User contributions

Search for contributions

  • 14:59, 14 September 2010 (diff | hist) . . (+234). . Documentation-list(Added Jostein's master thesis)
  • 14:57, 14 September 2010 (diff | hist) . . (0). . m File:Characterization of Scintillation Crystals for Positron Emission Tomography.pdf(Protected "File:Characterization of Scintillation Crystals for Positron Emission Tomography.pdf" ([move=sysop] (indefinite))) (current)
  • 14:46, 14 September 2010 (diff | hist) . . (+2,163). . N File:Characterization of Scintillation Crystals for Positron Emission Tomography.pdf(The main purpose of this thesis has been to characterize BGO and LYSO crystals of different sizes with respect to decay time and energy resolution. BGO crystals have been used as a reference material. The work presented here is part of a research project initiated by the Department of Physics and Technology, University of Bergen, and the Department of Radiology, Haukeland University Hospital. The project is entitled “Improved diagnostics in Positron Emission Tomography (PET) through the extraction of temporal characteristics from detector system and tissue.” The main objective of the project is to use temporal information to improve sensitivity and specificity in imaging with PET technology. For the BGO crystals, a decay time of 305 +/- 6 ns has been found. The energy resolution measured with the use of the best optical grease was 16.6 +/- 0.1%. Ten small (2x2x16 mm3) LYSO crystals have been found to have a decay time of 47.0 +/- 0.3 ns. The best obtained energy resolution for these crystals is 13.3 +/- 0.2%. The larger crystals generally show a somewhat longer decay time. The 5x5x20 mm3 crystals show decay times of 48.0 to 48.5 ns. Of the crystal sizes tested, the 5x5x20 mm3 crystals show the best energy resolution. With the use of optical grease, an energy resolution of 11.4 +/- 0.1% has been measured. The linearity of the energy spectra has been investigated by the use of two different radioactive sources with a total of three different energy peaks. The linearity is very good both for the BGO and LYSO crystals. A qualitative investigation of the interaction efficiency of LYSO crystals of different sizes has been performed. The number of counts in the photopeak is compared to the total number of counts in the spectrum. No apparent difference is found increasing crystal length. The thickness of the crystal influences the interaction efficiency greatly. In addition to the characterization of different crystals, an introductory experiment concerning the rate of single, random, and true counts as a function of the activity has been performed in the PET scanner at the PET centre at Haukeland University Hospital (HUH).)
  • 14:43, 14 September 2010 (diff | hist) . . (-9). . m Detector lab(Removed Jostein from the student list. This list should be updated.)
  • 12:05, 6 October 2009 (diff | hist) . . (+40). . Detector lab
  • 12:04, 6 October 2009 (diff | hist) . . (0). . N File:PET-presentasjon-Detectorlab english.pdf(current)