Design and validation of a robotic needle positioning system for small animal imaging applications

A needle-positioning robot has been developed for image-guided interventions in small animals. The device is designed to position a needle with an error < or =100 microm. The robot has two rotational axes (pitch and roll) to control needle orientation, and one linear axis to perform needle insertion. The three axes intersect at a single point, creating a remote center of motion. Needle positioning error was quantified at ten target locations for each rotational plane. The measured needle positioning accuracy in free space was 54 +/-12 microm and 91 +/- 21 microm for the pitch and roll axes, respectively. The device's accuracy compares favorably with the sizes of typical interventional targets in mouse models.