The beam quality correction factor,kQ, which corrects for the difference in the ionization chamber response between the reference and clinical beam quality, is an integral part of radiation therapy dosimetry. The uncertainty ofkQis one of the most significant sources of uncertainty in the dose determination. To improve the accuracy of availablekQdata, four partners calculatedkQfactors for 10 ionization chamber models in linear accelerator beams with accelerator voltages ranging from 6 MV to 25 MV, including flattening-filter-free (FFF) beams. The software used in the calculations were EGSnrc and PENELOPE, and the ICRU report 90 cross section data for water and graphite were included in the simulations. Volume averaging correction factors were calculated to correct for the dose averaging in the chamber cavities. A comparison calculation between partners showed a good agreement, as did comparison with literature. ThekQvalues from TRS-398 were higher than our values for each chamber where data was available. ThekQvalues from TRS-398 were higher than our values for each chamber where data was available. ThekQvalues for the FFF beams did not follow the same TPR20,10,kQrelation as beams with flattening filter (values for 10 MV FFF beams were below fits made to other data on average by 0.3%), although our FFF sources were only for Varian linacs.

中文翻译：

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MV光子束中电离室的计算束质量校正因子。

校正参考离子束质量和临床离子束质量之间的电离室响应差异的离子束质量校正因子kQ是放射治疗剂量法不可或缺的一部分。kQ的不确定性是剂量确定中最重要的不确定性来源之一。为了提高可用kQdata的准确性，四个合作伙伴计算了线性加速器束中10个电离室模型的kQ因子，加速器电压范围为6 MV至25 MV，包括无展平滤波器（FFF）束。计算中使用的软件为EGSnrc和PENELOPE，而ICRU报告的90个水和石墨横截面数据也包括在仿真中。计算体积平均校正因子以校正腔室内的平均剂量。合作伙伴之间的比较计算与文献比较显示出很好的一致性。TRS-398的kQ值高于我们可获得数据的每个隔室的kQ值。TRS-398的kQ值高于我们可获得数据的每个隔室的kQ值。FFF光束的kQ值与带平坦滤波器的光束不遵循相同的TPR20,10，kQ关系（10 MV FFF光束的值比其他数据的拟合值平均低0.3％），尽管我们的FFF光源仅用于瓦里纳直线加速器。