نتایج جستجو برای: photon energy
تعداد نتایج: 722810 فیلتر نتایج به سال:
Background: The presence of a wedge filter in the beam trajectory can modify the beam quality and cause some changes in the dosimetry parameters which are usually difficult to be measured directly and accurately. Material and Methods: In this study the MCNP-4C Monte Carlo code was used to simulate the 9 MV photon beam generated by a linear accelerator. Upon getting a good agreement bet...
background: to enhance the dose to tumor, the use of high atomic number elements has been proposed. objective: the aim of this study is to investigate the effect of gold nanoparticle distribution on dose enhancement in tumor when the tumor is irradiated by typical monoenergetic x-ray beams by considering homogeneous and inhomogeneous distributions of gold nanoparticles (gnps) in the tumor. meth...
Background and purpose: Electron beams are extensively used in superficial cancer therapy. Unlike photon therapy, percentage depth dose curves (PDD) do not specify a maximum point in high energy electron therapy and include a depth range. The aim of this study was to obtain PDD by an analytical formulation which can be helpful to acquire the size of treatment area and other treatment factors su...
Photon energy spectra up to the kinematic limit have been measured in 190 MeV proton reactions with light and heavy nuclei to investigate the influence of the multiple-scattering process on the photon production. Relative to the predictions of models based on a quasifree production mechanism, a strong suppression of bremsstrahlung is observed in the low-energy region of the photon spectrum. We ...
Emission spectra of avalanching n(+)p junctions manufactured in a standard CMOS technology with no process modifications were measured over a broad photon energy spectrum ranging from 0.8 eV to 2.8 eV at various temperatures. The temperature coefficients of the emission rates at different photon energies were determined. Below a photon energy of 1.35 eV the temperature coefficient of emission w...
the dependence of the lateral distribution of cherenkov light in simulated extensive air showers to the energy and the mass of the primary cosmic rays has been studied. it has been shown that a previous claim about mass independent proportionality of shower energy to the total cherenkov photon number is not valid in energies below eeas ~ 1014 ev. we have found that the core distance of the so c...
In this chapter, the chiral molecule Methyloxirane is studied using femtosecond multi-photon ionization at 400 nm in combination with masscorrelated photoelectron coincidence imaging. The ion time-of-flight spectrum and the mass-correlated photoelectron kinetic energy distribution are discussed. The appearance energy of the parent ion and the fragment ion C2H + 4 in multi-photon excitation is r...
A novel fluorescence resonance energy transfer (FRET) system containing a two-photon absorbing dye and a nile red chromophore has been synthesized. Upon two-photon excitation by laser at 815 nm this molecule displays efficient energy transfer from the two-photon absorbing dye to the nile red moiety, with an 8-fold increase in emission compared to the model compound. Similarly, single-photon exc...
An evaluation of the dependence of detective quantum efficiency (DQE) on the incident energy spectrum has been made for mammography. The DQE dependence on the energy spectrum has been evaluated for energy-integrating detectors, photon-counting detectors, and detectors that measure the energy of each photon. To isolate the effect of the x-ray energy spectrum the detector has been assumed to be i...
This study investigated radiation dose variations in pre-clinical irradiation due to the photon beam energy and presence of tissue heterogeneity. Based on the same mouse computed tomography image dataset, three phantoms namely, heterogeneous, homogeneous and bone homogeneous were used. These phantoms were generated by overriding the relative electron density of no voxel (heterogeneous), all vox...
نمودار تعداد نتایج جستجو در هر سال
با کلیک روی نمودار نتایج را به سال انتشار فیلتر کنید