Curtis S B, Nealy J E, Wilson J W
Department of Cell and Molecular Biology, Lawrence Berkeley Laboratory, Berkeley, California 94720.
Radiat Res. 1995 Jan;141(1):57-65.
Radiation risk cross sections (i.e. risks per particle fluence) are discussed in the context of estimating the risk of radiation-induced cancer on long-term space flights from the galactic cosmic radiation outside the confines of the earth's magnetic field. Such quantities are useful for handling effects not seen after low-LET radiation. Since appropriate cross-section functions for cancer induction for each particle species are not yet available, the conventional quality factor is used as an approximation to obtain numerical results for risks of excess cancer mortality. Risks are obtained for seven of the most radiosensitive organs as determined by the ICRP [stomach, colon, lung, bone marrow (BFO), bladder, esophagus and breast], beneath 10 g/cm2 aluminum shielding at solar minimum. Spectra are obtained for excess relative risk for each cancer per LET interval by calculating the average fluence-LET spectrum for the organ and converting to risk by multiplying by a factor proportional to R gamma L Q(L) before integrating over L, the unrestricted LET. Here R gamma is the risk coefficient for low-LET radiation (excess relative mortality per Sv) for the particular organ in question. The total risks of excess cancer mortality obtained are 1.3 and 1.1% to female and male crew, respectively, for a 1-year exposure at solar minimum. Uncertainties in these values are estimated to range between factors of 4 and 15 and are dominated by the biological uncertainties in the risk coefficients for low-LET radiation and in the LET (or energy) dependence of the risk cross sections (as approximated by the quality factor). The direct substitution of appropriate risk cross sections will eventually circumvent entirely the need to calculate, measure or use absorbed dose, equivalent dose and quality factor for such a high-energy charged-particle environment.
在估算来自地球磁场范围外的银河宇宙辐射对长期太空飞行造成的辐射诱发癌症风险的背景下，讨论了辐射风险截面（即每粒子注量的风险）。此类量对于处理低传能线密度（LET）辐射后未观察到的效应很有用。由于尚未获得每种粒子种类诱发癌症的合适截面函数，因此使用传统的品质因数作为近似值来获取超额癌症死亡率风险的数值结果。针对国际辐射防护委员会（ICRP）确定的七个最放射敏感器官（胃、结肠、肺、骨髓（BFO）、膀胱、食道和乳腺），在太阳活动极小期低于10 g/cm²铝屏蔽的情况下，得出了风险。通过计算器官的平均注量-LET谱，并在对无限制LET（L）积分之前乘以与RγL Q（L）成比例的因子将其转换为风险，从而获得每个LET区间内每种癌症的超额相对风险谱。此处Rγ是所讨论特定器官的低LET辐射风险系数（每希沃特的超额相对死亡率）。对于太阳活动极小期的1年暴露，女性和男性机组人员的超额癌症死亡率总风险分别为1.3%和1.1%。这些值的不确定性估计在4至15倍之间，并且主要由低LET辐射风险系数以及风险截面的LET（或能量）依赖性（由品质因数近似）方面的生物学不确定性所主导。直接代入合适的风险截面最终将完全避免在这种高能带电粒子环境中计算、测量或使用吸收剂量等效剂量和品质因数的需求。
