Navigation for PDT in the paranasal sinuses using virtual views

Successful surgical or radiation treatment of cancer in the paranasal sinuses in which the tumor will not recur is a challenge. Photo Dynamic Therapy (PDT) can extend the margins after surgery. Without a 3D view of the surgical scene, the task of navigation is difficult inside this area with many critical structures. The proposed system improves navigation ability of the surgeon during PDT through generating an intuitive view of the 3D representation of the surgical scene, combined with extra information. The system consists of protocols and subsystems. First a calibration protocol is defined. The next part consist of registration of the CT coordinates to the sensor coordinate system of an EM sensor attached to a phantom. The calibration and registration together provide all information that is necessary to transform the position of a sensor on the endoscope into the position of the endoscopic camera in CT coordinates. A real-time 2D visualization is made, consisting of 3D model of the head and the critical structures, seen from a virtual camera. A 3D view is created by positioning two virtual cameras near to each other and creating different images for each eye. These images are shown on an auto stereoscopic 3D screen.