Department of Radiology, University of Iowa, Iowa City, Iowa;
Department of Biomedical Engineering, University of Iowa, Iowa City, Iowa.
J Nucl Med. 2022 Aug;63(8):1131-1135. doi: 10.2967/jnumed.121.262650. Epub 2022 Jan 6.
The purpose of this work was to perform an independent and National Institute of Standards and Technology-traceable activity measurement of Y SIR-Spheres (Sirtex). γ-spectroscopic measurements of the Y internal pair production decay mode were made using a high-purity germanium detector. 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. Measured SIR-Spheres vials ( = 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%. The primary SIR-Spheres activity calibration appears to be a significant underestimate of true activity.
这项工作的目的是对 Y 型 SIR-Spheres（Sirtex）进行独立的、可溯源至美国国家标准与技术研究院的放射性活度测量。使用高纯锗探测器对 Y 内双湮没衰变模式进行了γ能谱测量。对放射性衰变、死时间、源衰减和源几何效应进行了修正，以校正获取期间的湮没辐射探测率。通过 2 种独立的、可溯源至美国国家标准与技术研究院的方法确定探测效率。对 5 个 Y 型 SIR-Spheres 小瓶进行了测量，其放射性活度高于制造商校准规定值；平均而言，测量活度与校准活度的比值为 1.233 ± 0.030。使用 2 种不同的效率校准方法进行的活度测量结果在 1%以内一致。主要的 SIR-Spheres 放射性活度校准似乎严重低估了真实活度。
