Sökning: "radiation quality"

Visar resultat 6 - 10 av 304 avhandlingar innehållade orden radiation quality.

  1. 6. On the use of aerosol optical properties and satellite-retrieved trace gases in regional air quality modelling

    Författare :Emma Andersson; Chalmers tekniska högskola; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; Model; Climate; Radiation; Satellite; Air Quality;

    Sammanfattning : The effects of anthropogenic pollutants in the lower atmosphere (troposphere) have been shown, historically and scientifically, to have a deleterious effect on both plant and animal life. Pollutants such as near-surface ozone and soot (black carbon) are two notorious examples with clear anthropogenic sources. LÄS MER

  3. 7. Radiation Hardness of 4H-SiC Devices and Circuits

    Författare :Sethu Saveda Suvanam; Anders Hallén; Carl-Mikael Zetterling; Ulrike Grossner; KTH; []
    Nyckelord :Silicon carbide; radiation hardness; protons; gamma radiation; bipolar junction transistors; aluminium oxide; surface recombination.; Informations- och kommunikationsteknik; Information and Communication Technology;

    Sammanfattning : Advances in space and nuclear technologies are limited by the capabilities of the conventional silicon (Si) electronics. Hence, there is a need to explore materials beyond Si with enhanced properties to operate in extreme environments. In this regards, silicon carbide (4H-SiC), a wide bandgap semiconductor, provides suitable solutions. LÄS MER

  4. 8. Quality assurance for magnetic resonance imaging (MRI) in radiotherapy

    Författare :Mary Adjeiwaah; Tufve Nyholm; Anders Garpebring; Joakim Jonsson; Sofie Ceberg; Umeå universitet; []
    Nyckelord :MEDICIN OCH HÄLSOVETENSKAP; MEDICAL AND HEALTH SCIENCES; magnetic resonance imaging; MRI; radiotherapy; RT; geometric distortions; magnetic susceptibility; B0 maps; quality assurance; radiofysik; radiation physics;

    Sammanfattning : The use of Magnetic Resonance Imaging (MRI) in the radiotherapy (RT) treatment planning workflow is increasing. MRI offers superior soft-tissue contrast compared to Computed Tomography (CT) and therefore improves the accuracy in target volume definitions. LÄS MER

  5. 9. Radiation dose and image quality in diagnostic radiology : optimization of the dose - image quality relationship with clinical experience from scoliosis radiography, coronary intervention and a flat-panel digital detector

    Författare :Håkan Geijer; Hans Ringertz; Linköpings universitet; []
    Nyckelord :MEDICINE; MEDICIN;

    Sammanfattning : Det är känt att röntgenstrålning kan orsaka cancersjukdomar, hudskador och andra sidoeffekter. Därför är det viktigt och även föreskrivet i lag att strålexpaneringen inom diagnostisk radiologi skall sänkas så långt som möjligt. Detta kallas på engelska ALARA-principen (As Low As Reasonably Achievable). LÄS MER

  7. 10. Development and evaluation of an independent system for absorbed dose calculations in radiotherapy

    Författare :Stefan Johnsson; Lund Medicinsk strålningsfysik; []
    Nyckelord :MEDICIN OCH HÄLSOVETENSKAP; MEDICAL AND HEALTH SCIENCES; medicinsk instrumentering; tomografi; radiologi; Klinisk fysiologi; tomography; medical instrumentation; radiology; Clinical physics; cancer; Cytologi; onkologi; cancerology; oncology; Cytology; PDA; mini-phantom; in-air equivalence; primary kerma; transmission measurement; stopping power ratio; entrance dose; beam quality; quality control; error prevention; monitor unit calculation; radiation therapy; dose calculation;

    Sammanfattning : The aim of this work was to develop, implement and evaluate an independent system with which to calculate the absorbed dose, delivered by high-energy X-ray beams, to the prescription point and the depth of dose maximum. The introduction of such a system in the clinical routine may help ensure high-quality treatment and avoidance of errors which may jeopardise the clinical outcome of the treatment (i. LÄS MER