低水平放射性测量的判断限和探测限

目的 对低本底情况下放射性测量的判断限和探测限的计算方法进行讨论。方法 基于对18个生物样品的α谱仪测量数据，分别用IAEA RSG1.2、美国NUREG1576和IAEA AQ48号报告中推荐的判断限和探测限相关公式进行了判断和比较。结果 通过比较分析发现对于本底计数较低的情况，NUREG1576和IAEA AQ48号中推荐的公式相较于RSG1.2中的公式更加保守，根据不同的公式进行判断部分数据给出的结果可以截然不同。结论 在测量水平接近本底的情况下，应该重视判断限和探测限的应用，根据测量的实际情况进行判断（如本底计数、本底测量时间、样品测量时间等因素）选取合适的公式，从而保证对测量结果的判断更加可靠。

Decision threshold and detection limit in low-levels of radioactivity measurements

Objective The calculation methods for decision threshold and detection limit of radioactivity measurement for low background were discussed.Methods Based on the data from 18 biological samples measured by Alpha spectrometer, formulas of decision threshold and detection limit given in RSG1.2(IAEA), NUREG 1576(USA)and AQ48(IAEA) were used and discussed.Results Parts of the results decided by these three kinds of formulas would be entirely different,which indicated that formulas of NUREG 1576 and AQ48 were much more conservative than the formulas of RSG1.2 for low background counts(as<100).Conclusion To ensure the reliability when judging the measured data, formulas of decision threshold and detection limit must be chosen according to the actual condition (such as background counts, background count time and gross count time, etc.), especially in low-level radioactivity measurements.