Sökning: "radiology Clinical physics tomography medical instrumentation Klinisk fysiologi tomografi medicinsk"
Visar resultat 21 - 25 av 54 avhandlingar innehållade orden radiology Clinical physics tomography medical instrumentation Klinisk fysiologi tomografi medicinsk.
21. Development and evaluation of an independent system for absorbed dose calculations in radiotherapy
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
22. Image Processing for Quantitative Scintillation-Camera Imaging. Application to Radionuclide Therapy
Sammanfattning : Individual-based determinations of the absorbed dose in radionuclide therapy largely rely on absolute measurement of the activity distribution and its redistribution over time. Scintillation-camera imaging is the most commonly employed measuring technique, applied in planar or SPECT mode, sometimes in combination with structural images from CT. LÄS MER
23. Verification of Dose Calculation Algorithms in Treatment Planning Systems for External Radiation Therapy: A Monte Carlo Approach
Sammanfattning : This thesis presents a new verification concept, the virtual accelerator, for dose calculation algorithms used in treatment planning systems (TPSs) for external beam radiotherapy. The algorithm input data required to implement a treatment unit in the TPS are generated by Monte Carlo simulations as are the beam reference data needed for the subsequent evaluation of the dose calculation algorithm. LÄS MER
Sammanfattning : Radionuclide therapy requires patient-specific planning of the absorbed dose to target volumes, in most cases tumours, in order to achieve an expected biological effect, taking into account that the absorbed doses to normal organs and tissues should be kept as low as reasonably achievable. Therefore, the calculation of absorbed doses has to be as accurate as possible. LÄS MER
Sammanfattning : The studies presented in this thesis concern the optimisation and evaluation of the dynamic susceptibility contrast magnetic resonance imaging (DSC-MRI) technique for the assessment of perfusion-related parameters of the brain, such as cerebral blood flow (CBF), cerebral blood volume (CBV) and mean transit time (MTT). Several methodological factors influence these measurements, for example, contrast-agent administration, arterial input function (AIF) registration, choice of deconvolution algorithm and the choice of pulse-sequence parameters. LÄS MER