Abstract: An X-ray detector is disclosed for detecting individual quanta. In at least one embodiment, the X-ray detector includes a plurality of detector elements and an evaluation unit that is connected to the latter for data purposes and is set up in such a way that each detector element is assigned a first energy threshold, wherein in each case one portion of various radiation spectra that can be picked up by the detector element exhibits an energy below the energy threshold, and a further portion of the respective radiation spectrum exhibits an energy above the energy threshold.

Abstract: A detecting apparatus is disclosed for detecting an object by way of a projection through the object onto a detection plane. In at least one embodiment, the detecting apparatus has a transmitter that is designed to emit quanta. In at least one embodiment the detection apparatus also has a detector, arranged in a detection plane, for detecting the emitted quanta, the detector being designed and arranged to generate at least one detector signal at least partially representing the object in a projection, as a function of the quanta received through the object. In at least one embodiment, the detecting apparatus is designed to generate as a function of the generated detector signal for a detected quantum a quantum signal that represents the quantum energy of one detected quantum. Finally, in at least one embodiment the detecting apparatus is designed to generate a sum signal that corresponds to a sum of the quantum energies of the quantum energies represented by the quantum signals.

Abstract: A computed tomography unit includes at least one X-ray tube, that scans an object in a fashion rotating in a circle or spiral about a z-axis, in combination with an oppositely situated detector having a multiplicity of detector rows. Each detector row includes an aperture ?z in the z-direction, having a multiplicity of detector elements. Between the X-ray tube and detector, a detector diaphragm is arranged that reduces the aperture ?z of the detector rows in the z-direction. The X-ray tube includes a focus, of variable location relative to the X-ray tube and which alternatingly assumes during scanning at least two different positions that have different z-coordinates relative to the X-ray tube R.

Abstract: A radiation detection unit is disclosed for a computer tomograph, and a computer tomograph having a radiation detection unit is also disclosed. In at least one embodiment, the radiation detection unit for a computer tomograph includes at least one scattered radiation sensor, set up and arranged to measure scattered radiation.

Abstract: A method is disclosed for image reconstruction of an object with the aid of at least one-dimensional projections of the object into a three-dimensional volume image data record, it being possible to generate the projections by at least one detector/source system with reference to different positions and angles relative to the object, and at least two projections forming a reconstruction volume in an overlap region as basis for a backprojection of the projections into the three-dimensional volume image data record, in particular computed tomography. An apparatus for carrying out the method is further disclosed. In at least one embodiment, supplemented reconstruction volumes are generated by supplementing reconstruction volumes, covered only partially by projections, by way of virtual projections that are derived from volume image data records.

Abstract: It is proposed to estimate the scattered radiation on the basis of a sinogram, which is measured in any case. In at least one embodiment, a method includes determining the potential scattering site for each measuring beam from the object tangents in the sinogram and calculating the scattered intensity from the primary radiation striking the scattering site and the angle ratios of scattering beam, object tangent and measuring beam. Also proposed, in at least one embodiment, is an X-ray CT having at least bifocal detector systems and a control and computer unit for producing tomographic pictures, the control and arithmetic unit of which contains a program code that, upon being executed, carries out the method.

Abstract: In a method for non-iterative focus adjustment in a CT apparatus the position of the center ray with regard to the movement direction of the focus and the correct phase between the detector sampling frequency and the focus springing frequency are calculated with a minimal number of sinogram acquisitions and is adjusted without iterative steps, corresponding to predetermined values.

Abstract: A method is disclosed for a multislice computer assisted tomograph, capable of carrying out a spiral scan of an object volume with a pitch p selected to be small enough that each slice of the object volume is multiply detected during the spiral scan. The method includes calculating, using measured data of two temporally consecutive at least one of revolutions and half revolutions, an image of the object volume from which a change inside the object volume between the two temporally consecutive at least one of revolutions and half revolutions is directly visible. An embodiment of the method can permit, for example, the detection and visualization of dynamic processes with an enhanced time resolution.

Abstract: In a tomography apparatus and operating method, at least two acquisition systems are respectively each disposed in the azimuthal direction at respective specific system angles around a common rotation axis. Both system angles can be determined for a substantially constant rotation angle speed of the two acquisition systems on the basis of measurement values, which are calculated at a rotation angle position of a reference object that can be introduced into both measurement planes. The tomography apparatus in this manner enables artifact-free reconstruction of a slice or volume image using the system angles determined in this manner.

Abstract: An imaging method is disclosed for a multi-slice spiral CT scan. A CT unit is disclosed for carrying out this method. In the method, the filtering may be formed by use of multiple applications of a ramp filter and a masking operation to a projection image in a different sequence. The CT unit may include, for filtering purposes, multiple applications of a ramp filter and a masking operation to a projection image in a different sequence.

Abstract: A detector for x-ray computer tomography scanners, includes a number of adjacent detector lines extending in an x direction, whereby each detector line is formed from a multitude of adjacent scintillator elements. In order to increase the resolution in the z direction and to simplify the design of the detector, the surface of the scintillator elements are partially covered, which further serves to reduce the size of the aperture in the z direction.

