摘要目的:提出使用EBT3胶片精确测量200 kV中能X射线辐照下培养皿中超薄细胞溶液吸收剂量的方法，以提升细胞辐照实验的剂量精度。方法:在6 MV X射线下对EBT3胶片进行剂量标定，并测量和计算研究所用小动物精准放疗辐照仪产生的200 kV射线的射线质（半价层）和有效能量，以确定EBT3胶片能量响应修正因子。使用该200 kV射线照射注有超薄液体并置入EBT3胶片的三款常用培养皿，将修正后的EBT3胶片剂量作为液体吸收剂量，并测量分析水中胶片的剂量线性度。此外，基于MCNP5程序对辐照环境建模后，用蒙特卡罗方法对液体吸收剂量作独立计算，将计算结果与胶片测量结果进行比较，以验证测量剂量的精确度。结果:所用200 kV射线半价层为8.77 mmAl，有效能量为57.4 keV，对应的能量响应修正因子为0.889。EBT3胶片测得的大、中、小三款培养皿在200 kV射线指定参数下的液体吸收的平均剂量经修正后分别为（1.434±0.004）Gy、（1.467±0.011）Gy、（1.469±0.027）Gy，与对应蒙特卡罗计算值的百分偏差分别为0.07%、-0.70%、0.47%，二者结果接近。此外，水中EBT3胶片剂量线性度亦良好，决定系数 R2=0.9972。 结论:采用本研究所提出的EBT3胶片测量超薄细胞溶液剂量的方法可行，在200 kV射线下的剂量测量结果具有较高的精确度。

abstractsObjective:To improve the dosimetric accuracy of cell irradiation experiments by developing a method of accurately measuring the absorbed dose of ultra-thin solution in culture dishes under 200 kV medium-energy X-rays using EBT3 films.Methods:EBT3 film dose calibration was performed under Cyberknife 6 MV beam, and the beam quality (half-value layer) and effective energy of the 200 kV beam used in this study generated from Small Animal Radiation Research Platform through measurements and calculations were obtained to determine the EBT3 energy response correction factor. The 200 kV beam was utilized to irradiate three commonly used culture dishes filled with ultra-thin liquid placed on EBT3 films and the corrected EBT3 doses were taken as the liquid absorbed doses. The dose linearity of immersed films was also measured and analyzed. In addition, after modeling the irradiation environment, the independent Monte Carlo calculations of the liquid absorbed dose were performed by MCNP5 program. The calculation results were compared with the film measurement results to verify the accuracy of the measured doses.Results:The 200 kV beam had a half-value layer of 8.77 mm aluminum and effective energy of 57.4 keV, corresponding to an energy response correction factor of 0.889. The average liquid absorbed doses of large, medium and small culture dishes measured by EBT3 films under the specified parameters of 200 kV beam were (1.434±0.004) Gy, (1.467±0.011) Gy and (1.469±0.027) Gy after correction, respectively. The percentage errors from the corresponding Monte Carlo calculation doses were 0.07%, -0.70%, and 0.47%, respectively, where the relatively consistent results could be found. In addition, the dose linearity of immersed EBT3 films was also good, with coefficient of determination R2=0.9972. Conclusion:The method of measuring the dose of ultra-thin cell solution using EBT3 films proposed in this study is feasible, and the dose results obtained yield high accuracy under 200 kV beam.