Stepanenko Valeriy, Rakhypbekov Tolebay, Otani Keiko, Endo Satoru, Satoh Kenichi, Kawano Noriyuki, Shichijo Kazuko, Nakashima Masahiro, Takatsuji Toshihiro, Sakaguchi Aya, Kato Hiroaki, Onda Yuichi, Fujimoto Nariaki, Toyoda Shin, Sato Hitoshi, Dyussupov Altay, Chaizhunusova Nailya, Sayakenov Nurlan, Uzbekov Darkhan, Saimova Aisulu, Shabdarbaeva Dariya, Skakov Mazhin, Vurim Alexandr, Gnyrya Vyacheslav, Azimkhanov Almas, Kolbayenkov Alexander, Zhumadilov Kasym, Kairikhanova Yankar, Kaprin Andrey, Galkin Vsevolod, Ivanov Sergey, Kolyzhenkov Timofey, Petukhov Aleksey, Yaskova Elena, Belukha Irina, Khailov Artem, Skvortsov Valeriy, Ivannikov Alexander, Akhmedova Umukusum, Bogacheva Viktoria, Hoshi Masaharu
Medical Radiological Research Center (MRRC) named after A.F. Tsyb - National Medical Research Radiological Center of the Health Ministry of the Russian Federation, Koroliova Str. 4, Obninsk, Kaluga Region, 249036, Russian Federation.
Semey State Medical University, Kazakhstan, Abay Str., 103, Semey, 071400, Republic of Kazakhstan.
Radiat Environ Biophys. 2017 Mar;56(1):47-54. doi: 10.1007/s00411-016-0678-x. Epub 2017 Feb 10.
There were two sources of ionizing irradiation after the atomic bombings of Hiroshima and Nagasaki: (1) initial gamma-neutron irradiation at the moment of detonation and (2) residual radioactivity. Residual radioactivity consisted of two components: radioactive fallout containing fission products, including radioactive fissile materials from nuclear device, and neutron-activated radioisotopes from materials on the ground. The dosimetry systems DS86 and DS02 were mainly devoted to the assessment of initial radiation exposure to neutrons and gamma rays, while only brief considerations were given for the estimation of doses caused by residual radiation exposure. Currently, estimation of internal exposure of atomic bomb survivors due to dispersed radioactivity and neutron-activated radioisotopes from materials on the ground is a matter of some interest, in Japan. The main neutron-activated radionuclides in soil dust were Na, Al, Si, P, Cl, K, Ca, Sc, Mn, Fe, Co, and Cs. The radionuclide Mn (T = 2.58 h) is known as one of the dominant beta- and gamma emitters during the first few hours after neutron irradiation of soil and other materials on ground, dispersed in the form of dust after a nuclear explosion in the atmosphere. To investigate the peculiarities of biological effects of internal exposure to Mn in comparison with external gamma irradiation, a dedicated experiment with Wistar rats exposed to neutron-activated Mn dioxide powder was performed recently by Shichijo and coworkers. The dosimetry required for this experiment is described here. Assessment of internal radiation doses was performed on the basis of measured Mn activity in the organs and tissues of the rats and of absorbed fractions of internal exposure to photons and electrons calculated with the MCNP-4C Monte Carlo using a mathematical rat phantom. The first results of this international multicenter study show that the internal irradiation due to incorporated Mn powder is highly inhomogeneous, and that the most irradiated organs of the experimental animals are: large intestine, small intestine, stomach, and lungs. Accumulated absorbed organ doses were 1.65, 1.33, 0.24, 0.10 Gy for large intestine, small intestine, stomach, and lungs, respectively. Other organs were irradiated at lower dose levels. These results will be useful for interpretation of the biological effects of internal exposure of experimental rats to powdered Mn as observed by Shichijo and coworkers.
（1）爆炸瞬间的初始伽马 - 中子辐射，以及（2）残余放射性。残余放射性由两部分组成：含有裂变产物的放射性沉降物，包括核装置中的放射性裂变材料，以及地面物质产生的中子活化放射性同位素。剂量测定系统DS86和DS02主要用于评估初始中子和伽马射线辐射暴露，而对于残余辐射暴露所致剂量的估算仅作了简要考虑。目前，在日本，估算原子弹幸存者因地面物质中分散的放射性和中子活化放射性同位素导致的内照射情况备受关注。土壤尘埃中的主要中子活化放射性核素为钠、铝、硅、磷、氯、钾、钙、钪、锰、铁、钴和铯。放射性核素锰（半衰期T = 2.58小时）是土壤及其他地面物质经中子照射后的最初几小时内主要的β和γ发射体之一，在大气核爆炸后以尘埃形式分散。为了研究与外照射伽马射线相比，内照射锰的生物效应特点，七条等及其同事最近用受中子活化二氧化锰粉末照射的Wistar大鼠进行了一项专门实验。本文描述了该实验所需的剂量测定方法。基于测量的大鼠器官和组织中的锰活度以及使用数学大鼠模型通过MCNP - 4C蒙特卡罗方法计算的内照射光子和电子吸收分数，对内照射剂量进行了评估。这项国际多中心研究的初步结果表明，摄入的锰粉末所致内照射极不均匀，实验动物中受照射最多的器官是：大肠、小肠、胃和肺。大肠、小肠、胃和肺累积的器官吸收剂量分别为1.65、1.33、0.24、0.10戈瑞。其他器官的照射剂量较低。这些结果将有助于解释七条等及其同事观察到的实验大鼠内照射粉末状锰的生物效应。
