Craven P A, Rycroft M J
College of Aeronautics, Cranfield University, Bedfordshire, U.K.
Adv Space Res. 1996;18(1-2):45-9. doi: 10.1016/0273-1177(95)00788-g.
Beyond the magnetic influence of the Earth, the flux of galactic cosmic radiation (GCR) represents a radiological concern for long-term manned space missions. Current concepts of radiation quality and equivalent dose are inadequate for accurately specifying the relative biological "efficiency" of low doses of such heavily ionising radiations, based as they are on the single parameter of Linear Energy Transfer (LET). Such methods take no account of the mechanisms, nor of the highly inhomogeneous spatial structure, of energy deposition in radiation tracks. DNA damage in the cell nucleus, which ultimately leads to the death or transformation of the cell, is usually initiated by electrons liberated from surrounding molecules by the incident projectile ion. The characteristics of these emitted "delta-rays", dependent primarily upon the charge and velocity of the ion, are considered in relation to an idealised representation of the cellular environment. Theoretically calculated delta-ray energy spectra are multiplied by a series of weighting algorithms designed to represent the potential for DNA insult in this environment, both in terms of the quantity and quality of damage. By evaluating the resulting curves, and taking into account the energy spectra of heavy ions in space, a relative measure of the biological relevance of the most abundant GCR species is obtained, behind several shielding configurations. It is hoped that this method of assessing the radiation quality of galactic cosmic rays will be of value when considering the safety of long-term manned space missions.
除了地球的磁影响外，银河宇宙辐射（GCR）通量对长期载人航天任务构成了辐射方面的担忧。基于线性能量转移（LET）这一单参数，当前的辐射质量和当量剂量概念不足以准确确定低剂量此类高电离辐射的相对生物“效率”。此类方法未考虑辐射径迹中能量沉积的机制，也未考虑其高度不均匀的空间结构。细胞核中的DNA损伤最终会导致细胞死亡或转化，通常是由入射的弹丸离子从周围分子中释放出的电子引发的。这些发射出的“δ射线”的特性主要取决于离子的电荷和速度，文中结合细胞环境的理想化表示对其进行了考虑。理论计算的δ射线能谱乘以一系列加权算法，这些算法旨在从损伤的数量和质量两方面表示这种环境中DNA受损伤的可能性。通过评估所得曲线，并考虑太空中重离子的能谱，得出了几种屏蔽配置下最丰富的银河宇宙射线种类的生物相关性相对度量。希望这种评估银河宇宙射线辐射质量的方法在考虑长期载人航天任务的安全性时能发挥作用。
