Magae Junji, Hoshi Yuko, Furukawa Chiharu, Kawakami Yasushi, Ogata Hiromitsu
Institute of Research and Innovation, 1201 Takada, Kashiwa 277-0861, Japan.
Radiat Res. 2003 Nov;160(5):543-8. doi: 10.1667/rr3071.
Because biological responses to radiation are complex processes that depend on both irradiation time and total dose, consideration of both dose and dose rate is necessary to predict the risk from long-term irradiations at low dose rates. Here we mathematically and statistically analyzed the quantitative relationships between dose, dose rate and irradiation time using micronucleus formation and inhibition of proliferation of human osteosarcoma cells as indicators of biological response. While the dose-response curves did not change with exposure times of less than 20 h, at a given dose, both biological responses clearly were reduced as exposure time increased to more than 8 days. These responses became dependent on dose rate rather than on total dose when cells were irradiated for 20 to 27 days. Mathematical analysis demonstrates that the relationship between effective dose and dose rate is well described by an exponential function when the logarithm of effective dose is plotted as a function of the logarithm of dose rate. These results suggest that our model, the modified exponential (ME) model, can be applied to predict the risk from exposure to low-dose/low-dose-rate radiation.
由于生物对辐射的反应是复杂的过程，取决于照射时间和总剂量，因此在预测低剂量率长期照射的风险时，必须同时考虑剂量和剂量率。在此，我们以人骨肉瘤细胞的微核形成和增殖抑制作为生物反应指标，对剂量、剂量率和照射时间之间的定量关系进行了数学和统计学分析。虽然剂量-反应曲线在照射时间少于20小时时没有变化，但在给定剂量下，当照射时间增加到超过8天时，两种生物反应均明显降低。当细胞照射20至27天时，这些反应变得依赖于剂量率而非总剂量。数学分析表明，当有效剂量的对数作为剂量率的对数的函数绘制时，有效剂量与剂量率之间的关系可用指数函数很好地描述。这些结果表明，我们的模型，即修正指数（ME）模型，可用于预测低剂量/低剂量率辐射暴露的风险。
