Improved resolution via 3D iterative reconstruction for PET volume imaging
- Univ. of Minnesota and VA Medical Center, Minneapolis, MN (United States)
The removal of interplane septa in multi-ring detector cameras to allow oblique coincidence events to be collected has significantly increased the sensitivity of signal detection in positron emission tomography (PET) for 3D volume imaging. However, the oblique penetration of photons in the detector degrades the axial resolution compared to data acquired with the septa extended (2D). In addition, in the standard 3D reconstruction algorithm (Promis), the use of forward projections to estimate the missing part of the truncated 2D projections smooths the estimated data and causes the resolution to degrade towards the end slices compared to the central slices. Studies in 2D have shown that iterative reconstructions that allow the incorporation of a resolution model can improve the image resolution. To show that this also applies for 3D imaging, we conducted the following experiment. A set of point sources located at the center and at radial distances of 4cm and 8cm transaxially were scanned with a Siemens CTI 953B PET camera in 3D mode at 3 axial positions. Images were reconstructed by 3D iterative filtered backprojection algorithm, with the same filter as used in Promis. A spatially invariant 3D Gaussian function approximating the resolution of the camera was used as the resolution kernel in IFBP reconstruction. The same Gaussian function was also used as the post reconstruction sieve filter for regularization. Axial and transaxial resolution were measured in FWHM of a fitted Gaussian for each point source in the reconstructed images. For IFBP at 15 iteractions without sieve, the transaxial resolution improves 30% at the center and 32% at the edge of the axial FOV compared to those of Promis. The axial resolution also shows improvements of 15% at both locations. For IFBP at 15 iterations with sieve, the improvements in transaxial resolution are reduced to 6% at the center and 9% at the edge of the axial FOV.
- OSTI ID:
- 197925
- Report Number(s):
- CONF-940605-; ISSN 0161-5505; TRN: 95:007029-0060
- Journal Information:
- Journal of Nuclear Medicine, Vol. 35, Issue Suppl.5; Conference: 41. annual meeting of the Society of Nuclear Medicine, Orlando, FL (United States), 5-8 Jun 1994; Other Information: PBD: May 1994
- Country of Publication:
- United States
- Language:
- English
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