摘要:
The invention relates to a method for correcting truncation artifacts in a reconstruction method for computed tomography recordings. The projection images are recorded by an x-ray image detector being extended by determining the attenuation of the radiation outside the projection image for pixels. Non-horizontal filter lines are extended by transaxial and axial artificial extension of the x-ray image detector for the purposes of truncation correction. The truncation correction for non-horizontal filter lines being carried out according to a method from at least one of the following groups: truncation correction takes place regardless of the specific location and orientation of the filter lines; truncation correction takes place as a function of the specific position and orientation of the filter lines, with the filter lines themselves being retained; and truncation correction takes place by introducing new modified filter lines, with filtering taking place along offset artificially extended filter lines.
摘要:
The invention relates to a method for determining gray-scale values for volume elements of bodies to be mapped using an x-ray image recording system. When a body to be mapped is not mapped in full on a single projection image for a rotational position, a second projection image must be made and a virtual projection image derived from the two projection images, this being back-projected onto the volume elements. For calibration the present invention proposes making the same two projection images in each case at a calibration phantom and additionally a further projection image, corresponding to the position and orientation of the virtual projection image. As a result the mathematical relationships between the projection images and the virtual projection image and for the back-projection can be derived.
摘要:
A computer receives a number of groups of projection images of a reference object already known to the computer. Each projection image was captured via a recording arrangement with corresponding positioning of the recording arrangement. The computer uses one projection image for the respective position of the recording arrangement to determine an interim projection matrix, which describes a mapping of the three-dimensional space to a projection image captured with the respective positioning of the recording arrangement. The interim projection matrices relate to coordinate systems that are specifically assigned to each group. The computer uses interim projection matrices of different groups determined for the same position of the recording arrangement to determine locations of the other coordinate systems related to one of the coordinate systems. The computer uses the interim projection matrices and locations of the other coordinate systems to define a final projection matrix, that relates to a uniform coordinate system, for every position of the recording arrangement.
摘要:
X-ray images are recorded of a patient's heart and the heartbeat phase is registered as that is done. The heartbeat phases are coarsely divided into intervals and all X-ray images that have been assigned heartbeat phase from the interval are used for reconstructing a 3D image dataset. The movement fields of the other 3D image datasets are then calculated for one of said 3D image datasets. Movement fields are vector fields indicating the movements of similar structures from one local area to the other. A departure is then made from the coarse interval division, and for each heartbeat phase a movement field is interpolated individually or at least for fairly short intervals from the movement fields determined in advance, which field is used for generating a deformed 3D image dataset that has been imaged onto a reference heartbeat phase. The deformed 3D image datasets are then added together.
摘要:
The invention relates to a method for three-dimensional presentation of a moved structure using a tomographic method, in which a plurality of projection images are recorded from different imaging angles between a start angle with a start node point and an end angle with an end node point by an imaging unit during a number of rotation passes, with three-dimensional image data being able to be reconstructed from the projection images, with the projection images being spaced by a path or an edge. For determining the three-dimensional presentation for each angle of projection only those projection images are selected which minimize the sum of the paths or weighted edges between adjacent projection angles for a gating.
摘要:
The invention relates to the use of 2D projection images which belong to a specific common heart phase. A 3D image data set can be used to generate a reference projection image for the same projection angle for each of the 2D projection images and a differential image can be derived from the reference projection image and 2D projection image. The differential images are back-projected and combined in one 3D differential image data set and, by using this, a deformed 3D image data set is obtained from the previously recorded 3D image data set. Iterations guarantee that the deformed 3D image data set ensues with the smallest possible distance from the 2D projection images for the existing common heart phase. Finally, a 3D image data set is available for a different heart phase other than the reference heart phase and the possibilities for imaging a patient's heart are extended.
摘要:
The invention relates to a method for recording x-ray images with a C-arm system, which comprises an image recording system rotatable about a center of rotation in a recording plane, a number of x-ray fluoroscopic images of an area of interest of an object lying on an object supporting device are recorded at a plurality of angles of rotations by the image recording system, from which one or more cross-sectional images or a three dimensional can be reconstructed. The method is characterized in that the object supporting device is guided synchronously and in a non-colliding manner with the rotation of the image recording system, such that at every angle of rotation at which the recording of an image takes place, the area of interest of the object lies within a beam cone of the x-ray radiation beam of the image recording system.
摘要:
The invention relates to a device for making visible a pathological change in a part of a patient's body labeled with a fluorescent dye, the device having: a first selectable light source (11, 17), which emits light in the excitation wavelength range of the fluorescent dye, in order to trigger the emission of light in the emission wavelength range of the fluorescent dye, a second selectable light source, which emits visible light outside the emission wavelength of the fluorescent dye, and a means for selectively switching the first and the second light source on and off.
摘要:
In a method for dynamic computed tomography wherein, a contrast agent is injected into a patient, and a region of interest of the patient where the contrast agent is flowing is then scanned with a computed tomography machine, the computed tomography machine has a ray source and a ray detector. At least the ray source rotates relative to the region of interest of the patient. At a first rotational position of the ray source for a first rotation at a first time point a first image is obtained, and at said first rotational position for at least another rotation at a second time point a second image is obtained, the first and second images being different from one another in view of the flowing contrast agent. At least another rotational position of the ray source for the first rotation at a third time point a third image is obtained, and at the another rotational position for the another rotation at a fourth time point a fourth image is obtained, the third and fourth images being different from one another in view of the flowing contrast agent. A first time interpolation is performed for at least the first and second images at an intermediate time point between the first and second time points, and at least a second time interpolation is performed for the third and fourth images at an intermediate time point between the third and fourth time points. Using at least the first and second time interpolations, a reconstructed image is created.
摘要:
The invention relates to a method for three-dimensional image reconstruction of a dynamically moved object from projection data of an imaging device comprising: a) determining a reference volume from the projection data which simulates a similar static object instead of the dynamically moved object; b) assigning the projection data to at least two disjoint consistent subsets, with a volume part reconstruction of the dynamically moved object being undertaken for each subset from projection data assigned to the subsets; c) applying a transformation to the respective volume part reconstructions representing a dynamic movement of the object; d) comparing the volumes of the transformed part reconstructions with a corresponding part of the reference volume, whereby, depending on the comparison, result step c) may be at least partly repeated; and e) summing the volume part reconstructions resulting from step c) and d) to form an overall three-dimensional image reconstruction.