Abstract: In a method for computed tomography and a computed tomography apparatus for scanning a subject with a conical ray beam emanating from a focus that detects a matrix-like detector array, the focus is moved relative to the subject on a spiral path around a system axis, and the detector array supplies output data corresponding to the incident radiation, and images having an inclined image plane are reconstructed from output data respectively supplied during the movement of the focus on a spiral segment, the image planes of these images are inclined by an inclination angle ? around a first axis intersecting the system axis at a right angle and also are inclined by a tilt angle ? with respect to the system axis around a second axis that intersects the first axis as well as the system axis at a right angle.

Abstract: A method is disclosed for reconstructing a tomographic representation of an object from projection data off a moving radiation source through this object onto a detector, filtering and back projection of the projection data being executed in the reconstruction. In an embodiment of the method, by using at least one identical spatial arrangement of the radiation source, the detector and a test object instead of the object to be scanned, there is determined by test projections and an iterative reconstruction technique, a filter that in the given arrangement results in an optimum filtering and back projection of the projection data of the test object for the tomographic representation. Further, the object is scanned instead of the test object in the given arrangement and projection data are determined. Finally, the reconstruction of the tomographic representation is carried out using these projection data and the filter determined.

Abstract: A method is disclosed for generating CT displays in x-ray computed tomography with contrast medium support, the blooming effect being reduced by decomposing an object into three material components when scanning the object with two different energy spectra, and determining a first component and determining the material thickness thereof by segmentation. Subsequently, in at least one embodiment, the two other material components and their material thicknesses are determined on the basis of the measured attenuation values of the two spectra for each beam, and virtual absorption data with virtual absorption coefficients are constructed for the individual material components from the material strengths thus known for the different material components, and are used to reconstruct the CT display.

Abstract: A method for scattered radiation correction of a CT system, including at least two focus/detector systems operated angularly offset from one another, is disclosed. In the method, at at least one phantom, similar to the examined object at least in a subregion, for at least one of the focus/detector systems, the scattered radiation intensity occurring is determined in the detector of a focus/detector system during the operation of the at least one focus of at least one other focus/detector system. Further, the spatial distribution thereof is stored for a number of angles of rotation of the focus/detector systems. During scanning of the object, the scattered radiation intensities, determined with the aid of a similar phantom that originate from the at least one other focus/detector system, are subtracted from the measured intensities of the first focus/detector system while taking account of the spatial orientation of the focus/detector systems and the beam respectively considered.

Abstract: A method and a CT unit are proposed for producing CT images of an examination object having a periodically moving subregion, preferably a beating heart, by multi-planar reconstruction. Subsequent to joining the axial images with pixels from a number of partial volumes calculated for the rest phases, a reduction takes place to reduce artifacts occurring in overlap regions. This is done by carrying out threshold value formation in the zone of the boundary regions of the partial volumes with result image Dz. A pixel-oriented median filtering then occurs, resulting in image Mz. A differential value image is then produced using Fz=Dz?Mz. Subsequently, two-dimensional lowpass filtering is applied to Fz to produce a result image Gz. Finally, a calculation of Bz?Gz is used to form the final image Ez.

Abstract: A method is for determining a parameter in an image area as a measure of a homogeneity of a substance in an object, and to a method for segmenting a substance in an image that uses the parameter as an additional segmentation criterion. In the method, at least two X-ray images are acquired in relation to different energies E1, E2 of an X-radiation, and the parameter is determined from the statistical distribution of attenuation values Di(E1),Di(E2) where i=1, . . . , N in the image area such that faulty classifications can be avoided in a simple way during the segmentation.

Abstract: A method is disclosed for compiling computer tomographic representations using a CT system with at least two angularly offset ray sources. A first ray cone with a relatively larger fan angle and a second ray cone with a relatively smaller fan angle scan an object circularly or spirally. The first ray cone generates a first dataset A and the second ray cone generates a dataset B. The dataset B of the smaller ray cone is supplemented with other data at the edge to give an expanded dataset B+ for reconstruction of the CT representation. The expanded dataset B+ of the second, smaller ray cone and the dataset A of the first, larger ray cone is subjected to a convolution operation to give datasets B+? and A?. Finally, a back projection to reconstruct sectional images or volume data is respectively carried out from the convoluted datasets B+? and A?. The dataset B is supplemented with data of the dataset A and supplementary data are removed from the dataset B+? after the convolution but before the back projection.

Abstract: In a method for non-iterative focus adjustment in a CT apparatus the position of the center ray with regard to the movement direction of the focus and the correct phase between the detector sampling frequency and the focus springing frequency are calculated with a minimal number of sinogram acquisitions and is adjusted without iterative steps, corresponding to predetermined values.

Abstract: The functional dependency of a first X-ray absorption value of density and atomic number is determined in the instance of a first X-ray spectrum, and at least the functional dependency of a second X-ray absorption value of density and atomic number is determined in the instance of a second X-ray spectrum. Based on a recording of a first distribution of X-ray absorption values of the object to be examined in the instance of a first X-ray spectrum, and on a recording of at least one second distribution of X-ray absorption values of the object to be examined in the instance of a second X-ray spectrum, the values for density and atomic number are determined by comparing the functional dependency of a first X-ray absorption value of the first distribution of X-ray absorption values with the functional dependency(ies) of the X-ray absorption values, which are assigned to the first X-ray absorption value, of the second and/or other distributions of X-ray absorption values.