Search results for "artifacts"
showing 10 items of 105 documents
Introduction to coronary imaging with 64-slice computed tomography
2005
The aim of this article is to illustrate the main technical improvements in the last generation of 64-row CT scanners and the possible applications in coronary angiography. In particular, we describe the new physical components (X-ray tube-detectors system) and the general scan and reconstruction parameters. We then define the scan protocols for coronary angiography with the new generation of 64-row CT scanners to enable radiologists to perform a CT study on the basis of the diagnostic possibilities.
Comparison of transflection and transmission FTIR imaging measurements performed on differentially fixed tissue sections
2015
The widespread and cost-effective use of transflection substrates in Fourier transform infrared (FTIR) imaging of clinical samples is affected by the presence of artefacts including the electric field standing wave (EFSW) and contributions from light dispersion. For IR-based diagnostics, the manifestation of undesirable artifacts can distort the spectra and lead to erroneous diagnosis. Nevertheless, there is no clear consensus in the literature about the degree of influence of these effects. The aim of this work is to contribute to this discussion by comparing transflection and transmission images of the same tissue. For this purpose two adjacent sections of the same tissue (lymphoma sample…
Pervasive access to MRI bias artifact suppression service on a grid.
2009
Bias artifact corrupts magnetic resonance images in such a way that the image is afflicted by illumination variations. Some of the authors proposed the Exponential Entropy Driven - Homomorphic Unsharp Masking (E2D-HUM) algorithm that corrects this artifact without any a priori hypothesis about the tissues or the Magnetic Resonance image modality. Moreover, E2D-HUM does not care about the body part under examination and does not require any particular training task. People who want to use this algorithm, which is Matlab-based, have to set their own computers in order to execute it. Furthermore, they have to be Matlab-skilled to exploit all the features of the algorithm. In our work we propos…
ERP denoising in multichannel EEG data using contrasts between signal and noise subspaces
2009
Abstract In this paper, a new method intended for ERP denoising in multichannel EEG data is discussed. The denoising is done by separating ERP/noise subspaces in multidimensional EEG data by a linear transformation and the following dimension reduction by ignoring noise components during inverse transformation. The separation matrix is found based on the assumption that ERP sources are deterministic for all repetitions of the same type of stimulus within the experiment, while the other noise sources do not obey the determinancy property. A detailed derivation of the technique is given together with the analysis of the results of its application to a real high-density EEG data set. The inter…
Worm-like artifacts in exfoliative cytology.
2006
The presence of worms in cytological smears is occasionally reported, although various other structures exist that may be confused with such parasites. We present eight worm-like artifacts observed in routine Papanicolaou smears. Recognition of these structures is important to avoid overvaluation or confusion with true worms. Diagn. Cytopathol. 2006;34:636–639. © 2006 Wiley–Liss, Inc.
Maximum likelihood difference scaling of image quality in compression-degraded images.
2007
International audience; Lossy image compression techniques allow arbitrarily high compression rates but at the price of poor image quality. We applied maximum likelihood difference scaling to evaluate image quality of nine images, each compressed via vector quantization to ten different levels, within two different color spaces, RGB and CIE 1976 L(*)a(*)b(*). In L(*)a(*)b(*) space, images could be compressed on average by 32% more than in RGB space, with little additional loss in quality. Further compression led to marked perceptual changes. Our approach permits a rapid, direct measurement of the consequences of image compression for human observers.
Le cimetière du second Âge du fer de la Tournière à Lailly (Yonne) : nouvelle analyse des fouilles anciennes
2021
International audience; Cette étude présente de manière critique les découvertes qui ont été faites à la fin du xix e siècle et au début du xx e siècle à Lailly La Tournerie (Yonne). Elle propose un classement typologique et chronologique de tous les objets mis au jour par catégorie fonctionnelle, ainsi que la reconstitution, pour la première fois, de plusieurs ensembles clos. Elle a ainsi permis de proposer une évolution de ce cimetière entre le second quart du v e siècle (La Tène A ancienne) et la première décennie du ii e siècle avant J.-C. (La Tène C1). L'analyse des pratiques funéraires a également été abordée à l'aide d'un dépouillement systématique des rares données existantes. Leur …
NEW APPLICATIONS IN THE USE OF CELLULOSE PULP FOR THE INTEGRATION OF WOODEN SUPPORTS
2017
Cellulose pulp, mainly utilized as a support for cleaning stone material, in this study, is proposed as a filler for wooden supports. In the last 10 years, pulp has been used in many restoration works carried out in the laboratory of the Diocesan Museum (MDP) in Palermo, including both wooden sculptures and panel paintings. These artworks, exhibited in the MDP, are constantly monitored in order to evaluate the effectiveness of cellulose pulp as a filler, assessing its durability and bio-receptivity. In particular, structural characteristics, drying time, shrinkage, loss in weight, affinity to the pigments, etc., were simultaneously evaluated. Tests were also carried out on artificially aged…
Re-exposure in cone beam CT of the dentomaxillofacial region: a retrospective study.
2018
Cone beam CT (CBCT) often uses a smaller field of view compared to conventional CT scans. This might lead to a wrong field of view with the need for secondary exposure (“retakes”). The purpose of this retrospective study was to assess the frequency of re-exposures in CBCT and to identify whether the parameters age, gender, and field of view have an influence on the re-exposure of the patient. Additionally, the causes of re-exposures were determined and categorized. METHODS: In a retrospective cohort study CBCT images of 4986 patients from the patient database from the Department of Oral Radiology, University Medical Center of the Johannes Gutenberg University, Mainz, Germany were included a…
Kvalitātes nosacījumi kontrastmammogrāfijā pie krūts vēža izmeklējumiem
2022
Autora izvēlētā bakalaura darba tēma - “Kvalitātes nosacījumi kontrastmamogrāfijā pie krūts vēža izmeklējumiem”. Bakalaura darbs sastāv no ievada daļas, teorētiskās daļas, pētnieciskās daļas, secinājumiem un ieteikumiem. Bakalaura darbā apskatīta un analizēta literatūra par krūts dziedzera anatomiju un fizioloģiju, krūts dziedzeru onkopatoloģijām, kontrastmamogrāfijas izmeklējumiem, izmeklējumu artefaktiem un protokolu vadlīnijām. Darba autore izvirzīja darba mērķi: noskaidrot kontrastmamogrāfijas nozīmi krūts vēža diagnostikā. Kā pētniecības metode tika izmantota - kvalitatīvā kontentanalīze.