The invention relates to a medical tomosynthesis system (10) having an interventional device (15) and an image acquisition device (11 12) for acquiring images of a subject volume in a plurality of angular positions around the subject volume. In the system a three-dimensional geometrical model of the interventional unit is used to identify the projection angles of the image acquisition device that actually can be used. Preferably this three-dimensional model is achieved by reconstructing it from projection images acquired with the X-ray image acquisition device. The invention also relates to a method for acquiring images with such a system. Fig.2