Voxel Basis Function is Not Optimal for Tomographic Reconstruction of Plane-Integral Data

Background: Though voxels are widely used in image representation and reconstruction, they suffer from lack of continuity and symmetry leading to inferior reconstruction quality. This study aims to address whether voxel stand the test of time in the era of blob basis function in reconstruction of plane-integral projections.Methods: For this purpose, a small-animal SPECT camera equipped with a rotating slithole collimator was modeled within GATE platform and tomographic data acquisition was performed for NEMA IQ phantom. The slithole is a high-sensitivity magnifying collimator measuring convergent-plane-integral projections of the object being imaged. The collimation data were then reconstructed using an ad hoc OSEM algorithm using cubic voxels. The image reconstruction was repeated for blobs.Results: Both voxel and blob reconstruction algorithms were verified using noisy 3D MOBY phantom prior to reconstructing the simulation data, with an error of 7.5% and 9.2%, respectively. Blob modeling leads to a lower computational burden by a factor of ~2.1 in on-the-fly calculation of the system matrix. A 13% increase in SNR of the largest hot rod of the NEMA IQ phantom is obtained when voxels are replaced by blobs. Blob reconstruction shows an advantage over voxel reconstruction by offering a monotonically decreasing NSE across all iterations indicating a more robust statistical noise handling.Conclusion: Blobs outperform voxels by exhibiting a superior projector/backprojector pair due to their inherent symmetric and smooth shape. Therefore, they should be the basis functions of choice in the case of plane-integral-based reconstruction.

کلیدواژه ها:

Voxel ، blob ، Monte Carlo ، plane-integral ، reconstruction