Sökning: "Monte Carlo calculation"

Visar resultat 21 - 25 av 64 avhandlingar innehållade orden Monte Carlo calculation.

  1. 21. 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

  3. 22. Calculation of scatter in cone beam CT : Steps towards a virtual tomograph

    Författare :Alexandr Malusek; Michael Sandborg; Gudrun Alm Carlsson; Michael Ljungberg; Linköpings universitet; []
    Nyckelord :MEDICIN OCH HÄLSOVETENSKAP; MEDICAL AND HEALTH SCIENCES; Radiology; Radiologi;

    Sammanfattning : Scattered photons—shortly scatter—are generated by interaction processes when photon beams interact with matter. In diagnostic radiology, they deteriorate image quality since they add an undesirable signal that lowers the contrast in projection radiography and causes cupping and streak artefacts in computed tomography (CT). LÄS MER

  4. 23. Internal Dosimetry Development and Evaluation of Methods and Models

    Författare :Lena M Jönsson; Lund Medicinsk strålningsfysik; []
    Nyckelord :MEDICIN OCH HÄLSOVETENSKAP; MEDICAL AND HEALTH SCIENCES; tomografi; Klinisk fysiologi; medical instrumentation; tomography; radiology; Clinical physics; crypt cells; intestine; radionuclide; scintillation camera; sestamibi; activity quantification; conjugate view method; Monte Carlo simulation; internal dosimetry; Nuclear medicine; radiobiology; Nukleärmedicin; radiobiologi; medicinsk instrumentering; radiologi;

    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

  5. 24. Modeling of dose and sensitivity heterogeneities in radiation therapy

    Författare :Kristin Wiklund; Bengt K. Lind; Iuliana Toma-Dasu; Marco Zaider; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Monte Carlo simulations; Tumor control probability; Modeling; Beam characterization; Medical Radiation Physics; medicinsk strålningsfysik;

    Sammanfattning : The increased interest in the use of light ion therapy is due to the high dose conformity to the target and the dense energy deposition along the tracks resulting in increased relative biological effectiveness compared to conventional radiation therapy. In spite of the good clinical experience, fundamental research on the characteristics of the ion beams is still needed in order to be able to fully explore their use. LÄS MER

  7. 25. Pointwise and Genomewide Significance Calculations in Gene Mapping through Nonparametric Linkage Analysis: Theory, Algorithms and Applications

    Författare :Lars Ängquist; Matematisk statistik; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; programming; actuarial mathematics; Statistik; cytogenetics; Genetik; cytogenetik; Mathematics; Matematik; Statistics; operations research; Genetics; ROC curves; conditioning loci; optimal score functions; noncentrality parameter; cost adjusted relative efficiency; exponential tilting; importance sampling; Monte Carlo simulation; normal approximation; crossover rate; process maximum; analytical approximation; significance calculations; NPL score; conditional linkage analysis; two-locus linkage analysis; Allele sharing; aktuariematematik; operationsanalys; programmering; gene-gene interaction; composite hypotheses; genetic disease models; classes of score functions; nonparametric linkage analysis;

    Sammanfattning : In linkage analysis or, in a wider sense, gene mapping one searches for disease loci along a genome. This is done by observing so called marker genotypes (alleles) and phenotypes (affecteds/unaffecteds) of a pedigree set, i.e. LÄS MER