A comparative study of three tomographic reconstruction methods in cone beam off-centered circular geometry

The development of integrated PET/CT micro-scanners is an active research area for small animal imaging. In order to enable simultaneous acquisition, a novel off-centered circular CT cone-beam geometry was introduced. We recently proposed a generalized Feldkamp formula (alpha-FDK) for this geometry which produced severe CB artifacts owing to the missing reconstruction methods applied to the off-centered geometry and their ability to reduce CB artifacts. We consider the alpha-FDK, the adaptation of a shift-variant FBP method to our geometry, and an algebraic method (SART). The results show that some artifacts can be corrected with the shift-variant method and the SART to achieve good quality images in return for a time expense. However geometrical deformations are not compensated for by these techniques