Abstract: Improvement of the picture quality of tomograms in an X-ray CT apparatus using a multi-row x-ray detector is to be realized. When conventional scanning (axial scanning) or cine-scanning is to be performed in consecutive different scanning positions in the z-axis direction, the width of the X-ray beam at scanning positions at both ends is kept at exactly or approximately D/2 relative to the multi-row x-ray detector. Alternatively, the interval between one scanning position and another is kept at not more than D. Unevenness of picture quality dependent on positions on the z-axis on a reconstructed plane can be improved.

Abstract: The invention relates to a method and device for reconstructing a 3D image data set of a moving object from a set of projection images, which were recorded at least partially one after the other from different projection directions. The projection images are hereby assigned by ECG gating to a motion phase of the object in each instance and an incomplete 3D image of the object is computed in this motion phase from these few projection images using local tomography. Motion fields are determined from these 3D images and are used during the final 3D image reconstruction for motion correction.

Abstract: A radiographic apparatus removes lag-behind parts from radiation detection signals taken from an FPD as X rays are emitted from an X-ray tube, on an assumption that the lag-behind part included in each X-ray detection signal is due to an impulse response formed of a plurality of exponential functions with different attenuation time constants. When a single attenuation time constant and intensity are provisionally set, checking is made whether an attenuation to a noise level of X-ray detection signals occurs in an X-ray non-emission state following an X-ray emission state. When the set attenuation time constant and intensity are found appropriate (OK), the impulse response having the single exponential function is determined valid. Corrected radiation detection signals are obtained by removing the lag-behind parts using the impulse response determined.

Abstract: A method for real-time target reconstruction from target image projections including dividing an object into external and internal sub-objects, acquiring external sub-object data, acquiring internal projections, each internal projection including an internal-internal projection which is the projection of the internal sub-object only as if the external sub-object is null, and an internal-external projection which is the projection of the external sub-object only as if the internal sub-object is null, using the external sub-object data to estimate internal-external projections, subtracting the estimated internal-external projections from the acquired internal projections to obtain internal-internal projections, and reconstructing the internal sub-object from the internal-internal projections.

Abstract: A method of reconstructing an image includes substantially minimizing a cost function of the form x ^ = arg ? ? min x ? { ? m = 0 M ? ? D m ? ( y m , F m ? ( x ) ) + S ? ( x ) } , where {circumflex over (x)} is the value of x which achieves the minimum summation, ym is an integral projection, Fm(x) is an forward projection function, and S(x) is a stabilizing function, to obtain {circumflex over (x)}, and using the obtained {circumflex over (x)} to perform a multislice Computed Tomography (CT) reconstruction to generate an image.

Abstract: Methods, systems and processes for providing efficient, accurate and exact image reconstruction using portable and easy to use C-arm scanning devices and rotating gantries, and the like, that combines both a circle and a curve scan. The invention can provide exact convolution-based filtered back projection (FBP) image reconstruction by combining two curved scans of the object. The curved scan can be less than or greater than a full circle about an object being scanned. The invention can be done by a first curve within a first plane followed by a second curve within a second plane that is transversal to the first plane.

Abstract: Relative movement about an axis of rotation is caused as between an energy source/detector array with respect to an object (where the object can comprise either an object to be projected to facilitate a study of the object or a calibration object to be projected as part of calibrating usage of the energy source/detector array). The energy source/detector array are used during this relative movement to scan the object and to obtain corresponding object project data. That object projection data is then used to determine a parameter as corresponds to at least one scanning geometry characteristic as corresponds to using the energy source and the corresponding detector array while causing the aforementioned relative movement to scan the object.

Abstract: The quality of an image can be improved and radiation can effectively be utilized. In an imaging area of a subject where a main scan is performed, a specific scan area setting unit sets a specific scan area where a scan is performed under a specific scan condition allowing radiation exposure dose on the subject to be low. Then, the scan condition setting unit sets a main scan condition so that the specific scan area is scanned under the specific scan condition allowing the radiation exposure dose on the subject to be low.

Abstract: In method and module for calculation of an orthogonal x-ray attenuation of a subject using a measured reference x-ray attenuation in computed tomography, the reference x-ray attenuation and the orthogonal attenuation are provided as input quantities for an automatic dose control of the computed tomography apparatus. The positioning of the subject with regard to the rotation axis of the computed tomography apparatus is taken into account in the calculation of the orthogonal x-ray attenuation detection of the table height of the subject table.

