Ohta K, Takamoto M, Kai M, Kusama T, Aoki Y
Department of Radiological Health, Faculty of Medicine, University of Tokyo.
Nihon Koshu Eisei Zasshi. 1993 Jun;40(6):475-81.
In Japan, mass chest X-ray examinations are mandated by law for schoolchildren and students. Recently, questions of the justification of such X-ray examination have arisen. In this study the absorbed doses of each organ, and the health detriments from the mass chest X-ray examinations to schoolchildren and students were estimated. The doses of organs were measured by the TLDs (Mg2SiO4), slab phantom, and anthropomorphic phantom. The probability of fatal cancer, and the resultant reduction in life expectancy induced by mass chest X-ray examinations were calculated by the multiplicative risk projection model of the ICRP-1990. The absorbed doses of lung, thyroid glands, esophagus, stomach, breast, and red bone marrow in first-year elementary schoolchildren were 90, 30, 90, 60, 90, and 30 muGy, respectively, and the doses in ovaries and testes were almost nil. Each organ dose of first-year students of junior high school was about 1.5 times that for elementary schoolchildren. The total radiation-induced lifetime cancer risk of schoolchildren and students was from 0.3 x 10(-5) to 0.9 x 10(-5) per person by the multiplicative risk projection model of the ICRP-1990 and a factor of 2 for the DDREF (dose and dose rate effectiveness factor). The reduction in life expectancy by radiation induced fatal cancer was from 15 x 10(-5) years to 50 x 10(-5) years per person. The results of this study suggest that subjects of mass chest X-ray examinations should be carefully selected from the viewpoint of radiation protection.
在日本，法律规定对学童和学生进行大规模胸部X光检查。最近，此类X光检查的合理性引发了一些问题。在本研究中，估算了大规模胸部X光检查对学童和学生各器官的吸收剂量以及健康损害。通过热释光剂量计（Mg2SiO4）、平板模型和人体模型测量器官剂量。采用国际放射防护委员会（ICRP）1990年的倍增风险预测模型，计算了大规模胸部X光检查导致致命癌症的概率以及预期寿命的相应缩短。小学一年级学生肺部、甲状腺、食管、胃、乳房和红骨髓的吸收剂量分别为90、30、90、60、90和30微戈瑞，卵巢和睾丸的剂量几乎为零。初中一年级学生各器官的剂量约为小学生的1.5倍。根据ICRP 1990年的倍增风险预测模型以及剂量与剂量率效能因子（DDREF）为2的系数，学童和学生因辐射导致的终生患癌总风险为每人0.3×10−5至0.9×10−5。辐射诱发致命癌症导致的预期寿命缩短为每人15×10−5年至50×10−5年。本研究结果表明，从辐射防护的角度来看，应谨慎选择大规模胸部X光检查的对象。
