Continuous bed motion data processing for a high resolution LSO PET/CT scanner

Continuous whole-body PET scanning, Continuous Bed Motion (CBM) acquisition has a number of advantages over the traditional Step-and-Shoot (SS) mode. Strengths of CBM include a uniform axial signal-to-noise ratio, continuous sampling in the axial direction that reduces resolution artifacts, reduction of noise from detector normalization, and reduction of sensitivity to small patient movements. This work highlights the acquisition and data handling methodology that was implemented for a series of phantoms and over 40 patient studies acquired on a high resolution, 16-slice LSO combined PET/CT scanner (CPS Innovations, Knoxville, TN). CBM data were acquired in 32-bit listmode with the bed moving at a constant speed of typically 0.6 mm/s to match the acquisition time per plane of the SS mode. CBM data were processed using the novel, virtual scanner concept that can be applied to a scanner of any axial length. For the high resolution scanner, the LSO PET detectors are arranged in a truncated spherical geometry and therefore normalization and geometrical corrections are applied on an event-by-event basis during histogramming of the 32-bit listmode data. Scatter correction is calculated on the entire image volume, in contrast to the SS mode where scatter is estimated for each bed position. The final 3D data set was reconstructed using Ordinary Poisson OSEM3D. This paper will present results from phantom studies and compare clinical patient scans acquired in both SS and CBM modes.