Comparing Yield and Efficiency of Two Approved Rubidium-82 Generators for PET Imaging

1499 Introduction: The exact amount of delivered radioisotopes for perfusion positron emission tomography (PET) is a defining parameter for imaging accuracy and repeatability. In this study the yield and efficiency of two strontium-82/rubidium-82 (82Sr/82Rb) generators were sought for. Methods: The sequential daily quality assurance (QA) reports from 9 CardioGen-82® and 9 RUBY-FILL® generators were collected for 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) to RUBY-FILL® equivalent values (integrated ‘total’ of 35 mL elution at 20 mL/min). The generator yield (82Rb) and production efficiency (82Rb yield / 82Sr parent activity) was measured and compared after this conversion to a common scale. Results: At the start of clinical use, the 82Rb activity measured during daily QA was lower for CardioGen-82® vs RUBY-FILL® (2.3 ± 0.2 vs 3.0 ± 0.2 GBq, p<0.001). Dose-calibrator ‘maximum’ values were found to under-estimate the integrated ‘total’ activity by ~24% at 50 mL/min. After converting 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). Conclusions: 82Rb generator yield was significantly under-estimated using the CardioGen-82® vs RUBY-FILL® daily QA procedure. At the common scale of integrated total activity, the estimated 82Rb production efficiency of the CardioGen-82® system was ~7% lower than RUBY-FILL® over the full period of clinical use.