Instituto de Física, Universidad Nacional Autónoma de México, 04510 Coyoacan Mexico City, Mexico.
Biomed Phys Eng Express. 2020 Mar 4;6(3):037001. doi: 10.1088/2057-1976/ab78db.
For many years, track-average linear energy transfer (LET), [Formula: see text] has been used to quantify the radiation-induced phenomena in biological and physical systems. However, due to the need for including into the radiotherapy treatment planning system, parameters that are clinical and biologically relevant, a precise knowledge of the dose-average LET, [Formula: see text] becomes essential. Besides, several dosimetric studies have revealed that [Formula: see text] is fundamental to describe the dosimeter's response induced by photons. The most important data sets publicly available for [Formula: see text] of electron generated by photons are those reported for measurements performed in methane-based tissue-equivalent gas. However, comparing to liquid water, the electron spectra generated by low photon energy might not be similar due to the photoelectric effect. Thus, this work aimed at investigating the [Formula: see text] of electron spectra generated in liquid water and LiF:Mg,Ti by ten x-ray beams from 20 kV to 300 kV, Cs and Co gamma. The results suggest that [Formula: see text] is more sensitive to the surrounding environment than [Formula: see text] and consequently, it might be a more appropriate parameter to quantify the radiation effect and damage in matter induced by photons. Besides, good agreement (6% to 12% differences versus 10% to 15% uncertainties in the experiments) was observed between the data obtained in this work for liquid water and the experimental values published for methane-based tissue-equivalent gas at energies above 60 keV. Whereas at lowest energies, the minimum difference is around 18% which can be associated to the difference between the two media.
多年来，轨道平均线性能量转移（LET），[公式：见正文]一直被用于量化生物和物理系统中的辐射现象。然而，由于需要将与临床和生物学相关的参数纳入放射治疗计划系统，因此精确了解剂量平均线性能量转移（LET），[公式：见正文]变得至关重要。此外，几项剂量学研究表明，[公式：见正文]对于描述光子诱导的剂量计响应是基本的。目前可用于光子产生的电子[公式：见正文]的最重要数据集是那些在基于甲烷的组织等效气体中进行测量报告的数据。然而，与液体水相比，由于光电效应，低光子能量产生的电子谱可能不相似。因此，这项工作旨在研究在液体水和 LiF：Mg，Ti 中由十种从 20 kV 到 300 kV 的 X 射线束和 Cs 和 Co 伽马产生的电子谱的[公式：见正文]。结果表明，[公式：见正文]比[公式：见正文]对周围环境更敏感，因此它可能是一个更合适的参数，可以量化光子辐射效应和物质损伤。此外，在这项工作中获得的液体水的数据与发表的用于能量高于 60 keV 的基于甲烷的组织等效气体的实验值之间观察到了良好的一致性（差异在 6%至 12%，而实验不确定性在 10%至 15%）。然而，在最低能量下，最小差异约为 18%，这可能与两种介质之间的差异有关。
