Comparison of FORE and FOREX for a preclinical PET scanner with large axial aperture

For fast volumetric PET reconstruction, rebinning methods such as Fourier Rebinning (FORE) and Exact Fourier Rebinning (FOREX) are frequently used to estimate a series of 2D sinograms from oblique sinograms. This is particularly useful in whole-body imaging and dynamic imaging, where reconstruction with 3DRP or 3D OSEM is time consuming. As an approximate algorithm, FORE has been widely used for its simplicity in implementation and excellent accuracy in systems with small to medium axial aperture. In this work, we investigated the validity of FORE in a preclinical scanner with a 38° axial aperture through phantom simulations and real measurements, and compared it with the FOREX which is an exact method. Though computationally more intensive than FORE, FOREX leads to undistorted and more accurate reconstructions. For scanners with large axial aperture, FOREX is the preferred rebinning algorithm.