نتایج جستجو برای: ray vrx ct scanner

تعداد نتایج: 414092  

Journal: :Measurement Science and Technology 2022

Abstract Artifacts due to imperfect determination of the scanner geometry, beam hardening (BH), and diffuse Compton scattering, limit quantitative exploitation radiographs or tomographies for non-destructive evaluation. Exploiting computer-aided design (CAD) model an industrial part, a methodology is proposed refine estimation computed tomography (CT)-scanner geometry up scale factor, correct a...

2009
J. Přibil Pawel Gryboś

− The work describes the present status of development of the portable X–ray CT mini system. The system is capable to operate also as a quantum digital X–ray scanner. Detection unit is constructed from double line of 2×1024 SI GaAs pixel detectors with pitch of 250 μm. The system allows operation in the single photon counting regime and the energy separation (one energy window) with estimated s...

2016
MATS PERSSON

Computed tomography (CT) is a widely used medical imaging modality. By rotating an x-ray tube and an x-ray detector around the patient, a CT scanner is able to measure the x-ray transmission from all directions and form an image of the patient’s interior. CT scanners in clinical use today all use energy-integrating detectors, which measure the total incident energy for each measurement interval...

2006
Zhengrong Ying Ram Naidu Carl R. Crawford

Single energy computed tomography (CT) scanners use measurements of densities to detect explosives in luggage. It is desirable to apply dual energy techniques to these CT scanners to obtain atomic number measurements to reduce false alarm rates. However, the direct application of existing dual energy techniques has practical problems, such as, approximation errors and lack of boundary constrain...

Journal: :Medical physics 1979
K M Hanson

The detection limitations inherent in statistically limited computed tomographic (CT) images are described through the application of signal detection theory. The detectability of large-area, low-contrast objects is shown to be chiefly dependent upon the low-frequency content of the noise power spectral density. For projection data containg uncorrelated noise, the resulting ramplike, low-freque...

Journal: :Medical physics 2006
Marc Kachelriess Michael Knaup Willi A Kalender

Phase-correlated CT, as it is used for cardiac imaging, is the most popular and the most important but also the most demanding special CT application in the clinical routine, today. Basically, it fulfills the four-dimensional imaging task of depicting a quasiperiodically moving object at any desired motion phase with significantly reduced motion artifacts. Although image quality with phase-corr...

Journal: :Proceedings of SPIE--the International Society for Optical Engineering 2013
A A Muhit S Arora M Ogawa Y Ding W Zbijewski J W Stayman G Thawait N Packard R Senn D Yang J Yorkston C O Bingham K Means J A Carrino J H Siewerdsen

PURPOSE We describe the initial assessment of the peripheral quantitative CT (pQCT) imaging capabilities of a cone-beam CT (CBCT) scanner dedicated to musculoskeletal extremity imaging. The aim is to accurately measure and quantify bone and joint morphology using information automatically acquired with each CBCT scan, thereby reducing the need for a separate pQCT exam. METHODS A prototype CBC...

Journal: :Anatomical record 2015
Lena Öhrström Bernd M Fischer Andreas Bitzer Jan Wallauer Markus Walther Frank Rühli

During the last few years, terahertz (THz) imaging has been used to investigate artwork and historic artifacts. The application of THz imaging to mummy investigations is very attractive since it provides spectroscopic information over a broad frequency range and its radiation has proven to be harmless to human cells. However, compared with the current standard imaging methods in mummy imaging-X...

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