Abstract: A method for acquiring fusion images of a periodically moving body organ and an apparatus adapted to implement such method is described. In a preferred embodiment of the method, X-rays are irradiated to the body organ and a multiplicity of mask images is acquired by X-ray detection at a high image acquisition rate of at least 60 frames per second. Then, contrast medium is injected into vessels of the body organ and subsequently at least one contrast image of the body organ with the contrast medium included in the vessels is acquired by X-ray detection. A matching image from the multiplicity of mask images is determined which has been acquired at substantially the same stage of the movement of the body organ as the contrast image. By calculating the difference between the matching mask image and the at least one contrast image a subtraction image of the body organ can be obtained and displayed.

Abstract: An image pick-up apparatus including an image sensor with a matrix of radiation-sensitive elements, notably a CCD image sensor, is provided with a control circuit for selecting gate electrodes as collecting gate electrodes or as isolating gate electrodes by application of an electric potential of suitable polarity. Groups of collecting gate electrodes are separated from one another by isolating gate electrodes. The surface area of such a group of collecting gate electrodes co-determines the modulation transfer function and hence the spatial resolution of the image sensor; this surface area, and hence the spatial resolution, can be adjusted by adjustment of the electric potentials. Notably the spatial resolution can be rendered dependent on the different modes of operation of the image pick-up apparatus, for example when the image pick-up apparatus forms part of an X-ray examination apparatus which is suitable for fluoroscopy as well as for making X-ray images.

Abstract: An image pick-up apparatus (1) for picking up a plurality of sub-images and combining them so as to form a composite image, including a correction unit (5) for correcting brightness values of the composite image. The correction unit (5) includes a selection unit (6) for selecting bright and dark parts from the sub-images. There is also provided an arithmetic unit (10) for deriving a gain correction factor from the bright parts and an offset correction term from the dark parts. The correction unit (5) also includes a multiplier unit (8) and an adder unit (9) for multiplying signal levels of a sub-image signal by the gain correction factor and for adding the offset correction term thereto.

Abstract: An X-ray examination apparatus includes an X-ray image intensifier for deriving an optical image from an X-ray image. The optical image is picked up by means of an image pick-up apparatus which includes a correction unit which is arranged to form a dark image signal and to derive test image signals from the optical image. Correction values are derived on the basis of the test image signals and the dark image signal. The correction unit is arranged to form a dark image signal, to derive one or more test image signals from the optical image, and to derive the correction values from said test image signals and the dark image signal. The dark image signal is picked up in the absence of incident light on the image sensor. The test image signals have a signal level which represents brightness values of the optical image which have been amplified by individual gain values.

Abstract: An X-ray device comprising an image pick-up system with at least two image sensors (11 and 12) and a control circuit (41) arranged so that the image sensors are not simultaneously but alternately sensitized in the cine mode. This arrangement enables the number of object images picked up per second to be increased in comparison with a similar system in which the sensors are simultaneously sensitized. When CCD sensors are used, the control circuit can also be arranged so that the integration time of the sensors becomes adjustable. These two steps reduce motion artefacts in images of quickly moving objects, for example images of a moving heart.

Abstract: Compensating for vignetting (loss of brightness at the edge of an image) is achieved by electronically multiplying the pixel-values of the vignetted image by a gain characteristic so as to obtain an unperturbed image. A gain characteristic pertaining to a particular vignetting effect is formed by a set of correction factors for all pixels. These correction factors are obtained from the image of an object having a spatially homogeneous brightness distribution. Various gain characteristics can be stored so that vignetting is compensated for even when the adjustments of the imaging system are varied. When, in order to improve spatial resolution, the image formed on the output screen of an image intensifier in an x-ray examination apparatus is split into two sub-images which are subsequently recombined, the vignetting effects in either of the sub-images are inevitably different due to the use of a beam splitter.

Abstract: An imaging system includes an image pick-up device with an image sensor having a rectangular detection face which is subdivided into discrete detection sub-faces for converting a radiation intensity distribution on the detection face into an electric signal, the detection sub-faces being arranged in a matrix of n rows and p columns respectively dividing short and long sides of the detection face, an object plane and an optical system which images a radiation intensity distribution in a circle situated in the object plane onto an ellipse situated on the detection face in accordance with a compression factor m. The compression factor may be chosen so that the ellipse spans no more than p/2 columns of the detection face so that video images can be formed at twice the conventional rate. In the case of non-square detection sub-faces, the compression rate may be chosen so that the ellipse spans an equal number of rows and columns, thereby making each detection sub-face correspond to a square in the object plane.