Publication: First: fast iterative reconstruction software for (PET) tomography
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ISSN: 0031-9155 (Print)
ISSN: 1361-6560 (Online)
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2006
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Institute of Physics
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Abstract
Small animal PET scanners require high spatial resolution and good sensitivity.
To reconstruct high-resolution images in 3D-PET, iterative methods, such as OSEM, are superior to analytical reconstruction algorithms, although their high computational cost is still a serious drawback. The higher performance
of modern computers could make iterative image reconstruction fast enough
to be viable, provided we are able to deal with the large number of probability coefficients for the system response matrix in high-resolution PET scanners, which is a difficult task that prevents the algorithms from reaching peak computing performance. Considering all possible axial and in-plane
symmetries, as well as certain quasi-symmetries, we have been able to reduce
the memory requirements to store the system response matrix (SRM) well below 1 GB, which allows us to keep the whole response matrix of the system inside RAM of ordinary industry-standard computers, so that the reconstruction algorithm can achieve near peak performance. The elements of the SRM are
stored as cubic spline profiles and matched to voxel size during reconstruction.
In this way, the advantages of ‘on-the-fly’ calculation and of fully stored SRM are combined. The on-the-fly part of the calculation (matching the profile functions to voxel size) of the SRM accounts for 10–30% of the reconstruction
time, depending on the number of voxels chosen. We tested our approach with
real data from a commercial small animal PET scanner. The results (image quality and reconstruction time) show that the proposed technique is a feasible solution
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Bibliographic citation
Physics in Medicine and Biology, 2006, vol. 51, n. 18, p. 4547-4565