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首页> 外文期刊>Medical Physics >Modeling gold nanoparticle radiosensitization using a clustering algorithm to quantitate DNA double‐strand breaks with mixed‐physics Monte Carlo simulation
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Modeling gold nanoparticle radiosensitization using a clustering algorithm to quantitate DNA double‐strand breaks with mixed‐physics Monte Carlo simulation

机译：用聚类算法建模金纳米粒子放射胶质敏化，使DNA双链与混合物理蒙特卡罗模拟进行定量

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Purpose The radiosensitization properties of gold nanoparticles (GNPs) are investigated using a simple Geant4 cell model considering a realistic cell geometry and a clustering algorithm to characterize the number of DNA double‐strand breaks (DSBs). Materials and methods A mixed‐physics approach is taken for accurate modeling of low‐energy photon interactions in the different regions of the model using Geant4‐DNA physics within the cell, and Livermore physics within gold. Density‐based spatial clustering of applications with noise (DBSCAN), a clustering algorithm, is used to directly quantitate DNA DSBs after irradiation. The simulation was run using different sizes of GNPs, different distances of GNPs from the cell nucleus, and several combinations of these two conditions. Results Four types of radiation were simulated in the work: 80‐keV monoenergetic photons, 100‐keV monoenergetic photons, a 250‐kVp photon spectrum, and a 6‐MV flattening filter free (FFF) photon spectrum. A variable enhancement in DSB yield, nucleus dose, and cell dose was observed when there are GNPs in the cell cytoplasm, and increases with larger GNPs and proximity to the nucleus. The distance of the GNPs from the nucleus has a large impact on the DSB yield and nucleus dose, but little to no effect on the cell dose. The cell dose enhancement factor of 80?keV photons varies from 1.037–1.125 at 0.2?μm for 30–100?nm GNPs to 1.040–1.127 at 4?μm. The DSB enhancement factor varies from 1.050 to 1.174 at 0.2?μm to a marginal effect of 1.01 at 4?μm. For 100?keV, the dose enhancement factor is from 1.142–1.470 at 0.2?μm to 1.106–1.371 at 4?μm. The DSB enhancement factor varies from 1.249–1.813 at 0.2?μm to almost no effect at 4?μm. For 250?kVp, the dose enhancement factor is from 1.117–1.393 at 0.2?μm to 1.110–1.342 at 4?μm. The DSB enhancement factor varies from 1.183–1.600 at 0.2?μm to a marginal effect of ~1.03 at 4?μm. A 6‐MV FFF shows a dose enhancement factor of 1.061–1.103 at 0.2?μm and 1.053–1.107 at 4?μm. The DSB yield varies from 1.070–1.143 at 0.2?μm to a marginal effect at 4?μm. Conclusion The stark difference in behavior for DSB yield when compared to cell dose highlights the importance of evaluating more complex radiobiological quantities rather than dose alone when evaluating the radiosensitization properties from metallic nanomaterials. The nucleus dose showed similar characteristics to the DSB yield demonstrating the ability of the method to predict DNA damage and its relationship with nuclear dose. The proposed method provides a way to explore the radiobiological mechanisms of radiation‐induced DNA damages, and it aids to evaluate the physical radiosensitization properties of GNP‐aided radiotherapy, which can be easily combined with radiochemical DSB quantitation in order to better understand the intricate DNA damage induction mechanisms that are involved in GNP‐aided radiotherapy.
机译：目的，使用简单的GEANT4电池模型研究金纳米颗粒（GNP）的放射敏化性质，考虑到现实的细胞几何形状和聚类算法，以表征DNA双链断裂（DSB）的数量。材料和方法采用混合物理方法，用于使用细胞内的GEANT4-DNA物理学的模型不同地区的低能量光子相互作用的精确建模，以及金的Livermore物理。基于密度的空间聚类具有噪声（DBSCAN），聚类算法的应用程序，用于在照射后直接定量DNA DSB。使用不同尺寸的GNPS，来自细胞核的不同距离的模拟，以及这两个条件的几种组合。结果在工作中模拟了四种类型的辐射：80-keV单元菌光子，100-keV单元光子，250 kVp光子谱和6-MV扁平滤波器无（FFF）光子谱。当细胞细胞质中存在GNP时，观察到DSB产量，核剂量和细胞剂量的可变增强，并且随着较大的GNP和核的近似增加。 GNP与细胞核的距离对DSB产量和核剂量的影响很大，但对细胞剂量没有任何影响。 40℃的细胞剂量增强因子为0.2Ω·keV的0.2Ω·μm的1.037-1.125，在4.040-1.127，4Ωμm处变化至1.040-1.127。 DSB增强因子在0.2Ωμm以1.050至1.174变化到4.1.01的边际效果。对于100？KeV，剂量增强因子为1.142-1.470，在4.1Ωμm至1.106-1.371时为1.142-1.470。 DSB增强因子在0.2Ωμm的1.249-1.813之间变化至几乎在4Ωμm的几乎没有效果。对于250 kVP，剂量增强因子为0.2Ωμm至1.110-1.342的1.117-1.393。 DSB增强因子在0.2Ωμm的1.183-1.600之间变化至4≤1μm的边际效果。 6MV FFF显示0.2Ωμm和1.053-1.107的剂量增强因子为1.061-1.103和4Ωμm。 DSB产量在0.2Ωμm的1.070-1.143之间变化至4μm的边际效果。结论与细胞剂量相比，DSB产量的行为差异突出了评估更复杂的放射性量而不是单独评估来自金属纳米材料的放射敏化性能的重要性。核剂量显示出类似的特征，以证明该方法预测DNA损伤及其与核剂量的关系的能力。该方法提供了一种方法来探讨辐射诱导的DNA损伤的放射生物学机制，并且有助于评估GNP辅助放射治疗的物理放射敏化性能，这可以容易地与放射化学DSB定量相结合，以便更好地理解复杂的DNA涉及GNP辅助放射治疗的损伤感应机制。

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