Abstract: An X-ray CT examination installation, having an X-ray tube including a focus, that creates a fan beam or a conical beam which X-rays the whole of a detector at a fixed distance from the focus, and an examination carriage, for supporting an object to be examined, the carriage having an axis of rotation perpendicular to the fan beam, wherein the examination carriage can be fixed inside the fan beam close to an edge axis which meets the detector at the edge, and can be moved on a measuring line that centrally runs at an angle to a central axis which meets the detector. The invention also relates to a CT method of examining objects, in particular of various sizes, by means of an X-ray CT examination installation generally identified above.

Abstract: Stationary x-ray digital breast tomosynthesis systems and related methods are disclosed. According to one aspect, the subject matter described herein can include an x-ray tomosynthesis system having a plurality of stationary field emission x-ray sources configured to irradiate a location for positioning an object to be imaged with x-ray beams to generate projection images of the object. An x-ray detector can be configured to detect the projection images of the object. A projection image reconstruction function can be configured to reconstruct tomography images of the object based on the projection images of the object.

Abstract: A method for associating EKG waveform data with computed tomography image data using a data synchronization scheme including generating the EKG waveform data using an electrocardiogram device, operating a computed tomography imaging system so as to create the computed tomography image data, communicating an exposure marker-in signal to the electrocardiogram device such that the exposure marker-in signal is associated with the EKG waveform data and processing the computed tomography image data, the EKG waveform data and the exposure marker-in signal, so as to correlate the EKG waveform data with the computed tomography image data. Also claimed is a medium encoded with a machine-readable computer program code for associating EKG waveform data with image data generated by an imaging system using a data synchronization scheme, the medium including instructions for causing controller to implement the aforementioned method.

Abstract: The invention relates to a computer tomograph and to a radiation detector for detecting elastically scattered rays. The computer tomograph comprises a radiation source for radiating primary radiation through an object which is present in an examination region. The primary radiation is partly scattered in the object owing to interactions with the object. A detector comprises detector elements by which the scattered rays are detected. These detector elements lie outside the region through which the primary radiation is passed, and their effective dimensions become smaller in the direction in which the scattering angles become smaller.

Abstract: A method of and a system for variable pitch CT scanning for baggage screening and variable pitch image reconstruction are disclosed.

Abstract: A weighting function is created according to an arbitrary bio-movement correction range and a projection data angle for back-projection (width in the view direction used for reconstruction), set by a user, by considering the degree of the bio-movement and redundancy. By using this weighting function, an image reconstruction is performed. The bio-movement correction range is set as a correction angle width index ? expressing the width guaranteed as a slope portion of the weighting function. The projection data angle for back-projection (data width) is determined by considering the data redundancy, SN, time width (time resolution) contributing to the image. By determining the weight according to these two parameters, it is possible to apply reconstruction of projection data of all the scan ranges in the reconstruction of the tomogram and prevent lowering of the data contribution ratio as well as reduce the motion artifact, thereby obtaining a high-quality image.

Abstract: One provides (101) fan-beam data via a translate-rotate computed tomography acquisition process and then reconstructs (102) an image from this data without resampling any pixel positions other than to optionally resample pixel positions to compensate for non-uniform translation intervals. These embodiments also provide for reconstructing this image from this data without interpolating any pixel positions other than to optionally interpolate pixel positions as again may be useful to compensate for non-uniform translation intervals.

Abstract: In a method for non-iterative focus adjustment in a CT apparatus the position of the center ray with regard to the movement direction of the focus and the correct phase between the detector sampling frequency and the focus springing frequency are calculated with a minimal number of sinogram acquisitions and is adjusted without iterative steps, corresponding to predetermined values.

Abstract: A computerized tomography process (100) that provides, optionally, for preliminary scans (101), helically-oriented full scans (102), and/or improved resolution scans (103). In some instances, partial cross-sectional views are captured which views are then later joined to yield a complete view. In some instances a helical image-capture path is used. In yet other instances small lateral shifts to the position of the X-ray source are used to provide higher resolution views of the object being scanned.

Abstract: An imaging system and method for taking an image of an object. The imaging system comprises a mechanism that propels the object linearly in a direction of motion through an imaging region that has a top, bottom, front, and rear; an x-ray source located below the bottom, aligned with the front, and emitting an x-ray cone beam to the imaging region; and a plurality of x-ray detector assemblies, each of the detector assemblies including a linear row of detectors above and parallel to the top and perpendicular to the direction of motion, and a linear column of detectors outside of and parallel to the rear right side and extending at an angle to the direction of motion, wherein each of the detector assemblies defines an x-ray fan beam within the x-ray cone beam. A second system embodiment duplicates the x-ray source/detector assemblage and rotates the second assemblage by 90° around the object.

