Method and system for obtaining low dose tomosynthesis and material decomposition images

Method and system for obtaining tomosynthesis and material decomposition images of an object of interest using a system comprising an x-ray source facing a detector. The method comprises generating a 2D material 240 decomposition image of an object of interest from at least two sets of acquisitions, wherein each set is performed at a different energy spectrum and comprises at least one projection image or a plurality of projection images acquired at different x-ray source angulation positions. The 2D material decomposition image can be generated for a predetermined orientation selected from one of said different x-ray source angulation positions or from a virtual orientation. Preferably, multiple 2D projection images tomosynthesis data are generated at a first energy spectrum and a synthetic 2D image 201 from said data is generated. A 2D material decomposition image 220 may be generated by combining the synthetic image and a 2D image 202 acquired at a second energy spectrum. This may result in a lower exposure of radiation to the patient. The material 240 may be a contrast agent such as silver or iodine. The object of interest may be a patients breast.