Lateral skull base navigation intervention is applied

Patient preparation: The participant is prepared for the surgery according to clinical standards.

System setup: The hardware components of the investigational device are set up

Tripod fixation: The tripod with integrated registration fiducials is fixed on the participant's skull.

CBCT imaging: A CBCT image of the participant is acquired

Image processing: The CBCT data is loaded on the navigation platform. The registration fiducials are automatically detected in the image data and relevant anatomy is segmented using an otologic planning software.

Measurements: The navigation software is started, and the fiducial positions and segmentations loaded. The measurements are conducted.

Treatment: The surgery is conducted by the surgeon according to clinical standards

The primary endpoint is the localization accuracy of predefined artificial target positions on the registration tripod measured in millimetres.

The tracked instrument is positioned on the target positions. The Euclidean distance between the location of the instrument in the image data as indicated by the stereotactic image guidance system and to the true location of the target point in the image data is measured. The true location of the target points in the image data is determined by alignment of the 3D model of the tripod (including the known target positions on the tripod) with the image data.

The main secondary endpoint is the qualitative assessment of the guidance accuracy at anatomical landmarks through user rating.

While the tracked pointer is placed on a landmark, a screenshot of the microscope view is taken. Additionally, the pose of the pointer instrument in the image data indicated by the navigation system is stored. Postoperatively, the alignment of the pointer with the anatomical models compared to the microscope view is rated by multiple surgeons using a questionnaire. A five-level Likert scale (Strongly agree, Agree, Undecided, Disagree, Strongly disagree) is used to measure agreement with statements concerning

• Accuracy: The position indicated in the navigation view is correct at a clinically relevant geometric scale
• Usefulness: The information provided by the navigation view is useful to identify anatomical structures during the surgery
• Usability: The application of the navigation system during the surgical procedure is straightforward.