Modelling the penumbra in Computed Tomography1
نویسندگان
چکیده
منابع مشابه
Modelling the penumbra in Computed Tomography1
BACKGROUND In computed tomography (CT), the spot geometry is one of the main sources of error in CT images. Since X-rays do not arise from a point source, artefacts are produced. In particular there is a penumbra effect, leading to poorly defined edges within a reconstructed volume. Penumbra models can be simulated given a fixed spot geometry and the known experimental setup. OBJECTIVE This p...
متن کاملEvidence against a perihemorrhagic penumbra provided by perfusion computed tomography.
BACKGROUND AND PURPOSE Several recent studies analyzing perfusion changes in acute intracerebral hemorrhage fed the debate whether there is secondary ischemic tissue damage in the vicinity of intracerebral hemorrhage. We used perfusion CT to address this question. METHODS We examined 36 patients between 2001 and 2002 with acute intracerebral hemorrhage (within 24 hours after symptom onset). A...
متن کاملThe cerebral ischemic penumbra.
When neuronal activity is suppressed by ischemia of sufficient severity, maintained for a long enough period of time, permanent clinical deficit can be accompanied by radiographic signs of cerebral infarction and histological evidence of ischemic damage. Recent work suggests that this is not an all-ornone event. Between the most densely ischemic region and the more normally perfused brain, an i...
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The uncombed penumbral model explains the structure of the sunspot penumbra in terms of thick magnetic fibrils embedded in a magnetic surrounding atmosphere. This model has been successfully applied to explain the polarization signals emerging from the sunspot penumbra. Thick penumbral fibrils face some physical problems, however. In this contribution we will offer possible solutions to these s...
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BACKGROUND In the last 3 decades, and from a therapeutic point of view, the classical concept of ischemic penumbra based on hemodynamic and electrophysiological parameters has loosened up the rigidity of therapeutic windows in acute stroke management. Thirty years later, the ischemic penumbra is an evolved concept that presents more applications. Thus, the ischemic penumbra is a diagnostic targ...
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ژورنال
عنوان ژورنال: Journal of X-Ray Science and Technology
سال: 2016
ISSN: 0895-3996,1095-9114
DOI: 10.3233/xst-160576