Koskinas Marina F, Moreira Denise S, Yamazaki Ione M, de Toledo Fábio, Brancaccio Franco, Dias Mauro S
Instituto de Pesquisas Energéticas e Nucleares (IPEN-CNEN/SP), Centro do Reator de Pesquisas-CRPq, São Paulo, SP, Brazil.
Appl Radiat Isot. 2010 Jul-Aug;68(7-8):1344-8. doi: 10.1016/j.apradiso.2009.12.011. Epub 2009 Dec 29.
This work describes the method developed by the Nuclear Metrology Laboratory in IPEN, São Paulo, Brazil, for the standardization of a (57)Co radioactive solution. Cobalt-57 is a radionuclide used for calibrating gamma-ray and X-ray spectrometers, as well as a gamma reference source for dose calibrators used in nuclear medicine services. Two 4pibeta-gamma coincidence systems were used to perform the standardization, the first used a 4pi(PC) counter coupled to a pair of 76 mm x 76 mm NaI(Tl) scintillators for detecting gamma-rays, the other one used a HPGe spectrometer for gamma detection. The measurements were performed by selecting a gamma-ray window comprising the (122 keV+136 keV) total absorption energy peaks in the NaI(Tl) and selecting the total absorption peak of 122 keV in the germanium detector. The electronic system used the TAC method developed at LMN for registering the observed events. The methodology recently developed by the LMN for simulating all detection processes in a 4pibeta-gamma coincidence system, by means of the Monte Carlo technique, was applied and the behavior of extrapolation curve compared to experimental data. The final activity obtained by the Monte Carlo calculation agrees with the experimental results within the experimental uncertainty.
这项工作描述了巴西圣保罗IPEN核计量实验室开发的用于标准化（57）Co放射性溶液的方法。钴-57是一种放射性核素，用于校准伽马射线和X射线光谱仪，也是核医学服务中用于剂量校准器的伽马参考源。使用两个4πβ-伽马符合系统进行标准化，第一个系统使用与一对76毫米×76毫米碘化钠（铊）闪烁体耦合的4π（PC）计数器来检测伽马射线，另一个系统使用高纯锗光谱仪进行伽马检测。测量通过在碘化钠（铊）中选择包含（122 keV + 136 keV）总吸收能量峰的伽马射线窗口，并在锗探测器中选择122 keV的总吸收峰来进行。电子系统使用LMN开发的TAC方法来记录观察到的事件。应用了LMN最近开发的通过蒙特卡罗技术模拟4πβ-伽马符合系统中所有检测过程的方法，并将外推曲线的行为与实验数据进行了比较。蒙特卡罗计算得到的最终活度在实验不确定度范围内与实验结果一致。
