Search for dissertations about: "cone beam ct"

Showing result 1 - 5 of 17 swedish dissertations containing the words cone beam ct.

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

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

   Abstract : 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. READ MORE

4. 2. Calculation of scatter in cone beam CT : Steps towards a virtual tomograph

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

   Abstract : 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). READ MORE

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

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

   Abstract : 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. READ MORE

6. 4. Image Quality Optimisation and Dose Management in CT, SPECT/CT, and PET/CT

   Author : Marcus Söderberg; Malmö Medicinsk strålningsfysik; []
   Keywords : MEDICIN OCH HÄLSOVETENSKAP; MEDICAL AND HEALTH SCIENCES; MEDICIN OCH HÄLSOVETENSKAP; MEDICAL AND HEALTH SCIENCES; CT; SPECT; PET; dosimetry; image quality; optimisation; dose reduction; automatic exposure control; contrast medium; phantom; image reconstruction; human observer;

   Abstract : The significant increase in the use of CT, alone or combined with SPECT or PET, has raised concerns about patient radiation exposure and the consequent increased risk of malignancy later in life. The overall objective of this work was to evaluate and optimise different approaches for minimising patient radiation absorbed dose and maintaining or improving image quality in CT, SPECT/CT, and PET/CT. READ MORE

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

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

   Abstract : 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. READ MORE