Leach M O, Bell C M, Thomas B J
Phys Med Biol. 1983 Apr;28(4):389-405. doi: 10.1088/0031-9155/28/4/007.
The release rates and long term retention of 37Ar produced by the reaction 40Ca(n, alpha) 37Ar, following fast neutron irradiation, have been measured in vitro, in three samples of dried human femur. For each sample, the release rates were fitted to three exponential curves, of half-times approximately 2, 20 and 300 min. Some 60-80% of the 37Ar released was contained in the first component. The release rates for samples of trabecular and cortical bone were qualitatively similar, but after some 20 h the retained fraction of 37Ar was 28 +/- 0.6% in a sample of predominantly trabecular bone, and 33 +/- 0.7% in samples of predominantly cortical bone. The processes affecting the trapping and release of 37Ar from bone crystals are discussed. It is suggested that 37Ar escapes from bone mineral by back-diffusion along recoil damage tracks. The factors affecting the release of 37Ar from bone into the venous blood supply are discussed in the context of in vivo measurements of body calcium by the 37Ar method. The physiological processes and compartments likely to give rise to the long 37Ar exhalation half-times following irradiation in vivo: transfer from the mineralised bone matrix to blood capillaries, and uptake and washout from bone marrow, are considered. Uptake in bone marrow may be responsible for both of the observed half-times.
在体外对经快中子辐照后由反应40Ca(n,α)37Ar产生的37Ar在三个干燥人股骨样本中的释放率和长期保留情况进行了测量。对于每个样本，将释放率拟合为三条指数曲线，半衰期分别约为2分钟、20分钟和300分钟。释放的37Ar中约60 - 80%包含在第一个成分中。松质骨和皮质骨样本的释放率在定性上相似，但约20小时后，在主要为松质骨的样本中37Ar的保留分数为28±0.6%，在主要为皮质骨的样本中为33±0.7%。讨论了影响37Ar从骨晶体中捕获和释放的过程。有人提出37Ar通过沿反冲损伤轨迹的反向扩散从骨矿物质中逸出。在通过37Ar方法对体内钙进行测量的背景下，讨论了影响37Ar从骨释放到静脉血液供应中的因素。考虑了在体内辐照后可能导致37Ar呼气半衰期较长的生理过程和区室：从矿化骨基质转移到毛细血管，以及从骨髓摄取和清除。骨髓摄取可能是观察到的两个半衰期的原因。