Abstract: A method is for taking tomograms of a patient's beating heart with the aid of a computed tomography unit. ECG signals of the beating heart are recorded. In order to reconstruct the cardiac tomograms, use is made of detector data that originate from a selected cycle area of the cardiac cycle. The cycle area from which the data for the reconstruction originate is selected automatically and individually per cycle, for at least one cardiac cycle, by use of pattern recognition.

Abstract: An adaptive CT data acquisition system and technique is presented whereby radiation emitted for CT data acquisition is dynamically controlled to limit exposure to those detectors of a CT detector assembly that may be particularly susceptible to saturation during a given data acquisition. The data acquisition technique recognizes that for a given subject size and position that pre-subject filtering and collimating of a radiation beam may be insufficient to completely prevent detector saturation. Therefore, the present invention includes implementation of a number of CT data correction techniques for correcting otherwise unusable data of a saturated CT detector. These data correction techniques include a nearest neighbor correction, off-centered phantom correction, off-centered synthetic data correction, scout data correction, planar radiogram correction, and a number of others.

Abstract: The present invention provides a method comprising recursively partitioning an intensity modulated beam into plateaus; and partitioning the plateaus into segments. The present invention also provides a method for controlling administration of radiation therapy to a patient based on static leaf prescriptions. In addition, the present invention provides a method for partitioning an IMB.

Abstract: A method for reconstructing an image of an object includes scanning the object with a computed tomography (CT) system to obtain data, estimating a size of the object using the obtained data, using the estimated size of the object to perform scatter correction on the obtained data, and reconstructing an image using the scatter corrected data.

Abstract: Reconstructing images of objects spirally scanned with two-dimensional detectors with a novel algorithm under a variable pitch (nonconstant speed), where the object is not restricted to moving at a constant velocity. The object can move at variable speeds(increasing, decreasing, combinations thereof) during the scan of the object. The image reconstruction process is proven to create an exact image of the object under the ideal circumstances. The algorithm can have a convolution-based FBP (Filtered Back Projection) structure and works very efficiently. The algorithm uses less computer power and combines the benefits of Exact Algorithms and Approximate algorithms. An object can be moved at a nonconstant speed through a rotating source and oppositely located detector. Additionally, at least one source and oppositely located detector can be mounted on a coil stand for generating the spiral scan.

Abstract: A data consistency condition is derived for an array of attenuation values acquired with a divergent beam. Using this data consistency condition, estimates of selected attenuation values can be calculated from the other attenuation values acquired during the scan. Such estimates may be used to replace corrupted data in the acquired data set, or attenuation values may be added to the acquired data set to increase in-plane resolution of a reconstructed image.

Abstract: A method for calculating an element of a projection includes calculating an element Ai,j of a projection matrix using at least two different rays through a voxel.

Abstract: The invention relates to a medical X-ray device 5 arrangement for producing three-dimensional information of an object 4 in a medical X-ray imaging medical X-ray device arrangement comprising an X-ray source 2 for X-radiating the object from different directions and a detector 6 for detecting the X-radiation to form projection data of the object 4.

Abstract: A method includes performing a Cone Beam reconstruction of a thick image using a plurality of virtual planes.

Abstract: An imaging method is disclosed for a multi-slice spiral CT scan. A CT unit is disclosed for carrying out this method. In the method, the filtering may be formed by use of multiple applications of a ramp filter and a masking operation to a projection image in a different sequence. The CT unit may include, for filtering purposes, multiple applications of a ramp filter and a masking operation to a projection image in a different sequence.

Abstract: A computed tomography (CT) reconstruction method includes implementing an iterative image reconstruction process for CT metrology of an object, wherein the iterative reconstruction process utilizes accurate forward projection. During each of a plurality of iterations, a reconstructed image is constrained by utilizing prior outer edge information obtained from a modality in addition to CT, and then transformed to a projection domain so as to generate a calculated sinogram. A correction image is determined based on the calculated sinogram and a measured sinogram.

Abstract: A radiation tomographic imaging apparatus includes a scanning device for scanning a predefined region in a subject, a prescribing device for prescribing beforehand a position at which an image of said subject is to be produced at a higher priority in the scan region in said subject and a reconstructing device for sequentially reconstructing an image of said subject from projection data obtained by said scanning device, wherein once projection data at said prescribed higher-priority position has been obtained from said scanning device, said reconstructing device reconstructs an image at said higher-priority position at a higher priority.

Abstract: An imaging device accesses projection data collected by a medical imaging system during a scan of a body. The imaging device uses the projection data directly to render an image of a region of interest of the body.

