Abstract: A method and apparatus for image reconstruction in an imaging system having an x-ray source, an x-ray detector module having a plurality of detector channels, a data acquisition system coupled to the detector module, and a scanning axis z, in which a scan of an object is performed to obtain data, and a smoothing filter is applied to the data, wherein the smoothing applied to the data varies as a function of position. To compensate for increased noise near the edge of a field of view, for example, a z-smoothing filter applies an increased amount of smoothing to the data as a distance from an isochannel increases. A channel dependent primary speed/afterglow correction can also be used to provide smoothing.

Abstract: The present invention, in one form, includes an imaging system having a moving x-ray source and a movable detector array to generate depth information mammography images. More specifically, the depth information images are generated by collecting projection data from a plurality of projection angles. In one embodiment, the projection angle is altered by alter the x-axis position of an x-ray source and a detector array so that the entire object of interest remains within the field of view of the imaging system. The depth information mammography images improve diagnosis and pathology location information.

Abstract: In one aspect, the present invention is a method for computerized tomographic (CT) imaging of an object, the method including steps of scanning an object with a CT imaging system to acquire views including projection samples of an object; interpolating the views nonuniformly within a selected view range to produce nonuniformly interpolated views; weighting the views, including weighting the acquired views and the nonuniformly interpolated views, to compensate for the nonuniform interpolation; and filtering and backprojecting the views to generate an image of the object. Improved CT imaging is thus provided by reducing view aliasing artifacts without simultaneously reducing spatial resolution to clinically unacceptable levels.

Abstract: The present invention, in one form, is an imaging system for accurately determining a length of an object of interest (OOI). Particularly and in one embodiment, the OOI has a curvature in a direction non-parallel to a projection plane. Initially, after utilizing MIP images to identify the OOI, boundaries and a center of the OOI are determined for each image. Utilizing the determined boundaries and center, an OOI length is determined. Specifically, the OOI length is determined by determining a distance between each adjacent image and then summing the resulting values. The distance is then displayed on the MIP images by either distance indicators or numerical display.

Abstract: Methods and apparatus for weighting data collected in a computed tomography scan using a digital flat panel are described. In one embodiment, the method includes the steps of selecting a weighting function in which (a) a sum of weights of complementary samples equals unity, the weighting function is continuous and differentiable along &ggr; where &ggr; is the fan angle, the weighting function approaches zero near an edge of the panel and approaches unity near a panel boundary, and the weighting function remains constant for a range &xgr;1<&xgr;<&xgr;2, where &xgr;1 and &xgr;2 are determined based on an end intersecting point of a complimentary ray within a reconstruction field of view.

Abstract: The present invention, in one form, is a method for generating an image using data collected in a cone beam scan are described. In an exemplary embodiment, a method includes the steps of reconstructing an image &rgr; using the collected data, and segmenting image data for the image &rgr; into a plurality of data sets. At least one of the data sets corresponds to bone data. Then, an error image &PSgr; is generated by using the bone data image set, and a final corrected image &khgr; is generated using &rgr; and the error only image &PSgr;.

Abstract: In one aspect, the present invention is a method for generating an image using a digital flat panel detector wherein a pre-defined delay triggering sequence is utilized to acquire a set of parallel and tilted parallel samples. The image is then generated using a tilted parallel beam reconstruction algorithm.

Abstract: In one aspect, the present invention is a method for producing CT images of a patient's heart suitable for calcification scoring, in which the heart has a cardiac cycle. The method includes steps of acquiring data representative of a first scout-scanned CT image of physical locations of the patient's body including at least a portion of the patient's heart at phases &phgr;1(L) of the cardiac cycle, acquiring data representative of a second scout-scanned CT image of the physical locations of the patient's body including at least a portion of the patient's heart at phases &phgr;2(L) of the cardiac cycle different from &phgr;1(L) at physical positions L of interest, and determining a difference image from the acquired data representative of the first scout-scanned CT image and the acquired data representative of the second scout-scanned CT image data. It is not necessary that &phgr;1(L) and &phgr;2(L) be constant as a function of position L.

