Ramalho A T, Costa M L, Oliveira M S
Institute of Radioprotection and Dosimetry (IRD), National Commission of Nuclear Energy (CNEN), Av. Salvador Allende, Cx. P. 37750, Rio de Janeiro 22.780-160, Brazil.
Mutat Res. 1998 Aug 3;404(1-2):97-100. doi: 10.1016/s0027-5107(98)00099-2.
Frequency of chromosome aberrations detected by conventional cytogenetics is a very useful parameter in biological radiodosimetry. It can be used for estimating absorbed doses in individuals working with radioactive sources and individuals accidentally exposed to radiation. In the first case subjects wear physical dosimeters as a routine safety habit. Our laboratory at the Institute of Radioprotection and Dosimetry (IRD, Brazil) has been using conventional cytogenetic analysis to complement data obtained by physical dosimetry since 1983. Until now, we have investigated more than one hundred cases where individual physical dosimeters detected occupational exposure (above the safety limits allowed). In total, only 34% of these cases were confirmed by conventional cytogenetic dosimetry. We have also used conventional cytogenetic analysis following the radiation accident of Goiania (Brazil) in 1987. Peripheral lymphocytes from 129 exposed or potentially exposed individuals were analyzed for the frequencies of unstable chromosomal aberrations (dicentrics, centric rings and acentrics fragments) to estimate absorbed radiation doses. During the emergency period, doses were estimated to help immediate medical treatment using in vitro calibration curves produced before the accident. Later on, doses were assessed once more using new in vitro calibration curves. A drawback of this technique is that unstable aberrations are lost after exposure. To investigate the mean lifespan of lymphocytes containing dicentric and ring aberrations, we have followed 15 victims of the Goiania accident over all these years. Results suggest that the disappearance of unstable aberrations is dose-dependent. This could explain the variation in the results found among studies in this field.
通过传统细胞遗传学检测到的染色体畸变频率是生物辐射剂量测定中一个非常有用的参数。它可用于估算接触放射源的工作人员以及意外受辐射人员所吸收的剂量。在第一种情况下，作为日常安全习惯，受试者会佩戴物理剂量计。自1983年以来，我们巴西辐射防护与剂量测定研究所（IRD）的实验室一直使用传统细胞遗传学分析来补充通过物理剂量测定获得的数据。到目前为止，我们已经调查了一百多例个体物理剂量计检测到职业暴露（超过允许的安全限值）的案例。总体而言，这些案例中只有34%通过传统细胞遗传学剂量测定得到证实。我们还在1987年巴西戈亚尼亚辐射事故后使用了传统细胞遗传学分析。对129名暴露或可能暴露的个体的外周淋巴细胞进行分析，以检测不稳定染色体畸变（双着丝粒、着丝粒环和无着丝粒片段）的频率，从而估算吸收的辐射剂量。在紧急时期，利用事故前绘制的体外校准曲线来估算剂量，以帮助进行即时医疗救治。后来，又使用新的体外校准曲线再次评估剂量。该技术的一个缺点是，暴露后不稳定畸变会消失。为了研究含有双着丝粒和环状畸变的淋巴细胞的平均寿命，这些年来我们一直跟踪戈亚尼亚事故的15名受害者。结果表明，不稳定畸变的消失与剂量有关。这可以解释该领域不同研究结果之间的差异。
