Laser phonomicrosurgery is a demanding surgical technique requiring significant psychomotor skills. Scaleability, operative distance, and the anatomically small nature of the vocal folds all combine to create numerous surgical challenges. Currently the dominant user interface for remotely aiming a CO2 surgical laser is the manual micromanipulator. A micromanipulator is a electro-mechanical device that orientates an optical mirror system to control the aiming of the laser beam to ensure accurate localization on the tissue of interest. This device is capable of accurate laser aiming but is prone to error resulting from inexperience and ergonomic factors. The typical operative setup for laser phonomicrosurgery is depicted in Figure 1.
The mechanical micromanipulator is affixed to the base of the surgical microscope optics and the joystick then extends outward in space beneath the microscope. The surgeon is required to move the end of the joystick to alter the surgical laser aiming position. There is no physical support available to steady the surgeon’s arms or hands. In addition the joystick itself has limited adjustments for user preferences. It is possible to adjust the resistance to motion via a tension adjustment but this is the only user adjustable parameter. Additionally the operative field for the laser is quite small, on the order of 15-21 mm and the operative distance is 400 mm. As a result very small, precise changes in the joystick position are necessary to accurately alter the surgical laser aiming point. These movements are very difficult to make consistently and are a particular challenge to novice clinicians.
CRIM research has produced a medical robotic system for clinicians practicing laser phonomicrosurgery. This novel medical robot overcomes the problems discussed above. The device employs a classic computer gaming joystick as the user interface and adjusts the surgical laser aiming point in accordance with joystick movements, Figure 2. The appliance provides for adjusting movement sensitivity and also incorporates a playback function. A playback function allows the clinician to memorize particular target points and then have the appliance repeatedly and accurately position the laser to these points, Figure 3. Active contours have also been integrated into the system allowing rapid definition of excision perimeters which are then employed to automatically aim the surgical laser. Clinical characterization of the system is carried out at the UNC Chapel Hill School of Medicine.