نتایج جستجو برای: photon attenuation

تعداد نتایج: 118713  

2006
W. Kenji Myint Malgorzata Niedbala David Wilkins Lee H. Gerig

Carbon fiber is commonly used in radiation therapy for treatment tabletops and various immobilization and support devices, partially because it is generally perceived to be almost radiotransparent to high-energy photons. To avoid exposure to normal tissue during modern radiation therapy, one must deliver the radiation from all gantry angles; hence, beams often transit the couch proximal to the ...

1996
J. Protheroe P. L. Biermann

A new estimate of the extragalactic radio background and implications for ultra-high-energy gamma-ray propagation Abstract We make a new estimate of the extragalactic radio background down to kHz frequencies based on the observed luminosity functions and radio spectra of normal galaxies and radio galaxies. We have constructed models for the spectra of these two classes of objects down to low fr...

Journal: :Pramana 2023

Motivated by the increased interest in experiments which light appears to propagate tunnelling at superluminal velocity, Lorentz invariant theory proposed Partha Ghose explain these surprising effects is revisited. This based on Harish-Chandra formalism, describes relativistic dynamics of a massless spin-1 boson, like photon. By this Bohmian average transport velocity electromagnetic energy for...

Journal: :Journal of Materials Science: Materials in Electronics 2021

Penta-glasses with a 59B2O3–29SiO2–2LiF–( $$10-x$$ ) ZnO– $$x$$ TiO2 composition the melt-quench techniques were prepared. X-ray diffraction was used to examine nature of fabricated glasses. The changes in structure glasses studied by Fourier-transform infrared spectroscopy spectra. molar volume reduces as density increases. mechanical characteristics these evaluated. Besides, for glasses, Phy-...

2006

Fiber-optic microprobes for determining irradiance and scalar irradiance were used for light measurements in sandy sediments of different particle size. Intense scattering caused a maximum integral light intensity [photon scalar ~rradiance, E"(400 to 700 nm) and Eo(700 to 880 nm)] at the sediment surface ranging from 180% of incident collimated light in the coarsest sediment (250 to 500 pm grai...

Journal: :Journal of nuclear medicine : official publication, Society of Nuclear Medicine 2002
Sharlini Sankaran Eric C Frey Karen L Gilland Benjamin M W Tsui

UNLABELLED Attenuation, photon scatter, and distance-dependent collimator-detector response are major degrading factors in myocardial SPECT images. The current study investigated whether compensation for these factors improves perfusion defect detectability, and compared the results for human observers with a previous study using a mathematical observer. METHODS Four methods were investigated...

2014
Ryan D. Ross Lisa E. Cole Jennifer M. R. Tilley Ryan K. Roeder

Gold nanoparticles (Au NPs) have attracted interest as an X-ray contrast agent due to exhibiting high X-ray attenuation, colloidal stability, vascular retention, and facile surface functionalization for targeted delivery to cells and tissues. However, the effects of Au NP size on X-ray attenuation and binding affinity to a targeted surface are not well-understood. Therefore, the effect of Au NP...

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