Influences of parameter uncertainties within the ICRP-66 respiratory tract model:: Particle clearance
Influences of parameter uncertainties within the ICRP-66 respiratory tract model:: Particle clearance
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DOI：
10.1097/00004032-200304000-00002
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发表时间：
2003-04-01
期刊：
影响因子：
2.2
通讯作者：
Bolch, WE
中科院分区：
文献类型：
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作者：
Bolch, WE;Huston, TE;Bolch, WE
量化吸入放射性气溶胶后的辐射风险不仅需要评估呼吸道区域内的颗粒沉积，还需要全面计算颗粒可能转移到邻近呼吸组织区域、被血液吸收或释放到胃肠道的清除机制。ICRP第66号出版物中概述的模型是迄今为止对呼吸道内颗粒沉积和清除以及局部辐射剂量测定的最完整的总体描述之一。在本研究中，将先前对ICRP-66沉积模型的回顾扩展到后续清除模型的研究。对ICRP 66呼吸道模型中的清除成分进行了系统评价，其中对(PuO2)-Pu-239和(UO2)-U-238/(U3O8)-U-218的所有输入参数分配了概率密度函数。这些分布随后被纳入计算机代码LUDUC（肺剂量不确定性代码），其中使用拉丁超立方体采样技术为评估机械清除和颗粒溶解/吸收所需的所有模型参数生成多组（例如1000组）输入向量（即试验）。在不同的肺区域，核崩解的积分数U-s被证明是用对数正态概率分布很好地描述的。在呼吸道的四个胸外清除率区室中，U-s的不确定性（以其95%至5%的置信水平之比表示）在LNET组织中(PuO2)-Pu-239（比率为50至130）和ETseq组织中(UO2)-U-118/(U3O8)-U-238（比率为12至50）最高。在这些呼吸区，1中的峰值不确定度发生在类似于0.5-0.6 μ m的颗粒大小，其中ETseq颗粒沉积组分的不确定度仅占(PuO2)-Pu-239总U-s不确定度的10%，仅占(UO2)-U-238/(U3O8)-U-238总U-s不确定度的30%（其余部分仅归因于清除模型）。在呼吸道胸部区域的8个清除区室中，对于粒径小于5 μ m的颗粒，在LNTH组织中(PuO2)-Pu-239 2（60比80）和ETseq组织中(UO2)-U-238/(U3O8)-U-238（20比60）的U-s的不确定性最高。在空气动力学直径超过5 μ m的颗粒尺寸时，AI、bb（seq）和bb(1)间隙室在U-s中的峰值不确定性是值得注意的。当颗粒大小接近10 μ m时，这三个胸廓组织区域内U-s的不确定性接近1000倍，并由颗粒沉积的相应不确定性主导。
Quantifying radiological risk following the inhalation of radioactive aerosols entails not only an assessment of particle deposition within respiratory tract regions but a full accounting of clearance mechanisms whereby particles may be translocated to adjacent respiratory tissue regions, absorbed to blood, or released to the gastrointestinal tract. The model outlined in ICRP Publication 66 represents to date one of the most complete overall descriptions of particle deposition and clearance, as well as localized radiation dosimetry, within the respiratory tract. In this study, a previous review of the ICRP-66 deposition model is extended to the study of the subsequent clearance model. A systematic review of the clearance component within the ICRP 66 respiratory tract model was conducted in which probability density functions were assigned to all input parameters for both (PuO2)-Pu-239 and (UO2)-U-238/(U3O8)-U-218. These distributions were subsequently incorporated within a computer code LUDUC (Lung Dose Uncertainty Code) in which Latin hypercube sampling techniques are used to generate multiple (e.g., 1,000) sets of input vectors (i.e., trials) for all model parameters needed to assess mechanical clearance and particle dissolution/absorption. Integral numbers of nuclear disintegrations, U-s, in various lung regions were shown to be well-described by lognormal probability distributions. Of the four extrathoracic clearance compartments of the respiratory tract, uncertainties in U-s, expressed as the ratio of its 95% to 5% confidence levels, were highest within the LNET tissues for (PuO2)-Pu-239 (ratio of 50 to 130) and within the ETseq tissues for (UO2)-U-118/(U3O8)-U-238 (ratio of 12 to 50). Peak uncertainties in 1, in these respiratory regions occurred at particle sizes of similar to0.5-0.6 mum where uncertainties in ETseq particle deposition fractions accounted for only 10% of the total Us uncertainty for (PuO2)-Pu-239, and only similar to30% of the total U-s uncertainty for (UO2)-U-238/(U3O8)-U-238 (the remainder is attributed to the clearance model alone). Of the eight clearance compartments within the thoracic regions of the respiratory tract, and for particle sizes below similar to5 mum, uncertainties in U-s were highest within the LNTH tissues for (PuO2)-Pu-239 2 (ratio of 60 to 80) and within the ETseq tissues for (UO2)-U-238/(U3O8)-U-238 (ratio of 20 and 60). At particle sizes exceeding similar to5 mum in aerodynamic diameter, peak uncertainties in U-s are noted for the AI, bb(seq), and bb(1) clearance compartments. As the particle size approaches 10 mum in size, uncertainties in U-s within these three thoracic tissue regions approach a factor of 1,000 and are dominated by corresponding uncertainties in particle deposition.