Abstract: The invention relates to a computed tomography method for forming images of an object to be examined which is arranged in an examination zone. The examination zone is scanned by means of a conical X-ray beam. In order to enable images having a high image quality to be formed from a selected imaging zone while making an as small as possible computational effort, the invention proposes the following steps: a) selecting an imaging zone of the object to be examined, b) determining the sub-regions of the X-ray detector on which the imaging zone of the object to be examined is projected during the acquisition of the projection data, c) forming sub-projection data by selecting the projection data associated with the sub-regions from the acquired projection data, and d) reconstructing the desired image from the sub-projection data by backprojection.

Abstract: Certain embodiments of the present invention provide a method for three-dimensional cine EBA/CTA imaging. The method includes monitoring a cardiac cycle of a patient and selecting a trigger point along the cardiac cycle. When the cardiac cycle of the patient reaches the trigger point, a computed tomography (CT) scan of the patient is initiated. At least two CT scans of the patient are performed during a time period over two or more cardiac cycles. A cine angiography image is constructed from the at least two CT scans.

Abstract: An X-ray computed tomography apparatus includes a first X-ray tube configured to generate X-rays with which a subject to be examined is irradiated, a first X-ray detector configured to detect X-rays transmitted through the subject, a second X-ray tube which generates X-rays with which a treatment target of the subject is irradiated, a rotating mechanism which rotates the first X-ray tube, the first X-ray detector, and the second X-ray tube around the subject, a reconstructing unit configured to reconstruct an image on the basis of data detected by the first X-ray detector, and a support mechanism which supports the second X-ray tube. The central axis of X-rays from the second X-ray tube tilts with respect to a body axis of the subject. This makes it possible to reduce the dose on a portion other than a treatment target.

Abstract: This invention presents a method of image reconstruction based on static and irregular detector positioning using fan-beam back projection technique of computerized tomography.

Abstract: A CT apparatus with alternating focus, in which the detector elements deliver output data when picking up individual projections corresponding to the beam attenuation of the X-rays proceeding to the detector element, the number of data items correspond to twice the number of detector elements participating in the pick-up of each projection. The output data are converted into image reconstruction data, which contain a number of data items per projection which is greater than twice the number of detector elements participating in the pick-up of the respective projection.

Abstract: In an improved computerized tomography scanner, the X-ray source is configured to have a focal spot that is variable in position in a direction parallel to or substantially parallel to the longitudinal or rotation axis of the scanner. Data are sampled from two different focal spot positions displaced in the longitudinal direction as the gantry rotates through successive projection angles, thereby providing two fan beams at different longitudinal positions. The data may be sampled at a detector array having a single or multiple rows. In this manner, at least two slices are scanned contemporaneously, and thus the scan throughput rate is at least doubled. The invention is further applicable to a system utilizing multiple detector rows.

Abstract: In an improved method and apparatus for cone-beam reconstruction, an improved detector array is provided in an asymmetric shape with respect to the translation axis. In a first embodiment, a standard symmetric array is rotated by a tilt angle .alpha. about the beam axis. In a second embodiment, the array is formed to have a substantially helical contour. In this manner, efficient use of detector elements is achieved, system pitch is increased, and image quality is enhanced.

Abstract: A technique to modify the input data to any system so as to cancel errors in the transfer function of that system. The system error response to each possible input amplitude transition is determined. A compensating input sequence is calculated which compensates for this error. The error-correcting sequence is stored in memory for each possible transition. These pattern sequences exactly cancel errors in the response to each of the possible, individual sample-to-sample transitions. For each of any series of input data sample transitions, the appropriate correction sequence is recalled from memory. The composite corrected input is the sum of Y correction sequences from Y preceding sample transitions.

Abstract: An X-ray computed tomography apparatus has a radiation detector composed of X-ray converters so that the scattering of light in a scintillator or the inductive disturbance in a directly converting semiconductor is minimized or eliminated. Each X-ray converter, e.g. a scintillator is in fixed contact with a number of signal converters, e.g. photodiodes. From the output signals of the signal converters, the unsharpness can be calculated and then compensated.

