8th Baltic Congress of Radiology

Nuclear Medicine

oral abstract

In accordance with international guidelines and recommendations, the quality assurance program should cover all clinical aspects of nuclear medicine related to the smooth operation, including quality control of radiopharmaceuticals. In order to reduce risk of repeated study, misinterpretation of the images and to protect patient from unnecessary radiation exposure due to poor quality radiopharmaceuticals, quality control procedures should always be performed on a daily basis prior to radiopharmaceuticals administration by appropriately trained personnel. The objective of this study was to evaluate quality control results of technetium (99mTc) based radiopharmaceuticals and determine the molybdenum (99Mo) content in a 99Mo/99mTc generator eluate.

The study was performed in Vilnius University Hospital Santaros Klinikos, Vilnius, Lithuania. Patients were not included in the study and no personal or health data was used in the study. The data used in study were obtained by the method of document analysis. The quality control of radiopharmaceutical preparations and eluate was performed by radiology technologists working in the Nuclear Medicine department. Measurements of eluate purity were performed every Monday, radiopharmaceuticals purity were performed after labelling prior to injection into patients. The data was collected from January 2021 until December 2021. For estimating radionuclidic purity of a 99Mo/99mTc generators (manufacturer: POLATOM POLTECHGEN) 99Mo breakthrough test in a pertechnetate solution of 99mTc was done. 99Mo content was measured with Veenstra VDC-405 radionuclide activity calibrator. To measure 99mTc labeled radiopharmaceuticals, radiochemical purity thin layer chromatography (TLC) system was used. The Sigma-Aldrich Chemie solvents and reagents were used to perform each chromatography test. A total of 230 different results of measurements of the preparations radiopharmaceutical purity and 25 eluate quality control measurements were obtained during the analysis of the data. The collected data were processed using „Microsoft Excel“program. A total of 9 different radiopharmaceutical preparations quality controls were performed and 8 radiopharmaceutical preparations were included in the study.

Data from almost all eluate measurements show that the amount of 99Mo impurities are in accordance with the vendors recommendations <0,1%. The amount of impurities in the eluate was 0-0,242%. Therefore, the radionuclidic purity of the eluate was 99,758-100%. Impurities in the eluate have been estimated to be only 0,013% on average. According to the European Pharmacopoeia for most radiopharmaceuticals the lower limit of radiochemical purity is ≥95%, for 99mTc-MIBI is ≥94%. 99mTc-MIBI quality control measurements accounted for 42,8% (n=99), 99mTc-MDP 17,9% (n=41) 16,6% (n=38), 99mTc-DTPA and 99mTc-TEKTROTYD each accounting for 7% (n=16), 99mTc- MAG3 and 99mTc-PYP accounting for 3,1% (n=7) each and 99mTc-HSA 2,2% (n=5). Data obtained during the quality control of 99mTc-DMSA were not used further in the study due to the small sample size (n=1). 99mTc-MIBI average purity was calculated to be 93,67% ± 3,79%, 99mTc-TEKTROTYD 95,71% ± 4,38% 99mTc-MDP 97,07% ± 3,41%, 99mTc-DTPA 97,54% ± 3,12%, 99mTc-PYP 97,89% ± 1,71%, 99mTc-MAA 98,73% ± 2,03%, 99mTc-MAG3 was 99, 33% ± 0,38% and 99mTc-HSA 99,86% ± 0,17%. The data show that the average unbound 99mTc content in 99mTc-MIBI was 6,13%, in 99mTc-PYP 2,42%, in 99mTc-TEKTROTYD 1,87%, in 99mTc-DTPA 1,66%, in 99mTc-MAA 1,23%, in 99mTc-MDP 0,66%, in 99mTc- MAG3 0,35% and in 99mTc-HSA was 0,14%. The average content of hydrolyzed reduced 99mTc in 99mTc-MDP was 2,75%, in 99mTc-TEKTROTYD 2,48%, in 99mTc-DTPA 1,42%, in 99mTc-PYP 1,11% and in 99mTc- MAG3 was 0,54%.

Impurities in radiopharmaceuticals may reduce imaging quality, resulting in incomplete or incorrect information and may increase the absorption dose. The working eluate and prepared radiopharmaceuticals should be checked for radionuclidic, chemical and radiochemical purity prior to injection into patients. The analysis of quality control measurements showed that the radiopharmaceuticals prepared in the facility meet all the established quality requirements. When evaluating the purity of 99mTc eluate, it was observed that the obtained results do not deviate from the established norm. Also, the average purity of one preparation, 99mTc-MIBI, did not meet the purity limit, but this result was negligible. Also, based on the data obtained from the study, 2 types of impurities were identified in specific preparations, which further clarified the impact on the purity of radiopharmaceuticals.

Literature and data analysis were performed, quality control methods and results were described. After reviewing the literature, it was clarified what determines the quality of the eluate and 99mTc labeled radiopharmaceuticals. Purity of eluate and 99mTc labeled pharmaceuticals were better than recomend European Pharmacopoeia and international guidlines.

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