title: An investigation into truncation artefacts experienced in cardiac imaging using a dedicated cardiac SPECT gamma camera with transmission attenuation correction.
abstract: BACKGROUND
  In SPECT images truncation artefacts may occur when the object does not remain in the field of view (FOV). This truncation may lead to distortions in the transmission map (μ map), which would affect the attenuation correction (AC) and possibly the final image. Our aim was to investigate this distortion on our dedicated small FOV cardiac camera and evaluate the efficacy of the truncation correction.
  
  
  METHODS
  Using a phantom, transmission data were acquired with our cardiac camera using arrays of (153)Gd sources. The width of the phantom was varied by adding attenuating material. AC and non-AC images were analysed.
  
  
  RESULTS
  The results showed that distorted µ maps were produced, which remained distorted even after the application of correction algorithms for chest width measurements greater than 43 ± 1 cm. This distortion was observed to worsen with increasing chest width measurements. Artefacts were not seen for chest width measurements smaller than 43 cm, even when significant anterior attenuation was modelled.
  
  
  CONCLUSIONS
  Our findings demonstrate that AC-corrected images acquired with our dedicated small FOV cardiac camera are not suitable for patients with chest width measurements greater than 43 cm.
authors.affiliation: Department of Medical Physics, Northampton General Hospital NHS Trust, Northampton, UK. sem89@cam.ac.uk
authors.forename: Stacey E
authors.initials: SE
authors.lastname: McGowan
authors.forename: Claire D
authors.initials: CD
authors.lastname: Greaves
authors.forename: Stephen
authors.initials: S
authors.lastname: Evans
mesh_terms: D000465:Algorithms; D016477:Artifacts; D049628:Body Size; D015902:Gamma Cameras; D006321:Heart / Q000000981:diagnostic imaging*; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D019047:Phantoms, Imaging; D013909:Thorax / Q000033:anatomy & histology; D015899:Tomography, Emission-Computed, Single-Photon / Q000295:instrumentation*