Abstract: A method is disclosed for selecting a radiation form, to change spatial distribution of the intensity and/or the spectrum of x-ray radiation of an x-ray source of an imaging system including a plurality of radiation form filters. The method includes acquiring a plurality of radiation absorption profiles of an examination object, of which image data is to be generated with the aid of the imaging system, in parallel with the patient axis from various directions; calculating an effective radiation absorption profile by averaging the recorded radiation absorption profiles; and selecting the radiation form filter on the basis of the effective radiation absorption profile of the examination object from a plurality of radiation form filters. An x-ray imaging system is further disclosed.

Abstract: A method is disclosed for the reconstruction of image data of an examination object from measurement data. First and second image data are reconstructed from the measurement data with a first and second respective image characteristic, with an enhanced signal-to-noise ratio of the second image characteristic relative to the first image characteristic. Enhanced image data is calculated using an iterative algorithm using the first and the second image data. In the case of the iterative algorithm, a low pass is applied to a difference between the first image data and the image data of an iteration cycle, and a high pass to a difference between the second image data and the image data of the iteration cycle.

Abstract: A method and an X-ray system are disclosed for generating a phase contrast image of an examination object. In an embodiment, the distribution of an electron density in the examination object is determined by defining energy-dependent attenuation values for X-radiation with at least two different X-ray energy spectra, phase-shift values are obtained from the previously determined electron density distribution, and a phase contrast image is generated from the calculated phase-shift values.

Abstract: A method is disclosed for reducing step artifacts in the forward increment direction of a cardio CT representation. In at least one embodiment, volume recordings or section images of first and second sub-volumes of a heart volume, which lie adjacent to one another in the forward increment direction and partially overlap in an overlap region, are recorded by a computer tomography system. Each sub-volume's detector data is used for the reconstruction coming from different heart cycles. Finally, a displacement vector relative to a second sub-volume is determined at least for a selected point of the overlap region of a first sub-volume and the second sub-volume is subjected at least partially to a spatial transformation according to the at least one displacement vector.

Abstract: A method is disclosed for reducing metal artifacts in CT image datasets. An embodiment of the method includes reconstructing a first CT image dataset with and a second CT image dataset without metal artifact correction, weighted summation of a high-pass-filtered first and a high-pass-filtered second CT image dataset plus a low-pass-filtered second CT image dataset, wherein the weightings are dependent on the proximity to metal in the CT image datasets. A computing unit, a CT system and a C-arm system designed to execute the method are also disclosed.

Abstract: A method is disclosed for reconstructing image data of an examination object from measurement data, wherein the measurement data were captured previously during a relative rotational movement between a radiation source of a computed tomography system and the examination object. Filtered measurement data are calculated from the measurement data. First image data are calculated from the measurement data. Edge information is obtained from the first image data, wherein the edge information, depending on position, specifies strength and direction of edges within the first image data. New measurement data are calculated using the edge information by mixing the measurement data and the filtered measurement data and second image data are calculated from the new measurement data.

Abstract: The method includes a weighted highpass filtering of the image data takes place here, with the weighting taking account, image element by image element, of an image noise on the respective image element in different directions such that increasing noise results in a stronger highpass effect. A noise-reducing smoothing of the image data takes place using the weighted highpass filtering.

Abstract: A method is disclosed for reconstructing image data of an examination object from measured data, wherein the measured data was captured previously during a relative rotary motion between a radiation source of a computed tomography system and the examination object. In at least one embodiment, the measured data is modified to achieve a particular grayscale characteristic of the image data to be reconstructed. The image data is calculated by way of an iterative algorithm using the modified measured data, wherein no arithmetic step for reducing noise is employed in the iterations.

Abstract: In a method and x-ray device to determine the value of an x-ray tube voltage to generate at least one image of defined tissue to be examined, at least one provided parameter is used that establishes or describes the desired image quality; based on the dependency of the contrast of the defined tissue to be examined on the spectrum of the x-ray radiation or on the value of the tube voltage of the x-ray tube. The tube voltage is determined also based on a contrast-to-noise ratio that is constantly maintained under consideration of the aforementioned parameter such that the dose of x-ray radiation applied to the patient is optimally low upon setting the value of the tube voltage at the x-ray tube and the acquisition of at least one x-ray projection of the defined tissue.

Abstract: The value of a tube voltage of an x-ray tube, used to acquire x-ray projections of a patient in order to generate at least one image in each phase of a multiphase examination, is determined from a contrast-to-noise ratio that establishes the desired image quality of the image in each phase, and the tube current for each tube voltage for each phase is determined given a constantly maintained contrast-to-noise ratio for different tube voltages. For each phase, a value for the dose of x-ray radiation is defined for each different tube voltage and the associated determined tube current. From among the different tube voltages, a tube voltage is set that causes the total dose of x-ray radiation applied to the patient to be as low as possible for all phases of the examination.

