The purpose of this work was to perform an independent and National Institute of Standards and Technology–traceable activity measurement of ⁹⁰Y SIR-Spheres (Sirtex). γ-spectroscopic measurements of the ⁹⁰Y internal pair production decay mode were made using a high-purity germanium detector. Methods: Measured annihilation radiation detection rates were corrected for radioactive decay during acquisition, dead time, source attenuation, and source geometry effects. Detection efficiency was determined by 2 independent and National Institute of Standards and Technology–traceable methods. Results: Measured SIR-Spheres vials (n = 5) contained more activity than specified by the manufacturer calibration; on average, the ratio of measured activity to calibrated was 1.233 ± 0.030. Activity measurements made using 2 distinct efficiency calibration methods agreed within 1%. Conclusion: The primary SIR-Spheres activity calibration appears to be a significant underestimate of true activity.

这项工作的目的是对⁹⁰ Y SIR-Spheres (Sirtex) 进行独立的、美国国家标准与技术研究院的可追溯活动测量。使用高纯度锗探测器对⁹⁰ Y 内部对产生衰减模式进行γ 光谱测量。方法：测量的湮没辐射探测率根据采集期间的放射性衰变、死区时间、源衰减和源几何效应进行校正。检测效率由 2 种独立的美国国家标准与技术研究院可追溯方法确定。结果：测量的 SIR-Spheres 样品瓶（n= 5) 含有比制造商校准规定更多的活性；平均而言，测量活动与校准活动的比率为 1.233 ± 0.030。使用 2 种不同的效率校准方法进行的活动测量在 1% 范围内达成一致。结论：主要 SIR-Spheres 活动校准似乎严重低估了真实活动。