objective: the aim of this study is to evaluate the effect of tissue composition on dose distribution in electron beam radiotherapy. methods : a siemens primus linear accelerator and a phantom were simulated using mcnpx monte carlo code. in a homogeneous cylindrical phantom, six types of soft tissue and three types of tissue-equivalent materials were investigated. the tissues included muscle (s...

Background: In radiotherapy, low-energy photon beams are better adapted to the treated volume, and the use of high-energy beams can reduce hot spots in the radiation therapy. Therefore, mixing low and high energies with different ratios can control the rate of hotspots, as well as the dose distribution of the target volume.Material and Methods: The percentage depth doses (PDDs) were calculated ...

background: in radiation therapy, the peripheral dose is important when anatomical structures with very low dose tolerances are involved. in this study, the two available calculation algorithms of the varian eclipse 8.6 treatment planning system(tps), the anisotropic analytic algorithm (aaa) and pencil-beam convolution (pbc) was used to compare measured and calculated peripheral dose distributi...

PURPOSE Linac-magnetic resonance (MR) systems have been proposed in order to achieve realtime image guided radiotherapy. The design of a new linac-MR system with the in-line 6 MV linac generating x-rays along the symmetry axis of an open MR imager is outlined. This new design allows for a greater MR field strength to achieve better quality images while reducing hot and cold spots in treatment p...

Background: Boron neutron capture therapy (BNCT) is a radiotherapy that combines biological targeting and high linear energy transfer. A potential therapeutic approach for non-small cell lung cancer (NSCLC) is considered. However, dose in lung tumor is not homogeneous, and it will reduce the effect of BNCT treatment. In order to improve the dose distribution of BNCT, the multi-field irradiation...

in this paper, the hartree-fock method has been formulated to investigate some of the ground state properties of quasi-one-dimensional interacting electron gas in the presence of the magnetic field. the bare coulomb interaction between electrons has been assumed. for this system, we have also computed some of its thermodynamic and magnetic properties such as the energy, pressure, incompressibil...

PURPOSE In proton therapy, uncertainty in the location of the distal dose edge can lead to cautious treatment plans that reduce the dosimetric advantage of protons. After radiation exposure, vertebral bone marrow undergoes fatty replacement that is visible on magnetic resonance imaging (MRI). This presents an exciting opportunity to observe radiation dose distribution in vivo. We used quantitat...

Introduction Accurate estimation of the skin-absorbed dose in external radiation therapy is essential to estimating the probability of secondary carcinogenesis induction Materials and Methods Electron contamination in prostate radiotherapy was investigated using the Monte Carlo (MC) code calculation. In addition, field size dependence of the skin dose was assessed. Excess cancer risk induced by...