background: this work investigated the dosimetry limitations of the random and systematic uncertainties of sliding window (sw) intensity modulated radiation therapy (imrt). materials and methods: a varian 21ex linear accelerator, pinnacle3 treatment planning system and radiographic film dosimetry was used. the limitations of the sw were studied using beam modulation ranging from 2 to 100 mu/bea...

In this research, using the results of 6 tests, the effect of Carbon Fiber Reinforced Polymer (CFRP) sheets on the behavior of reinforced concrete coupling beams of shear walls is studied. First, in the experimental part of the study, four coupling beams with different reinforcements were manufactured and tested. Then, after the failure of the specimens, two of them were rehabilitated and stren...

objective(s): in this study we evaluate the impact of the different aspects of gold nano-particles (gnps) on the target absorptive dose enhancement factor (def) during external targeted radiotherapy with photon beams ranging from kilovolt to megavolt energies using monte carlo simulation. methods: we have simulated the interaction of photon beams with various energies of radiation using water s...

in investigation of dynamic specifications of castellated beams, it is necessary to be studied the excitation intensity of dynamic mode shapes for different loading conditions. it is evident that for a specific loading, not all modes of a structure are excited and the structural response depends on the applied loading specifications. in this paper using the finite element method (based on ansys...

We show that in addition to well-known Bessel, Hermite–Gauss and Laguerre– Gauss beams of electromagnetic radiation, one may also construct exponential beams. These beams are characterized by a fall-off in the transverse direction described by an exponential function of ρ. Exponential beams, like Bessel beams, carry definite angular momentum and are periodic along the direction of propagation, ...

this paper deals with volume fraction optimization of functionally graded (fg) beams resting on elastic foundation for maximizing the first natural frequency. the two-constituent functionally graded beam consists of ceramic and metal. these constituents are graded through the thickness of beam according to a generalized power-law distribution. one of the advantages of using generalized power- l...

introduction: in clinical electron beams, most of bremsstrahlung radiation is produced by various linac head structures. this bremsstrahlung radiation dose is influenced by the geometry and construction of every component of the linac treatment head structures. thus, it can be expected that the amount of the contaminated photon dose due to bremsstrahlung radiation varies among different linacs,...

This study presents the basic dosimetric properties of photon beams of a Versa HD linear accelerator (linac), which is capable of delivering flattening filter-free (FFF) beams with a beam quality equivalent to the corresponding flattened beams based on comprehensive beam data measurement. The analyzed data included the PDDs, profiles, penumbra, out-of-field doses, surface doses, output factors,...

An overview of two types of beam solutions is presented, Gaussian beams and Bessel beams. Gaussian beams are examples of non-localized or diffracting beam solutions, and Bessel beams are example of localized, non-diffracting beam solutions. Gaussian beams stay bounded over a certain propagation range after which they diverge. Bessel beams are among a class of solutions to the wave equation that...

An overview is given of two types of focused beams, Gaussian beams and Bessel beams. First I describe some of the basic properties of Gaussian beams in homogeneous media which stay collimated over a certain distance range after which they diverge. Bessel beams are then described which are among a class of solutions to the wave equation that are diffraction-free and do not diverge when they prop...