Marking of the stereotactic target point by a radiopaque silicone sphere. Technical note.

We present a simple but efficient technique for marking the site of a stereotactic biopsy. This is done by a radiopaque Barium impregnated silicone sphere, which is introduced through the stereotactic cannula and placed at the target point. This allows a postoperative check of the target point by computer tomography or Magnetic Resonance Imaging and offers a landmark for further stereotactic intervention as well as for planning of high precision radiotherapy. Moreover it gives information about the growing direction of a tumour. The silicone spheres are well tolerated; no complications have occurred so far.