Rezaei Hadi, Zabihzadeh Mansour, Ghorbani Mahdi, Goli Ahmadabad Foad, Mostaghimi Hesameddin
Department of Medical Physics, Faculty of Medicine, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran.
Department of Radiology, Faculty of Paramedical Sciences, Shiraz University of Medical Sciences, Shiraz, Iran.
Australas Phys Eng Sci Med. 2017 Sep;40(3):545-553. doi: 10.1007/s13246-017-0555-1. Epub 2017 May 16.
In recent years, the use of gold nanoparticles in radiation therapy has been introduced as a new approach in radiotherapy. The aim of this study is to investigate the effect of gold nanoparticles (GNPs) in plaque brachytherapy for choroidal melanoma using Monte Carlo (MC) simulation. MCNPX code was used for simulation of human eye, Pd (model 200) brachytherapy source and the 20 mm COMS eye plaque that was loaded with 24 Pd seeds and standardized by Collaborative Ocular Melanoma Study (COMS). The tumour was defined from the inner surface of choroid with 0.55 cm height and latticed with gold nanospheres and it was filled with different concentrations of 5, 10 and 15 mg/g GNPs, separately. Dose rate and dose enhancement factor in tumour and normal tissues of the eye (without gold) was examined for this case and compared with gold-water mixture of the same concentrations distributed in the tumour. The results show that with increasing the concentration of GNPs, the dose in the tumour increases and the dose to the normal tissues decreases. Furthermore, the time that is required to deliver the prescribed dose to the tumour decreases. In the gold nanosphere case for 5, 10 and 15 mg/g concentrations, the DEF in the apex of the tumour are 1.28, 1.46, 1.44 and at the distance of 6.5 mm in the normal tissue (outside the tumour) this factor would be 0.82, 0.73 and 0.68. The comparison between two cases of gold nanospheres and gold-water mixture shows that when the gold concentrations are defined as mixed with water, the dose enhancement in the first depths are higher than when the gold-nanoparticles are distributed inside the tumour. Furthermore due to more reduced particle flux for water-mixture case, by an increase in the depth the dose enhancement in gold-nanosphere increases compared with gold-water mixture case.
近年来，金纳米颗粒在放射治疗中的应用已作为放射治疗的一种新方法被引入。本研究的目的是使用蒙特卡罗（MC）模拟研究金纳米颗粒（GNPs）在脉络膜黑色素瘤斑块近距离放射治疗中的效果。MCNPX代码用于模拟人眼、Pd（型号200）近距离放射治疗源以及装有24颗Pd种子并经协作性眼黑色素瘤研究（COMS）标准化的20毫米COMS眼斑块。肿瘤从脉络膜内表面定义，高度为0.55厘米，用金纳米球网格化，并分别填充不同浓度的5、10和15毫克/克的GNPs。研究了这种情况下肿瘤和眼正常组织（无金）中的剂量率和剂量增强因子，并与肿瘤中分布的相同浓度的金 - 水混合物进行比较。结果表明，随着GNPs浓度的增加，肿瘤中的剂量增加，正常组织中的剂量降低。此外，向肿瘤输送规定剂量所需的时间减少。在金纳米球情况下，对于5、10和15毫克/克的浓度，肿瘤顶端的DEF分别为1.28、1.46、1.44，在正常组织（肿瘤外）6.5毫米处，该因子分别为0.82、0.73和0.68。金纳米球和金 - 水混合物两种情况的比较表明，当金浓度定义为与水混合时，前几个深度的剂量增强高于金纳米颗粒分布在肿瘤内部的情况。此外，由于水混合物情况下粒子通量减少更多，随着深度增加，金纳米球中的剂量增强比金 - 水混合物情况增加。
