Abstract: A method and apparatus for quality assurance of an image guided radiation treatment delivery system. A quality assurance (“QA”) marker is positioned at a preset position under guidance of an imaging guidance system of a radiation treatment delivery system. A radiation beam is emitted from a radiation source of the radiation treatment delivery system at the QA marker. An exposure image of the QA marker due to the radiation beam is generated. The exposure image is then analyzed to determine whether the radiation treatment delivery system is aligned.

Abstract: A method and a computed tomography system are disclosed for producing computed tomograms of an object. A set of detector output data that represent beams over a specific angular range and a scan of a specific subregion of the object, are divided into m?2 complete partial detector output data records that respectively cover the same complete angular range, but are reduced with their sampling density by 1/m and have mutually independent data records. Intermediate image data records (m records) that represent the identical object region are reconstructed from the m complete partial detector output data records. A correlation analysis is carried out between the m intermediate image data records. Finally, an image data record is produced that consists only of correlated data and includes no uncorrelated data.

Abstract: The invention relates to an imaging method, in which a projection data record of an examination area to be reconstructed is generated by acquiring projections from different projection directions, in particular with the aid of a computer tomograph. For each projection direction, a filter operator is determined that is optimally adapted to a projection geometry allocated to the respective projection direction. An image of the examination area is reconstructed from the projection data record by filtering the projections with the filter operators determined and by back projection of these filtered projections.

Abstract: Methods, systems and processes for providing efficient image reconstruction using local cone beam tomography which provide a reduced level of artifacts without suppressing the strength of the useful features; and in a dynamic case provide reconstruction of objects that are undergoing a change during the scan. An embodiment provides a method of reconstructing an image from cone beam data provided by at least one detector. The method includes collecting CB projection data of an object, storing the CB projection data in a memory; and reconstructing the image from the local CB projection data. In the reconstructing step, a combination of derivatives of the CB projection data that will result in suppressing the artifacts are found. The combination of derivatives includes collecting cone beam data that represents a collection of integrals that represent the object.

Abstract: A method for reconstructing an image in a tomographic imaging system is described. The method includes improving a spatial resolution of the image by iteratively reconstructing the image.

Abstract: An X-ray CT apparatus is provided which can be suppressed or eliminated of aliasing occurrence in the R-R scheme. The X-ray CT apparatus has a reconstructing device for processing the collected data on each view to thereby obtain projection data and making a backprojection operation on the projection data to thereby reconstruct an image. In the reconstructing device, when the X-ray detector element closest to a rotation center of the detector system determines that an X-ray path for detecting the X-ray irradiated is in a position deviated by a sampling offset (first value) from the rotation center, projection data of the X-ray detector element at least in a vicinity of the rotation center upon the backprojection operation is backprojected to a position deviated by a backprojection offset (second value: different from the first value) from the rotation center.

Abstract: A CT image reconstruction method includes substituting other projection data, which has a predetermined positional relationship to projection data that is found defective during scanning, for the defective data, and interpolating back projection data using a value and information on a scanned position that are contained in the substitute data.

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.

Abstract: Image quality is an important feature for CT scanning, in particular for helical cone-beam CT scanning. By using projection data acquired at two different positions of the focal spot of the radiation beam and rebinning that projection data from a first geometry to a second geometry the two sub-sets of projection data are combined to one rebinned projection data set, thereby improving the radial resolution of the data set. Advantageously, according to an aspect of the present invention, a further rebinning may be performed, from the second geometry back to the first geometry, therefore resulting in a projection data set in the initial geometry with a higher radial resolution.

Abstract: The invention relates to an imaging method, especially a computerized tomography method, with which an object is penetrated by rays from different directions and measured values, which depend upon the intensity of the rays after penetrating the object, are acquired by a detector unit. From these measured values, an object image is reconstructed by means of back projection of measured-value-dependent back projection values. Therein, the object image is divided into overlapping, quasi-spherically symmetric image segments, each being defined by an image value and a quasi-spherically symmetric base function.

Abstract: In an X-ray computerized tomography scanner, a correction phantom embedding an X-ray absorbing object is put on or around a non-vertical rotary axis between an X-ray source and a two-dimensional X-ray detector, and two dimensional imaging data of the phantom is acquired. Then a locus of the X-ray absorbing material is determined in the two-dimensional imaging data, and based on the locus an ideal locus is obtained in the direction of the rotary axis. Next, a difference between the calculated position of the ideal locus and a measured position is determined in the direction of the rotary axis. The difference is used to correct deviation in the direction of the rotary axis.

