background: the shielding methods in radiotherapy due to delivering an accurate radiation dose to cancer tissues and avoiding unnecessary dose to normal tissues are very important. these methods include lead standard blocks, individual molding and multi leaf collimator (mlc). the mlc method is not still common in iran radiotherapy centers. individual molding is better than the lead block shield...

The oscillation of electrons, in a sufficiently intense pump wave, frustrates Debye shielding in the direction of the oscillation. One finds that such oscillating electrons cannot shield charge fluctuations over distances smaller than the distance they sample in a plasma period. One consequence is that the frequency of ion waves can be increased from the ion acoustic frequency to the ion plasma...

With the purpose of reducing stray radiation dose (SRD) in out-of-field region (OFR) during radiotherapy with 6 MV intensity-modulated radiation therapy (IMRT), a body-shielding device (BSD) was prepared according to the measurements obtained in experimental testing. In experimental testing, optimal shielding conditions, such as 1 mm lead, 2 mm lead, and 1 mm lead plus 10 mm bolus, were investi...

When considering the space limit of high energy LINAC facility in a hospital, the design of shielding wall is strongly required to optimize the wall thickness. Shielding wall usually consists of concrete, and iron plate is sometimes added in concrete to decrease the wall thickness. We investigated the optimum design of the shielding wall in medical LINAC facility by simulation. The calculations...

Good integration of metallic implant as for example endoprosthesis with a bone determines its stability and durability. There are many biological, structural and mechanical factors affecting interactions between bone tissue and a surface of prosthesis. Among the mechanical parameters local stress and strain distributions play a crucial role. The loading conditions, shape and mechanical characte...

The load-transfer mechanism and stress patterns in the acetabulum reconstructed with a threaded cup were investigated relative to the normal hip using the Finite Element Method (FEM). Several models were applied in the analysis to investigate the effects of axisymmetric 3-D versus 2-D approaches, inclusion of the femoral head, and local stress patterns around the threads in three types of impla...

Katsumi Ohata* Junichi Sato* ABSTRACT: Magnetic shielding for strong magnets using a high-temperature superconductor that can be operated at liquid nitrogen temperature has been studied. Long and large-cross-section (9 mm wide and 0.5 mm thick) 54-filament Bi-2223/Ag tape was developed. Double pancake coils were wound using the tapes having sufficient bending strain tolerance for the react-and-...

In 1992, E.E.Podkletnov and R.Nieminen find that, under certain conditions, ceramic superconductor with composite structure has revealed weak shielding properties against gravitational force. In classical Newton’s theory of gravity and even in Einstein’s general theory of gravity, there are no grounds of gravitational shielding effects. But in quantum gauge theory of gravity, the gravitational ...