Results 211 to 220 of about 331,435 (254)

Improving the contrast-to-noise ratio by averaging in scintillation detectors

2016 IEEE Nuclear Science Symposium, Medical Imaging Conference and Room-Temperature Semiconductor Detector Workshop (NSS/MIC/RTSD), 2016
From the point of view of the image quality, the contrast-to-noise ratio (CNR) is a crucial parameter. In case of the scintillation detectors, which are widely used in X-ray radiography and computed tomography, CNR is determined by the static image noise caused mainly by the non-uniformity of the response of particular pixels, and by the stochastic ...
Michal Vopalensky, Ivana Kumpova, Daniel Vavrik   +2 more
openaire   +1 more source

Contrast-to-Noise-Ratio Measurements in Three-Dimensional Magnetic Resonance Angiography

Investigative Radiology, 1993
The authors report on the development and preliminary validation of a technique for measuring contrast-to-noise ratio (CNR) at all points along selected vessel segments in the original three-dimensional magnetic resonance angiography (MRA) dataset.Contrast-to-noise ratio dependencies on flow rate, field of view, and flip angle were measured on images ...
Y, Du, D L, Parker, W L, Davis, D D, Blatter   +3 more
openaire   +2 more sources

Theoretical predictions of the generalized contrast-to-noise ratio for photoacoustic images

2020 IEEE International Ultrasonics Symposium (IUS), 2020
Target detectability in photoacoustic imaging applications is traditionally analyzed using image quality metrics, such as signal-to-noise ratio, contrast, and contrast-to-noise ratio. These metrics are difficult to interpret in the context of target detectability due to their lack of an upper bound and their sensitivity to image manipulation techniques
Mardava R. Gubbi, Muyinatu A. Lediju Bell   +1 more
openaire   +1 more source

Blind Estimation for Localized Low Contrast-to-Noise Ratio BOLD Signals

IEEE Journal of Selected Topics in Signal Processing, 2008
Accurate detection of low contrast-to-noise ratio (CNR) blood oxygenation level dependent (BOLD) signals in functional magnetic resonance imaging (fMRI) data is important for presurgical planning and cognitive research. Robust detection is challenging in small regions of low CNR activation since the probability of detecting each individual voxel is low.
Ian C. Atkinson, Farzad Kamalabadi, Douglas L. Jones, Keith R. Thulborn   +3 more
openaire   +1 more source

Contrast-to-Noise Ratios of Different Elements in Digital Mammography

Investigative Radiology, 2007
To determine the contrast-to-noise ratios (CNRs) of different elements at different energies using various anode/filter combinations currently employed in digital mammography. The elements investigated included not only elements already used in conventional contrast agents such as gadolinium and iodine but also other elements to investigate their ...
Felix, Diekmann, Alexander, Sommer, Ruediger, Lawaczeck, Susanne, Diekmann, Hubertus, Pietsch, Ulrich, Speck, Bernd, Hamm, Ulrich, Bick   +7 more
openaire   +2 more sources

Evaluation of both image resolution and contrast-to-noise ratio in scanning electron microscopy

Journal of Electron Microscopy, 2007
The contrast-to-gradient (CG) resolution has been defined as a weighted harmonic mean of the local resolution, i.e. the length defining the object's local fine structure at each pixel position. The newly defined resolution Res is defined as 2 sigma/ sqrt 2, where 2 sigma is a sharpness factor of the image pattern obtained by the conversion 2 sigma ...
Tohru, Ishitani, Mitsugu, Sato
openaire   +2 more sources

Contrast-to-noise ratio optimization for a prototype phase-contrast computed tomography scanner

Review of Scientific Instruments, 2015
In the field of biomedical X-ray imaging, novel techniques, such as phase-contrast and dark-field imaging, have the potential to enhance the contrast and provide complementary structural information about a specimen. In this paper, a first prototype of a preclinical X-ray phase-contrast CT scanner based on a Talbot-Lau interferometer is characterized ...
Mark Müller, Andre Yaroshenko, Astrid Velroyen, Martin Bech, Arne Tapfer, Bart Pauwels, Peter Bruyndonckx, Alexander Sasov, Franz Pfeiffer   +8 more
openaire   +2 more sources

A novel method for contrast-to-noise ratio (CNR) evaluation of digital mammography detectors

European Radiology, 2009
The purpose of this study was to test a new, simple method of evaluating the contrast-to-noise ratio (CNR) over the entire image field of a digital detector and to compare different mammography systems. Images were taken under clinical exposure conditions for a range of simulated breast thicknesses using poly(methyl methacrylate) (PMMA).
P, Baldelli, N, Phelan, G, Egan
openaire   +2 more sources

Nonlinear stress-strain relationships in tissue and their effect on the contrast-to-noise ratio in elastograms

Ultrasound in Medicine & Biology, 2000
The practice of elastography is generally limited to small applied compressions (typically 1%), under the assumption of a linear stress-strain relationship in biological tissue. However, the recent reports of larger applied compressions and precompression levels to increase the strain contrast violate the above assumption.
T, Varghese, J, Ophir, T A, Krouskop
openaire   +2 more sources

Improvement of signal‐to‐noise and contrast‐to‐noise ratios in dual‐screen computed radiography

Medical Physics, 1997
A dual‐screen computed radiography (CR) technique has been developed to improve and optimize the overall image signal‐to‐noise ratio (SNR) and contrast‐to‐noise ratio (CNR). With this technique, two CR screens are exposed together and separately scanned to form a front and a back image.
C C, Shaw, T P, Wang, D S, Breitenstein, D, Gur   +3 more
openaire   +2 more sources