3PC-031 Study on the adsorption of radiopharmaceuticals on syringe walls and sterilisation filters

<h3>Background and Importance</h3> Radiopharmaceuticals (RPs) are prepared in plastic syringes, but adsorption can compromise dose accuracy and treatment effectiveness. Additionally, sterilisation filters used in homemade RPs may retain activity, affecting yield synthesis. This study aims to address the lack of knowledge on RP retention in plastic syringes and sterilisation filters. <h3>Aim and Objectives</h3> This study aimed to screen RPs used in scintigraphy and positron emission tomography (PET) for their tendency to adsorb onto plastic syringes, and to evaluate the activity retention of two experimental RPs on selected sterilisation filters. <h3>Material and Methods</h3> Seven technetium-based RPs (99mTc-hydroxy-diphosphonate, 99mTc-sestamibi, 99mTc-albumin, 99mTc-dimercaptosuccinic acid, 99mTc-mercaptoacetyltriglycine, 99mTc-macroaggregates of albumin, and 99mTc-nanocolloid) and seven PET RPs (18F-choline, 18F-dopa, 18F-fluorodeoxyglucose, 18F-fluorothymidine, 18F-fluoroestradiol, 68Ga-DOTA-TOC, and 68Ga-PSMA) were tested. Two types of syringes were compared: 2-part (5 ml, Bbraun) and 3-part (3 ml, BD Plastipak). Residual activity was measured (n≥3) after filling, emptying, and rinsing the syringes with saline. Retention tests were performed on 0.22 µm final sterilisation filters for 68Ga-NODAGA-Exendin-4 and 68Ga-EMP100. Six Filters with varying membrane compositions were tested: polyvinylidene fluoride, polytetrafluoroethylene, polyether sulfone, and cellulose esters. Filters were rinsed with saline, and their activity and collection vials were measured to determine retention. <h3>Results</h3> Most RPs showed minimal adsorption (&lt;5%) on syringe. Only 99mTc-sestamibi exhibited significant adsorption in 3-part syringes, retaining 20% of the RP compared to 5% for 2-part syringes. The use of 2-part syringes for 99mTc-sestamibi has reduced acquisition time by up to 17% compared to the 3-part syringes used before. For sterilisation filters, a polyvinylidene fluoride filter showed the lowest retention for both 68Ga-NODAGA-Exendin-4 and 68Ga-EMP100 (10.4% and 7.5% retention, respectively). In contrast, the cellulose esters filter retained 97.7% and 93.1% of the RPs. <h3>Conclusion and Relevance</h3> For clinical RPs, this study demonstrates significant adsorption of 99mTc-sestamibi in 3-part syringes, indicating that the type of syringe can affect the accuracy of the dose administered. For sterilisation filters, a polyvinylidene fluoride filter had the lowest activity retention for 68Ga-NODAGA-Exendin-4 and 68Ga-EMP100, guiding the selection of the filter for their synthesis. These results highlight the importance of selecting appropriate syringes and filters for radiopharmaceutical preparation. This work should be generalised to all clinical and experimental RPs. <h3>References and/or Acknowledgements</h3> <h3>Conflict of Interest</h3> No conflict of interest