The invention relates to a system and a method for the investigation of a body volume (3), particularly for the diagnosis of breast cancer According to the method, a sequence of X-ray projections (P, P′) from different directions is produced by a rotatable X-ray source (1) and a stationary digital X-ray detector (5). From these projections (P, P′), a set of sectional images (a, b, c, d) is calculated by tomosynthesis. A physician may indicate a suspicious structure on a reference image (R) that is derived from one of the projections (P, P′) or sectional images (a, b, c, d) and displayed on a monitor (6). The computer (7) may then locate the structure on all sectional images (a, b, c, d) and calculate the similarity of a corresponding image feature. The sectional 10 image at which the similarity is strongest then indicates the depth (zo) at which the structure (4) is positioned in the body volume (3). Based on this information, a biopsy device (9) with a needle (10) can be advanced into the body volume (3) until it reaches the suspicious structure (4).