Carlisle Sara M, Burchart Patricia A, McCauley Candace, Surette Richard A
Radiation Biology and Health Physics Branch, Atomic Energy of Canada Limited, Chalk River Laboratories, Chalk River, ON, Canada K0J 1J0.
Appl Radiat Isot. 2005 Jun;62(6):847-60. doi: 10.1016/j.apradiso.2005.01.010.
Current dosimetric models for radioactive methane assume 1% of inhaled methane is absorbed, all 3H activity is converted immediately to [3H]H2O, and 14C activity is converted immediately to [14C]CO2 (50%) and organically bound carbon (50%). Results of a pilot study using rats to test these models suggest the models overestimate uptake but underestimate organic fixation of 3H and 14C, especially in liver. Also, the biokinetic properties of organically bound 3H and 14C in liver were markedly different from other tissues. Preliminary dose estimates based on observed uptake and organic fixation of label suggest current methane models likely overestimate radiation doses from radioactive methane by 3- to 10-fold.
目前用于放射性甲烷的剂量学模型假定，吸入的甲烷有1%被吸收，所有的³H活性立即转化为[³H]H₂O，而¹⁴C活性立即转化为[¹⁴C]CO₂（50%）和有机结合碳（50%）。一项用大鼠测试这些模型的初步研究结果表明，这些模型高估了摄取量，但低估了³H和¹⁴C的有机固定，尤其是在肝脏中。此外，肝脏中有机结合的³H和¹⁴C的生物动力学特性与其他组织明显不同。基于观察到的标记摄取和有机固定的初步剂量估计表明，目前的甲烷模型可能将放射性甲烷的辐射剂量高估了3至10倍。
