نتایج جستجو برای: scatter

تعداد نتایج: 12375  

2006
Robert Saunders

Scattered radiation plays a significant role in mammographic imaging, with scatter fractions over 50% for larger, denser breasts. For screen-film systems, scatter primarily affects the image contrast, reducing the conspicuity of subtle lesions. While digital systems can overcome contrast degradation, they remain susceptible to scatter’s impact on the image resolution and noise. To better unders...

Journal: :Physics in medicine and biology 2010
J L Ducote S Molloi

X-ray scatter is a major cause of nonlinearity in densitometry measurements using digital mammography. Previous scatter correction techniques have primarily used a single scatter point spread function to estimate x-ray scatter. In this study, a new algorithm to correct x-ray scatter based on image convolution was implemented using a spatially variant scatter point spread function which is energ...

2001
Chuanyong Bai Gengsheng L. Zeng Grant T. Gullberg

The modeling of 3D Compton scatter in SPECT is complicated by the use of a variety of collimator geometry. To date, effective and efficient modeling of 3D Compton scatter in parallel-beam SPECT has been made possible by Frey and Tsui [1], Zeng et al [2], and Bai et al [3]. For fan-beam and cone-beam SPECT, the model in [3] can effectively model first order 3D Compton scatter. But for varying-fo...

Journal: :European Journal of Operational Research 2006

Journal: :The Annals of Statistics 2005

Journal: :Fatigue & Fracture of Engineering Materials and Structures 1994

H. Rasooli S., S. K. Seyyedi S. S. Zabihi

The electronic conductance at zero temperature through a quantum wire with side-connected asymmetric quantum ring (as a scatter system) is theoretically studied using the non-interacting Hamiltonian Anderson tunneling method. In this paper we concentrate on the configuration of the quantum dot rings. We show that the asymmetric structure of QD-scatter system strongly influences the amplitude an...

1999
Victor Venema Jan Erkelens Herman Russchenberg Leo Ligthart

In two recent articles Erkelens et al. (1999a and 1999b) showed that coherent particle scatter (scatter of radiowaves by spatial variations in particle mass density) can explain the dual wavelength radar measurements made by Knight and Miller (1998) and dual wavelength measurements of a smoke plume made by Roger and Brown (1997). The 1999articles also showed quantitatively that coherent particl...

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