Transmission measurements using iterative conebeam reconstruction on the Inveon DPET

Transmission measurements are performed on PET tomographs to create attenuation correction factors for quantitatively accurate images. There are several opportunities within the Inveon Dedicated PET (DPET) to improve the overall performance of the system. The transmission mechanism has a number of characteristics that make it suitable for conebeam-like reconstruction techniques similar to those used in X-ray CT, leading to more accurate attenuation correction factors. Typical reconstruction techniques used in CT with curved detectors involve relatively narrow transaxial fan angles, even narrower axial cone angles, and a source to detector distance which is the detector’s radius of curvature. The Inveon DPET transmission source to detector distance is approximately twice the detector’s radius of curvature, resulting in a number of challenges for reconstruction. In addition, the use of a lower energy 60 keV source could provide additional contrast. In this work we describe and present preliminary results on the issues introduced by the extreme geometry of the system, reconstruction approaches incorporating system models, iterative techniques and source optimization.