The resent invention relates to a method of x-ray projection geometry calibration in x-ray cone beam computed tomography, the method comprising: at least one step (S1) of obtaining two-dimensional x-ray images (1) or a sinogram (2) of at least a part of an object (3), generated through relatively rotating around the object (3) a detector and an x-ray source projecting x-rays towards the detector； characterized by further comprising: at least one step (S4) of detecting in the two dimensional x-ray images (1) or the sinogram (2) at least one feature (3a) of the object (3) by using a trained artificial intelligence algorithm； and at least one step (S5) of creating, based on the detection, calibration information which defines the geometry of the x-ray projection.
