摘要:
An x-ray CT system and a method are disclosed for creating tomographic recordings with the aid of an x-ray CT system, with two emitter/detector arrangements operating with an angular offset on a gantry with at least two different x-ray energy spectra. In at least one embodiment, at least one first recording is reconstructed from detector data from two quarter rotations with different x-ray energy spectra and at least one second recording is created from detector data of a scan of at least one of the emitter/detector arrangements over a half rotation. According to at least one embodiment of the invention, the recordings are subjected to high-pass filtering or low-pass filtering in respect of their spatial frequencies and then the filtered recordings are combined to give a resulting recording.
摘要:
A method, a computational unit and a CT system are disclosed for improving the quality of CT image series. In at least one embodiment, the method includes scanning an examination object over a period of time which permits the acquisition of at least two temporally offset projection data records of an identical recording region; generating at least two temporally offset tomographic image data records, each having a multiplicity of pixels, by reconstructing the projection data records; transforming the image data records into transformation data records of at least two spatial frequency ranges; calculating temporal fitted values of the transformation data records for some of the spatial frequency ranges, and replacing the values of the transformation data records which were fitted by the calculated fitted values; performing an inverse transform of the transformation data records with the fitted values to form new image data records; and displaying the new image data records.
摘要:
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.
摘要:
A method is disclosed for producing tomographic images relating to different movement phases of a periodically moving object with the use of a tomography unit that includes a recording system that is arranged rotatably about a z-axis of the tomography unit, the recording system including an X-ray tube to which a tube current can be applied and a detector (17, 18) for acquiring projections. In at least one embodiment, the recording system is initially positioned relative to the object at a first z-position, and projections are acquired from a multiplicity of different projection dimensions at this z-position, in a fashion triggered by a movement signal representing the movement of the object, projections relating to a first movement phase of the object being acquired in a prospectively defined first time window and projections relating to at least a second movement phase of the object being acquired in a prospectively defined second time window. In at least one embodiment, a modulation of the tube current is performed in such a way that different tube current values are set in the first and the second time window to attain a prescribable different signal-to-noise ratio in the produced images. The recording system is then positioned sequentially at further z-positions, and respectively corresponding projections are acquired there for the two movement phases until a prescribed examination area is scanned at the desired z-positions. Tomographic images are reconstructed in real time or subsequently on the basis of the obtained projections.
摘要:
A method, a computational unit and a CT system are disclosed for improving the quality of CT image series. In at least one embodiment, the method includes scanning an examination object over a period of time which permits the acquisition of at least two temporally offset projection data records of an identical recording region; generating at least two temporally offset tomographic image data records, each having a multiplicity of pixels, by reconstructing the projection data records; transforming the image data records into transformation data records of at least two spatial frequency ranges; calculating temporal fitted values of the transformation data records for some of the spatial frequency ranges, and replacing the values of the transformation data records which were fitted by the calculated fitted values; performing an inverse transform of the transformation data records with the fitted values to form new image data records; and displaying the new image data records.
摘要:
At least one embodiment of the present invention relates to a CT scanner and/or a method for helical scanning of an examination object which has at least one portion undergoing periodic motion. In at least one embodiment, the CT scanner includes at least one bearing apparatus, arranged along a system axis of the CT scanner, for bearing the examination object, two scanning systems which can rotate around the system axis and which are arranged coaxially, respectively having a focus from which a beam can be emitted and a flat-design detector array, arranged opposite the respective focus, including a multiplicity of distributed detector elements which can detect the rays of the beam, wherein projection data can be generated by the scanning systems which represents the attenuation of the rays while traversing the examination object, and wherein the bearing apparatus and/or the scanning systems can be displaced along the system axis, a first device/module, preferably an EKG, which can detect and store rest and movement phases of the examination object which has at least one portion undergoing periodic motion in the form of measurement data, and a second device/module which can, based on the measurement data and/or data derived therefrom, trigger and/or control a displacement of the scanning systems and/or the bearing apparatus along the system axis.
摘要:
A method and a CT system are disclosed for determining movement and rest phases of a partial object that moves at times in an examination object during a CT examination. In at least one embodiment, at least two different radiation sources are used for the comparative measurement, and a first radiation source emits a first fan beam at a specific rotation angle at a first instant, the absorption of said beam being measured in beamwise fashion, a second radiation source emits a second fan beam, at the same rotation angle at a second, later instant, the absorption of the beam likewise being measured in beamwise fashion, and the relative movement or relative rest of the partial object between the first and second instants is deduced by comparing deviating absorption values of a multiplicity of spatially equivalent and equidirectional fan beams proceeding from the same angular position of the radiation sources.
摘要:
A method is for taking tomograms of a patient's beating heart with the aid of a computed tomography unit. ECG signals of the beating heart are recorded. In order to reconstruct the cardiac tomograms, use is made of detector data that originate from a selected cycle area of the cardiac cycle. The cycle area from which the data for the reconstruction originate is selected automatically and individually per cycle, for at least one cardiac cycle, by use of pattern recognition.
摘要:
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.
摘要翻译:提出一种方法和CT单元,用于通过多平面重建来产生具有周期性移动子区域,优选地跳动心脏的检查对象的CT图像。 在从针对其余阶段计算的多个部分体积的像素连接轴向图像之后,发生减少以减少在重叠区域中发生的伪影。 这通过在部分体积的边界区域中执行阈值形成来获得,其中结果图像为D z z。 然后发生像素取向的中值滤波,导致图像M SUB。 然后使用F z = z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z Z 随后,将二维低通滤波应用于F z z以产生结果图像G z z。 最后,使用B a>-z z z z z z to to to to to to to to to to to to to to to to to to to to to to to to to to
摘要:
A method is for production of tomographic section images, in particular X-ray CT images, of an at least partially periodically moving examination object with periodically changing movement and rest phases, preferably of a heart of a living being. A number of focus detector combinations are used, with the time resolution of the CT scanner being significantly increased by supplementary combination of detector data in the correct phase. On the one hand, a number of focus detector combinations which scan an examination object at the same time are used; and on the other hand a number of adjacent movement cycles of a periodically moving examination object are performed.