摘要:
A computer tomography apparatus (100) for examination of an object of interest (107) comprising an electromagnetic radiation source (104) adapted to emit electromagnetic radiation to an object of interest (107), a detecting device (108) adapted to detect electromagnetic radiation generated by the electromagnetic radiation source (104) and passed through the object of interest (107), and a motion generation device (101, 119) adapted to move the electromagnetic radiation source (104) and the detecting device (108) with respect to the object of interest (107) along a first trajectory and along a second trajectory which differs from the first trajectory, wherein the second trajectory is selected in such a manner that electromagnetic radiation detected during performing the second trajectory provides data which complete mathematically incomplete data detected during performing the first trajectory to thereby allow a reconstruction of structural information concerning the object of interest (107).
摘要:
The invention relates to a method and a system for the reconstruction of an object function (f(x)) based on projections acquired during the motion of a radiation source on a helical trajectory (17). The method is particularly suited for an n-PI+ acquisition which by definition completely comprises an n-PI and additionally some overscan data from the (n+2)-PI window. According to the method, two sets (Σ≦m, Σ>m) of filtered projections are generated from the measuring values and separately back-projected to yield two absorption functions. The first absorption function (flf(x)) is based on contributions of Radon-planes with at most m intersections with the source trajectory (17), while the second absorption function (fhf(x)) is based on Radon-planes with more than m intersections with the source trajectory (17). The two absorption functions are added to yield the final absorption function (f(x)) of an object in the examination zone. In an approximative version of the method, the sets (Σ≦m, Σ>m) of filtered projections are first added and then back-projected.
摘要:
A computer tomography apparatus (100) for examination of an object of interest (107) comprising an electromagnetic radiation source (104) adapted to emit electromagnetic radiation to an object of interest (107), a detecting device (108) adapted to detect electromagnetic radiation generated by the electromagnetic radiation source (104) and passed through the object of interest (107), and a motion generation device (101, 119) adapted to move the electromagnetic radiation source (104) and the detecting device (108) with respect to the object of interest (107) along a first trajectory and along a second trajectory which differs from the first trajectory, wherein the second trajectory is selected in such a manner that electromagnetic radiation detected during performing the second trajectory provides data which complete mathematically incomplete data detected during performing the first trajectory to thereby allow a reconstruction of structural information concerning the object of interest (107).
摘要:
A diagnostic imaging system (8) images a subject at a preselected phase point (46) which occurs in one or more successive pulmonary cycles. A breathing monitor (44) monitors a cyclic physiological parameter in the pulmonary cycle and generates a cyclic pulmonary phase indicative signal. A CT scanner (12) is disposed adjacent an examination region (28) to generate transmission radiation data. A data processor (60) reconstructs an attenuation map (96) from the transmission data by weighting the transmission radiation data such that each of the pulmonary phases contributes substantially equally to the attenuation map.
摘要:
A diagnostic imaging system (8) images a subject at a preselected phase point (46) which occurs in one or more successive pulmonary cycles. A breathing monitor (44) monitors a cyclic physiological parameter in the pulmonary cycle and generates a cyclic pulmonary phase indicative signal. A CT scanner (12) is disposed adjacent an examination region (28) to generate transmission radiation data. A data processor (60) reconstructs an attenuation map (96) from the transmission data by weighting the transmission radiation data such that each of the pulmonary phases contributes substantially equally to the attenuation map.
摘要:
The invention relates to a method and a system for the reconstruction of an object function (f(x)) based on projections acquired during the motion of a radiation source on a helical trajectory (17). The method is particularly suited for an n-PI+ acquisition which by definition completely comprises an n-PI and additionally some overscan data from the (n+2)−PI window. According to the method, two sets (Σ≧m, Σ≧m) of filtered projections are generated from the measuring values and separately back-projected to yield two absorption functions. The first absorption function (flf(x)) is based on contributions of Radon-planes with at most m intersections with the source trajectory (17), while the second absorption function (fhf(x)) is based on Radon-planes with more than m intersections with the source trajectory (17). The two absorption functions are added to yield the final absorption function (f(x)) of an object in the examination zone. In an approximative version of the method, the sets (Σ≧m, Σ≧m) of filtered projections are first added and then back-projected.
摘要:
The invention relates to a method of acquiring MRI image data comprising the following steps: performing a 3-dimensional B1 mapping of a first volume using a first voxel size, selecting an MRI protocol, performing the B1-shim in accordance with the MRI protocol, performing the MRI protocol to acquire MRI imaging data of a second volume using a second voxel size, wherein the first voxel size is larger than the second voxel size, wherein the first volume is larger than the second volume, and wherein the second volume is contained within the first volume.
摘要:
Using only projection data in one temporal gating window around a certain target phase point may lead to motion artifacts such as blurred images. By using projection data corresponding to three temporal gating windows, which are slightly shifted with respect to each other but at least partially overlap, motion within the gating window may be estimated and, according to an exemplary embodiment of the present invention, this estimation may be used for improving the image quality. Advantageously, only the projection data inside the at least partially overlapping gating windows are used for reconstruction and motion compensation.
摘要:
Magnetic resonance examination system comprises displaceable carrier for supporting an object to be examined. The carrier can be moved over a two dimensional area. The magnetic resonance examination system is configured to acquire sets of magnetic resonance signals from the object for various positions of the carrier in the two dimensional area.
摘要:
A computed tomography method and apparatus are provided wherein a radiation source moves circularly relative to an examination zone about an axis of rotation (14). The radiation source produces a cone beam of x-rays and the focal point of this cone beam is switched between at least two positions (23a, 23b) spaced apart from each other and arranged on a line parallel to the axis of rotation to enlarge the reconstructable examination zone parallel to the axis of rotation. Preferably, the image of the examination zone is reconstructed using an iterative reconstruction method, in particular an algebraic reconstruction method or a maximum likelihood method.