Sökning: "Radiofysik"
Visar resultat 16 - 20 av 106 avhandlingar innehållade ordet Radiofysik.
16. Cerebral blood flow and intracranial pulsatility studied with MRI : measurement, physiological and pathophysiological aspects
Sammanfattning : 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. LÄS MER
17. Calibration of Ionization Chambers for Measuring Air Kerma Integrated over Beam Area in Diagnostic Radiology
Sammanfattning : 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. LÄS MER
18. Radon in natural waters : Analytical Methods; Correlation to Environmental Parameters; Radiation Dose Estimation; and GIS Applications
Sammanfattning : 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. LÄS MER
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
Sammanfattning : 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. LÄS MER
20. Quantifying image quality in diagnostic radiology using simulation of the imaging system and model observers
Sammanfattning : 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. LÄS MER