Sökning: "Peter Björk"

Hittade 3 avhandlingar innehållade orden Peter Björk.

  1. 1. Absorbed Dose Determination and Characteristics of Degraded Electron Beams: Application to Intraoperative Radiation Therapy

    Författare :Peter Björk; Internmedicin - epidemiologi; []
    Nyckelord :MEDICIN OCH HÄLSOVETENSKAP; MEDICAL AND HEALTH SCIENCES; Clinical physics; radiology; tomography; medical instrumentation; Klinisk fysiologi; radiologi; tomografi; medicinsk instrumentering; absorbed dose distribution; output factor; stopping-power ratio; beam characteristics; Monte Carlo calculation; electron beam dosimetry; applicator system; radiation therapy; linear accelerator; intraoperative radiotherapy;

    Sammanfattning : The aim of this work was to quantify limitations of and uncertainties in commonly used dosimetric techniques for relative absorbed dose determination in degraded electron beams, such as those encountered in intraoperative radiation therapy (IORT) and small-electron-field radiotherapy. Three different detector types were investigated with regard to measurements of output factors and relative absorbed dose distributions: (1) a parallel-plate ionization chamber, (2) a p-type silicon diode detector and (3) a diamond detector. LÄS MER

  3. 2. Contributions to Signal Processing for MRI

    Författare :Marcus Björk; Peter Stoica; Andreas Jakobsson; Uppsala universitet; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Parameter estimation; efficient estimation algorithms; non-convex optimization; multicomponent T2 relaxometry; artifact reduction; T2 mapping; denoising; phase estimation; RF design; MR thermometry; in-vivo brain; Elektroteknik med inriktning mot signalbehandling; Electrical Engineering with specialization in Signal Processing;

    Sammanfattning : Magnetic Resonance Imaging (MRI) is an important diagnostic tool for imaging soft tissue without the use of ionizing radiation. Moreover, through advanced signal processing, MRI can provide more than just anatomical information, such as estimates of tissue-specific physical properties. LÄS MER

  4. 3. Sociala identiteter i seriösa fritidsaktiviteter : - om samspelen mellan seriösa fritidsaktiviteter, platser, sociala världar och konsumtionsföremål i downhillcykling

    Författare :Helena Lindahl; Agneta Marell; Jessica Eriksson; Peter Björk; Umeå universitet; []
    Nyckelord :SAMHÄLLSVETENSKAP; SOCIAL SCIENCES; Business studies; Företagsekonomi; företagsekonomi; Business Studies;

    Sammanfattning : Background This study is about social identity processes within downhill mountain biking. Downhill is portrayed as reflecting the development of consumer culture in today’s society. LÄS MER