A dual-source scanning-based radiation detecting apparatus comprises at least two radiation sources provided for emitting ionizing radiation of optionally different energies, direction sensitive line detectors arranged in an array, and a device for scanning the line detectors across an object to be examined. The line detectors are alternately pointing towards different ones of the radiation sources. The device for scanning is arranged for keeping the line detectors aligned during scanning to enable each of the line detectors to record multiple line images of the object. The scanning is preferably performed at least a distance corresponding to N times the distance between two adjacent ones of the line detectors, where N is the number of the radiation sources, to thereby enable recording of line images sufficient to form a two-dimensional image of the object at each of the different energies.