Feasibility study of radioactivity estimation of 99m Tc and 123 I-labeled radiopharmaceuticals using shielded syringes.

This study investigates the feasibility of estimating the radioactivity of radiopharmaceuticals using shielded syringes. The radioactivities of ^99m Tc-MDP, ^99m Tc-HMDP, ^99m Tc-ECD, ^99m Tc-MAG ₃ , and ¹²³ I-IMP were measured using a dose calibrator. Correlation coefficients and regression equations were obtained from the radioactivity in the shielded and unshielded syringes. ^99m Tc-MDP was also measured for residual radioactivity after the administration. The correlation coefficients of ^99m Tc-MDP, ^99m Tc-HMDP, ^99m Tc-ECD, ^99m Tc-MAG ₃ , and ¹²³ I-IMP were r _s  = 0.9998, r _s  = 0.9997, r _s  = 0.9999, r _s  = 0.9998, and r _s  = 0.9888, respectively. The regression equations were y = 0.0364x + 0.0913, y = 0.0349x + 0.0273, y = 0.0343x - 0.0018, y = 0.0522x + 0.1215, and y = 0.0383x + 0.0058, respectively. The correlation coefficient for the residual radioactivity of ^99m Tc-MDP was r _s  = 0.9887 and the regression equation was y = 0.1505x + 0.0853. The radioactivity of ^99m Tc- and ¹²³ I-labeled radiopharmaceuticals in shielded syringes was accurately measured. It was suggested that the measuring shielded syringes could provide an estimate of the actual radioactivity.
(© 2024. The Author(s), under exclusive licence to Japanese Society of Radiological Technology and Japan Society of Medical Physics.)