Sökning: "radiofysik"

Visar resultat 31 - 35 av 106 avhandlingar innehållade ordet radiofysik.

1. 31. ESR dosimetry in the radiation therapy dose range : development of dosimetry systems and sensitive dosimeter materials

   Författare :Sara Olsson; Bartolomieij Ciesielski; Linköpings universitet; []
   Nyckelord :MEDICINE; MEDICIN;

   Sammanfattning : ESR dosimetry with L-α-alanine as a dosimeter material is a well known and frequently used method for measuring high absorbed doses, for example at sterilisation and food irradiation. The increased sensitivity of modem spectrometers and an increased knowledge of the radiochemical properties of alanine have lowered the detection limit of ESR/alanine dosimetry to the dose range relevant for radiation therapy. LÄS MER

3. 32. Free radical dosimetry employing ESR spectroscopy for clinical use

   Författare :Sara Olsson; Linköpings universitet; []
   Nyckelord :MEDICINE; MEDICIN;

   Sammanfattning : In all radiation therapy treatment it is important to thoroughly determine the absorbed dose in the tumour, in surrounding normal tissue and in risk organs. The dose distributions are usually calculated by means of computerised dose-planning systems. LÄS MER

4. 33. Analysis of ICP pulsatility and CSF dynamics : the pulsatility curve and effects of postural changes, with implications for idiopathic normal pressure hydrocephalus

   Författare :Sara Qvarlander; Anders Eklund; Jan Malm; Richard Birgander; Martin U Schuhmann; Umeå universitet; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Cerebrospinal fluid; CSF dynamics; Intracranial pressure; Pulse pressure; Normal pressure hydrocephalus; Posture; Predictive tests; Mathematical modelling; Magnetic resonance imaging; Infusion tests;

   Sammanfattning : The volume defined by the rigid cranium is shared by the brain, blood and cerebrospinal fluid (CSF). With every heartbeat the arterial blood volume briefly increases and venous blood and CSF are forced out of the cranium, leading to pulsatility in CSF flow and intracranial pressure (ICP). LÄS MER

5. 34. Effective use of X rays in diagnostic radiology : Guidance for the optimisation of image quality and absorbed dose in the patient by use of a Monte Carlo computational model of the imaging chain

   Författare :Michael Sandborg; Heang-Ping Chan; Linköpings universitet; []
   Nyckelord :MEDICINE; MEDICIN;

   Sammanfattning : The primary objective of this thesis is to give guidance for the reduction of absorbed dose in the patient and the improvement of image quality by the optimisation of the various parameters which control the performance of the radiological imaging system. The optimisation means that image quality (contrast in screen-film imaging and signal-to-noise ratio in digital imaging) is kept constant and combinations of operating parameters which yields the lowest mean absorbed dose in the patient is determined. LÄS MER

7. 35. Contributions to deep learning for imaging in radiotherapy

   Författare :Attila Simkó; Joakim Jonsson; Tommy Löfstedt; Anders Garpebring; Tufve Nyholm; Veronika Cheplygina; Umeå universitet; []
   Nyckelord :MEDICIN OCH HÄLSOVETENSKAP; MEDICAL AND HEALTH SCIENCES; deep learning; medical imaging; radiotherapy; artefact correction; bias field correction; contrast transfer; synthetic CT; reproducibility;

   Sammanfattning : Purpose: The increasing importance of medical imaging in cancer treatment, combined with the growing popularity of deep learning gave relevance to the presented contributions to deep learning solutions with applications in medical imaging.Relevance: The projects aim to improve the efficiency of MRI for automated tasks related to radiotherapy, building on recent advancements in the field of deep learning. LÄS MER