Establishment of low-dose rate X-ray radiation quality and calibration of the instruments

Background: Calibration is an important way to assess the performance of radiation monitoring instruments and to ensure their accuracy and reliability for measurement. Purpose: This study aims to solve the traceability problem of dose meters at low dose rate. Methods: First of all, reference radiation masses of 55 kV, 70 kV, 100 kV, 170 kV, 240 kV were established and their energy spectra were measured by adding additional filtering to the X-ray radiation field. Then, the energy spectrum of each radiative mass was simulated by the EGS (Electron Gamma Shower) program to obtain the radiative mass half-value layer and the average energy. Finally, the kerma rate at the reference point was measured by using a large volume spherical ionization chamber, followed by calibration of conventional radiation environmental monitoring instruments. Results & Conclusions: The results showed that the relative deviation between the simulated energy spectra and measured spectra does not exceed 1.6% and the dose rate decreases with more additional filtration. The established dose rates for the radiation masses ranged from 606 nGy·h-1 to 4 451 nGy·h-1 the uncertainty is 6.0% (k=2). The uncertainty of the calibration measurement results of the high-pressure ionization chamber 6150AD dose rate meter is 7.0% (k=2). © 2022, Science Press. All right reserved.