Preparation of a homemade ultrasound biopsy phantom

Sonographic guidance has long been employed for biopsy with sector scanners by utilizing attachable offset guides,’-5 by dedicated linear array system^,^,^ or by “free hand.”’ All of these techniques are bimanual, in contrast to a diagnostic scan or biopsy alone. The dedicated systems provide a slot that causes the needle to be directed into the center of the scanning plane. When the procedure is done free hand, a greater degree of hand-eye coordination is necessary to achieve success. Based on the position and depth of the target, one must estimate the correct angle of attack, as well as maintain the axis of the needle within the scan plane. Recent papers by Fournage et al.’ and Reading et a1.l’ have confirmed that with skill and experience, excellent results can be obtained free hand with linear array probes. We believe use of a biopsy phantom can shorten the “learning curve” by allowing the learning and practice of the bimanual skills and hand-eye coordination necessary for successful biopsy. In this paper, we present a method for easily making a biopsy phantom. The substance of the phantom is a hyperconcentrated gel solution. Flour serves as a scatterer and produces background echogenicity similar to liver parenchyma. Our favorite target is a small water-filled balloon containing a pebble.