Accurate attenuation correction for a 3D PET system.
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.
McKee
B T
BT
Department of Medicine, Queen's University, Kingston, Ontario, Canada.
Clack
R
R
Harvey
P J
PJ
Hiltz
L G
LG
Hogan
M J
MJ
Howse
D C
DC
D007091:Image Processing, Computer-Assisted / Q000379:methods*; D014055:Tomography, Emission-Computed / Q000295:instrumentation / Q000379:methods*