2D-3D Registration of CT Vertebra Volume to Fluoroscopy Projection: A Calibration Model Assessment
1 Department of Biomedical, Electronic and Telecommunication Engineering, University of Naples Federico II, 80125 Napoli, Italy
2 Institute of Sound and Vibration Research, University of Southampton, Southampton S017 1BJ, UK
EURASIP Journal on Advances in Signal Processing 2010, 2010:806094 doi:10.1155/2010/806094Published: 30 June 2009
This study extends a previous research concerning intervertebral motion registration by means of 2D dynamic fluoroscopy to obtain a more comprehensive 3D description of vertebral kinematics. The problem of estimating the 3D rigid pose of a CT volume of a vertebra from its 2D X-ray fluoroscopy projection is addressed. 2D-3D registration is obtained maximising a measure of similarity between Digitally Reconstructed Radiographs (obtained from the CT volume) and real fluoroscopic projection. X-ray energy correction was performed. To assess the method a calibration model was realised a sheep dry vertebra was rigidly fixed to a frame of reference including metallic markers. Accurate measurement of 3D orientation was obtained via single-camera calibration of the markers and held as true 3D vertebra position; then, vertebra 3D pose was estimated and results compared. Error analysis revealed accuracy of the order of 0.1 degree for the rotation angles of about 1 mm for displacements parallel to the fluoroscopic plane, and of order of 10 mm for the orthogonal displacement.