In the present work, Monte Carlo simulations were employed to study the characteristics of the dose distribution of high energy electron beam in the presence of uniform transverse magnetic field. The simulations carried out the transport processes of the 30 MeV electron beam in the homogeneous water phantom with different magnetic field. It was found that the dose distribution of the 30 MeV electron beam had changed significantly because of the magnetic field. The result showed that the range of the electron beam was decreased obviously and it formed a very high dose peak at the end of the range, and the ratio of maximum dose to the dose of the surface was greatly increased. The results of this study demonstrated that we could change the depth dose distribution of electron beam which is analogous to the heavy ion by modulating the energy of the electron and magnetic field. It means that using magnetic fields in conjunction with electron radiation therapy has great application prospect, but it also has brought new challenges for the research of dose algorithm.
Three dimensional (3D) printing is considered as an advanced manufacturing technology because of its additive nature. Electron beam melting (EBM) is a widely used 3D printing processes for the manufacturing of metal components. However, the products printed via this process generally contain micro porosities which affect mechanical properties, especially the fatigue property. In this paper, two types of EBM printed samples of the Ti-6Al-4V alloy, one with a round cross section and the other with a triangle cross section, were employed to investigate the existence of porosities using computed tomography (CT). Statistical analyses were conducted on the number, volume, shape, and distribution of pores. The results show that small pores (less than 0.000 2 mm3) account for 80% of all pores in each type of samples. Additionally, to some extent, the shape of sample has influence on the number of micro porosities in EBM made Ti-6Al-4V. The sphericity of the pores is relatively low and is inversely proportional to pore volume. It is found that re-melting on the free surface effectively reduce pore density near the surface. This study may help produce a medical implant with better fatigue resistance.