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[目的]探讨平行板电离室的三种不同校准方法和校准精度,及电子线测量中不同电离室的应用范围。[方法]分别采用高能电子束校准法、60Coγ射线模体校准法和60Coγ射线空气校准法平行板电离室进行校准后,测量4～18MeV的加速器高能电子线输出剂量,并与指形电离室测量结果进行比较。[结果]与高能电子束校准法相比,60Coγ射线模体内校准法得到的平行板电离室空气吸收剂量校准因子数值几乎相等(差别仅为0.27‰),而60Coγ射线空气校准法差别大于>2%。指形电离室对6～18MeV的电子束输出剂量测量误差小于0.8%,对4MeV电子束的测量误差则达2.59%。[结论]60Coγ射线模体校准法与高能电子线校准平行板电离室精度相近,而60Coγ射线空气校准法误差较大。对能量大于6MeV的电子束,使用指形电离室也能得到较准确的测量结果,但4MeV以下电子束必须使用平行板电离室测量才能满足临床质控要求。
[Objective] The research aimed to discuss three different calibration methods and calibration accuracy of parallel plate ionization chamber and the application range of different ionization chambers in electron wire measurement. [Method] The energetic electron beam calibration method, 60Co γ ray phantom calibration method and 60Co γ ray air calibration parallel plate ionization chamber were used for calibration respectively. The dose of 4-18 MeV accelerator electron beam was measured and compared with that of finger ionization chamber The results are compared. [Result] Compared with the high-energy electron beam calibration method, the calibration values of air absorption dose of parallel plate ionization chamber obtained by the 60Co γ-ray in-vivo calibration method were almost equal (only 0.27 ‰), while the difference of 60Co γ- . The measurement error of the electron beam output dose of 6-18 MeV is less than 0.8% and the measurement error of 4MeV electron beam is 2.59%. [Conclusion] The calibration accuracy of 60Coγ-ray phantom was similar to that of high-energy electron-beam parallel plate ionization chamber, but the error of 60Coγ-ray air calibration was larger. For electron beams with energies greater than 6 MeV, the use of a finger ionization chamber results in a more accurate measurement. However, electron beams below 4 MeV must be measured using parallel plate ionization chambers to meet clinical quality control requirements.