An image processing apparatus (IP) comprising an input port (IN) for receiving projection data through respective 3D locations in an imaging region, said projection date collected in a scan operation by an imaging apparatus (IM). An image segment generator (IGS) of said apparatus (IP) is configured to generate, based on said projection data, a first image segment for said 3D locations. A visualizer (VIZ) configured to effect displaying said first image segment on a display device before or whilst the image apparatus collects projection data for a different 3D location.
