Anatomically correct deformable colon phantom

We describe a technique to build a soft-walled colon phantom that provides realistic lumen anatomy in computed tomography (CT) images. The technique begins with the geometry of a human colon measured during CT colonography (CTC). The three-dimensional air-filled colonic lumen is segmented and then replicated using stereolithography (SLA). The rigid SLA model includes large-scale features (e.g., haustral folds and tenia coli bands) down to small-scale features (e.g., a small pedunculated polyp). Since the rigid model represents the internal air-filled volume, a highly-pliable silicone polymer is painted onto the rigid model. This thin layer of silicone, when removed, becomes the colon wall. Small 3 mm diameter glass beads are affixed to the outer wall. These glass beads show up with high intensity in CT scans and provide a ground truth for evaluating performance of algorithms designed to register prone and supine CTC data sets. After curing, the silicone colon wall is peeled off the rigid model. The resulting colon phantom is filled with air and submerged in a water bath. CT images and intraluminal fly-through reconstructions from CTC scans of the colon phantom are compared against patient data to demonstrate the ability of the phantom to simulate a human colon.