Abstract

Introduction

Nowadays, some nanoparticles (NPs) are known and used as radiosensitizers in radiotherapy and radiobiology, due to their desired biological, physical, and chemical effects on cells. This study aimed to evaluate and compare the dose enhancement factor (DEF) and the biological effectiveness of some common NPs through EGSnrc and MCDS Monte Carlo (MC) simulation codes.

Materials and methods

To evaluate considered NPs’ DEF, a single NP with 50 nm diameter was simulated at the center of concentric spheres. NP irradiations were done with 30, 60, and 100 keV photon energies. The secondary electron spectra were scored at the surface of considered NPs, and the dose values were scored at surrounding water-filled spherical shells which were distributed up to 4000 nm from the NP surface. The electron spectra were used in the MCDS code to obtain different initial DNA damages for the calculation of enhanced relative biological effectiveness (eRBE).

Results

By decreasing the photon energy, an increment of DEF was seen for all studied NPs. The maximum DEF at 30, 60, and 100 keV photon energies were respectively related to silver (Ag), gadolinium (Gd), and bismuth (Bi) NPs. The maximum double-strand break (DSB) related (eRBE_DSB) values for the 30 keV photon belonged to Ag, while BiNPs showed the maximum values at other photon energies. The minimum eRBE_DSB values were also related to iron (Fe) NPs at the entire range of studied photon energies.

Conclusions

The compared nanoscale physical and biological results of our study can be helpful in the selection of optimum NP as a radiosensitizer in future radiobiological studies. Bi, gold (Au), Ag, and platinum (Pt) NPs had great potential, respectively, as radiosensitizers relative to the other studied NPs.

中文翻译：

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基于蒙特卡罗的纳米级剂量增强因子计算和使用不同纳米颗粒作为放射增敏剂的相对生物有效性

 抽象的

 介绍

如今，一些纳米颗粒（NP）因其对细胞所需的生物、物理和化学作用而被公知并用作放射治疗和放射生物学中的放射增敏剂。本研究旨在通过EGSnrc和MCDS蒙特卡罗（MC）模拟代码评估和比较一些常见纳米粒子的剂量增强因子（DEF）和生物有效性。

 材料和方法

为了评估所考虑的纳米颗粒的 DEF，在同心球的中心模拟了直径为 50 nm 的单个纳米颗粒。 NP 照射采用 30、60 和 100 keV 光子能量进行。二次电子能谱在所考虑的纳米粒子表面进行评分，剂量值在周围充满水的球壳处进行评分，这些球壳分布在距纳米粒子表面 4000 nm 以内。 MCDS 代码中使用电子能谱来获取不同的初始 DNA 损伤，用于计算增强相对生物有效性 (eRBE)。

 结果

通过降低光子能量，所有研究的纳米粒子的 DEF 都增加了。 30、60 和 100 keV 光子能量下的最大 DEF 分别与银 (Ag)、钆 (Gd) 和铋 (Bi) NP 相关。 30 keV 光子的最大双链断裂 (DSB) 相关 (eRBE _DSB ) 值属于 Ag，而 BiNPs 在其他光子能量下显示出最大值。在整个研究光子能量范围内，最小 eRBE _DSB值也与铁 (Fe) NP 相关。

 结论

我们研究的比较纳米级物理和生物学结果有助于在未来的放射生物学研究中选择最佳的纳米粒子作为放射增敏剂。相对于其他研究的纳米颗粒，Bi、金 (Au)、Ag 和铂 (Pt) 纳米颗粒分别作为放射增敏剂具有巨大的潜力。