Zimmerman B E, Altzitzoglou T, Rodrigues D, Broda R, Cassette P, Mo L, Ratel G, Simpson B, van Wyngaardt W, Wätjen C
Physics Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899-8462, USA.
Appl Radiat Isot. 2010 Jul-Aug;68(7-8):1477-81. doi: 10.1016/j.apradiso.2009.11.046. Epub 2009 Dec 1.
A comparison exercise for data analysis was recently conducted by the Liquid Scintillation Counting Working Group (LSCWG) of the International Committee on Radionuclide Metrology (ICRM) to evaluate the uncertainties involved in applying different analysis methodologies (including computer programs) for the triple-to-double coincidence ratio (TDCR) method. The goals of the comparison were to (1) study differences in calculation results from different TDCR analysis programs, (2) investigate differences in analysis techniques and uncertainty assessment philosophies between laboratories, and (3) study the effect of not taking asymmetry of photomultiplier tube (PMT) efficiencies into account on the calculated activity. To achieve this, a single set of TDCR data for the pure beta emitter (99)Tc, was distributed to the participants, who analyzed the data according to their normal procedures and report the activity concentration of the (99)Tc solution from their results. The results indicate that the presently used programs are generally able to calculate the same activity values, assuming that the correct input parameters are used and that not taking PMT asymmetry into account in the calculations can lead to significant (0.6% for (99)Tc) errors in reported results. The comparison also highlighted the need for a more rigorous approach to estimating and reporting uncertainties.
放射性核素计量国际委员会（ICRM）的液体闪烁计数工作组（LSCWG）最近开展了一项用于数据分析的对比活动，以评估在三重与二重符合比（TDCR）方法中应用不同分析方法（包括计算机程序）所涉及的不确定性。该对比活动的目标是：（1）研究不同TDCR分析程序计算结果的差异；（2）调查各实验室之间分析技术和不确定度评估理念的差异；（3）研究未考虑光电倍增管（PMT）效率不对称性对计算活度的影响。为实现这一目标，向参与者分发了一组用于纯β发射体（99）Tc的TDCR数据，参与者按照各自的常规程序对数据进行分析，并根据结果报告（99）Tc溶液的活度浓度。结果表明，假设使用了正确的输入参数，目前使用的程序通常能够计算出相同的活度值，且在计算中未考虑PMT不对称性会导致报告结果出现显著误差（对于（99）Tc为0.6%）。该对比活动还突出了采用更严格方法来估计和报告不确定度的必要性。
