Sökning: "cone-beam CT"

Visar resultat 1 - 5 av 18 avhandlingar innehållade orden cone-beam CT.

  1. 1. Iterative Filtered Backprojection Methods for Helical Cone-Beam CT

    Författare :Johan Sunnegårdh; Michael Felsberg; Michel Defrise; Linköpings universitet; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Iterative reconstruction; filtered backprojection; regularization; cone-beam CT; Medical engineering; Medicinsk teknik;

    Sammanfattning : State-of-the-art reconstruction algorithms for medical helical cone-beam Computed Tomography (CT) are of type non-exact Filtered Backprojection (FBP). They are attractive because of their simplicity and low computational cost, but they produce sub-optimal images with respect to artifacts, resolution, and noise. LÄS MER

  3. 2. Combining analytical and iterative reconstruction in helical cone-beam CT

    Författare :Johan Sunnegårdh; Gösta Granlund; Per-Erik Danielsson; Michel Defrise; Linköpings universitet; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; cone-beam tomography; forward projection; image reconstruction; iterative reconstruction; ordered subsets; regularization; WFBP; Signal processing; Signalbehandling;

    Sammanfattning : Contemporary algorithms employed for reconstruction of 3D volumes from helical cone beam projections are so called non-exact algorithms. This means that the reconstructed volumes contain artifacts irrespective of the detector resolution and number of projection angles employed in the process. LÄS MER

  4. 3. 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

  5. 4. Cone Beam Computed Tomography - radiation dose and image quality assessments

    Författare :Sara Lofthag-Hansen; Göteborgs universitet; []
    Nyckelord :MEDICIN OCH HÄLSOVETENSKAP; MEDICAL AND HEALTH SCIENCES; Cone beam computed tomography; anatomic landmarks; dose-area product; image quality; implant planning; periapical diagnosis; radiation dosimetry;

    Sammanfattning : Diagnostic radiology has undergone profound changes in the last 30 years. New technologies are available to the dental field, cone beam computed tomography (CBCT) as one of the most important. LÄS MER

  7. 5. Cone Beam Computed Tomography in Evaluations of Some Side Effects of Orthodontic Treatment

    Författare :Henrik Lund; Göteborgs universitet; []
    Nyckelord :MEDICIN OCH HÄLSOVETENSKAP; MEDICAL AND HEALTH SCIENCES; Cone beam computed tomography; orthodontics; adolescents; root resorption; marginal bone height;

    Sammanfattning : In the late 1990s a new imaging modality, Cone Beam CT (CBCT) that enables high quality three-dimensional imaging at lower doses than Computed Tomography (CT), was introduced in dento-maxillofacial imaging. In 2005 the Swedish Council on Health Technology Assessment (SBU), in a review of scientific articles on Malocclusions and Orthodontic Treatment in a Health Perspective, found low or contradictive evidence for an association between orthodontic treatment and risks for negative side effects. LÄS MER