at 50 ml·min−1. when these data were used to convert the cardiogen-82 values to a common measurement scale (integrated total activity) the cardiogen-82® efficiency remained slightly lower than the ruby-fill® system on average (88 ± 4% vs 95 ± 4%, p < 0.001). the efficiency of 82rb production improved for both systems over the respective periods of clinical use. 82rb generator yield was significantly under-estimated using the cardiogen-82® vs ruby-fill® daily qa procedure. when generator yield was expressed as the integrated total activity for both systems, the estimated 82rb production efficiency of the cardiogen-82® system was ~ 7% lower than ruby-fill® over the full period of clinical use.