1. An image processing apparatus comprising: a scatter simulation processor configured to use single-scatter simulation, SSS, for processing measured sinograms generated from imaging data acquired for an imaging subject by an imaging apparatus to produce a single-scatter scatter sinogram that represents a shape of scatter contribution; a scatter scaling processor configured to utilize a short Monte Carlo simulation to determine a scatter fraction based on a ratio of a total number of scattered event pairs to a total number of event pairs in a Monte Carlo simulated sinogram and to scale the single-scatter scatter sinogram to generate a scaled scatter sinogram that matches the scatter contribution in the measured sinogram; and a reconstruction processor configured to reconstruct the imaging data into an image representation using the scaled scatter sinogram for scatter correction.