50~120kV脉冲X射线参考辐射场建立及剂量率测量

Establishment of 50-120 kV Pulsed X-ray Reference Radiation Field and Dose Rate Measurement

为满足国内医疗、安检等脉冲辐射场所对剂量监测仪表准确溯源的需求,基于栅控技术建立满足规范和标准要求的50~120 kV毫秒级脉冲X射线参考辐射场,其脉冲宽度在1~6 300 ms范围内可调。通过对该辐射场的管电压稳定性、剂量线性、重复性、脉冲波形等关键参数进行研究测试,建立脉冲X射线参考波形,并使用30 cm3的圆柱电离室开展脉冲剂量率测量研究。结果表明,管电压预设60 kV时,介入法、非介入法测量管电压的相对偏差均不超过±1.5%;可输出参考波形脉冲的最小脉冲宽度为20 ms,在1 m处95%均匀辐射野直径约为5.5 cm;且N系列、RQR系列辐射质条件下的剂量率范围可分别扩展至0.002~10 mGy/s和0.03~250 mGy/s,可用于防护仪表的量值溯源。

In order to meet the needs of accurate traceability of dose monitoring instruments in domestic medical,security inspection and other pulse radiation places,a 50-120 kV millisecond pulse X-ray reference radiation field that meets the requirements of norms and standards was established,based on the gate control technology,and its pulse width can be adjustable in the range of 1-6300 ms.The pulse X-ray reference waveform was established by studying and testing the tube voltage stability,dose linearity,repeatability,pulse waveform and other key parameters of the radiation field,and the pulse dose rate was measured using a cylindrical ionization chamber with a sensitive volume of 30 cm 3,and obtained the following research results:when the tube voltage was preset to 60 kV,the relative deviation of the intervened and non-intervened measuring tube voltage did not exceed±1.5%;the minimum pulse width of the reference waveform pulse output was 20 ms,and a 95%uniform radiation field with a diameter of about 5.5 cm could be generated at 1 m.Moreover,the dose rate range of N series and RQR series radiation quality was extended to 0.002-10 mGy/s and 0.03-250 mGy/s,respectively,which can be used for the metrological traceability of protective instruments.