gms | German Medical Science

Objective: Recent robotic technology allows the integration of conventional manual control and automated systems. We fitted a standard operating microscope with robotic elements enabling fully automated control of all axis of movement while retaining all features of a conventional operating microscope.

Method: A HR1000 Müller-Wedel operating microscope was fitted with motors and control instruments, with the manual control mode and balance preserved. In the robot-supported mode, the microscope was directed by a remote control. External encoders and accelerometers tracked microscope movements. The microscope was additionally fitted with an optical coherence tomography (OCT)-scanning module for surface scanning of tissue samples and larger tissue areas.

Results: The robotized microscope was tested in a model setting and in animal experimentation. Using the remote control the microscope could be positioned without taking the hands from instruments by the surgeon. Positioning error was found to be about 1 mm, and vibration following automated movement of the microscope faded in 1 second. The vector of the movement initiated by the remote was symbolized and indicated in the microscopes occulars. Tracking of microscope movements while keeping the focus by use of the autofocussing function, allowed to track the exact focus position within the 3-dimensional space. This could be used as a second loop of navigation which might be used to assess accuracy of external image-guidance or to calculate the extend of brainshift or ongoing resection. In the robot mode, automated optical coherence tomography scanning of large surface areas was feasible.

Conclusions: The tested prototype of a robotized operating microscope combined the advantages of a conventional manually control and roboted remote-controlled positioning. The technique could further be used to self-navigate the microscope system or to check external image-guidance accuracy. Combined with imaging capabilities such as OCT allowed for automated scanning of large tissue areas. This demonstrates that, in the future, operating microscopes may be used to acquire intraoperative spatial data, volume changes, and structural data of brain or brain tumor tissue.