1. An imaging apparatus comprising: a coded aperture mask having a set of multiple holes and configured to pass radiation from a radiation source through said set of multiple holes; a radiation detector located at an image plane at an opposite side of said radiation source relative to said coded aperture mask and configured to generate an image of an object placed between said coded aperture and said radiation detector; and an image decoder unit that constructs multiple decoded images based on said image, wherein each of said multiple decoded images is representative of a two-dimensional cross-sectional area of said object in a plane parallel to said imaging plane and located at different distances from said imaging plane.