Carnes B A, Grahn D
Biological and Medical Research Division, Argonne National Laboratory, Illinois 60439.
Radiat Res. 1991 Oct;128(1 Suppl):S141-6.
The impact of the biological end point selected as a synoptic measurement of mortality for the detection of protraction effects and the estimation of RBE values was investigated. Life shortening was chosen as an end point because it summarizes, in a single index, the cumulative effect of all injuries experienced by an organism. Cumulative mortality at a single time point and the hazard function (age-specific failure rate) were chosen to incorporate progressively more information, respectively, about the distribution of mortality through time. Data for both sexes of the B6CF1 mouse exposed to fission neutrons from the JANUS biomedical research reactor and 60Co gamma rays were analyzed. Three basic patterns of exposure were compared: single exposures, 24 equal once-weekly exposures, and 60 equal once-weekly exposures. The interpretation of results was influenced by the biological end point used as the synoptic measurement. An augmented response with protraction of the neutron exposure depended on the accumulated dose using the life-shortening response while this effect was nonexistent when cumulative mortality or the hazard function was used. A reduced effectiveness of protracted gamma-ray exposures was apparent for all end points. The hazard function analyses suggest that the time domain must be considered in the detection of protraction effects for either radiation quality and the subsequent estimation of RBE values.
研究了选择作为死亡率概要测量指标的生物学终点对检测延长效应和估算相对生物效应（RBE）值的影响。选择寿命缩短作为终点，是因为它以单一指标概括了生物体所经历的所有损伤的累积效应。分别选择单个时间点的累积死亡率和风险函数（年龄特异性失效率），以便逐步纳入更多关于死亡率随时间分布的信息。分析了暴露于JANUS生物医学研究反应堆裂变中子和60Coγ射线的B6CF1小鼠两性的数据。比较了三种基本暴露模式：单次暴露、24次每周一次的均等暴露和60次每周一次的均等暴露。结果的解释受到用作概要测量指标的生物学终点的影响。当中子暴露延长时，使用寿命缩短反应，增强反应取决于累积剂量，而使用累积死亡率或风险函数时，这种效应不存在。对于所有终点，延长γ射线暴露的有效性降低是明显的。风险函数分析表明，在检测任何辐射质量的延长效应以及随后估算RBE值时，必须考虑时域。
