Sökning: "radiofysik"

Visar resultat 11 - 15 av 69 avhandlingar innehållade ordet radiofysik.

  1. 11. Improving accuracy of in situ gamma-ray spectrometry

    Detta är en avhandling från Umeå : Radiofysik

    Författare :Jonas Boson; Christer Samuelsson; [2008]
    Nyckelord :MEDICIN OCH HÄLSOVETENSKAP; MEDICAL AND HEALTH SCIENCES; gamma-ray spectrometry; in situ measurement; HPGe detector; 137Cs; Monte Carlo; efficiency calibration; measurement uncertainty; MEDICINE Physiology and pharmacology Radiological research Radiological physics; MEDICIN Fysiologi och farmakologi Radiologisk forskning Radiofysik;

    Sammanfattning : Gamma-ray spectrometry measurements performed on site, or “in situ”, is a widely used and powerful method that can be employed both to identify and quantify ground deposited radionuclides. The purpose of this thesis is to improve the calibration of high purity germanium (HPGe) detectors for in situ measurements, and calculate the combined uncertainty and potential systematic effects. LÄS MER

  2. 12. Modeling Silicon Diode Dose Response in Radiotherapy Fields using Fluence Pencil Kernels

    Detta är en avhandling från Uppsala : Acta Universitatis Upsaliensis

    Författare :Karin Eklund; Anders Ahnesjö; Erik Grusell; Hugo Palmans; [2010]
    Nyckelord :MEDICIN OCH HÄLSOVETENSKAP; MEDICAL AND HEALTH SCIENCES; MEDICINE Physiology and pharmacology Radiological research Radiological physics; MEDICIN Fysiologi och farmakologi Radiologisk forskning Radiofysik; Medicinsk radiofysik; Medical Radiophysics;

    Sammanfattning : In radiotherapy, cancer is treated with ionizing radiation, most commonly bremsstrahlung photons from electrons of several MeV. Secondary electrons produced in photon-interactions results in dose deposition. The treatment response is low for low doses, raises sharply for normal treatment doses and saturates at higher doses. LÄS MER

  3. 13. Measurement of T1 relaxation time in lungs - Preclinical and clinical MRI applications to COPD

    Detta är en avhandling från Göteborg : University of Gothenburg

    Författare :Daniel Alamidi; Göteborgs universitet.; Gothenburg University.; [2015]
    Nyckelord :MEDICIN OCH HÄLSOVETENSKAP; MEDICAL AND HEALTH SCIENCES; Magnetic Resonance Imaging; biomarker; tobacco smoke; mouse; smoking; lung imaging; Chronic Obstructive Pulmonary Disease; ultrashort echo time UTE ; T1 mapping; longitudinal relaxation time;

    Sammanfattning : Monitoring of regional lung function in clinical trials of chronic obstructive pulmonary disease (COPD) requires alternative endpoints beyond global pulmonary function tests (PFTs), which is the most common approach for diagnosing lung function abnormalities in humans. A promising magnetic resonance imaging (MRI) biomarker of lung disease in humans and animals is the T1 relaxation parameter. LÄS MER

  4. 14. Detection of pulmonary nodules in chest tomosynthesis: Comparison with chest radiography, evaluation of learning effects and investigation of radiation dose level dependency

    Detta är en avhandling från Göteborg : Aidla Trading AB/Kompendiet

    Författare :Sara Asplund; Göteborgs universitet.; Gothenburg University.; [2014]
    Nyckelord :MEDICIN OCH HÄLSOVETENSKAP; MEDICAL AND HEALTH SCIENCES; Chest radiography; Chest tomosynthesis; Nodule detection; Observer performance; Free-response receiver operating characteristics;

    Sammanfattning : Chest tomosynthesis is a relatively recently introduced technique in healthcare, which produces section images of the chest at a lower radiation dose than computed tomography (CT) and with better depth resolution than conventional chest radiography. The primary aims of the studies described in this dissertation were to compare chest tomosynthesis with conventional radiography, to evaluate the effects of clinical experience and learning with feedback on the performance of observers analyzing tomosynthesis images, and to investigate the effect of radiation dose level in tomosynthesis, in the detection of pulmonary nodules. LÄS MER

  5. 15. Pharmacokinetics and dosimetry of radiolabelled octreotide for tumour therapy

    Detta är en avhandling från Göteborg

    Författare :Peter Bernhardt; Göteborgs universitet.; Gothenburg University.; [2000]
    Nyckelord :MEDICIN OCH HÄLSOVETENSKAP; MEDICAL AND HEALTH SCIENCES; pharmacokinetics; radiation dosimetry; therapy; radionuclides; octreotide; neuroendocrine tumours; nude mice; patients;

    Sammanfattning : Somatostatin (SS) receptors (sstr) are usually highly expressed on neuroendocrine (NE) tumours. The radiolabelled SS analogue 111In-DTPA-D-Phe1-octreotide is today widely used to scintigraphically visualise NE tumours, and high 111In activity concentrations are obtained in tumour vs. normal tissues. LÄS MER