Abstract: A CT apparatus employing a cone beam of x-rays reduces image artifacts by employing full as opposed to half scans of less than 360.degree.. The present invention recognizes that rays of a cone beam that cross the imaging plane are not redundant with opposing rays in the scan, as is the case with the rays within the imaging plane. In a second embodiment, half scans of less than 360.degree. are obtained using in-plane and cross-plane rays of the cone beam and the data from the in-plane rays is used to estimate the missing data from that collected with the cross-plane rays.

Abstract: An x-ray computed tomography system for helically scanning a patient, by translating the patient as projections of the patient at various beam angles are obtained, employs a detector array having multiple rows displaced in along the direction of translation. The voxel attenuation values reconstructed from the multiple rows are combined to produce an image having an improved beam profile in along the translation direction. A cone beam reconstruction method, which accounts for the divergence of the rays of a fan beam of x-rays, and helical scanning is used to further improve the slice profile. The voxels may be selected so that they cluster closely about the position of the desired slice plane.

Abstract: A method and apparatus for acquiring scanning cone beam projection data along a three dimensional scanning trajectory is disclosed. The technique ensures acquisition of a substantially uniform distribution of Radon data that is sufficiently complete for exact image reconstruction of an object irradiated by a scanning cone beam source. By choosing a scanning trajectory whose planar projection onto a plurality of coaxial planes, when taken together, forms a continuous, convex, closed curve about a corresponding projection of the object being scanned; the Radon information obtained therefrom is complete and information coverage is uniform over the region of support of the object. Accordingly, this condition provides a practical, easy to implement, visual method for evaluating candidate three dimensional scanning trajectories.

Abstract: An improved method and apparatus is disclosed for retaining only necessary cone beam projection data acquired along a three dimensional scanning trajectory in order to ensure more computationally efficient processing of Radon data for computerized tomographic image reconstruction consistent with the overall shape of an object irradiated by a cone beam source. If the scanning trajectory is such that an otherwise complete see of Radon data is acquired the image so reconstructed will also be exact. The invention is directed to restricting image reconstruction processing to only that region of support in Radon space actually occupied by the object itself; therefore, computational approximations consistent with the overall shape of the object can be applied to improve image reconstruction efficiency.

Abstract: Apparatus and method for mounting on an existing x-ray simulator and calculating a back projected computed tomographic image. The detector array is linear and outputs signals from the photodiodes mounted therein to a preprocessor for smoothing, correcting and filtering and subsequent processing to transform the signal from that produced by an x-ray originating from a fan beam source, e.g., in a polar coordinate system, into the signal which would have been produced by a detector in an array on which a parallel beam is incident on a Cartesian coordinate system. The transformed data is converted to a gray scale value for a picture element having a specific position in the Cartesian coordinate system and output to an appropriate display. Data is taken at each incremental angle as the beam source and detector array rotate around a target object.

Abstract: A multi-isotope study is carried out using a plurality of imaging agents which are imaged simultaneously. The information obtained is weighted using as many energy weighting functions as there are isotopes. The weighting reduces "crosstalk" between each of the single-isotope images which are produced as a result of the study. This produces improved results in, for example, dual-isotope (Tc-99m and Tl-201) myocardial perfusion studies.

Abstract: A CT apparatus reduces errors in projection data acquired in helical scanning. The imaged object moves concurrently along a translation axis and the x-ray beam is periodically translated with the imaged object so as to subtend a single predetermined volume element during the acquisition of one projection set of data for a first slice. The x-ray beam then returns to its starting position and tracks a second predetermined volume element within a next slice. The x-ray beam may be translated by moving the focal point or a collimator or a combination of both. Helical scans with a pitch requiring sweeping of the x-ray beam beyond the detector limits are accommodated by limiting the sweep to a lessor compliance distance. The angular rate of the sweep is held constant within this compliance distance during the sweep.

Abstract: A method of reducing artifacts in images acquired with fan beam, helical scanning, tomographic imaging systems, applies a weighting function to the tomographic projection set. The weighting function reduces the contribution to the final image of projection data with large helical offset. Other redundant data within the projection set is increased in weight by the weighting function to prevent image artifacts from the weighting. In one embodiment, the projection set is centered on the slice plane to avoid discontinuities in the projection data caused by the weighting functions.