Abstract: An X-ray CT apparatus comprising a scanner that includes an X-ray source and an X-ray detector having two-dimensionally arranged X-ray detector elements, disposed on the opposite side of the subject to the X-ray source and carries out helical scanning around the revolving axis and an image processor for creating a tomogram of the subject from the data collected by helical scanning using the X-ray detector, wherein the image processor creates a tomogram by reconstructing an image from data on the subject including a plurality of sets of projection data of different phases of helical scanning at the same point on the revolving axis and adding the reconstructed images of different phases, whereby a good image is created while suppressing aritifacts.

Abstract: In a method for computed tomography and a computed tomography apparatus for scanning a subject with a conical ray beam emanating from a focus that detects a matrix-like detector array, the focus is moved relative to the subject on a spiral path around a system axis, and the detector array supplies output data corresponding to the incident radiation, and images having an inclined image plane are reconstructed from output data respectively supplied during the movement of the focus on a spiral segment, the image planes of these images are inclined by an inclination angle ? around a first axis intersecting the system axis at a right angle and also are inclined by a tilt angle ? with respect to the system axis around a second axis that intersects the first axis as well as the system axis at a right angle.

Abstract: A method to make a common procedure adaptable to reconstruction planes whose positions relative to a multi-channel detector are different from one another. A reference procedure required for construction of a CT image based on reference linear data representing one line or a plurality of lines formed on a reference reconstruction plane is preserved. Real data associated with a first reconstruction plane different from the reference reconstruction plane is used to produce virtual reference linear data equivalent to the reference linear data. A CT image is reconstructed based on the virtual reference linear data using the reference procedure.

Abstract: A reprojection/backprojection technique and apparatus for carrying out such a technique provides a hierarchical solution to speeding-up reprojection and backprojection of tomographic images. In the context of reprojection, a tomographic image is divided into a series of subimages. Each subimage is shifted to the origin, projected at a reduced number of views, and then up-sampled and shifted back (in the sinogram space). The resulting sinograms are then combined to provide a single sinogram. This process is applied one or more times recursively. In the context of backprojection, the above steps are transposed such that a sinogram is divided into a series of subsinograms. The subsinograms are then shifted and decimated by a given decimation factor. The decimated subsinograms are then backprojected onto hexagonal tiles whereupon the tiles are composited into a final image.

Abstract: A generalized projection-slice theorem for divergent beam projections is disclosed. The theorem results in a method for processing the Fourier transform of the divergent beam projections at each view acquired by a CT system to the Fourier transform of the object function. Using this method, an inverse Fourier transform may be used to reconstruct tomographic images from the acquired divergent beam projections.

Abstract: A technique for simplifying the processing of tomographic imagery (e.g., CT and PET) via statistical smoothing is disclosed. An image smoothness criterion is imposed in the projection domain while identifying data that matches observed data within a desired tolerance. The present invention thus amounts to a computation entirely in the projection domain. As a result, the standard (and somewhat expensive) practice of numerically iterating between the image and projection domains is avoided. Also, the fundamental system of equations having on the order of m p unknowns is decoupled into p independent systems of m unknowns each, where there are p projections of m measurements each. The present invention thus provides a processing technique defined in a single domain, which may be carried out via parallel processing.

Abstract: An X-ray computed tomographic apparatus includes a gantry, a reconstructing portion, and a tube current value determining portion. The gantry acquires projection data of an arbitrary range in a body axial direction by continuously moving a tabletop on which a subject is laid down and by continuously rotating an X-ray tube about the subject. The reconstructing portion reconstructs image data from the acquired projection data according to reconstruction processing selected by an operator from plural types of reconstruction processing. The tube current value determining portion determines plural tube current values respectively corresponding to discrete, plural positions within the range, on the basis of the selected type of reconstruction processing and an image quality level specified or selected by the operator.

Abstract: Methods, systems and processes for providing efficient, accurate and exact image reconstruction using portable and easy to use C-arm scanning devices and rotating gantries, and the like. The invention can provide exact convolution-based filtered back projection (FBP) image reconstruction by combining a curved scan of the object and a line scan of the object. The curved scan can be done before or after the line scan. The curved scan can be less than or greater than a full circle about an object being scanned.

Abstract: A method for treating noise in low-dose computed tomography projections and reconstructed images comprises acquiring raw data at a low mA value, applying a domain specific filter in a sinogram domain of the raw data, and applying an edge preserving smoothing filter in an image domain of the raw data after filtering in the sinogram domain.

Abstract: A method for obtaining data includes scanning an object with radiation to collect projection data using an imaging system having a detector array with detector cells and a post-patient collimator, wherein the post-patient collimator has plates having non-uniform thicknesses. The method further includes applying a correction to the projection data to shift an effective center of at least some of the detector cells to compensate for the non-uniform thicknesses of the collimator plates.

