Normalisation of listmode data with application to HiDAC data

Many PET scanners nowadays have the possibility to record event-by-event information, known as listmode data. This has the advantage to keep the data in the highest possible resolution (both temporal and spatial). In most cases, listmode data are then binned into sinogram format before reconstruction. In this paper, we discuss at which stage normalisation factors should be introduced. It is shown that noise is greatly reduced by performing the normalisation after the binning. We also briefly discuss the consequences for strictly listmode-based algorithms. We illustrate this with acquired and simulated data for the quad HiDAC camera.