辐射场剂量学特性自动化测量系统研究

Study on Automatic Measuring System of Dosimetric Parameters for Radiation Field

  • 摘要: X、γ射线参考辐射场是开展X、γ辐射剂量仪校准工作的必备设施,辐射场的剂量学特性直接影响量值传递的可靠性。为了快速开展辐射场剂量学特性测量,研制一套新型辐射场剂量学特性自动化测量系统,利用自动化测量系统对137Cs γ射线参考辐射场、60Co γ射线参考辐射场和低能、中高能X射线参考辐射场的剂量率分布、散射辐射特性、均匀性等进行测量。结果表明,距离137Cs多源照射装置和60Co单源照射装置1~6 m处的空气比释动能率范围分别为0.67~25.61 mGy/h和0.19~7.25 Gy/h;137Cs多源照射装置、60Co单源照射装置、低能X光机和中高能X光机参考辐射场的散射辐射占比均<4%,距离1 m处辐射场照射野直径分别为22、14、16、7 cm。自动化测量系统能够满足辐射场快速精确测量需求,可大幅降低人员手动操作工作量,贯彻落实辐射防护最优化原则。

     

    Abstract: X and γ ray reference radiation field is a necessary facility for the calibration of X and γ radiation dosimeter. The dosimetric parameters of radiation field directly affects the reliability of the transmission of numerical values. To measure the dosimetric parameters of the radiation field rapidly, a new automatic measuring system of dosimetric parameters for radiation field has been investigated, which enables remote control of the positioning of the manipulator and the measurement of the ionization chamber. It features preset measurement paths, automated measurements, readout and recording data, and the ability to derive measurement results. The dose-rate distribution, scattered radiation characteristics and uniformity of 137Cs γ-ray reference radiation field, 60Co γ-ray reference radiation field, low-energy, medium-energy and high-energy X-ray reference radiation field were measured by an automated measurement system. The results show that the air kerma rates at 1-6 m away from the 137Cs multi-source irradiation device and the 60Co single-source irradiation device are 0.67-25.61 mGy/h and 0.19-7.25 Gy/h, respectively. For the 137Cs multi-source irradiation device, the 60Co single-source irradiation device, the low energy X-ray machine and the medium and high energy X-ray machine, the scattered radiation are all less than 4%, and the radiation field diameter of radiation field at the distance of 1 m is 22 cm, 14 cm, 16 cm and 7 cm, respectively. The automated measurement system can achieve fast and accurate measurements of the radiation field, which can greatly reduce the workload of the operator and implement radiation protection optimization principles.

     

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