Abstract: A CT apparatus reduces errors in projection data acquired in helical scanning. The imaged object moves concurrently along a translation axis and the x-ray beam is periodically translated with the imaged object so as to subtend a single predetermined volume element during the acquisition of one projection set of data for a first slice. The x-ray beam then returns to its starting position and tracks a second predetermined volume element within a next slice. The x-ray beam may be translated by moving the focal point or a collimator or a combination of both.

Abstract: A computer tomography apparatus has an x-ray source which emits a fan-shaped x-ray beam which irradiates a slice of an examination subject. The x-ray source is rotatable around the examination subject to irradiate the slice from different angular directions in the plane of the slice. A row of detector elements is disposed to receive radiation attenuated by the examination subject as the x-ray source rotates around the patient. The radiation detector is disposed on a ring which is rotatable around the examination subject separately from the x-ray source. This permits to meet the conditions of the sampling theorem, applied to the projections with the focus as projection center, without increasing the number of defectors.

Abstract: An industrial CT apparatus capable of obtaining a good image quality by a simple configuration. The apparatus is the second generating type incorporating the rotational motions as well as the traverse motions, in which the detector is positioned nearby a center of rotation of the object to be examined. When the object to be examined is a ring shaped object, the detector is positioned inside the center bore of the object. Also, the X-ray is emitted in a form of fan shaped beam whose symmetrical axis is deviated from an axial direction perpendicular to the traverse direction.

Abstract: A computer tomograph apparatus of the type having a rotating frame which carriers an x-ray source and a radiation detector includes a mount for the radiation detector which resiliently seats the radiation detector on the rotating frame permitting slight displacement of the radiation detector in a direction tangent to the orbit of the detector around a patient. The resilient mounting of the radiation detector suppresses the transmission of mechanical jolts and other jarring forces from the rotating frame to the detector. Because of the resilient mounting, the weight of the radiation detector will cause a slight dislocation of the detector during a revolution. To compensate for this dislocation the rated position of the focus is determined dependent upon the detector position, so that the position of the focus can be adjusted corresponding to this detector displacement.

Abstract: In computerized tomography apparatus having a radiation source and a detector, when the radiation source and the detector are rotated in a rotational direction, acquisition of computerized tomogram data takes place in accordance with a data acquiring direction. When the radiation source and the detector are rotated in a rotational direction opposite to the rotational direction, acquisition of the computerized tomogram data is also performed from a data acquiring direction opposite to the data acquisition direction, thereby agreeing with the position of imaginary source. The position of imaginary source is near a subject than that of the radiation source, so that a high resolution is obtained.

Abstract: A method and apparatus for computed axial tomography (CAT) image reconstruction applicable to X-ray scanning of the human body. Successive series of calculations determine the values of a characteristic in defined segmented areas of an examination plane. A reduction in the time and equipment requirements for reconstruction calculations may thereby be effected.Images representative of the difference between the value of the characteristic at a reconstruction point and the average value of the characteristic in adjacent regions (.DELTA..mu.) may be calculated and displayed from measurements taken within a localized contiguous region of the examination plane. Radiation dose to patients and computation time in X-ray computerized axial tomography scanning systems is thus reduced. Differential displays of the type described may be adjusted to image boundaries, in which case they do not suffer from gray scale resolution problems which are typical of prior art displays.

Abstract: A CT scanner has an X-ray source for producing a fan beam that is rotatable relative to the axis of the scanner in a plane perpendicular to the axis, and a plurality of X-ray detectors mounted in a non-rotatable helical detector ring whose axis is colinear with the scannner axis for reeiving X-rays from the fan beam, the detectors extending 360.degree. around the axis. The detector ring has an inner surface facing the axis of the helix, and the detectors are mounted on the inner surface so that their photosensitive areas face the axis of the helix. At any given axial position of the detector ring, a given group of detectors will have an unobstructed view of certain of the X-ray sources through the space between adjacent leaves of the helix.

Abstract: Disclosed are x-ray machines using fan-beams of x-rays to examine sectional slices of patients and to form detailed x-ray pictures of such slices, and methods of so examining patient slices. A source of a fan-beam of x-radiation, and a system detecting the radiation after it passes through a slice of the patient, rotate around the patient.

Abstract: A data disc system for a computed tomography X-ray scanner employing a plurality of disc drives for writing data into and reading data from corresponding discs. The disc drives are asynchronously operated in conjunction with a processor which writes data in parallel into the same cylinder of different ones to the discs and subsequently reads data in parallel from different cylinders of different ones of the discs to convert data from source fan format into detector fan format. In the alternative, the processor writes data in parallel to different cylinders of different ones of the discs and reads data in parallel from the same cylinder of different ones of the discs to convert data from source fan format into detector fan format.

