1. A tomosynthesis system comprising: an x-ray source selectively emitting an imaging x-ray beam, a breast immobilizing structure defining a volume for a patient's breast, and an x-ray imaging receptor arranged such that said x-ray beam passes first through the volume for the patient's breast before impinging on the imaging receptor; a source support mounting the x-ray source for selective movement relative to the breast immobilizing structure; an x-ray data acquisition control configured to: cause the x-ray source to move through a plurality of different imaging positions relative to the breast immobilizing structure and selectively illuminate the imaging receptor with the x-ray beam for each of the imaging positions, and cause the imaging receptor to provide imaging data in response to being illuminated with the x-ray beam for the different imaging positions; a processing and image reconstruction unit configured to receive and process the imaging data and generate a plurality of projection x-ray images Tp and a plurality of reconstructed slices images Tr, wherein: each image Tp is a projection x-ray image of the volume for the patient's breast taken with the x-ray beam for a respective one of the plurality of different positions of the x-ray source relative to the breast immobilizing structure; and each image Tr is an image of a respective 3-dimensional slice of the volume for the patient's breast reconstructed through computer processing using at least several of the projection images Tp; and an image display unit configured to selectively display selected ones of the slice images Tr and projection images Tp concurrently with indicia identifying each displayed image as a projection or a slice image.