Abstract: A method and a CT unit are proposed for producing CT images of an examination object having a periodically moving subregion, preferably a beating heart, by multi-planar reconstruction. Subsequent to joining the axial images with pixels from a number of partial volumes calculated for the rest phases, a reduction takes place to reduce artifacts occurring in overlap regions. This is done by carrying out threshold value formation in the zone of the boundary regions of the partial volumes with result image Dz. A pixel-oriented median filtering then occurs, resulting in image Mz. A differential value image is then produced using Fz=Dz?Mz. Subsequently, two-dimensional lowpass filtering is applied to Fz to produce a result image Gz. Finally, a calculation of Bz?Gz is used to form the final image Ez.

Abstract: A method and apparatus of generating a hybrid three dimensional reconstruction of a vascular structure affected by periodic motion is disclosed. At least two x-ray images of the vascular structure are acquired. Indicia of the phases of periodic motion are obtained and correlated. Images from a similar phase of periodic motion are selected and a three dimensional modeled segment of a region of interest in the vascular structure is generated. A three dimensional volumetric reconstruction of a vascular structure is generated that is larger than the modeled segment. The modeled segment of interest and the volumetric reconstruction of the larger vascular structure are combined and displayed in human readable form.

Abstract: A method of reducing the distance of rectilinear motion in a helical scan includes defining a rectilinear motion start point La and a rectilinear motion end point Lb within a region of interest ROI for which a CT image is to be created, collecting projection data from the rectilinear motion start point La to the rectilinear motion end point Lb, and creating a CT image at a desired image position in the region of interest ROI using the collected projection data.

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 having a smallest cone angle in comparison with that of the conjugate rays of the radiation beam; and reconstructing an image of the object utilizing projection data obtained from the selected radiation beams while avoiding the use of redundant projection data from unselected conjugate rays of the selected radiation beams.

Abstract: An imaging method for an X-ray CT apparatus having an X-ray source and an X-ray detector disposed to face the X-ray source with a subject placed therebetween, for rotating at least one of the X-ray source and X-ray detector around the subject and detecting X-rays emitted from the X-ray source toward the subject by the X-ray detector, comprises the steps of: defining a reconstruction plane for the subject in a plane non-parallel to a plane formed by rotation of at least one of the X-ray source and X-ray detector around the subject; scanning the subject by emitting cone-shaped X-rays from the X-ray source; and reconstructing a tomographic image of the subject based on the defined reconstruction plane.

Abstract: An X-ray computed tomography apparatus includes a helical scanning device configured to collect projection data while at least one of a gantry and a couch moves along a body axial direction of an object on the couch when at least one of the gantry and the couch is tilted, the helical scanning device including an X-ray source configured to generate X-rays, and a detector disposed opposite the X-ray source and having detector elements arranged in a plurality of rows along the body axial direction, and a reconstructing device configured to reconstruct an image based on the projection data using cone-beam Feldkamp reconstruction.

Abstract: A method to plan a scan in consideration of past patient exposures. The method includes a step of sampling information on a patient exposure the subject has received during a scan performed for reconstructing tomographic images, which is appended to each of the reconstructed tomographic images, on the basis of identification information with which the subject is identified; a step of creating a distribution of patient exposures calculated relative to an axis orthogonal to the scanning directions on the basis of the sampled information on the patient exposure (an estimated patient exposure, which is estimated in planning a scan, and an exposure limit); and a step of displaying the created exposure distribution.

Abstract: To obtain a tomographic image suffering little from artifact and the determination of the quality of image. (1) Step 1: With the axis of abscissas as the fan angle or channel direction of an X-ray detector and the axis of ordinates as the projection angle direction of an X-ray source 11, projection data are arranged side by side to thereby prepare a sinogram. (2) Step 2: from the sinogram, the projection data of an opposite fan beam is prepared at each projection angle. (3) Step 3: the degree of consistency with the projection data of the opposite fan beam is obtained at each projection angle. (4) Step 4: The region of reference error of the degree of consistency is obtained, and a projection angle region is determined from this region of reference error. (5) Step 5: the projection data in the projection angle region obtained at the step 4 is reconstructed to thereby prepare a tomographic image.

Abstract: Techniques are provided for generating three-dimensional images, such as may be used in mammography. In accordance with these techniques, projection images of an object of interest are acquired from different locations, such as by moving an X-ray source along an arbitrary imaging trajectory between emissions or by individually activating different X-ray sources located at different locations relative to the object of interest. The projection images may be reconstructed to generate a three-dimensional dataset representative of the object from which one or more volumes may be selected for visualization and display. Additional processing steps may occur throughout the image chain, such as for pre-processing the projection images or post-processing the three-dimensional dataset.

