Broggio D, Lechaftois X, Franck D
Institut de Radioprotection et de Sûreté Nucléaire, IRSN/PRP-HOM/SDI/LEDI, 92262 Fontenay-aux-Roses Cedex, France.
J Radiol Prot. 2015 Mar;35(1):63-73. doi: 10.1088/0952-4746/35/1/63. Epub 2014 Dec 17.
In vivo lung counting aims at assessing the retained activity in the lungs. The calibration factor relating the measured counts to the worker's specific retained lung activity can be obtained by several means and strongly depends on the chest wall thickness. Here we compare, for 374 male nuclear workers, the activity assessed with a reference protocol, where the material equivalent chest wall thickness is known from ultrasound measurements, with two other protocols. The counting system is an array of four germanium detectors.It is found that non site-specific equations for the assessment of the chest wall thickness induce large biases in the assessment of activity. For plutonium isotopes or (241)Am the proportion of workers for whom the retained activity is within ± 10% of the reference one is smaller than 10%.The use of site-specific equations raises this proportion to 20% and 58% for plutonium and (241)Am, respectively.Finally, for the studied population, when site-specific equations are used for the chest wall thickness, the standard uncertainties for the lung activity are 42% and 12.5%, for plutonium and (241)Am, respectively. Due to the relatively large size of the studied population, these values are a relatively robust estimate of the uncertainties due to the assessment of the chest wall thickness for the current practice at this site.
体内肺部计数旨在评估肺部的滞留活度。将测量的计数与工作人员特定的肺部滞留活度相关联的校准因子可通过多种方法获得，并且强烈依赖于胸壁厚度。在此，我们对374名男性核工作者进行比较，将通过参考方案评估的活度（其中通过超声测量已知等效胸壁厚度）与另外两种方案进行比较。计数系统是由四个锗探测器组成的阵列。结果发现，用于评估胸壁厚度的非特定部位方程在活度评估中会导致较大偏差。对于钚同位素或镅-241，滞留活度在参考值±10%范围内的工作人员比例小于10%。使用特定部位方程可将钚和镅-241的这一比例分别提高到20%和58%。最后，对于所研究的人群，当使用特定部位方程来计算胸壁厚度时，钚和镅-241的肺部活度标准不确定度分别为42%和12.5%。由于所研究人群规模相对较大，这些值是对该场所当前实践中因胸壁厚度评估导致的不确定度的相对可靠估计。
