A navigated 4-DOF mechanical aiming device for percutaneous ablation of liver tumours

During percutaneous interventional procedures, the orientation and position and of a needle-like instrument can be constrained relative to the patient’s coordinate system using a variety of aiming devices. Physicians align the aiming device in space according to a pre-defined plan and advance the instrument without excessive bending, resulting in a higher targeting accuracy. However, available systems have been developed for non-stereotactic procedures and their use in combination with optical tracking systems is limited due to a tedious alignment process, non-intuitive usage and operational complexity. Thus, an intuitive 4-DOF aiming device, for specific integration with an optical navigation system, was developed and evaluated. Effective accuracy was assessed during 20 image-guided needle punctures (using an anthropomorphic torso phantom) carried out by three interventional radiologists. Additionally, physicians assessed usability and design properties using a questionnaire. In this work, we report on our findings in terms of the learning curve for maneuvering the device and adequacy of needle stabilization.