Farhood Bagher, Ghorbani Mahdi
Medical Physics Department, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran.
J Contemp Brachytherapy. 2015 Jan;6(4):377-85. doi: 10.5114/jcb.2014.48031. Epub 2014 Dec 31.
The aim of this study is evaluation of the effect of diameter of (10)B nanoparticles and various neutron capture cross-section libraries on macroscopic dose enhancement in boron neutron capture therapy (BNCT).
MCNPX Monte Carlo code was used for simulation of a (252)Cf source, a soft tissue phantom and a tumor containing (10)B nanoparticles. Using (252)Cf as a neutron source, macroscopic dose enhancement factor (MDEF) and total dose rate in tumor in the presence of 100, 200, and 500 ppm of (10)B nanoparticles with 25 nm, 50 nm, and 100 nm diameters were calculated. Additionally, the effect of ENDF, JEFF, JENDL, and CENDL neutron capture cross-section libraries on MDEF was evaluated.
There is not a linear relationship between the average MDEF value and nanoparticles' diameter but the average MDEF grows with increased concentration of (10)B nanoparticles. There is an increasing trend for average MDEF with the tumor distance. The average MDEF values were obtained the same for various neutron capture cross-section libraries. The maximum and minimum doses that effect on the total dose in tumor were neutron and secondary photon doses, respectively. Furthermore, the boron capture related dose component reduced in some extent with increase of diameter of (10)B nanoparticles.
Based on the results of this study, it can be concluded that from physical point of view, various nanoparticle diameters have no dominant effect on average MDEF value in tumor. Furthermore, it is concluded that various neutron capture cross-section libraries are resulted to the same macroscopic dose enhancements. However, it is predicted that taking into account the biological effects for various nanoparticle diameters will result in different dose enhancements.
本研究旨在评估硼（10）B纳米颗粒直径及各种中子俘获截面库对硼中子俘获疗法（BNCT）中宏观剂量增强的影响。
使用MCNPX蒙特卡罗代码模拟（252）Cf源、软组织体模和含有硼（10）B纳米颗粒的肿瘤。以（252）Cf作为中子源，计算了存在直径为25 nm、50 nm和100 nm的硼（10）B纳米颗粒浓度分别为100、200和500 ppm时肿瘤中的宏观剂量增强因子（MDEF）和总剂量率。此外，评估了ENDF、JEFF、JENDL和CENDL中子俘获截面库对MDEF的影响。
平均MDEF值与纳米颗粒直径之间不存在线性关系，但平均MDEF随硼（10）B纳米颗粒浓度的增加而增大。平均MDEF随肿瘤距离呈增加趋势。不同中子俘获截面库获得的平均MDEF值相同。对肿瘤总剂量产生影响的最大和最小剂量分别是中子剂量和次级光子剂量。此外，硼俘获相关剂量分量随硼（10）B纳米颗粒直径的增加而有所降低。
基于本研究结果，可以得出结论，从物理角度来看，不同的纳米颗粒直径对肿瘤中的平均MDEF值没有显著影响。此外，可以得出结论，各种中子俘获截面库导致相同的宏观剂量增强。然而，可以预测，考虑到不同纳米颗粒直径的生物学效应将导致不同的剂量增强。
