From top to bottom: (1) MLEM reconstruction of list-mode PET data from a point source (1, 10, 100, 1000 Bq) moving at 0.5 mm/s in an S pattern (100 iterations). (2) Same data, processed using a single backprojection. (3) Source trajectory estimated directly from list-mode data using the minimum-distance method used in PEPT, which splits the events into independent frames. (4) Same data, reconstructed using a third-order B-spline. Spline parameters were optimized for each activity level.