1. A conebeam computed tomography imaging system including: a conebeam computed tomography scanning means for acquiring oversampled conebeam projection data along a generally helical source trajectory around an examination region; and an exact reconstruction means including: a convolving means for performing at least one convolution of the acquired projection data, the convolving operating on projection data falling within an exact reconstruction window and on at least some redundant projection data falling outside the exact reconstruction window to produce convolved projection data, and an aperture-weighted backprojecting means for performing aperture-weighted backprojecting of the convolved projection data using an aperture weighting function that weightedly combines at least some convolved redundant projection data with convolved projection data falling within the exact reconstruction window to generate a reconstructed image with contributions from redundant projection data.