Abstract：Objective To explore the influence of various factors on the ionization recombination rate (pion) and provide reference for
the measurement of that value. Methods To explore the rationality of “two-voltage” method to calculate pion value. The measurement
tool was a three-dimensional water tank, SSD was 100 cm, and the field size was 10 cm×10 cm. The measurement depth of 6 MV,
6 MV-FFF energy was 5.2 cm, and that of 10 MV, 10 MV-FFF energy was 10.2 cm. Under the above measurement setups, the “twovoltage”
method and “Jaffé - plots” method were applied to calculate the pion value with different energies and different bias voltage
pairs and their rationality was evaluated. Then the relationship between pion value and dose rate, beam energy, type of ionization
chamber, type of electrometer and measurement depth was explored. Results Under the above settings, the pion value calculated
by some bias voltage pair had a good consistency (< 0.1%) between “two-voltage” and “Jaffé - plots” in each beam energy. The
influence of different ionization chamber and electrometer on the pion value was less than 0.5% in each beam energy. There was no
statistical correlation between the change of dose rate and the pion value. In the 10 MV-FFF energy, the differences of pion value with
the measurement depth, and the maximum value was more than 2%. Conclusion Based on the above results, it is suggested that a
comprehensive measurement of the pion value should be carried out before the machine commissioning, data collection procedure.
汪之群，杨波，于浪，王贝，李文博，胡克，张福泉，邱杰. 非均整与传统均整X线射束的电离电荷复合率研究[J]. 中国医疗设备, 2021, 36(4): 99-103.
WANG Zhiqun, YANG Bo, YU Lang, WANG Bei, LI Wenbo, HU Ke, ZHANG Fuquan, QIU Jie. Study on Ion Recombination Rate of Inhomogeneous and Conventional Homogeneous X-ray Beams. China Medical Devices, 2021, 36(4): 99-103.
