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Overlay of visibility data in a camera image to enable easier setup of computer aided surgery systems

IP.com Disclosure Number: IPCOM000177384D
Publication Date: 2008-Dec-11
Document File: 4 page(s) / 108K

Publishing Venue

The IP.com Prior Art Database

Abstract

The addition of an additional matrix camera to the tracking system in computer aided surgery systems is disclosed. The camera is equipped with an optical system which allows about the same, potentially larger, field of view as the working volume of the tracking camera.

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Field of Invention:

Computer Assisted Surgery (CAS) systems frequently use optical tracking to find the spatial relationship between patient anatomy and various surgical tools. In these systems, a tracking camera consisting of either one, two (stereo) or more matrix cameras or three or more linear CCD cameras are used to reconstruct the position of markers or fiducials in three-dimensional space. Quite commonly, the tracking systems used under these circumstances are based on infrared light. Active infrared tracking systems use infrared light emitting fiducials whose light is then captured by the camera. Passive optical tracking systems use fiducials with some form of retro-reflective coating. The camera is equipped with an infrared light source or flashlight source. The camera is equipped with infrared bandpass filters to avoid disturbance from visible light.

Current problem:

For computer aided surgery, it is important to setup the tracking system in a way such that during the whole surgical procedure, the fiducials of the used surgical tools are visible.

In most cases, the system is not rigidly mounted into the operating room but rather set up individually for each procedure.

Due to the nature of the tracking system cameras, it is not directly possible for the person setting up the system to see what the field of view of the camera and therefore the working volume of the tracking system is. Current computer assisted surgery systems assist in setting up the working volume by displaying either the image of the infrared camera(s) directly or a post-processed image of the infrared cameras where the detected fiducials are highlighted. Other variations display a projection of the already reconstructed three-dimensional scene from various angles.

None of these methods provides a good overview over the working volume since only the fiducials can be seen and the connection to the reality is mainly lost.

Visibility problems and the difficulty of setup is frequently described as one of the major annoyances during the usage of computer assisted surgery systems.

Solution:

The proposed solution is the addition of an additional matrix camera to the tracking system. This camera operates in the visible light spectrum and the image can be easily interpreted by the person setting up the system. The camera is rigidly mounted to the tracking camera(s) and

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pointed in the same direction. The camera is equipped with an optical system which allows about the same, potentially larger, field of view as the working volume of the tracking camera.

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During the setup of the system and in case of visibility and tracking problems, the CAS system displays the image of the additional camera to the person setting up the system. The camera image is overlaid with graphical representations of the detected fiducials and...