Needle tip dexterity is advantageous for transthoracic lung biopsies, which are typically performed with rigid,
straight biopsy needles. By providing intraoperative compensation for trajectory error and lesion motion, tendon-driven
biopsy needles may reach smaller or deeper nodules in fewer attempts, thereby reducing trauma. An
image-guided robotic system that uses these needles also has the potential to reduce radiation exposure to the
patient and physician. In this paper, we discuss the design, workflow, kinematic modeling, and control of both
the needle and a compact and inexpensive robotic prototype that can actuate the tendon-driven needle for
transthoracic lung biopsy. The system is designed to insert and steer the needle under Computed Tomography
(CT) guidance. In a free-space targeting experiment using a discrete proportional control law with digital camera
feedback, we show a position error of less than 1 mm achieved using an average of 8.3 images (n=3).
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