一种X射线透射仪的辐射场重建与事故受照者手部剂量估算

Radiation field reconstruction and hand dose estimation for operators injured by a X-ray device radiological accident

目的客观评估辐射事故中受伤人员的受照剂量,指导放射性损伤的诊断、治疗和判断辐射事故等级。方法使用自制辐射场测量架和LiF(Mg,Cu,P)热释光探测器,模拟重建事故源项X射线透射仪出束时的辐射场,以剂量率与距离平方反比关系拟合得到辐射水平空间分布图,作为剂量估算基础;根据实际操作情况,提出了手部皮肤吸收剂量估算的参数计算方法。结果X射线透射仪出束口方向附近的空气吸收剂量率水平在mGy/h量级以上,出束口外200 cm空间内的空气吸收剂量率最高值为262μGy/h,最低值为2.1μGy/h,比环境本底水平高2个量级以上;无论是正常操作还是极端操作情况,辐射事故中两名女性受照射人员短期内总的手部皮肤吸收剂量均超过16.9 Gy,达Ⅲ度或Ⅳ度急性放射性皮肤损伤。结论手部皮肤受照剂量估算结果为受照射人员放射性损伤的诊断、治疗以及辐射事故等级确定提供了有效支持,辐射场重建方法及剂量估算方法可为同类辐射事故的处置提供参考。

Objective To evaluate the radiation dose to the injured persons in a radiological accident,provide the guidance on the diagnosis and treatment of radiation injury,and provide the basis for determination of the level of radiological accident.Method Firstly,the air-absorbed dose rates at 206 locations surrounding a X-ray device were measured by using LiF(Mg,Cu,P)thermoluminescence detectors and self-made radiation field measuring frames.Secondly,the spatial distribution of radiation level was obtained by fitting the inverse square law between absorbed dose rate and distance,which is used as the basis of dose estimation.Finally,based on the actual working conditions of injured operators,a parameter calculation method was proposed for estimating hand skin absorbed dose.Results The air-absorbed dose rate surrounding X-ray beam outlet was higher than 1.0 mGy/h.The maximum air-absorbed dose rate value in the space of within 200 cm outside X-ray beam outlet was 262μGy/h and the minimum value was 2.1μGy/h,2 orders of magnitude higher than environmental background level.During normal operation,the total absorbed doses to the hand skin of two injured female operators were 36.9 and 16.9 Gy,respectively.During extreme operation,the hand skin-received total absorbed doses to the two operators were 85.2 and 38.9 Gy,respectively.Under the occupational health standard GBZ 106-2020,the two persons had acute radiation skin injury of gradeⅢorⅣon their hands.Conclusions The results of hand skin exposure doses provide effective support for diagnosis and treatment of radiation injuries and for the determination of radiological accident level.The method used in radiation field reconstruction and dose estimation mentioned in this study can provide reference for the treatment in the similar radiological accident.