摘要:
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.
摘要:
A method for generating image data relating to a virtually prescribable X-ray tube voltage U3 from first and second dual energy CT image data is disclosed. In at least one embodiment, the method includes providing the first and second CT image data; prescribing the virtual X-ray tube voltage U3 with U3≠U1 and U3≠U2, on the basis of the first and second CT image data for two prescribable base materials A, B; determining in each case a spatial density distribution ρA(x), ρB(x), assigned to the base materials A, B, in the reconstructed object volume, ρ(x)=ρA(x)+ρB(x) holds true for a density ρ(x) of a voxel x in the reconstructed object volume; providing an effective mass attenuation coefficient U3 for the base material A, and an effective mass attenuation coefficient U3 for the base material B, the effective mass attenuation coefficients U3 and U3 respectively being valid for an X-ray spectrum S(E, U3) assigned to the virtual X-ray tube voltage U3; and determining the image data as a third distribution of linear attenuation coefficients μ3(x) in the reconstructed object volume on the basis of the following relationship: μ3(x)= U3·ρA(x)+ U3·ρB(x).
摘要:
A method for generating image data relating to a virtually prescribable X-ray tube voltage U3 from first and second dual energy CT image data is disclosed. In at least one embodiment, the method includes providing the first and second CT image data; prescribing the virtual X-ray tube voltage U3 with U3≠U1 and U3≠U2, on the basis of the first and second CT image data for two prescribable base materials A, B; determining in each case a spatial density distribution ρA(x), ρB(x), assigned to the base materials A, B, in the reconstructed object volume, ρ(x)=ρA(x)+ρB(x) holds true for a density ρ(x) of a voxel x in the reconstructed object volume; providing an effective mass attenuation coefficient U3 for the base material A, and an effective mass attenuation coefficient U3 for the base material B, the effective mass attenuation coefficients U3 and U3 respectively being valid for an X-ray spectrum S(E, U3) assigned to the virtual X-ray tube voltage U3; and determining the image data as a third distribution of linear attenuation coefficients μ3(x) in the reconstructed object volume on the basis of the following relationship: μ3(x)= U3·ρA(x)+ U3·ρB(x).
摘要:
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. Moreover, an embodiment of a tomography unit for carrying out this method is also disclosed.
摘要:
A method and a computed tomography unit are disclosed, that render it possible in a simple way to remove ring artifacts from tomograms Ik, particularly in the case of a fast feed of the recording region per revolution of the recording system of the computed tomography unit by calculating a ring artifact image Ik for each tomogram Ik. In this procedure, temporary ring artifact images Rtk are firstly calculated for each tomogram Ik, and subsequently the final ring artifact image Rk is formed for the purpose of correcting the respective tomogram Ik by averaging over at least a portion Tsub of the temporary ring artifact images Rtk, the temporary ring artifact images Rtk being rotated before averaging in such a way that the ring artifacts present in the temporary artifact images Rtk substantially coincide and their position substantially corresponds to the ring artifacts present in the tomogram Ik.
摘要翻译:公开了一种方法和计算机断层摄影单元,其可以以简单的方式从断层图像中去除环形伪影,特别是在每一周的记录区域的快速馈送的情况下 通过针对每个断层图像I N k计算环形伪像图像I N k来计算断层摄影单元的记录系统。 在该过程中,首先针对每个断层图像I N k来计算临时环形伪影图像R SUB,并且随后最终的环形伪影图像R≠K 其目的是通过对临时环形伪影图像Rt SUB的至少一部分T N进行平均来校正相应的断层图像I< k> 临时环形伪影图像Rt N在平均之前旋转,使得存在于临时假象图像Rt1k中的环形伪像基本上重合,并且它们的位置基本上对应于 存在于断层图像I SUB>中的环形伪像。
摘要:
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 Δz 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 Δz 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.
摘要:
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.
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 calculating absorber-specific weighting coefficients and a method is disclosed for improving a contrast-to-noise ratio, dependent on an absorber, in an x-ray image of an object to be examined produced by an x-ray machine. A weighted summation of detector output signals from different energy windows of an energy-selector detector are used to improve the contrast-to-noise ratio as a function of the absorber.
摘要:
A method is disclosed for generating computer tomography images using a 3D image reconstruction method. According to the method, to scan an object to be examined using a cone-shaped bundle of rays originating from a focal point and a planar, preferably multi-line detector for detecting the bundle of rays, the focal point is displaced along a spiral trajectory around the object to be examined. The detector delivers output data corresponding to the detected radiation and image voxels from the scanned examined object are reconstructed from the optionally pre-processed output data, the image voxels reflecting the attenuation coefficients of the respective voxel. Each image voxel is reconstructed separately from projection data, which covers a projection angular range of at least 108° and an approximate weighting is carried out for each voxel considered in order to standardise the projection data using the voxel.