Abstract: The present invention relates to an apparatus and a method for influencing and/or detecting magnetic particles in a field of view (28), in particular for magnetic particle imaging (MPI). The proposed apparatus comprises selection means for generating a magnetic selection field (50) and drive means for generating a magnetic drive field for moving a field-free point along a predetermined trajectory through the field of view so that the magnetization of the magnetic material changes locally.

Abstract: The invention relates to an imaging system for imaging a region of interest comprising a moving object, which moves less in small motion phases than in large motion phases. Detection values are provided and a small motion determination unit (15) determines the motion of the object in the region of interest in the small motion phases from the 5 detection values. A large motion determination unit (16) determines the motion of the object in the large motion phases from the determined motion of the object in the small motion phases. A reconstruction unit (17) reconstructs an image of the region of interest from the detection values, wherein the reconstruction unit (17) is adapted for performing a motion compensation using the determined motions in the small and large motion phases.

Abstract: A scanning method and apparatus useful for correcting artifacts which may appear in a primary short circular CT scan are provided. A secondary helical scan performed on a stationary subject, or a secondary circular scan, may be used to correct for artifacts. The secondary scan may be performed with a smaller radiation dosage than the primary circular CT scan.

Abstract: The present invention relates to an imaging system for imaging a field of interest, in particular to a computed tomography system. The imaging system comprises an irradiation unit (2) which moves relative to a field of interest along a first trajectory (501) and along a second trajectory (503). While the irradiation unit (2) moves along the first trajectory (501), first detection data are acquired and, while the irradiation unit (2) moves along the second trajectory (503), second detection data are acquired. An intermediate image of the field of interest is reconstructed from at least the second detection data, and virtual detection data are determined by forward projection through the intermediate image. Finally, an image of the field of interest is reconstructed from the first detection data and the virtual detection data.

Abstract: A method and system to perform region-of-interest (ROI) reconstruction is provided, even if the original projection data are truncated. The reconstruction is performed on a superset of the ROI, including the ROI as well as other areas which are outside the scan field-of-view of the imaging system but still within the imaging bore.

Abstract: A medical imaging system includes a generally stationary gantry (102) and a rotating gantry (106), rotatably supported by the generally stationary gantry (102), that rotates about a longitudinal axis around an examination region. The medical imaging system further includes a radiation source (112) that emits a radiation beam that traverses the examination region. The radiation source (112) is moveably affixed to the rotating gantry (106) so as to translate in a direction of the longitudinal axis with respect to the rotating gantry (106) while scanning a subject in the examination region. The medical imaging system further includes a detector array (120) that detects the radiation beam that traverses the examination region and generates a signal indicative thereof. The detector array (120) is moveably affixed to the rotating gantry (106) so as to move in coordination with the radiation source (112) while scanning the subject in the examination region.

Abstract: The invention relates to a computed tomography method in which a periodically moving object is irradiated by a conical beam bundle. An nPi-relative movement is generated between a radiation source, which generates the conical beam bundle, and the object. During the nPi-relative movement, measured values are acquired, which depend on the intensity in the beam bundle on the other side of the object and from these measured values filter values are determined, which are divided into different groups. The filter values of at least one group are weighted in dependence on the movement of the object, wherein, when filter values of several groups are weighted, filter values of different groups are weighted differently in dependence on the movement of the object. Finally, a CT image of the object is reconstructed from the filter values.

Abstract: If, in cardiac CT, the time window becomes shorter than the time required for a complete rotation of the gantry, the volume that can be reconstructed becomes small due to the non-existence of related pi-lines. According to an exemplary embodiment of the present invention, an examination apparatus is provided which generates a radiation beam oscillating in z-direction with an oscillation frequency higher than the rotational frequency of the source. This may provide for an exact image reconstruction of large volumes.

Abstract: 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).

