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: A description is given of a method and a device for the calibration of an image pick-up device which is sensitive to gravity. 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. During imaging the direction of the force of gravity relative to the supporting construction is measured; therefrom the position data is calculated and the calibration data associated with this data in the table is read out and used for the correction of the acquired image.

Abstract: The invention relates to a method enabling the localization of objects, for example surgical instruments, in interventional radiology. The method utilizes the known geometrical shape of the object to be localized in order to simulate projections therefrom for comparison with real projection images. Optimum correspondence between simulation and real image yields the desired object position and object orientation. The invention is based on digital image processing and can be used in conjunction with customary radiological diagnostic apparatus such as C-arm fluoroscopy apparatus, computed tomography apparatus or magnetic resonance tomography apparatus. Objects to be localized can be provided with markers whose spatial position yields an unambiguous projection image.

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: 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: 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: An imaging modality, in particular a mobile CT system, comprises an imaging system for imaging an object to be examined. The imaging modality is also provided with an image guided surgery system which includes a position measuring system for measuring positions within the object and a data processor for deriving a transformation between positions within the object and the corresponding positions in the image. The position measuring device is also arranged to measure the position of the imaging system and the data processor is arranged to derive the transformation from the position and/or orientation of the imaging system. The position measuring system is notably an optical position measuring system which is arranged to measure the position of the gantry of the CT system. The data processor is arranged to derive the transformation from the measured position of the gantry.

Abstract: The invention relates to a method enabling the localization of objects, for example surgical instruments, in interventional radiology. The method utilizes the known geometrical shape of the object to be localized in order to simulate projections therefrom for comparison with real projection images. Optimum correspondence between simulation and real image yields the desired object position and object orientation. The invention is based on digital image processing and can be used in conjunction with customary radiological diagnostic apparatus such as C-arm fluoroscopy apparatus, computed tomography apparatus or magnetic resonance tomography apparatus. Objects to be localized can be provided with markers whose spatial position yields an unambiguous projection image.

Abstract: The invention relates to a method of and a device for determining the position of a medical instrument (13), partly introduced into an object to be examined, in a three-dimensional image data set (CT) of the object to be examined. In order to achieve an as high as possible accuracy of the position determination on the one hand and to minimize the expenditure required on the other hand, notably to save intricate registration steps prior to an intervention, the invention proposes to acquire, simultaneously with the acquisition of X-ray image (Ir), their spatial positions and the spatial position of a medical instrument (6) used, followed by determination of the spatial correlation between an X-ray image (Ir) and a three-dimensional image data set (CT), said correlation being used to transform the spatial position of the medical instrument (16) into a position relative to the three-dimensional image data set (CT).

Abstract: In medical imaging in which a plurality of images of an object under examination are formed, image distortions are corrected using a phantom body which is present in the examination zone of the imaging device when the images of the object are acquired. It is known that image distortions in computer tomography apparatus are caused, for example, by calibration errors, by deviations from the adjusted table displacement speed, or by bending of the table under the weight of the patient. These image distortions are detected in the image of the phantom body in an acquired image and a correction rule is derived for the correction of image distortions in the entire acquired image. The phantom body is in the form of a frame of three elements of X or N shape, two of which extend parallel to one another and perpendicular to the third.