Abstract: A gating device to delimit an x-ray beam, has a device housing, first and second absorber elements mounted in the device housing opposite each other, and an adjustment device for moving the absorber elements relative to each other to set a spacing therebetween forming a slit for passage of an x-ray beam therethrough. Each absorber element has an edge shaped to give the slit a slit width that varies in a longitudinal direction of the slit that increases outwardly from a central position toward respectively opposite ends of the slit. Each slit edge has a middle region producing a uniform width of the slit and further regions respectively disposed on opposite sides of the middle region that produce a linearly, longitudinally increasing slit width. The adjustment device produces a parallelogram-like relative movement between the absorber elements.

Abstract: In a method for calculating the temperature T of a solid body or the time t that is needed for a change of the temperature T of the solid body, a solution function to a dimensionless equation corresponding to the differential equation dT/dt=b?aT4?cT, is determined and used to create a matrix A=(aij) with which T or t can be easily calculated.

Abstract: In a method for diaphragm regulation in a computed tomography system and a computed tomography system with diaphragm regulation and a multi-line detector, the image detector signals are utilized for generating a setting signal for the diaphragm.

Abstract: In a method for generating a resultant tomogram from a number of tomograms registered with a computed tomography (CT) apparatus by scanning slices of an examination subject that have different, fixed positions during the scan on a system axis proceeding at a right angle relative to the slices, the attenuation values acquired in the scanning of the individual slices are superimposed to form resulting attenuation values, and the resultant tomogram is reconstructed from the resulting attenuation values.

Abstract: In a method for generating a resultant tomogram from a number of tomograms registered with a computed tomography (CT) apparatus by scanning slices of an examination subject that have different, fixed positions during the scan on a system axis proceeding at a right angle relative to the slices, the attenuation values acquired in the scanning of the individual slices are superimposed to form resulting attenuation values, and the resultant tomogram is reconstructed from the resulting attenuation values.

Abstract: In a method for image reconstruction in a computed tomography apparatus, whereby only the minimally possible projection angle range &agr;g(&bgr;) for the respective fan angle &bgr; is employed for all measured values S(&bgr;, &agr;) of the same fan angle &bgr;.

Abstract: A CT apparatus with alternating focus, in which the detector elements deliver output data when picking up individual projections corresponding to the beam attenuation of the X-rays proceeding to the detector element, the number of data items correspond to twice the number of detector elements participating in the pick-up of each projection. The output data are converted into image reconstruction data, which contain a number of data items per projection which is greater than twice the number of detector elements participating in the pick-up of the respective projection.

Abstract: In an image reconstruction method for a multi-row detector computed tomography apparatus operable in a helical/spiral scan mode, a spiral reconstruction with arbitrary pitch and an improvement of the z resolution with interlaced sampling are achieved by using the known Wang reconstruction algorithm expanded by a new type of interpolation technique wherein direct and complementary projections are employed those beams of either the direct or complementary projection always being selected which exhibit the smallest distance in the z-direction from the relevant voxel to be reconstructed.

Abstract: In a spiral scan computed tomography apparatus, and a method for reconstructing an image from spiral scan data, a measurement system composed of an x-ray source and a radiation receiver is rotated in a plane around an examination subject on a support table, while producing a feed of the support table relative to the rotation plane of the measurement system. Radiation emitted by the x-ray source, attenuated by the patient, strikes the radiation receiver, thereby producing measured signals representing spiral attenuation values. A computer is supplied with the spiral attenuation values and generates weighted spiral attenuation values therefrom using a weighting generator, by which data from a number of planar image superimpositions are employed. The number of superimpositions, the spacing of the superimpositions, and the strength of a k.sup.th superimposition contribution can be independently selected.

Abstract: In a computed tomography apparatus wherein an examination subject is irradiated by an x-ray beam from a number of different angular positions, a measured data set is obtained in a first geometry, and the reconstruction of the tomographic image ensues by interpolation of the measured data in a second geometry. The interpolation results in an unwanted smoothing of the data. In order to compensate for this smoothing, the data in the frequency space are divided by the average Fourier transform of the interpolation function, or alternatively, a discrete convolution of the data in the spatial domain is undertaken.

Abstract: In a computer tomography apparatus which conducts a spiral scan, many images can be calculated quickly from spiral data, because data from the region of only one slice thickness are required. From an initial image I.sub.lr (x) in the plane of a reference projection l.sub.r at a specific location along the system longitudinal axis and from an auxiliary image I.sup.d.sub.lr+1 (x) the computer recursively calculates a new image I.sub.lr+1 (x) at the distance d/N.sub.2.pi. from the initial image I.sub.lr (x) according to the equation:I.sub.lr+1 (x)=I.sub.lr (x)-I.sup.d.sub.lr+1 (x)whereby d is the slice thickness and N.sub.2.pi. is the number of projections on the circumferential angle 2.pi.. The auxiliary image I.sup.d.sub.lr+1 (x) was in turn also recursively acquired from its predecessor I.sup.d.sub.lr (x).

Abstract: A computer tomography apparatus undertakes a three-dimensional scanning of the examination subject with relative motion between the rotating measurement unit and the patient, the relative motion ensuing in the longitudinal direction of the patient support during the acquisition and processing of the detector data, so that a spiral scan is accomplished. For image reconstruction, data corresponding to the scanning of parallel slices are generated from the detector data by spiral interpolation, the interpolation being done with the detector data in the form of the relative intensities registered at the detector.