Smith J R H, Bailey M R, Etherington G, Shutt A L, Youngman M J
Health Protection Agency, Radiation Protection Division, Chilton OX11 0RQ, UK.
Radiat Prot Dosimetry. 2007;127(1-4):35-9. doi: 10.1093/rpd/ncm401. Epub 2007 Sep 6.
The ICRP human respiratory tract model (HRTM) assumes that the 'slow-cleared fraction' fs in the bronchial (BB) and bronchiolar (bb) regions decreases with increasing particle geometric diameter dp. To test this assumption, five volunteers inhaled 8-microm aerodynamic diameter, dae, (111)In-polystyrene (PSL) and (198)Au particles simultaneously. The particles were administered at the end of each breath to maximise deposition in BB and bb. Because of the difference in densities (1.05 vs. 19.3 g cm(-3)), corresponding dp values are approximately 8 and 1.8 microm, and fs values are approximately 2 and 50%, respectively. However, lung retention was somewhat greater for PSL than for gold, contrary to the HRTM prediction. Other recent human experimental studies found no difference in retention for particles with the same dae but different dp values. It is concluded that the HRTM model of particle clearance from BB and bb needs revision.
国际放射防护委员会（ICRP）的人体呼吸道模型（HRTM）假定，支气管（BB）和细支气管（bb）区域的“慢清除分数”fs会随着颗粒几何直径dp的增加而降低。为验证这一假设，五名志愿者同时吸入空气动力学直径dae为8微米的（111）铟 - 聚苯乙烯（PSL）颗粒和（198）金颗粒。在每次呼吸末给予颗粒，以使BB和bb区域的沉积最大化。由于密度不同（1.05与19.3 g/cm³），相应的dp值分别约为8和1.8微米，fs值分别约为2%和50%。然而，与HRTM预测相反，PSL在肺部的滞留量比金颗粒略大。最近的其他人体实验研究发现，对于具有相同dae但不同dp值的颗粒，滞留情况并无差异。结论是，HRTM模型中关于颗粒从BB和bb区域清除的部分需要修正。
