title: Aperture correction with an asymmetrically trimmed Gaussian weight in SPECT with a fan-beam collimator.
abstract: OBJECTIVE
  The aim of the study is to improve the spatial resolution of SPECT images acquired with a fan-beam collimator.
  
  
  METHODS
  The aperture angle of a hole in the fan-beam collimator depends on the position of the collimator. To correct the aperture effect in an iterative image reconstruction, an asymmetrically trimmed Gaussian weight was used for a model. To confirm the validity of our method, point source phantoms and brain phantom were used in the simulation, and we applied the method to the clinical data.
  
  
  RESULTS
  The results of the simulation showed that the spatial resolution of point sources improved from about 6 to 2 pixels full width at half maximum, and the corrected point sources were isotropic. The results of the simulation with the brain phantom showed that our proposed method could improve the spatial resolution of the phantom, and our method was effective for different fan-beam collimators with different focal lengths. The results of clinical data showed that the quality of the reconstructed image was improved with our proposed method.
  
  
  CONCLUSIONS
  Our proposed aperture correction method with the asymmetrically trimmed Gaussian weighting function was effective in improving the spatial resolution of SPECT images acquired with the fan-beam collimator.
authors.affiliation: Department of Applied Informatics, Faculty of Science and Engineering, Hosei University, 3-7-2 Kajinocho, Koganei, Tokyo, 184-8584, Japan.
authors.forename: Ryo
authors.initials: R
authors.lastname: Kamiya
authors.forename: Koichi
authors.initials: K
authors.lastname: Ogawa
mesh_terms: D005240:Feasibility Studies; D006801:Humans; D007089:Image Enhancement / Q000295:instrumentation*; D008962:Models, Theoretical; D016011:Normal Distribution; D019690:Technetium Tc 99m Exametazime; D015899:Tomography, Emission-Computed, Single-Photon / Q000295:instrumentation*
chemical_list: D019690:Technetium Tc 99m Exametazime