Departamento de Investigación en Física, Doctorado en Física Universidad de Sonora, 83000, Hermosillo, Sonora, México.
Departamento de Física, Doctorado en Nanotecnología, Universidad de Sonora, 83000, Hermosillo, Sonora, México.
Phys Med Biol. 2021 Jul 1;66(13). doi: 10.1088/1361-6560/abfce4.
experiments show significant reduction in the survival fraction of cells under irradiation treatments assisted with high-nanoparticles (NPs). In order to predict the radiosensitization effect of NPs, a modification of the local effect model (LEM), in which the energy deposition from NPs is assessed by Monte Carlo (MC) radiation transport codes, has been employed in the past. In this work, a combined framework that splits the consideration of the radiosensitization effect into two steps is proposed. The first step is the evaluation of the radial dose distribution (RDD) around a single NP ionized by a photon beam with given energy spectrum using MC simulation. Thereafter, an analytical approach based of the LEM and the calculated RDD is used for evaluation of the average dose and the average number of lethal lesions in a cell target due to a set of ionized NPs. The explicit expressions were derived for the case of a spherical cell target and the RDD describing by the power law function. RDDs around gold NPs (GNPs) of different radii were simulated using the MC technique and fitted by a power law function. The fitted RDD and the derived expressions were applied for calculation of the survival curves and relative biological effectiveness of a spherical MDA-MB-231 cell loaded with GNPs and irradiated with monoenergetic photons of 10-150 keV. The proposed framework provides a practical alternative to time-consuming MC simulations, enabling the assessment of the response of cell cultures to an irradiation treatment assisted with NPs for a wide variety of cell geometries, NP distributions and irradiation schemes.
实验表明，在高浓度纳米粒子（NPs）辅助的辐照处理下，细胞的存活率显著降低。为了预测 NPs 的放射增敏效应，过去曾采用局部效应模型（LEM）的修正方法，通过蒙特卡罗（MC）辐射输运代码评估 NPs 的能量沉积。在这项工作中，提出了一种将放射增敏效应的考虑分为两个步骤的综合框架。第一步是使用 MC 模拟评估给定能谱的光子束电离单个 NP 周围的径向剂量分布（RDD）。此后，基于 LEM 和计算出的 RDD 的分析方法用于评估由于一组电离的 NPs 而在细胞靶标中引起的平均剂量和平均致死损伤数。针对球形细胞靶标的情况，导出了显式表达式，并采用幂律函数来描述 RDD。使用 MC 技术模拟了不同半径的金纳米粒子（GNPs）的 RDD，并采用幂律函数进行拟合。拟合的 RDD 和导出的表达式用于计算加载 GNPs 并受到 10-150 keV 单能光子照射的 MDA-MB-231 球形细胞的存活曲线和相对生物效应。所提出的框架为耗时的 MC 模拟提供了一种实用的替代方法，使人们能够评估细胞培养物对各种细胞几何形状、NP 分布和照射方案的 NP 辅助照射处理的反应。
