%0 Journal Article %A John Sunderland %A David Dick %A Michael Schultz %A Gordon Watkins %A Levent Sensoy %T Quantitative assessment of Ge-68 breakthrough from a commercial titanium-dioxide based Ge-68/Ga-68 generator %D 2013 %J Journal of Nuclear Medicine %P 1186-1186 %V 54 %N supplement 2 %X 1186 Objectives To quantitatively assess Ge-68 breakthrough in the eluant of a commercial Ge-68/Ga-68 generator used for routine Ga-68 DOTATOC production, and to measure whether and where in the synthesis Ge-68 is trapped. Methods A series of 110 successive elutions of the Eckert & Ziegler (EZ) Ge-68/Ga-68 IGG-100 generator, including 60 Ga-68 DOTATOC syntheses (EZ Modular Lab), were performed over 6 months. In all cases, two generators were placed in series. The generators were routinely milked the day prior to a DOTATOC synthesis resulting in two datasets - the first with only raw eluant, the second associated with a DOTATOC synthesis. To quantitatively assess breakthrough, all eluant and synthesis components were counted using an energy and efficiency calibrated NaI well detector after all Ga-68 had decayed. Raw eluant samples and DOTATOC final product vials were also assessed by high purity germanium detector gamma spectroscopy to check for radionuclidic impurities. Results Depending upon generator age, elutions yielded 1.3-1.85 GBq (35-50 mCi), while DOTATOC syntheses typically yielded 600-900 MBq (16-25 mCi). Ge-68 breakthrough averaged 673 ± 514 Bq (18 ± 14 nCi) resulting in an average Ge-68/Ga-68 generator breakthrough ratio of approximately 0.5 Bq/MBq (0.5 nCi/mCi). The amount of Ge-68 in the eluant increased as a function of days between elutions, averaging 510±427 Bq (13.8 ± 11.5 nCi) for a single day, up to 1226 ± 862 Bq (33 ± 23 nCi) with 5+ days between elutions. Spectroscopic analysis of all synthesis components of the DOTATOC syntheses, including the final product, demonstrated that the combined cation exchange preconcentration step, radiolabeling reaction, and final reverse phase C-18 purification effectively removed all Ge-68 from the final DOTATOC product. Conclusions Elution of the EZ Ge-68/Ga-68 IGG-100 generator results in tolerably low Ge-68 breakthrough, on the order 500-1200 Bq (14-25 nCi). Routine DOTATOC syntheses demonstrated that Ge-68 breakthrough was quantitatively removed prior to delivery to the final product vial. %U