A system (SC) for controlling operation of a multi-focal-spot X-ray imager (IA). The system comprises a projection direction determiner (PDD) configured to determine a projection direction for an object (OB) to be imaged, based on a geometric structure of a model m(OB) for the object (OB). A selector (SX) of the system is configured to select, from the imager (IA)'s plurality of focal-spot-detector pairs (IPj) with different optical axes (OXj), at least one target pair whose optical axis corresponds to the determined projection direction.
