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Session: Surgical Techniques - Needles
Session starts: Thursday 24 January, 10:40
Presentation starts: 10:55
Room: Lecture room 557

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Nick van de Berg (Delft University of Technology)
John van den Dobbelsteen (Delft University of Technology)

Abstract:
During diagnosis and treatment of diseased tissue structures, needles form an increasingly popular and minimally invasive alternative to reach deep seated locations within the human body. One example of such procedures is radio frequency ablation (RFA) of tumorous structures. As the target depth increases, needle deflections, tissue deformations, and relative movement of the internal constellation can, however, lead to target errors. The development of a steerable needle tip was motivated by the desire to correct for these errors and ensure a successful and complete treatment. The presented work describes the design of a 3 degree of freedom (3 DOF) steerable needle actuator and control interface. A flexible needle (3 mm in diameter) is actuated by means of steering cables, running through the needle lumen. The cables are connected to a 2 DOF freely rotating disk that can be actuated independently by two servo motors. Opposing actuation cables are loosened and tightened by rotation of the disk, causing the tip element to steer. The third degree of freedom translates the entire setup forwards or backwards by means of a linear stage, simulating the needle insertion. All actuators are connected to a computer and controlled by either a keyboard or SpaceNavigator through MATLAB. The possibility to correct needle placement errors by means of a steerable instrument was demonstrated by a working prototype. Experiments to investigate placement accuracy are planned for the near future. As visual feedback on the needle location is lost in actual tissue (opposed to gel phantoms) and haptic feedback is lost in a robotic system, ongoing efforts aim to sensorize the steerable needle by means of fiber bragg gratings (FBG’s) in order to reconstruct the needle shape and measure interaction forces. This information can be fed back to the user, providing support on both a visual and haptic (e.g. shared control) level.