The University of Texas at San Antonio, Department of Physics and Astronomy, San Antonio, TX 78249, United States of America.
Phys Med Biol. 2020 Jul 6;65(13):135007. doi: 10.1088/1361-6560/ab9502.
Gold nanoparticles (GNPs) have been studied extensively as promising radiation dose enhancing agents. In the current study, the dose enhancement effect of GNPs for Ir-192 HDR brachytherapy is studied using Monte Carlo N-Particle code, version 6.2 (MCNP6.2) and compared with experimental results obtained using Burlin cavity theory formalism. The Ir-192 source is verified using TG-43 parameters and dose enhancement factors (DEFs) from GNPs are simulated for three different mass percentages of gold in the GNP solution. These results are compared to DEFs previously reported experimentally by our group (Bassiri et al 2019 Med. Phys.) for a GNP-containing volume in an apparatus designed in-house to measure dose enhancement with GNPs for high dose rate (HDR) Ir-192 brachytherapy. An HDR Ir-192 Microselectron v2 r HDR brachytherapy source was modeled using MCNP6.2 using the TG-43 formalism in water. Anisotropy and radial dose function were verified against known values. An apparatus designed to measure dose enhancement to a 0.75 cm volume of GNPs from an Ir-192 brachytherapy seed with average energy of 0.38 MeV was built in-house and modeled using MCNP6.2. Burlin cavity correction factors were applied to experimental measurements. The macroscopic DEF was calculated for GNPs of size 30 nm at mass percentages of gold of 0.28%, 0.56% and 0.77%, using the repeating structures capability of MCNP6.2. DEF was calculated by dividing dose to the GNP solution by dose to water in the same volume. The radial dose function and anisotropy factor values at varying angles and distances were accurate when compared against known values. DEFs of 1.018 ± 0.003, 1.031 ± 0.003, and 1.041 ± 0.003 for GNP solutions containing mass percent of gold of 0.28%, 0.56% and 0.77%, respectively, were computed. These DEFs were within 2% of experimental values with Burlin cavity correction factors applied for all three mass percentages of gold.
金纳米颗粒（GNPs）已被广泛研究作为有前途的辐射剂量增强剂。在当前的研究中，使用蒙特卡罗 N 粒子代码，版本 6.2（MCNP6.2）研究了 GNPs 对 Ir-192 HDR 近距离治疗的剂量增强效应，并与使用 Burlin 腔理论形式获得的实验结果进行了比较。Ir-192 源使用 TG-43 参数进行验证，并模拟了三种不同金纳米颗粒溶液中金的质量百分比的剂量增强因子（DEF）。这些结果与我们小组（Bassiri 等人，2019 年 Med. Phys.）以前报道的实验 DEF 进行了比较，该 DEF 是在为测量高剂量率（HDR）Ir-192 近距离治疗中使用 GNPs 的剂量增强而设计的装置中，对含有金纳米颗粒的体积进行了测量。使用 MCNP6.2 中的 TG-43 形式对 HDR Ir-192 Microselectron v2 r HDR 近距离治疗源进行建模，在水中。各向异性和径向剂量函数与已知值进行了验证。设计了一种装置，用于测量来自 Ir-192 近距离治疗种子的 0.75 厘米体积的 GNPs 的剂量增强，该种子的平均能量为 0.38 MeV，在内部使用 MCNP6.2 进行建模。对实验测量应用了 Burlin 腔校正因子。使用 MCNP6.2 的重复结构功能，计算了尺寸为 30nm 的 GNPs 的宏观 DEF，金的质量百分比为 0.28%、0.56%和 0.77%。通过将 GNP 溶液中的剂量除以相同体积中的水中的剂量来计算 DEF。当与已知值进行比较时，在不同角度和距离处的径向剂量函数和各向异性因子值是准确的。对于含有金质量百分比为 0.28%、0.56%和 0.77%的 GNP 溶液，计算得到的 DEF 值分别为 1.018±0.003、1.031±0.003 和 1.041±0.003。对于所有三个金的质量百分比，当应用 Burlin 腔校正因子时，这些 DEF 值与实验值相差在 2%以内。
