Sökning: "stopping-power ratio"

Hittade 4 avhandlingar innehållade orden stopping-power ratio.

  1. 1. Studies of clinical proton dosimetry using Monte Carlo simulation and experimental techniques

    Författare :Joakim Medin; Stockholms universitet; []
    Nyckelord :NATURAL SCIENCES; NATURVETENSKAP; Proton dosimetry; Proton stopping power; Monte Carlo; Proton stopping-power ratios; Ionization chamber calibration; medicinsk strålningsfysik; Medical Radiation Physics;

    Sammanfattning : The present work aims at improving clinical proton dosimetry based on ionization chambers, and to bring its state of development closer to the corresponding status of conventional photon and electron dosimetry. In order to accomplish this, both theoretical and experimental methods have been used. LÄS MER

  2. 2. Absorbed Dose Determination and Characteristics of Degraded Electron Beams: Application to Intraoperative Radiation Therapy

    Författare :Peter Björk; Internmedicin - epidemiologi; []
    Nyckelord :MEDICIN OCH HÄLSOVETENSKAP; MEDICAL AND HEALTH SCIENCES; MEDICIN OCH HÄLSOVETENSKAP; MEDICAL AND HEALTH SCIENCES; Clinical physics; radiology; tomography; medical instrumentation; Klinisk fysiologi; radiologi; tomografi; medicinsk instrumentering; absorbed dose distribution; output factor; stopping-power ratio; beam characteristics; Monte Carlo calculation; electron beam dosimetry; applicator system; radiation therapy; linear accelerator; intraoperative radiotherapy;

    Sammanfattning : The aim of this work was to quantify limitations of and uncertainties in commonly used dosimetric techniques for relative absorbed dose determination in degraded electron beams, such as those encountered in intraoperative radiation therapy (IORT) and small-electron-field radiotherapy. Three different detector types were investigated with regard to measurements of output factors and relative absorbed dose distributions: (1) a parallel-plate ionization chamber, (2) a p-type silicon diode detector and (3) a diamond detector. LÄS MER

  3. 3. 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; 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

  4. 4. Dosimetric effects of removing the flattening filter in radiotherapy treatment units

    Författare :Mårten Dalaryd; Lund Medicinsk strålningsfysik; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES;

    Sammanfattning : The aim of this work was to investigate the dosimetric effects of removing the flattening filter from conventional C-arm medical linear accelerators. In conventional linear accelerators used for radiotherapy, a flattening filter is positioned in the beam line to provide a uniform lateral dose profile at a specified depth in water. LÄS MER