Abstract: The present invention relates to an imaging apparatus for determining an image of a region of interest, wherein a motion generation unit (1, 7, 8) moves the radiation source (2) and a region of interest relative to each other along a first trajectory (32), while a detection unit (6) detects first detection data. A reconstruction data determination unit (12) determines reconstruction data among the first detection data and a second trajectory determination unit (13) determines a second trajectory (32) depending on the reconstruction data. After that the motion generation unit (1, 7, 8) moves the radiation source (2) and the region of interest relative to each other along the second trajectory (32), while the detection unit (6) detects second detection data. The reconstruction data and the second detection data are used by a reconstruction unit (14) for reconstructing an image of the region of interest.

Abstract: A computed tomography apparatus (10) acquires projection data along a trajectory which includes first (50) and second (50?) tilted circles. A reconstructor (22), includes a differentiator (24), a filter (26), and a backprojector (27). The filter (26) applies a filter function which varies according to a location (x) which is to be reconstructed. The parameters of the filter function are selected so that the reconstructor (22) performs an exact filtered backprojection.

Abstract: 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 (??m, ?>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.

Abstract: Motion is one of the most critical sources of artifacts in helical conebeam CT. By comparing opposite rays corresponding to projection data, the amount of motion may be estimated and, in the following suppression of corresponding motion artifacts may be performed according to an exemplary embodiment of the present invention. The method of motion artifact compensation may be implemented in both approximate reconstruction algorithms and exact reconstruction algorithms. Advantageously, motion during the data acquisition is detected automatically and related motion artifacts may be suppressed adaptively.

Abstract: A scanning method and apparatus useful for correcting artifacts which may appear in a primary short circular CT scan are provided. A secondary helical scan performed on a stationary subject, or a secondary circular scan, may be used to correct for artifacts. The secondary scan may be performed with a smaller radiation dosage than the primary circular CT scan.

Abstract: The invention relates to an imaging system for imaging a region of interest comprising a moving object, which moves less in small motion phases than in large motion phases. Detection values are provided and a small motion determination unit (15) determines the motion of the object in the region of interest in the small motion phases from the 5 detection values. A large motion determination unit (16) determines the motion of the object in the large motion phases from the determined motion of the object in the small motion phases. A reconstruction unit (17) reconstructs an image of the region of interest from the detection values, wherein the reconstruction unit (17) is adapted for performing a motion compensation using the determined motions in the small and large motion phases.

Abstract: A computer tomography apparatus (100) for examination of an object of interest (107), the computer tomography apparatus (100) comprising a first electromagnetic radiation source (104) adapted to emit electromagnetic radiation to an object of interest (107), a second electromagnetic radiation source (203) adapted to emit electromagnetic radiation to the object of interest (107), at least one detecting device (108) adapted to detect electromagnetic radiation generated by the first electromagnetic radiation source (104) and by the second electromagnetic radiation source (203) and scattered on the object of interest (107), and a determination unit (118) adapted to determine structural information concerning the object of interest (107) based on an analysis of detecting signals received from the at least one detecting device (108).

Abstract: 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 (??m, ??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.

Abstract: 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).

Abstract: It is described an X-ray tube (205), in particular for use in computed tomography, comprising an electron source (250), for generating an electron beam (255), an electron deflection device (256) for deflecting the generated electron beam (255), a control unit (257) being coupled to the electron deflection device (256) for spatially controlling the deflection, and an anode (206), which is arranged such that the electron beam (255) impinges onto a focal spot of a surface of the anode (206). Thereby the anode (206) is movable along a z-axis in an oscillating manner, the surface of the anode (206) is oriented oblique with respect to the z-axis, and the control unit (257) is adapted to spatially control the focal spot (255 a) in such a manner that the focal spot moves essentially in a discrete manner between a first focal spot position (106a, 406a) having a first z-coordinate and a second focal spot position (106b, 406b) having a second z-coordinate being different from the first z-coordinate.

Abstract: Known reconstruction techniques from coherent scattered x-rays apply non-exact reconstruction techniques. According to the present invention, a relatively wide spectrum of wave-vector transfers q of the scattered x-ray photons is acquired. The projection data is interpreted as line integrals in the x y-q space and the projection data is resorted to correspond to an acquisition along any source trajectory. Due to this, an exact helical reconstruction algorithms may be applied and redundant data may be used to obtain a better image quality.