Abstract: A method and system for reducing noise in an x-ray image generated by an imaging system using an adaptive projection filtering scheme including generating system information, obtaining original projection data, determining a data characteristic of the original projection data, processing the original projection data responsive to the system information and the data characteristic so as to create filtered projection data and calculating resulting projection data responsive to the filtered projection data. Also claimed is a medium encoded with a machine-readable computer program code for reducing noise in an x-ray image generated by an imaging system, the medium including instructions for causing controller to implement the aforementioned method.

Abstract: In one aspect, there is provided a method for reducing aliasing artifacts in a computed tomography system. The method includes scanning an object with a computed tomography system to acquire a projection data set of measured views; synthesizing additional views of the projection data set utilizing view interpolation; and filtering and backprojecting the projection data set utilizing a weighting function dependent upon parameters Rƒ and Rt, where radius Rƒ around an isocenter of the CT imaging system is selected in accordance with a low artifact criterion and Rt is a parameter defining a transition region outside of radius Rƒ around the isocenter of the CT imaging system.

Abstract: One aspect of the present invention is a method that includes helically scanning an object at a selected helical pitch to acquire projection data of the object. The acquired projection data includes conjugate samples from single rows of the detector array of the CT imaging system and interrow samples. Projections in a plane of reconstruction (POR) are estimated based upon a selection of the projection data from the group consisting of the conjugate samples from at least one of the single rows, the interrow samples, and combinations thereof, the selection dependent upon the selected helical pitch. The estimated projections are filtered and backprojected to reconstruct at least one image of the object.

Abstract: In one aspect, there is provided a method for reducing aliasing artifacts in a computed tomography system. The method includes scanning an object with a computed tomography system to acquire a projection data set of measured views; synthesizing additional views of the projection data set utilizing view interpolation; and filtering and backprojecting the projection data set utilizing a weighting function dependent upon parameters Rf and Rt, where radius Rf around an isocenter of the CT imaging system is selected in accordance with a low artifact criterion and Rt is a parameter defining a transition region outside of radius Rf around the isocenter of the CT imaging system.

Abstract: A method for reducing imaging artifacts in at least one image representative of an object with a scanning imaging system is provided. The imaging system has a multislice detector array and a radiation source configured to emit a radiation beam through the object and towards the multislice detector array. The multislice detector array has a plurality of detector elements arranged in a plurality of detector rows. The method includes scanning the object with the scanning imaging system to acquire a plurality of projection data acquired from a plurality of detector rows including two end rows and a plurality of interior detector rows. The method also includes defining a first plane of reconstruction (POR) for a particular detector row, and defining a second plane of reconstruction (POR) for the particular detector row.

Abstract: One aspect of the present invention is a method that includes helically scanning an object at a selected helical pitch to acquire projection data of the object. The acquired projection data includes conjugate samples from single rows of the detector array of the CT imaging system and interrow samples. Projections in a plane of reconstruction (POR) are estimated based upon a selection of the projection data from the group consisting of the conjugate samples from at least one of the single rows, the interrow samples, and combinations thereof, the selection dependent upon the selected helical pitch. The estimated projections are filtered and backprojected to reconstruct at least one image of the object.

Abstract: A CT imaging system and method are provided in which groups of adjacent detector elements of a detector array are ganged in an x-direction; and an object is scanned using the ganged groups of adjacent detector elements to acquire projection data. In one embodiment, to reduce degradation of images resulting from the ganged detector elements, an image of the object is reconstructed utilizing the acquired projection data and an adjusted iso-channel of the multislice detector array different from an iso-channel defined for scans performed without utilizing ganged groups of detector elements.

Abstract: A computed tomography system includes an x-ray source, an x-ray detector aligned with the x-ray source, a processor coupled to the x-ray detector, and a display for displaying reconstructed images. The processor is programmed to perform at least one of: generating a partially reconstructed image for display on the display; dynamically reformatting images for display on the display; communicating the partially reconstructed image, the reformatted images, or data associated with the system to a remote facility.

Abstract: A method for facilitating a reduction in reconstructed image noise in a computed tomography imaging system. The method includes generating projection data, characterizing a noise distribution of the projection data, performing an adaptive noise reduction operation on the projection data using the noise distribution characterization, and filtering the projection data.

Abstract: Degradation in reconstructed medical images is reduced by a method for calibrating a primary decay correction for a radiation detector having a decay curve that can be characterized by a plurality of components having different time constants. The method includes steps of: fitting the decay curve to a sum of a plurality of weighted exponentials having a first set of time constants; applying a correction to a measured response of the detector using a sum of the plurality of weighted exponentials having the first set of time constants to obtain a corrected response; selecting at least one additional exponential time constant dependent upon the corrected response; and fitting the decay curve to a sum of a second plurality of weighted exponentials including the first plurality of time constants and the at least one additional exponential time constant.

