Self-calibration of a biplane X-ray imaging system for an optimal three dimensional reconstruction.

The purpose of this paper is to elaborate a three dimensional (3D) reconstruction method, using biplane X-ray angiograms acquired daily by the clinician, without any special calibration procedure during the X-ray examination. The absolute geometry of the X-ray imaging system is determined by an iterative procedure based on the minimization of the mean square distance between observed and analytical projections of a set of reference points identified by the clinician on the simultaneous pair of images. Once the geometry of the imaging system is found the 3D structure of interest is retrieved from classical methods of binocular stereovision. This 3D information is a prerequisite for an accurate evaluation of the degree of severity of a vascular structure or motion anomaly and therefore, for establishing an appropriate diagnosis. The proposed 3D reconstruction method is validated on synthetic and real data and is shown to perform robustly and accurately in the presence of noise. The method should be particularly useful in clinical applications as it needs very little intervention from the clinician.