Identification of factors affecting the retention of <sup>99m</sup>Tc-DMSA in syringes among the paediatric population in Sri Lanka

Background: 99mTc-DMSA is a common paediatric renal scintigraphystudy, where radiopharmaceutical is introduced intravenously usingdisposable syringes. Radiopharmaceuticals can be retained on disposablesyringes, causing under-dosing, and impacting imaging quality inpaediatric patients. The study aimed to specify the factors affecting onretention of 99mTc-DMSA in disposable syringes. Furthermore, theinfluence of the medical staff, patient positioning, and the ascendancy ofthe MON.TEK 99mMo/99mTc generator were investigated.Methods: A study of 212 paediatric patients undergoing 99mTc-DMSA renalscintigraphy was conducted using CAPINTEC-CRC-15R and CAPINTEC-CRC/15 BETA radiation dose calibrators. The 99mTc-Pertechnetate waseluted with a MON.TEK 99mMo/99mTc generator and the radio-pharmaceutical volume were recorded. Six types of 1ml/1cc disposablesyringes (Types 1-6) and one 1ml insulin syringe (Type 7) were used. Pre-and post-doses of these syringes were measured.he administered activityvalue was considered to develop DRL.Results: Results showed a significant moderate, positive correlationbetween retention dose and dilution (radiopharmaceutical volume). Therewas no correlation between retention dose and pre-dose or patient weight.No significant difference in retention was found based on patient genderor position. Significant differences in retention dose were observed amongsyringe types, injection sites, labeling personnel, and administeringpersonnel.Conclusion: Retention of 99mTc-DMSA varies by syringe type, withType-1 syringes showing the highest retention and Type-7 the lowest,making Type-7 the most suitable. Retention is influenced byradiopharmaceutical dilution, labeling, injecting personnel, and injectionsite, while pre-dose, patient gender, weight, positioning, and decay timehave no significant effect. This highlights the importance of syringeselection and standardizing procedures to minimize retention, improvedosing accuracy, and enhance imaging quality.