This study investigates the effect of adding spinel ferrite nanoparticles to tissues irradiated with low energy photons and simulated effect of particle size on dosimetry quantities. The simulations have been carried out with MCNP 6.2 code which enables event-by-event electron transport. Firstly, dose enhancement factors have been determined with water/ferrite mixture and for MnFe₂O₄, CoFe₂O₄, Fe₃O₄, NiFe₂O₄, ZnFe₂O₄, at 5,10, and 20 mgg⁻¹ concentrations and individual nanoparticles of Fe₃O₄ in a 1 cm³ volume. Source photons used were iodine-125 spectrum and X-rays spectra with tube voltages 50 kVp, 100 kVp. The dose enhancement with 50 kVp source go as high as 1.73 with 20 mgg⁻¹ NP concentration, whereas with 100 kVp source, it drops to 1.13 with 5 mgg⁻¹. In a different simulation, an endothelial cell of tumor vasculature with nanoparticles attached to its surface has been modeled to handle the cellular level effects. The amount of self-absorption versus absorption in the cell has been compared for different particles size. Also, we presented the electron spectrum leaving the nanoparticle surfaces entering the cell volume. To achieve realistic dose enhancement for the macro scale, either high concentrations or very low photon energies are required. In the cellular scale simulations, results indicate an extraordinary difference in low energy electron spectrum, which contribute much to energy deposition within the vicinity of nanoparticles, showing the importance of targeting.

本研究调查了将尖晶石铁氧体纳米颗粒添加到用低能光子辐照的组织中的效果，并模拟了颗粒尺寸对剂量测定量的影响。已使用 MCNP 6.2 代码进行了模拟，该代码可实现逐个事件的电子传输。首先，已经用水/铁氧体混合物确定了剂量增强因子，对于 MnFe ₂ O ₄、CoFe ₂ O ₄、Fe ₃ O ₄、NiFe ₂ O ₄、ZnFe ₂ O ₄，在5.10和20 mgg ^-1 1 cm中 Fe ₃ O ₄的浓度和单个纳米颗粒³卷。使用的源光子是碘 125 光谱和 X 射线光谱，管电压为 50 kVp、100 kVp。^{50 kVp 源的剂量增强在 20 mgg -1} NP 浓度下高达 1.73 ，而对于 100 kVp 源，它在 5 mgg ^{-1时下降到 1.13}. 在不同的模拟中，已对肿瘤脉管系统的内皮细胞进行建模，其表面附着有纳米颗粒，以处理细胞水平的影响。已经比较了不同粒径的细胞自吸收量与吸收量。此外，我们展示了离开纳米颗粒表面进入细胞体积的电子光谱。为了实现宏观尺度的真实剂量增强，需要高浓度或非常低的光子能量。在细胞尺度模拟中，结果表明低能电子光谱存在显着差异，这对纳米粒子附近的能量沉积有很大贡献，显示了靶向的重要性。