IMAGING MODALITY FOR IMAGE GUIDED SURGERY

An imaging modality, in particular a mobile CT system, comprises an imaging system for imaging an object to be examined. The imaging modality is also provided with an image guided surgery system which includes a position measuring system for measuring positions within the object and a data processor for deriving a transformation between positions within the object and the corresponding positions in the image. The position measuring device is also arranged to measure the position of the imaging system and the data processor is arranged to derive the transformation from the position and/or orientation of the imaging system. The position measuring system is notably an optical position measuring system which is arranged to measure the position of the gantry of the CT system. The data processor is arranged to derive the transformation from the measured position of the gantry. A highly accurate result is obtained when a calibration is carried out which links the position of the CT gantry to the position of the scanning plane.