Distortion correction and geometric calibration for X-ray angiography system

Based on the knowledge that distortion is the result of pixel movement, a distortion correction method is developed by analyzing the principle of distortion change with imaging orientation, which can be used to correct the imaging distortion of a conventional X-ray angiography (XRA) system with an image intensifier. Distortion at any arbitrary imaging orientation can be corrected by integrating the movement model of every single pixel. Experiments show that the method is fast with subpixel accuracy. Meanwhile, for achieving the geometric calibration for the XRA imaging system, we propose a novel method with the kernel of a C-arm movement model which represents C-arm movement without any assumption for simplification purposes. Then extended models with high flexibility are obtained by taking into account the influence of C-arm movement on intrinsic parameters, which are applicable even for the situation with varying source-intensifier distance. Experiments demonstrate that the proposed method can be used to calculate the accurate imaging parameters, including intrinsic and extrinsic parameters.