Nadar M Y, Akar D K, Rao D D, Kulkarni M S, Pradeepkumar K S
Radiation Safety Systems Division, Bhabha Atomic Research Centre, Mumbai 400085, India.
Appl Radiat Isot. 2017 Sep;127:109-115. doi: 10.1016/j.apradiso.2017.05.019. Epub 2017 May 25.
Various parameters can introduce uncertainties in the lung activity measurements of actinides. In this study, uncertainties due to non-uniform distribution of activity in the lungs are evaluated. To study the effect of non-uniform distribution, lungs of ICRP male thorax voxel and resized phantoms are divided into upper and lower parts of both right and left lungs as well as into anterior and posterior lung regions. Simulation of uniform and non-uniform distribution of activity in lungs is carried out using thorax voxel phantoms in FLUKA for Phoswich and an array of three HPGe detectors for 18-238keV photons. Source sampling for non-uniform distribution of activity is carried out by selecting the source points by varying the weightage to 0.4, 0.5, 0.6 and 1 in different parts of lungs. Uncertainties in lung activity estimation at different energies are quantified in the form of scattering factors (SFs) which are geometric standard deviations. The SFs due to non-uniform distribution of activity of the order of 0.4-0.6 in different parts of the lungs are found to be ~ 1.25 for Phoswich and HPGe array detectors above 18keV.
各种参数可能会给锕系元素的肺部活度测量带来不确定性。在本研究中，对肺部活度非均匀分布所导致的不确定性进行了评估。为研究非均匀分布的影响，将国际放射防护委员会（ICRP）男性胸部体素模型和尺寸调整后的体模的肺部分为左右肺的上部和下部以及肺部的前部和后部区域。使用FLUKA中的胸部体素模型对肺部活度的均匀和非均匀分布进行模拟，该模型用于磷光体探测器，同时使用一组三个高纯锗（HPGe）探测器来探测18 - 238keV的光子。通过在肺部不同部位将权重分别设为0.4、0.5、0.6和1来选择源点，从而对活度的非均匀分布进行源采样。以散射因子（SFs）的形式量化不同能量下肺部活度估计的不确定性，散射因子即几何标准偏差。对于磷光体探测器和HPGe探测器阵列，在肺部不同部位活度非均匀分布程度为0.4 - 0.6时，在18keV以上，散射因子约为1.25。
