A robotic needle-positioning and guidance system for CT-guided puncture: Ex vivo results

Purpose: To test the feasibility of a robotic needle-guidance platform during CT-guided puncture ex vivo. Material and methods: Thin copper wires inserted into a torso phantom served as targets. The phantom was placed on a carbon plate and the robot-positioning unit (RPU) of the guidance platform (iSYS Medizintechnik GmbH, Kitzbuehel, Austria) was attached. Following CT imaging and automatic registration a double oblique trajectory was planned and the RPU was remotely moved into appropriate position and angulation. A 17G-puncture needle was then manually inserted until the preplanned depth, permanently guided by the RPU. The CT scan was repeated and the distance between the actual needle tip and the target was evaluated. Results: Automatic registration was successful in ten experiments and the median duration of an experiment was 9.6 (6.4-46.0) minutes. The angulation of the needle path in x-y and z-axis was within 15.6 degrees to 32.6 degrees, and -32.8 degrees to 3.2 degrees, respectively and the needle insertion depth was 92.8 +/- 14.4 mm. The Euclidean distance between the actual needle tip and the target was 2.3 +/- 0.8 (range, 0.9-3.7) mm. Conclusion: Automatic registration and accurate needle placement close to small targets was demonstrated. Study settings and torso phantom were very close to the clinical reality.