A medical X-ray device 5 arrangement for producing three-dimensional information of an object 4 in a medical X-ray imaging comprises an X-ray source 2 for X-radiating the object from at least two different directions; a detector 6 for detecting the X-radiation to form projection data of the object 4; a computational device 15 for modelling the object 4 mathematically utilizing the projection data to solve the imaging geometry and/or the motion of the object, where the solving concerns either some or all parts of the imaging geometry and/or the motion of the object. The computational device 15 utilizes said projection data and said mathematical modelling of the object in Bayesian inversion based on Bayes' formula p ⁡ ( x , θ ❘ m ) = p pr ⁡ ( θ ) ⁢ p pr ⁡ ( x ) ⁢ p ⁡ ( m ❘ x , θ ) p ⁡ ( m ) to produce three-dimensional information of the object.