Abstract: A process for tomodensitometric image display in the dynamic mode, and a tomodensitometer utilizing the process in medical radiology. The invention relates to a process and to a tomodensitometer for the real-time and simultaneous generation of several images at instants close to each other of one and the same plane cross-section of a body under examination. After appropriate processing, each projection obtained from a source of radiation passing through the plane cross-section to a receiver is fed to a calculator of the contributions of the projection at a given point of the cross-section. The contribution is supplied to a multiplexer which feeds the same to accumulator memories, each being allocated to an image of the cross-section at a given instant.

Abstract: A method and device for computer tomography in which the same filtering operation can be performed for the image reconstruction, regardless of the method used to measure the measured data. Before and after the filtering the data there is performed a multiplication by a pre-conditioning factor and a post-conditioning factor, respectively. The pre-conditioning and post-conditioning factors are dependent on the type of reconstruction and on the position of a data in the group of measured data. The fact that the same filter can be used is important notably for computer tomography apparatus in which a convolution filter is embodied in circuit hardware. The back-projection device is suitable for the back-projection of measured data along diverging measuring paths as well as measured data along parallel measuring paths with only modification of some constants.

Abstract: The present invention provides a digital system including circuitry for imaging items passing on a conveyor belt through an X-ray fan beam. The circuitry of the present invention enables detection of the items as soon as the X-ray beam is pierced and an image of the items is maintained on a monitor following removal of the items from the X-ray beam. This enables detection of all items entering the X-ray beam, and subsequent inspection of the items.

Abstract: Apparatus for examining a body, particularly useful in tomography, for producing transverse sectional images of the body, comprises scanning means supported by a carriage coupled to its mounting via a pair of links defining, with the carriage and its mounting, a four-link, parallel-motion mechanism which, upon oscillation of the links, effects a curvilinear movement of the carriage with respect to the body, and thereby a curvilinear traverse of the body by the scanning means. The carriage is also rotatably mounted on the machine frame enabling the carriage, and the scanning means supported thereon, also to be rotated about the body either incrementally or continuously.

Abstract: When only a part of a body slice to be examined, for example, a separate organ, is irradiated by means of a fan-shaped radiation beam during computer tomography, it is necessary to know the body contour in order to enable reconstruction. The body contour can be determined by means of radiation scattered in the body. The scattered radiation is measured, in a direction which deviates from the direction of the X-rays of the fan-shaped beam, along scattered radiation paths which do not intersect each other in the positioning zone. On the basis of the detected scattered radiation, the scattered radiation path which is situated most far from the center of the examination zone is selected, after which the position of the scattered radiation path within the fan-shaped radiation beam, and hence within the positioning zone, is recorded.

Abstract: During computer tomography examinations, ring-like artefacts occasionally occur because the X-ray source becomes hot, so that the X-ray focus changes its position in space. Because the distance between the detector and the diaphragm which stops the radiation beam is several times larger than the distance between the X-ray focus and the diaphragm, the shifting of the radiation beam on the detector is even greater. If the detector consists of detection elements which are not exactly identical, it may occur that the sensetivities of the detection elements apparently change with respect to each other due to such a shift, the reconstruction then giving rise to said artefacts. In accordance with the invention, the position where the radiation beam is incident on the detector is measured and the diaphragm for the stopping of the radiation beam is readjusted so that the radiation is each time incident in the same area.

Abstract: The exemplary embodiments disclose a computer tomograph which also is operable for the preparation of an x-ray shadow image. To this end every detector of the radiation receiver is extended in the longitudinal direction so as to permit the formation of the x-ray shadow image by line-by-line scanning of the radiation receiver with the radiation beam having a fan shape in a plane disposed perpendicularly to such longitudinal direction.

Abstract: In an exemplary embodiment, a radiation measuring arrangement has two x-ray tubes of different radiation energy which generate radiation beams penetrating the radiography subject, and also has a radiation receiver which determines the radiation intensity behind the subject. The radiography subject is irradiated from different directions. A computer determines, for every image point, the attenuation coefficient for every radiation energy and determines therefrom the mean ordinal number and the density. The radiation receiver is designed as a stationary detector ring. For scanning only the x-ray tubes are rotated about the radiography subject. They are maintained at such a distance from one another that no detector element is simultaneously impinged upon by both radiation beams.