Abstract: A description is given of a method and a device for the calibration of an image pick-up device which is sensitive to gravity, for example, because it is built into a projecting supporting construction, that is, a device in which the image geometry is influenced and notably image distortions can be induced by mechanical deformation of the supporting construction. Also described are a method and a device for imaging by means of such an image pick-up device; they are used in particular in X-ray systems, for example, systems provided with a C-arm. Calibration is performed essentially by forming and storing a look-up table whereby the calibration data required for the correction of distortions due to the supporting construction is associated with a plurality of position data of the supporting construction.

Abstract: A description is given of a method and a device for the calibration of an image pick-up device which is sensitive to magnetic fields and for the imaging by means of such an image pick-up device. The image pick-up device is notably an image intensifier in X-ray systems such as, for example, systems provided with a C-arm. Calibration is performed essentially by forming and storing a look-up table whereby a plurality of magnetic field data acting on the image pick-up device is associated with calibration data required for correcting the distortions caused thereby. During imaging, the magnetic field data acting on the image pick-up device during the formation of an image is measured and the calibration data associated with this magnetic field data in the table is read out and used for the correction of the acquired image.

Abstract: Method and device for determining the position of a medical instrument, partially introduced into an object being examined, in a three-dimensional image data set of the object. In order to achieve a high accuracy of the position determination and minimize the expenditure required and thus save intricate registration steps prior to an intervention, simultaneously with the acquisition of an X-ray image, the spatial positions of the X-ray image and the spatial position of a medical instrument are acquired. Then, the spatial correlation between an X-ray image and a three-dimensional image data set is determined. This correlation is used to transform the spatial position of the medical instrument into a position relative to the three-dimensional image data set. This enables the formation of images containing image information acquired pre-operatively as well as intra-operatively, and also the reproduction of the instantaneous position of the medical instrument in the images.

Abstract: The invention relates to an X-ray device, notable a device for X-ray fluoroscopy, which includes an X-ray source and an X-ray detector for the continuous formation of X-ray images of a patient (5) from an invariable position of the X-ray source (2) and the X-ray detector (3). The invention includes indicator means for illuminating and/or monitoring essentially the radiation zone over the patient which is traversed by X-rays. This offers the advantage that for the physician it quasi visualizes or monitors the radiation zone which is traversed by X-rays during a treatment with simultaneous formation of X-ray images so that the physician can make sure that he or she, notably his or her hands, is not inadvertently exposed to a continuous X-ray dose.

Abstract: The invention relates to an X-ray examination apparatus for and a method of forming distortion-free X-ray images, which apparatus and method enable the imaging properties of the C-arm X-ray system to be derived from the patient image. To this end, a reference image (FIG. 4) is formed in a reference orientation of the X-ray examination apparatus and the reference imaging properties of the C-arm X-ray system are determined on the basis of the positions of calibration members (7, 8), which are mounted on the image intensifier (2) and/or the X-ray source (3) and are reproduced, and the known geometry and position relative to the image intensifier (2) and/or the X-ray source (3); the positions of the calibration members (7, 8) reproduced in a patient X-ray image (FIG. 5) are compared with the positions of the calibration members (7, 8) in the reference image (FIG.