Abstract: A method is disclosed for increasing the quality of computer tomographic recording series, to a computation unit and to an X-ray CT system. An embodiment of the method includes scanning a subject over a period of time which makes it possible to record at least two temporally offset projection data sets of the same recording region; transforming the projection data sets into transformation data sets for at least two spatial frequency ranges; calculating temporal compensation values of the transformation data sets for some of the spatial frequency ranges and replacing the compensated values of the transformation data sets with the calculated compensation values in new transformation data sets, projection data of congruent rays always being compared; transforming the new transformation data sets back into new projection data sets; reconstructing image data sets on the basis of the new projection data sets and representing the image data sets.

Abstract: A method is disclosed for processing an output image of an examination object, with the output image having been reconstructed from measuring data acquired during a relative rotational movement between a radiation source of a computed tomography system and the examination object. An image frequency division of an output image takes place in at least a first and a second image. In at least one embodiment, the first image is changed by way of a first function, with the first function effecting a contrast intensification within the first image, and the changed first image and the second image are merged together.

Abstract: Method for the noise reduction of CT image data and an image processing system are disclosed, with a scanning of an examination object and generation of at least two CT image data records each taking place on the basis of a different x-ray energy spectrum. In at least one embodiment, a break-down of the data image records into at least two broken-down image data records takes place in each instance, with a lowest local frequency band (f(1)) with the index k=1 and at least one high local frequency band (f(k)) with the index k=2 to N.

Abstract: A method is disclosed for the reduction of image artifacts, in particular metal artifacts, during the generation of computed tomography image data of an object. In at least one embodiment of the method, two CT image data sets are generated with different medium x-ray energies. By way of a weighted combination of the two CT image data sets, a new image data set is calculated. The weighting factor employed in the weighted combination is here selected in such a way that the image artifacts in the new CT image data set are significantly reduced compared with the image artifacts in the two original CT image data sets. In this way it is possible in a simple manner significantly to reduce in particular metal artifacts in CT images.

Abstract: A method and an X-ray system are disclosed for reduction of the radiation dose used within the framework of an imaging X-ray examination. In at least one embodiment, for each pixel of a recorded image, structure information of a structure which may be present at a distance around the examined pixel is determined and a direction-dependent lowpass filter is applied to the pixel examined in each case, which filter's spatial coverage is less than the distance and which takes into account the morphological information of a structure which may be present with a direction-dependent weighting of the lowpass filter.

Abstract: A method is disclosed for reconstruction of image data of an examination object from measured data, wherein the measured data was captured during a relative rotational motion between a radiation source of a computed tomography system and the examination object. Image data of the examination object is determined from the measured data. In at least one embodiment, new image data is obtained by noise-reducing processing of the image data, in which weighted high-pass filtering of the image data is performed, the weighting taking account of differences between pixel values of different pixels such that increasing differences result in a weaker high-pass effect. A noise-reducing smoothing of the image data is performed using the weighted high-pass filtering.

Abstract: A method is disclosed for reconstruction of image data of an object under examination from measurement data, with the measurement data having been captured during a relative rotational movement between a radiation source of a computed tomography system and the object under examination. In at least one embodiment, first image data is computed by the measurement data being modified to obtain a specific gray value characteristic of the first image data to be reconstructed and the first image data is computed by way of an iterative algorithm using the modified measurement data. Second image data is also computed by a series of chronologically-consecutive images being reconstructed and processing being carried out on the series of images to reduce temporal noise. Finally a combination of the first and the second image data is carried out.

Abstract: A method is disclosed for reconstructing image data of a moving examination object from measurement data, wherein the measurement data was captured in the course of a relative rotational movement between a radiation source of a computed tomography system and the examination object. In at least one embodiment of the method, a first image of the examination object is calculated from a complete measurement data record of the measurement data for an image reconstruction and a second image of the examination object is calculated from an incomplete measurement data record of the measurement data for an image reconstruction. Frequency splitting of the first and second images takes place respectively in at least one low-frequency and one higher-frequency component and the image data of the second image is supplemented in the low-frequency component with image data of the low-frequency component of the first image.

Abstract: A method is disclosed for the reconstruction of picture data of a moving object under examination from measurement, with the measurement data having been recorded beforehand for a relative rotational movement between a radiation source of a computed tomography system and the object under examination. In at least one embodiment, first picture data is computed from a complete measurement dataset of the measurement data for a picture reconstruction, and second picture data is computed from an incomplete measurement dataset for a computed tomography picture reconstruction. The first picture data and the second picture data are combined into third picture data, with the combination being computed using location-dependent movement information of the object under examination.

Abstract: A method is disclosed for the reconstruction of image data of an examination object from measurement data. First and second image data are reconstructed from the measurement data with a first and second respective image characteristic, with an enhanced signal-to-noise ratio of the second image characteristic relative to the first image characteristic. Enhanced image data is calculated using an iterative algorithm using the first and the second image data. In the case of the iterative algorithm, a low pass is applied to a difference between the first image data and the image data of an iteration cycle, and a high pass to a difference between the second image data and the image data of the iteration cycle.