Abstract: The invention relates to a computed tomography method in which a rebinning operation is carried out so as to form parallel fan beams whose rays traverse a plane, containing the axis of rotation, in equidistant puncture points. Reconstruction is performed for rays which extend perpendicularly to said planes. Such a transition from a cone beam geometry to a parallel beam geometry enables very fast reconstruction which can be carried out notably for CT fluoroscopy.

Abstract: Techniques for tomographic reconstruction using non-linear diagonal estimators are disclosed. In a preferred embodiment, tomographic data from a tomographic device is decomposed in a wavelet vector family. Regularization of the tomographic data is accomplished by performing a thresholding operation on coefficients of the decomposed data. The regularized data is reconstructed into image data that may he displayed. In another preferred embodiment, a wavelet packet vector family is used to decompose the tomographic data. The wavelet packet is selected from a dictionary of wavelet packets using the best basis algorithm.

Abstract: A scanner is programmed with the capability to send images via a parallel port and report data via a serial port to a remote device, both images and report data being identified by the same study identifier. In particular, the images are sent out an Ethernet port in DICOM format, while the report data is sent out an RS232 port in ASCII format. The scanner preferably includes memory storing a frame of image data belonging to a study and report data belonging to said study; a parallel port; a serial port; and a computer programmed to perform the following steps: joining a study identifier with the frame of image data; sending the frame of image data and the study identifier in a first format out the parallel port; joining the study identifier with the report data; and sending the report data and the study identifier in a second format out the serial port.

Abstract: An apparatus and method for reconstructing image data for a region are described. A radiation source and multiple one-dimensional linear or two-dimensional planar area detector arrays located on opposed sides of a region angled generally along a circle centered at the radiation source are used to generate scan data for the region from a plurality of diverging radiation beams, i.e., a fan beam or cone beam. Individual pixels on the discreet detector arrays from the scan data for the region are reprojected onto a new single virtual detector array along a continuous equiangular arc or cylinder or equilinear line or plane prior to filtering and backprojecting to reconstruct the image data.

Abstract: A computed tomography apparatus configured to assist an operator in easily and correctly making an imaging plan thereby reducing the burden of the operator. The computed tomography apparatus selects at least one of reconstruction methods or changes a parameter by the information the operator inputs or displays its grade information, for example.

Abstract: A method is disclosed for generating images of a human or animal body on the basis of 3D-reconstructions from 3D-XRAY or 3D-Computer Tomography measurements, which bodies comprise both natural tissue and one or more high-density objects. The method comprises the steps of executing the measurements, distinguishing the one or more high-density objects and executing a separating procedure thereon for generating an improved image of regions of the natural tissue. In particular, the method comprises the following steps: applying a ramp filter on the various projection measurements to single out the one or more high-density objects; segmenting the singled-out one or more high-density objects into a separate 3D reconstruction; suppressing the reconstructed one or more high-density objects from the original projection measurements; and segmenting said projection measurements without the suppressed one or more high-density objects.

Abstract: In an operating method for user interface for a computed tomography examination procedure a menu and a workflow list are merged on a computer screen. One or more scanning programs can be selected in a parameter setting area on the computer screen, each scanning program corresponding to one default patient posture. When an “end of examination” option in the workflow list is selected, job status information is displayed in the parameter setting area, prompting an operator to check the status of the job selected in set reconstruction parameters. Using the interface the user can improve operational efficiency, thereby saving operational time and shortening time spent in examining each patient.

Abstract: A method for reconstructing an image that can be recognized stably during CAD. The method for reconstructing an image on the basis of a plurality of views of projection data items provided by X-rays having passed through a subject includes image reconstruction dedicated to a computer-aided detection (CAD) mode. The image reconstruction comprises a reconstruction function dedicated to the CAD mode, includes pre-processing that includes a noise removal filter for removing a noise from projection data, such as, a streaky artifact removal dedicated to the CAD mode, and also includes post-processing that includes a noise removal filter dedicated to the CAD mode.

Abstract: A method for computing volumetric perfusion in a spatially stationary organ using a computed tomography (CT) imaging system includes positioning an area detector such that the area detector encompasses a spatially stationary organ within the field of view of the imaging system for all view angles, operating the CT imaging system in a cine mode to acquire a plurality of projection data representative of the tissue dynamics in the spatially stationary organ, processing the projection data, temporally filtering respective signals from volume elements of the reconstructions of the projection data which are representative of the tissue dynamics and computing the volumetric perfusion in the organ using the temporally filtered signals from volume elements.