Search for dissertations about: "radiofysik"

Showing result 16 - 20 of 106 swedish dissertations containing the word radiofysik.

  2. 16. Cerebral blood flow and intracranial pulsatility studied with MRI : measurement, physiological and pathophysiological aspects

    Author : Anders Wåhlin; Anders Eklund; Jan Malm; Richard Birgander; William G Bradley; Umeå universitet; []
    Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Arterial Pulsatility; cerebrospinal fluid; cerebral blood flow; venous flow; intracranial pressure; pulse pressure; dementia; hippocampus; multiple sclerosis; magnetic resonance imaging; radiofysik; radiation physics;

    Abstract : During each cardiac cycle pulsatile arterial blood inflates the vascular bed of the brain, forcing cerebrospinal fluid (CSF) and venous blood out of the cranium. Excessive arterial pulsatility may be part of a harmful mechanism causing cognitive decline among elderly. READ MORE

  4. 17. Calibration of Ionization Chambers for Measuring Air Kerma Integrated over Beam Area in Diagnostic Radiology

    Author : Peter Larsson; Gudrun Alm Carlsson; Jan Persliden; Bertil Axelsson; Linköpings universitet; []
    Keywords : MEDICIN OCH HÄLSOVETENSKAP; MEDICAL AND HEALTH SCIENCES; KAP-meter; DAP-meter; PKA; kerma area product; energy dependence; calibration; Radiological physics; Radiofysik;

    Abstract : The air kerma area product PKA is an important quantity used by hospital physicists in quality assurance and optimization processes in diagnostic radiology and is recommended by national authorities for setting of diagnostic reference levels. PKA can be measured using a transmission ionization chamber (kerma area product (KAP) meter) mounted on the collimator housing. READ MORE

  5. 18. Radon in natural waters : Analytical Methods; Correlation to Environmental Parameters; Radiation Dose Estimation; and GIS Applications

    Author : Isam M. Musa Salih; Eva Lund; Håkan B.L. Pettersson; Christer Samuelsson; Linköpings universitet; []
    Keywords : MEDICIN OCH HÄLSOVETENSKAP; MEDICAL AND HEALTH SCIENCES; Radon analysis; radiation effects; Water chemistry; Water pollution; radioactive analysis; Radiological physics; Radiofysik;

    Abstract : Investigations of radon in natural water and its relation to physical and chemical parameters are outlined in this thesis. In particular, a method for measuring 222Rn in water at low concentrations (~20 mBq. READ MORE

  6. 19. Dosimetry and radiation quality in fast-neutron radiation therapy : A study of radiation quality and basic dosimetric properties of fast-neutrons for external beam radiotherapy and problems associated with corrections of measured charged particle cross-sections

    Author : Jonas Söderberg; Gudrun Alm Carlsson; Crister Ceberg; Linköpings universitet; []
    Keywords : MEDICIN OCH HÄLSOVETENSKAP; MEDICAL AND HEALTH SCIENCES; Neutron; Dosimetry; Radiotherapy; Monte Carlo; Microdosimetry; Cross-section; RBE; LET; Energy-loss corrections; Radiological physics; Radiofysik;

    Abstract : The dosimetric properties of fast-neutron beams with energies ≤80 MeV were explored using Monte Carlo techniques. Taking into account transport of all relevant types of released charged particles (electrons, protons, deuterons, tritons, 3He and α particles) pencil-beam dose distributions were derived and used to calculate absorbed dose distributions. READ MORE

  7. 20. Quantifying image quality in diagnostic radiology using simulation of the imaging system and model observers

    Author : Gustaf Ullman; Michael Sandborg; Gudrun Alm Carlsson; Nicolas Pallikarakis; Linköpings universitet; []
    Keywords : MEDICIN OCH HÄLSOVETENSKAP; MEDICAL AND HEALTH SCIENCES; radiology; radiation physics; image quality; optimisation; effective dose; chest radiography; Radiological physics; Radiofysik;

    Abstract : Accurate measures of both clinical image quality and patient radiation risk are needed for successful optimisation of medical imaging with ionising radiation. Optimisation in diagnostic radiology means finding the image acquisition technique that maximises the perceived information content and minimises the radiation risk or keeps it at a reasonably low level. READ MORE