Abstract: A method for reconstructing a computed tomographic (CT) image of an object is provided. The method includes initializing a CT imaging system in a step-and-shoot mode, scanning an object to generate a plurality of adjacent axial scans, wherein the distance between the adjacent axial scans is approximately equal to a projected detector height at the detector iso-center, and reconstructing an image of the object using the adjacent axial scans.

Abstract: There is therefore provided, in one aspect, a method for imaging an object utilizing a computed tomographic (CT) imaging system having a rotating gantry, a multislice detector array on the rotating gantry and using at least n>1 rows of detector channels, and a radiation source on the rotating gantry configured to project a beam of radiation towards the multislice detector array through an object to be imaged. The method includes helically scanning the object with the CT imaging system at a pitch p>n to acquire projection data from the n rows of detector channels; applying a combined helical weight and conjugate weight to at least a portion of the acquired projection data to produce virtual projection data compensating for incomplete helical row data of the acquired projection data; and reconstructing an image of the object utilizing the acquired projection data and the virtual projection data.

Abstract: Methods and apparatus for reducing motion-induced artifacts in CT imaging is described. The imaging system scans a patient's heart to obtain a plurality of projection views, a differential projection is determined from the projection views, a weighting function is applied to the differential projection to minimize motion artifacts, and an inconsistency index is determined from the differential projection, and the inconsistency index is used to locate an image reconstruction location. This method directly measures the mechanics of the heart, rather than an electrical signal and utilizes projection data to select the best locations to minimize image artifact.

Abstract: In one aspect, the present invention relates to tube-spit detection and correction. In an exemplary embodiment, and once a sample of projection data has been collected, the projection data is preprocessed in accordance with known preprocessing algorithms including applying a detector primary speed correction to the projection data. Such primary speed correction removes contamination of previous signal sample from the current sample. After primary speed correction, tube-spit detection is performed on the sample. Such detection can be performed using many different methods. Generally, the objective is to determine whether the x-ray source experienced a drop in power. If a tube-spit event is not detected, then processing proceeds with further preprocessing and image reconstruction. If a tube-spit event is detected, then a tube spit correction is performed. Generally, the objective of tube-spit correction is to remove image artifacts due to the occurrence of a tube-spit event.

Abstract: To reduce the computational load in comparison to the iso-center shift described above, instead of selecting the z-axis of the coordinate system as the iso-center for reconstruction, the gantry iso-center of one of the detector rows (e.g., one of the center rows) is selected as the reconstruction iso-center. In this arrangement, the detector row for which the iso-center is based need not to undergo protection shift, since the defined reconstruction iso-center is the row iso-center. Data from the other detector rows is shifted relative to the selected detector row. When the gantry iso-center of one of the detector rows (e.g., one of the center rows) is selected as the reconstruction iso-center, the reconstructed image will be shifted along y′-axis relative to the original compensation schemes described above. To ensure the images generated with both schemes are identical in location, an adjustment can be added in the backprojection process.

Abstract: Methods and apparatus for reducing motion-induced artifacts in CT imaging is described. The imaging system scans a patient's heart to obtain a plurality of projection views, a differential projection is determined from the projection views, a weighting function is applied to the differential projection to minimize motion artifacts, and an inconsistency index is determined from the differential projection, and the inconsistency index is used to locate an image reconstruction location. This method directly measures the mechanics of the heart, rather than an electrical signal and utilizes projection data to select the best locations to minimize image artifact.

Abstract: Methods and Apparatus to reduce image artifacts when reconstructing an image with a multislice computed tomographic (CT) imaging scanner. An object is helically scanned to obtain a plurality of projection views of an object, a plane of reconstruction is defined, a conjugate sample line is defined that does not intersect the plane of reconstruction, a weighting function is applied to the conjugate samples to reduce image artifacts, and the image is reconstructed after the weighted data is filtered and backprojected. The method reduces potential image artifacts without requiring additional hardware be used or replaced.

Abstract: Methods and apparatus to reduce and eliminate aliasing artifacts generated as a result of performing high speed scans are described. In one embodiment, the method includes the steps of applying a weighting function to the projection data, and determining an aliasing index from the weighted data. The aliasing index per view is utilized to determine the region and the amount of synthesized views required to reduce the aliasing artifact.

Abstract: Methods and apparatus are provided for reducing image artifacts from a computed tomography (CT) image generated using a CT system. A plurality of projection views of an object are obtained and a plane of reconstruction including reconstructed images is defined. A smoothing function is applied to the reconstructed images to reduce image artifacts wherein a greater amount of z-smoothing is applied to images located a greater distance from an iso-center.

Abstract: A method for estimating motion of a part of an object, using a CT imaging system, is therefore provided in one embodiment of the present invention. This method includes steps of: scanning the object with the CT imaging system so as to acquire conjugate data samples; analyzing the conjugate data samples to remove data representative of overlapping, non-moving portions of the object; and estimating a cardiac motion from the analyzed conjugate data samples. Advantageously, no EKG device is required estimating cardiac motion when this method for estimating motion is employed.