Abstract Incomplete charge collection efficiency of employed ion chamber for high energy photon dosimetry is one of the main concerns which should be compensated. In this regard, a correction factor, known as recombination correction factor (Ks), has been introduced by different methods. The aim of this study is to measure and compare the obtained Ks values by different recommended protocols for a Farmer-type ion chamber at different chamber voltages and dose rates. 30013 Farmer-type ion chamber (PTW) was considered in this study. Global dosimetry protocols including TRS-398 and TG-51 ones as well as the dose per pulse (DPP) method and Jaffe-plot approach were employed for Ks evaluation at various voltages of 200, 300, and 400 V and machine dose rates of 50, 100, 200, and 350 MU/min. The results showed that the obtained Ks values by different methods are very consistent so that the difference between the results was below 0.2% in all cases. Ks values were dependent on the applied voltage to the ion chamber, such that increasing the chamber voltage would reduce the Ks value. On the other hand, variations of the machine dose rate (MU/min) don't considerably affect the Ks value. Finally, it can be concluded that the different recommended approaches for Ks determination would result in analogous values (in comparison with the Jaffe-plot data as reference one). Therefore, the performance accuracy of studied approaches for simplified Ks determination has been confirmed.

中文翻译：

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通过不同推荐方法测定Farmer型离子室的电荷收集效率

摘要 用于高能光子剂量测定的离子室电荷收集效率不完全是需要补偿的主要问题之一。在这方面，已通过不同方法引入了称为重组校正因子 (Ks) 的校正因子。本研究的目的是测量和比较在不同腔室电压和剂量率下通过不同推荐的 Farmer 型离子室协议获得的 Ks 值。本研究考虑了 30013 Farmer 型离子室 (PTW)。采用包括 TRS-398 和 TG-51 在内的全球剂量学协议以及每脉冲剂量 (DPP) 方法和 Jaffe-plot 方法在 200、300 和 400 V 的各种电压和 50 的机器剂量率下进行 Ks 评估、100、200 和 350 MU/分钟。结果表明，通过不同方法获得的Ks值非常一致，因此在所有情况下结果之间的差异都在0.2%以下。Ks 值取决于施加到离子室的电压，因此增加室电压会降低 Ks 值。另一方面，机器剂量率 (MU/min) 的变化不会显着影响 Ks 值。最后，可以得出结论，用于 Ks 确定的不同推荐方法将产生类似的值（与作为参考的 Jaffe-plot 数据相比）。因此，已经证实了用于简化 Ks 确定的研究方法的性能准确性。这样增加腔室电压会降低 Ks 值。另一方面，机器剂量率 (MU/min) 的变化不会显着影响 Ks 值。最后，可以得出结论，用于 Ks 确定的不同推荐方法将产生类似的值（与作为参考的 Jaffe-plot 数据相比）。因此，已经证实了用于简化 Ks 确定的研究方法的性能准确性。这样增加腔室电压会降低 Ks 值。另一方面，机器剂量率 (MU/min) 的变化不会显着影响 Ks 值。最后，可以得出结论，用于 Ks 确定的不同推荐方法将产生类似的值（与作为参考的 Jaffe-plot 数据相比）。因此，已经证实了用于简化 Ks 确定的研究方法的性能准确性。