Abstract: Disclosed is a calibration object for an x-ray system and an optical system, the calibration object comprising: a first part made of a first material having a matte surface, the first material having a first attenuation coefficient of x-rays; a second part made of a second material having a second attenuation coefficient of x-rays different from the attenuation coefficient of the first material; wherein the first part is attached to the second part so that one or more features are detectable by one or more optical cameras.

Abstract: A method for improving the accuracy of a digital medical model of a part of a patient, the method includes obtaining a set of at least 2 medical images of the patient, where an element including a predefined geometry and/or predefined information was attached to the patient during the recording of the medical images; obtaining at least 2 tracking images taken with at least one camera having a known positional relationship relative to the medical imaging device, the tracking images depicting at least part of the element; determining any movement of the element between acquisition of the at least 2 tracking images; and generating the digital medical model from the acquired medical images, wherein the determined movement of the element is used to compensate for any movement of the patient between the acquisition of the medical images.