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.
Radiat Prot Dosimetry. 2017 Apr 15;173(4):308-317. doi: 10.1093/rpd/ncw015.
In case of internal contamination of actinides by ingestion pathway, activity will be transferred to various regions of the alimentary tract over a period of time. In this article, counting efficiencies (CEs) of Phoswich and an array of HPGe detectors are estimated for source in alimentary tract of voxel phantom. The phantom as well as Phoswich, and an array of three HPGe detectors are incorporated in Monte Carlo code 'FLUKA'. Human alimentary tract model is solved using default parameters to identify different compartments where activity will accumulate after an ingestion intake of 1 Bq as a function of time. Accordingly, CEs are evaluated on 0.5-5 d post ingestion intake for the source distributed in the contents of alimentary tract for photon energies in 18-238 keV range representing sources of actinides. The assessment of ingested activity of actinides from abdomen measurements is discussed. Higher CEs are observed with Phoswich detector compared with HPGe array due to its large size and high effective Z. Also, the CEs observed on Days 1-5 using both the detectors are found to decrease by 16-75 % with respect to the CE on half day. Thus, there is need to use CEs according to the observed activity distribution post ingestion intake. The contribution in the abdomen measurements due to source in the lungs and vice versa is also studied for intake by both inhalation and ingestion pathways. The contribution of source in the liver is found to be ∼30-50 % in chest and 75 % in abdomen measurements.
如果通过摄入途径发生锕系元素的体内污染，一段时间内活度会转移到消化道的各个区域。在本文中，针对体素体模消化道中的源，估算了磷闪烁探测器和一组高纯锗探测器的计数效率（CE）。该体模以及磷闪烁探测器和一组三个高纯锗探测器被纳入蒙特卡罗代码“FLUKA”中。使用默认参数求解人体消化道模型，以确定摄入1贝克勒尔后不同时间活度会在其中积累的不同隔室。相应地，针对分布在消化道内容物中的源，在摄入后0.5 - 5天评估计数效率，光子能量范围为18 - 238千电子伏，代表锕系元素源。讨论了通过腹部测量评估锕系元素摄入活度的问题。由于磷闪烁探测器尺寸大且有效原子序数高，与高纯锗探测器阵列相比，观察到其计数效率更高。此外，发现使用这两种探测器在第1 - 5天观察到的计数效率相对于半天时的计数效率下降了16 - 75%。因此，需要根据摄入后观察到的活度分布使用计数效率。还研究了通过吸入和摄入途径摄入时，肺部源对腹部测量的贡献以及反之亦然的情况。发现在胸部测量中肝脏源的贡献约为30 - 50%，在腹部测量中为75%。