Abstract: In a diagnostic imaging system (10) two-dimensional projection data is collected in a data memory (30). The data is sorted into the data sets collected during selected cardiac phases. A re-binning processor (38) re-bins the projection data into a parallel ray format. An adaptive filter (70) filters the parallel ray format data with each of a plurality of different filter channels based on a calculated photonic noise of each reading and assuming an arbitrary noise reduction factor, different for each filter channel. A convolver (78) convolves the data filtered with each of the filter channels. A noise reduction factor processor (84) determines the actual noise reduction factor occurring due to the weighted averaging of readings contributing to each voxel ? at an angle ??[0, 7?). A weighting processor (90) weights the convolved data from each of the filter channels based on the channels' noise reduction factors and the actual noise reduction factor.

Abstract: The invention relates to a computed tomography method in which an examination zone is irradiated along a helical trajectory by a conical radiation beam. The radiation transmitted by the examination zone is measured by means of a detector unit and therefrom the absorption distribution in the examination zone is reconstructed without approximations. The reconstruction comprises a derivation of the measuring values of parallel rays of different projections, an integration of these values along K lines, a weighting of these values and a back projection.

Abstract: Two-dimensional or three-dimensional, time-resolved CT frame images are acquired during a dynamic study of a subject. A composite image is produced and this is used to reconstruct each CT frame image by weighting the backprojection of each projection view acquired for that image frame by the corresponding value in the composite image. This weighted backprojection enables artifact-free image frames to be produced with far fewer projection views of the subject. The composite image may be reconstructed from views acquired separately, or it may be produced by combining views acquired during the course of the dynamic study.

Abstract: In the CT imaging of non-homogeneously moving objects such as the heart or the coronary vessel tree, there is a problem that different parts of the objects are at rest at different points in time. Thus, a gated reconstruction with a globally selected time point does not yield a sharp image of such objects. According to the present invention, a motion of the objects is estimated, describing the motion of selected regions of these objects. Then, on the basis of the estimated motion, time points are determined, where these areas have minimal motion. Then, an image is reconstructed, wherein the data from which the respective regions are reconstructed, correspond to the respective time points, where the regions have minimal motion. Due to this, an improved image qualify maybe provided.

Abstract: A method for reconstructing an image of an object utilizing a cone-beam volumetric computed tomographic imaging apparatus includes helically scanning the object with a radiation source utilizing the cone-beam volumetric computed tomographic imaging apparatus, selecting radiation beams emitted by the radiation source passing through a pixel P, a Tam-window, and a Katsevich window, filtering the selected projection data, and reconstructing an image of the object utilizing the filtered selected projection data including projection data within the Katsevich window and outside the Tam-window.

Abstract: Systems and methods for localizing a target for radiotherapy based on digital tomosynthesis are provided. According to one method, DTS verification image data of a target located within or on a patient is generated. The DTS verification image data is compared with DTS reference image data of the target. Radiotherapy positioning information is determined based on the comparison of the DTS verification and reference image data.

Abstract: The invention relates to a computer tomography method, in which a periodically moving object, especially a heart, is irradiated by a beam bundle. In that process, intermediate images of one and the same subregion of the object are reconstructed using measured values from time intervals from different periods. That is, in each case exactly one period can be allocated to each intermediate image. The time intervals in the individual periods are adjusted in such a way that, after a reconstruction of the intermediate images using measured values that lie in the adjusted time intervals, a similarity measure applied to the intermediate images of the same subregion is minimized. This method can be applied to one, several or all subregions of the object that are reconstructable using measured values from time intervals from different periods. Finally, a computer tomography image is reconstructed, wherein exclusively measured values from the adjusted time intervals are used.

Abstract: A reconstruction process for processing pixel data for tomographic volume image data uses a concise reconstruction algorithm based on an assumption that an axis of X-ray emission axis always exists on a plane orthogonal to an axis of revolution of an X-ray tube and an FPD. In time of the reconstruction process, a corrected parameter is applied to the reconstruction algorithm for correcting a mechanical displacement occurring between the axis of revolution of the X-ray tube and FPD and the axis of X-ray emission. Thus, errors due to the mechanical displacement may be avoided by a simple data processing of setting the corrected parameter to the reconstruction algorithm, without impairing lightness of a data processing load on the reconstruction algorithm.

Abstract: A method of producing CT images at a plurality of positions in phase, wherein data are collected by an axial or helical scan using a multi-row detector, and a plurality of CT images at different slice positions are produced from the data collected by one axial or helical scan.