Distribution of the radiation doses in South Urals of former Soviet Union investigated by Electron Spin Resonance dosimetry of mammal teeth

第二次世界大战后，前苏联在南乌拉尔建立了第一个生产钚的工厂，并于1948年开始运营。有三起重大事故，如Techa河污染，与该工厂有关。乌拉尔南部的这个地区已经被大量核废料的放射性核污染，尤其是锶-90。锶取代了骨骼和牙齿中的钙，因此，锶被吸收到牙釉质和牙本质的羟基磷灰石中，在本研究项目中进行了检查，给予内部剂量。在本研究中，研究人员检查了来自该工厂所在的奥泽尔斯克和周围村庄的25颗奶牛牙齿，以获得锶-90的浓度和辐射剂量。使用对射线敏感的成像板获得浓度。这些牙齿被切成两半，放在一个成像板上，在一个低背景的铅洞里待了一周。利用成像扫描仪从成像板上获得了锶-90的分布图像。通过测量含有已知锶-90浓度的牙本质标准样品，可以进行定量测量。在这些样本中发现了5颗牙齿的图像。锶-90在牙釉质中的浓度较低，而在牙本质与牙釉质之间的区域浓度较高。最大浓度约为15 Bq/g。来自高污染地区的牙齿的锶-90浓度较高，但存在一些差异。用ESR法测定牙釉质辐照剂量。4个牙齿样本的标称剂量为300至400毫戈瑞，但这些应被认为是暂定值，因为与人类牙齿不同的背景信号较大，这些值可能被高估。另一种从奶牛牙齿中获取剂量的方案应考虑到特定物种的背景信号。

After the World War II, former Soviet Union constructed its first plant complex in South Ural, which produces plutonium, starting its operation in 1948. There were three major accidents, such as contamination of Techa river, associated with this plant complex. This region of South Ural has been contaminated with huge amount of radioactive nuclei from nuclear waste, especially with Strontium-90. Strontium replaces calcium of bones and teeth, therefore, it is taken into hydroxyapatite of tooth enamel and dentin which are examined by the present research project, giving internal doses. In the present study, 25 cow teeth from Ozersk in which the plant complex is located and from surrounding villages were examined to obtain the concentrations of Strontium-90 and radiation doses. Imaging plates sensitive to beta rays were used to obtain the concentrations. The teeth were cut in half and were placed on an imaging plate for a week in a low background lead cave. The images of the Strontium-90 distribution were obtained by the imaging scanner from the imaging plate. Quantitative measurement was available by measuring the standard samples of dentin containing known concentrations of Strontium-90. The images were found for 5 teeth of those samples. The concentrations of Strontium-90 were low in enamel but higher in the region between dentin and enamel. The maximum concentration was about 15 Bq/g. Teeth from highly contaminated area have higher Strontium-90 concentrations but with some variations. The radiation doses given to tooth enamel were measured by ESR method. Nominal doses of 300 to 400 mGy were obtained for 4 teeth samples, however, these should be considered to be tentative values because these may be overestimated due to larger background signal which is different from human teeth. Another scheme to obtain doses from cow teeth should be developed with considering the species-specific background signal.