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.