Sökning: "penumbra"

Visar resultat 1 - 5 av 26 avhandlingar innehållade ordet penumbra.

  1. 1. Energy and intensity modulated radiation therapy with electrons

    Författare :Lennart Olofsson; Mikael Karlsson; Magnus Karlsson; Björn Zackrisson; Erik Traneus; Umeå universitet; []
    Nyckelord :MEDICIN OCH HÄLSOVETENSKAP; MEDICAL AND HEALTH SCIENCES; Radiation sciences; Radiation therapy; Conformal therapy; IMRT; Electrons; Electron treatment head; Electron MLC; Bremsstrahlung reduction; Integral dose; Penumbra; Output factor; Strålningsvetenskap; Radiation biology; Strålningsbiologi; radiofysik; radiation physics;

    Sammanfattning : In recent years intensity modulated radiation therapy with photons (xIMRT) has gained attention due to its ability to reduce the dose in the tissues close to the tumour volume. However, this technique also results in a large low dose volume. LÄS MER

  3. 2. Cerebral ischemia studied with positron emission tomography and microdialysis

    Författare :Peter Frykholm; Peter Kirkpatrick; Uppsala universitet; []
    Nyckelord :MEDICIN OCH HÄLSOVETENSKAP; MEDICAL AND HEALTH SCIENCES; Neurosciences; Cerebral ischemia; penumbra; positron emission tomography; microdialysis; middle cerebral artery occlusion; Neurovetenskap; Neurology; Neurologi; Neurosurgery; neurokirurgi;

    Sammanfattning : Stroke is the third leading cause of morbidity and mortality in the industrialized world. Subarachnoid hemorrhage (SAH), the least common form of stroke, is one of the most demanding diseases treated in neurointensive care units. Cerebral ischemia may develop rapidly, and has a major influence on outcome. LÄS MER

  4. 3. Regeneration in the adult brain after focal cerebral ischemia : exploration of neurogenesis and angiogenesis

    Författare :Wei Jiang; Jukka Jolkkonen; Umeå universitet; []
    Nyckelord :LANTBRUKSVETENSKAPER; AGRICULTURAL SCIENCES; neurogenesis; angiogenesis; rats; mice; gliosis; BrdU; CBF; protein synthesis; ATP; penumbra; reperfusion; VEGF; 3-D confocal; photothrombosis; MCAO; Medicine; Medicin;

    Sammanfattning : Background: Ischemic stroke ranks as the third major cause of clinical mortality and the leading cause of handicap in adults. Each year, stroke occurs in about 30,000 Swedes. The severity of an acute ischemic stroke depends mainly on the degree and duration of local cerebral blood flow (lCBF) reduction. LÄS MER

  5. 4. Three-dimensional mapping of fine structure in the solar atmosphere

    Författare :Vasco M. J. Henriques; Dan Kiselman; Göran Scharmer; Hector Socas-Navarro; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Sun; sunspots; Swedish 1-meter Solar Telescope; active regions; image processing; sunspot penumbra; Astronomy; astronomi;

    Sammanfattning : The effects on image formation through a tilted interference filter in a converging beam are investigated and an adequate compensation procedure is established. A method that compensates for small-scale seeing distortions is also developed with the aim of co-aligning non-simultaneous solar images from different passbands. LÄS MER

  7. 5. Penumbra oxygen metabolism and acute neuroinflammation in ischemic stroke : MRI and PET imaging of a M2 occlusion model in rat

    Författare :Philip Little; Karolinska Institutet; Karolinska Institutet; []
    Nyckelord :;

    Sammanfattning : Acute ischemic stroke (AIS) is caused by the sudden occlusion of a major artery of the brain, and results in infarction and severe ischemia within affected brain regions. If ischemic regions are rapidly revascularized, the neurological disability resulting from AIS can be significantly reduced. LÄS MER