نتایج جستجو برای: head scatter factor

تعداد نتایج: 1012383  

2002
Lars P. Dyrud Meers M. Oppenheim Sigrid Close Stephen Hunt

[1] Radar data of non-specular meteor trails shows two clear and consistent features: (1) non–specular meteor trails are observed from a narrower altitude range than are head echoes and (2) an approximately 20 ms delay between meteor head echoes and trail radar scatter. This paper shows that both features can result from meteor trail plasma instability. Simulations have demonstrated that trails...

Journal: :Medical physics 2004
J H Siewerdsen D J Moseley B Bakhtiar S Richard D A Jaffray

The influence of antiscatter x-ray grids on image quality in cone-beam computed tomography (CT) is evaluated through broad experimental investigation for various anatomical sites (head and body), scatter conditions (scatter-to-primary ratio (SPR) ranging from approximately 10% to 150%), patient dose, and spatial resolution in three-dimensional reconstructions. Studies involved linear grids in c...

Alireza Sadremomtaz, Zeinab Telikani

Introduction: Image quality and accuracy of in vivo activity quantification in SPECT are affected by collimator penetration and scatter components, especially in high energy imaging. These phenomena highly depend on the collimator characteristic and photon energy. The presence of penetrated and scattered photons from collimator in SPECT images degrades spatial resolution, contr...

Journal: :The Journal of Cell Biology 1994
E M Rosen S K Nigam I D Goldberg

Epithelia and mesenchyme interact during various physiologic and pathologic processes. Scatter factor is a mesenchyme-derived cytokine that stimulates motility, proliferation, and morphogenesis of epithelia. Recent studies suggest that scatter factor and its receptor (c-met) mediate mesenchyme/epithelia signalling and even interconversion. In this mini-review, we will discuss how scatter factor...

Journal: :Proceedings of the National Academy of Sciences 2006

Introduction: The Sc is an important parameter to monitor unit (MU) calculation in radiation therapy procedure. The aim of this study is to measurement and comparison of head scatter factor (Sc) for 9MV photon beam using the build-up cap and a columnar mini-phantom.   Materials and Methods: The measurements performed using a calibrated ion chamber (Scanditron...

Journal: :Development 1990
C D Stern G W Ireland S E Herrick E Gherardi J Gray M Perryman M Stoker

Scatter factor, a recently characterised protein secreted by certain embryonic fibroblasts, affects cultured epithelial by increasing cell motility, the breakdown of cell junctions and cell scattering. The process of gastrulation in higher vertebrate embryos, during which the primitive streak forms, involves an epithelial-to-mesenchymal transformation resembling the effects of the factor on cul...

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