نتایج جستجو برای: scatter

تعداد نتایج: 12375  

Journal: :BioMed research international 2016
Sorapong Aootaphao Saowapak S Thongvigitmanee Jartuwat Rajruangrabin Chalinee Thanasupsombat Tanapon Srivongsa Pairash Thajchayapong

Soft tissue images from portable cone beam computed tomography (CBCT) scanners can be used for diagnosis and detection of tumor, cancer, intracerebral hemorrhage, and so forth. Due to large field of view, X-ray scattering which is the main cause of artifacts degrades image quality, such as cupping artifacts, CT number inaccuracy, and low contrast, especially on soft tissue images. In this work,...

2008
J. Stuart B. Wyithe Abraham Loeb

We show that the observed scatter in the relations between the mass of supermassive black holes (SMBHs), Mbh, and the velocity dispersion σsph or mass Msph of their host spheroid, place interesting constraints on the process that regulates SMBH growth in galaxies. When combined with the observed properties of early-type SDSS galaxies, the observed intrinsic scatters imply that SMBH growth is re...

Journal: :Journal of Research of the National Bureau of Standards, Section D: Radio Propagation 1960

Journal: :Japanese Journal of Radiological Technology 1997

Journal: :Journal of Geophysical Research 2006

Journal: :Journal of nuclear medicine : official publication, Society of Nuclear Medicine 2006
Jianbin Xiao Tim C de Wit Steven G Staelens Freek J Beekman

UNLABELLED Cardiac SPECT images are degraded by photons scattered in the thorax. Accurate correction for scatter is complicated by the nonuniform density and varied sizes of thoraxes and by the additional attenuation and scatter caused by female patients' breasts. Monte Carlo simulation is a general and accurate method for detailed modeling of scatter. Hence, for 99mTc we compared statistical r...

Journal: :Medical physics 2001
J H Siewerdsen D A Jaffray

A system for cone-beam computed tomography (CBCT) based on a flat-panel imager (FPI) is used to examine the magnitude and effects of x-ray scatter in FPI-CBCT volume reconstructions. The system is being developed for application in image-guided therapies and has previously demonstrated spatial resolution and soft-tissue visibility comparable or superior to a conventional CT scanner under condit...

Journal: :Proceedings of SPIE--the International Society for Optical Engineering 2014
W Zbijewski A Sisniega J W Stayman A Muhit G Thawait N Packard R Senn D Yang J Yorkston J A Carrino J H Siewerdsen

PURPOSE Clinical performance studies of an extremity cone-beam CT (CBCT) system indicate excellent bone visualization, but point to the need for improvement of soft-tissue image quality. To this end, a rapid Monte Carlo (MC) scatter correction is proposed, and Penalized Likelihood (PL) reconstruction is evaluated for noise management. METHODS The accelerated MC scatter correction involved fas...

2010
A Akbarzadeh MR Ay H Ghadiri S Sarkar H Zaidi

PURPOSE The consummate 64-slice CT scanner that spawns a new generation of non-invasive diagnostic tool, however revolutionary, brings with it the incidental by-product that is scattered radiation. The extended detector aperture capability in the 64-slcie CT scanner allows the effects of scattered radiation to be more pronounced and therefore demands that the magnitude and spatial distribution ...

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