A stereotactic mammography biopsy system is a method of locating impalpable, non sonographic lesions for harvesting a tissue sample. It is an accurate means of locating and demonstrating the biopsy site. It requires a co operative client to remain still throughout the procedure who is assisted by skilled empathetic practitioners working as a team and include the patient in the process.

Stereotaxis works on the principle of parallax; that is the distance of shift of a lesion relative to a fixed point. It allows calculation of the depth or distance from that fixed point. A computer is used to calculate this depth using two 2D images taken at the same angulation (15°) each side of the vertical plane.