基于ISO 4037-1：2019对60~250 kV窄谱系列X射线参考辐射质的研建

以ISO 4037 1：2019为依托，使用大体积自由空气电离室作为测量器具，采用半值层法建立60~250 kV窄谱系列X射线参考辐射质，实验得出的各辐射质的第1半值层和第2半值层的值均在标准规定的误差范围内。使用高纯锗谱仪对建立的X射线参考辐射质进行测量，得到不同辐射质下的脉冲幅度谱。数据处理和分析结果表明，建立的60~250 kV窄谱系列X射线参考辐射质的谱分辨率、平均光子能量和有效能量与ISO 4037 1：2019的推荐值有较好的一致性。本次实验建立的60~250 kV窄谱系列X射线参考辐射质满足ISO 4037 1：2019要求。

Research and Establishment of 60-250 kV Narrow Spectrum Series X-ray Reference Radiation Quality Based on ISO 4037-1:2019

The establishment of X-ray reference radiation field is to realize the quantity traceability of X-ray measuring instruments. At present, the establishment of X ray reference radiation field in almost all countries refers to the ISO 4037 1 international standard issued in 1996. After a lapse of 23 years, ISO have updated and released this standard in 2019. Among them, X ray narrow spectrum radiation is usually used for the calibration and verification of protective instrument dosimeters because of its energy concentration and high energy resolution. Therefore, it is urgent to establish a narrow spectrum series reference radiometer in line with ISO 4037 1:2019 standard. This experiment is based on the ISO 4037 1:2019 standard. Through sorting, the difference between the radiation mass thickness and the filter thickness of the old and new ISO 4037 1 in the X ray reference radiation field was obtained. The 20 350 kV large volume free air ionization chamber and X ray reference radiation field independently developed by the Key Laboratory of Measurement and Calibration Technology of China Institute of Atomic Energy were used as experimental instruments. Firstly, the 60 250 kV narrow spectrum series X ray reference radiation quality was established by using the half value layer method. The experimental results show that the values of the first half value layer and the second half value layer of each radiation quality are within the error range specified in ISO 4037 1:2019 standard. High purity germanium spectrometer was used to measure the established X ray reference radiation quality, and the pulse amplitude spectrum under different radiation qualities was obtained. Through comparison, it is concluded that the spectra under each radiation quality are in good agreement with the recommended spectra of ISO 4037 1:1996 and ISO 4037 1:2019. The energy spectrum resolution and average photon energy corresponding to each radiation mass were calculated according to the spectrum. Compared with ISO 4037 1:2019, the errors are within ±4.0% and ±1.6% respectively. The effective energy under each radiation mass was calculated and analyzed by using the mass energy attenuation coefficient calculation method. Compared with ISO 4037 1:2019, the error is within ±27% respectively. The accuracy and scientificity of the radiation field were effectively reflected by comparing the radiation quality with the standard energy spectrum resolution, average photon energy and effective energy. The results show that the 60 250 kV narrow spectrum series X ray reference radiation quality established in this experiment meets the requirements of the new ISO 4037 1:2019 standard.