title: Accurate attenuation correction for a 3D PET system.
abstract: An accurate attenuation correction has been developed for a small-volume three-dimensional positron emission tomography (PET) system. Transmission data were measured as twenty-four 2D slices which were reconstructed and combined to form a 3D attenuation image. Emission data were reconstructed using a backproject-then-filter technique, and each event was corrected for attenuation at backprojection time by a reprojection through the attenuation image. This correction restores the spatial invariance of the point response function, thus allowing a valid deconvolution and producing an undistorted emission image. Scattering corrections were not applied to either the transmission or the emission data but simulation studies indicated that scattering made only a small contribution to the attenuation measurement. Results are presented for two phantoms, in which transmission scans of 57,500 and 18,700 events/slice were used to correct emission images of 5.2 and 2.8 million events. Although the attenuation images had poor statistical accuracy and a resolution of 13 mm, the method resulted in accurate attenuation-corrected images with no degradation in image resolution (which was 3 mm for the first emission image), and with little effect on image noise.
authors.affiliation: Department of Medicine, Queen's University, Kingston, Ontario, Canada.
authors.forename: B T
authors.initials: BT
authors.lastname: McKee
authors.forename: R
authors.initials: R
authors.lastname: Clack
authors.forename: P J
authors.initials: PJ
authors.lastname: Harvey
authors.forename: L G
authors.initials: LG
authors.lastname: Hiltz
authors.forename: M J
authors.initials: MJ
authors.lastname: Hogan
authors.forename: D C
authors.initials: DC
authors.lastname: Howse
mesh_terms: D007091:Image Processing, Computer-Assisted / Q000379:methods*; D014055:Tomography, Emission-Computed / Q000295:instrumentation / Q000379:methods*