Ahn Sang Hee, Chung Kwangzoo, Shin Jung Wook, Cheon Wonjoong, Han Youngyih, Park Hee Chul, Choi Doo Ho
Department of Health Sciences and Technology, Samsung Advanced Institute for Health Sciences and Technology, Sungkyunkwan University, Seoul 06351, Republic of Korea.
Phys Med Biol. 2017 Sep 15;62(19):7729-7740. doi: 10.1088/1361-6560/aa87fd.
Gold nanoparticles (GNPs) injected in a body for dose enhancement in radiation therapy are known to form clusters. We investigated the dependence of dose enhancement on the GNP morphology using Monte-Carlo simulations and compared the model predictions with experimental data. The cluster morphology was approximated as a body-centred cubic (BCC) structure by placing GNPs at the 8 corners and the centre of a cube with an edge length of 0.22-1.03 µm in a 4 × 4 × 4 µm water-filled phantom. We computed the dose enhancement ratio (DER) for 50 and 260 kVp photons as a function of the distance from the cube centre for 12 different cube sizes. A 10 nm-wide concentric shell shaped detector was placed up to 100 nm away from a GNP at the cube centre. For model validation, simulations based on BCC and nanoparticle random distribution (NRD) models were performed using parameters that corresponded to the experimental conditions, which measured increases in the relative biological effect due to GNPs. We employed the linear quadratic model to compute cell surviving fraction (SF) and sensitizer enhancement ratio (SER). The DER is inversely proportional to the distance to the GNPs. The largest DERs were 1.97 and 1.80 for 50 kVp and 260 kVp photons, respectively. The SF predicted by the BCC model agreed with the experimental value within 10%, up to a 5 Gy dose, while the NRD model showed a deviation larger than 10%. The SERs were 1.21 ± 0.13, 1.16 ± 0.11, and 1.08 ± 0.11 according to the experiment, BCC, and NRD models, respectively. We most accurately predicted the GNP radiosensitization effect using the BCC approximation and suggest that the BCC model is effective for use in nanoparticle dosimetry.
已知在放射治疗中为增强剂量而注入体内的金纳米颗粒（GNP）会形成团簇。我们使用蒙特卡罗模拟研究了剂量增强对GNP形态的依赖性，并将模型预测结果与实验数据进行了比较。通过将GNP放置在边长为0.22 - 1.03 µm的立方体的8个角和中心，在一个4×4×4 µm的充水体模中，将团簇形态近似为体心立方（BCC）结构。我们计算了12种不同立方体尺寸下，50和260 kVp光子的剂量增强比（DER）作为距立方体中心距离的函数。一个10 nm宽的同心壳形探测器放置在距立方体中心的GNP最远100 nm处。为了进行模型验证，使用与实验条件相对应的参数，基于BCC和纳米颗粒随机分布（NRD）模型进行模拟，实验测量了由于GNP导致的相对生物效应的增加。我们采用线性二次模型来计算细胞存活分数（SF）和敏化剂增强比（SER）。DER与到GNP的距离成反比。对于50 kVp和260 kVp光子，最大DER分别为1.97和1.80。BCC模型预测的SF在高达5 Gy的剂量范围内与实验值在10%以内相符，而NRD模型显示偏差大于10%。根据实验模型、BCC模型和NRD模型，SER分别为1.21±0.13、1.16±0.11和1.08±0.11。我们使用BCC近似最准确地预测了GNP的放射增敏效果，并表明BCC模型可有效地用于纳米颗粒剂量测定。
