Mattsson Sören, Nilsson Mats
Medical Radiation Physics, Department of Clinical Sciences Malmö, Lund University, Skåne University Hospital Malmö, Malmö SE-205 02, Sweden
Medical Radiation Physics, Department of Clinical Sciences Malmö, Lund University, Skåne University Hospital Malmö, Malmö SE-205 02, Sweden.
Radiat Prot Dosimetry. 2015 Jul;165(1-4):17-21. doi: 10.1093/rpd/ncv037. Epub 2015 Mar 22.
The article is intended to give a short overview of epidemiological data on cancer risks associated with very low absorbed doses of ionising radiation. The linear no-threshold (LNT) approach to estimate cancer risks involves the use of epidemiological data at higher doses (>100 mSv), but is supported by data from lower exposure of more sensitive population groups like fetuses and children and the presence of rare types of cancer. The International Commission on Radiological Protection (ICRP) concludes that the LNT model, combined with a dose and dose-rate effectiveness (reduction) factor (DDREF) of 2 for extrapolation from high doses, should be used. The numerical value of the DDREF is challenged by the findings from some recent epidemiological studies demonstrating risks per unit dose compatible with the risks observed in the higher dose studies. In general there is very limited knowledge about the cancer risk after low absorbed doses (10-100 mSv), as most of epidemiological studies have limitations in detecting small excess risks arising from low doses of radiation against fluctuations in the influence of background risk factors. Even if there may be significant deviations from linearity in the relevant dose range 0-100 mSv, one does not know the magnitude or even the direction of any such deviations. The risks could be lower than those predicted by a linear extrapolation, but they could also be higher. Until more results concerning the effects of low-dose exposure are available, a reasonable radiation protection approach is to consider the risk proportional to the dose.
本文旨在简要概述与极低吸收剂量电离辐射相关的癌症风险的流行病学数据。估计癌症风险的线性无阈（LNT）方法涉及使用高剂量（>100 mSv）的流行病学数据，但得到了胎儿和儿童等更敏感人群低暴露数据以及罕见类型癌症存在情况的支持。国际放射防护委员会（ICRP）得出结论，应使用LNT模型，并结合用于从高剂量外推的剂量和剂量率有效性（降低）因子（DDREF）为2。DDREF的数值受到一些近期流行病学研究结果的挑战，这些研究表明单位剂量的风险与高剂量研究中观察到的风险相符。一般来说，对于低吸收剂量（10 - 100 mSv）后的癌症风险了解非常有限，因为大多数流行病学研究在检测低剂量辐射引起的小额外风险相对于背景风险因素影响的波动方面存在局限性。即使在0 - 100 mSv的相关剂量范围内可能存在与线性有显著偏差的情况，人们也不知道任何此类偏差的大小甚至方向。风险可能低于线性外推预测的风险，但也可能更高。在获得更多关于低剂量暴露影响的结果之前，一种合理的辐射防护方法是认为风险与剂量成正比。