Abstract: The present invention, in one form, is a system which predicts contrast agent uptake in an organ of interest. In accordance with one embodiment, and after the contrast agent has been administered to a patient, a prep scan is performed to determine a base contrast agent uptake measurement. A predictive algorithm is then applied to the base measurement to predict a subsequent contrast agent uptake measurement. The predicted subsequent measurement is then compared to a scanning parameter. Particularly, if the predicted subsequent measurement satisfies the scanning parameter, then an image scan is initiated. If the predicted subsequent measurement does not satisfy the scanning parameter, however, then an additional prep scan is performed to determine a new base contrast agent uptake measurement. The predictive algorithm is then applied to the new base measurement to predict a subsequent contrast agent uptake measurement.

Abstract: The present invention, in one form, includes an imaging system having a x-ray source and a digital detector array. The system alters an angular spacing between samples of projection data as a function of the projection angle so that aliasing artifacts are reduced. More specifically and in one embodiment, after identifying at least two projection angle regions, a first view sampling rate is utilized to collect projection data for the first region. As the projection angle becomes equal to the second region, the view sampling rate is altered to a second view sampling rate. A complete volumetric image of an object is then generated from the data.

Abstract: The present invention, in one form, includes an imaging system having a x-ray source and detector array and a reconstruction algorithm. The algorithm removes overlapping structures from a patient scan so that enhanced images representing a moving heart are generated. More specifically and in one embodiment, an estimated background representing the overlapping structures is determined using the projection data. The estimated background is then subtracted from the projection data to generate filtered data. The filtered data is then used to generate an enhanced image so that cardiac calcification may be identified.

Abstract: The present invention, in one form, is a system for reducing artifacts in three-dimensional image formation. More specifically, a 3D image generation algorithm is utilized to generate a composite boundary profile of the object. In one embodiment, the composite boundary profile is determined by selecting an appropriate threshold intensity level. In another embodiment, the composite boundary profile is determined by determining the slope of the boundary, the starting angle of the data set, and the algorithm for helical computed tomography reconstruction. The composite boundary profile is then adaptively filtered to remove inconsistency and thus remove image artifacts in the 3D images.

Abstract: An apparatus and method is provided for use on the pickup head of an optical disc drive for the purpose of adjusting the pickup head to the optimal focus point through a featured tree-structured search algorithm. The apparatus and method can perform the adjustment automatically so as to eliminate the need to use laborious work to make the adjustment in manufacture. The apparatus is activated each time the optical disc drive is started so as to offset the unbalanced condition in the focusing error signal, which allows the optical disc drive to perform the access operation more reliably. Moreover, the apparatus is realized in a digital manner that allows easy implementation and a low manufacturing cost.

Abstract: Methods and apparatus of correcting image data for z-axis non-uniformity in a computed tomography (CT) system are described. In one embodiment, the CT system includes a configurable multislice detector array and a calibration algorithm. In accordance with one embodiment of the algorithm, output signals from a plurality of detector cells are sampled to generate an x-ray beam z-axis non-uniformity profile. The x-ray beam z-axis profile is then used to determine a detector z-axis non-uniformity profile for the detector array. Utilizing the z-axis profiles, the output signals from the detector cells may be calibrated to reduce z-axis non-uniformity errors.

Abstract: A method for controlling operation of a pre-patient collimator to sweep x-rays across a patient are described. Particularly, and rather than shuttling the patient back and forth to obtain scans of different locations, the x-ray beams are swept across the patient by adjusting the positions of the pre-patient collimator. The x-ray beam deviates from the nominal position in z (z is the axis perpendicular to the scan plane). Since the pre-patient collimator is very light, and since the amount of motion in collimator is very small due to the large magnification, the x-ray beam deflection can occur instantaneously without any ramp-up or ramp down periods. Therefore, a 100% duty cycle can be achieved and the image update rate may be reduced. Also, no modification to the reconstruction process is necessary. The nominal slice location for each reconstructed image can be easily estimated by the centroid of the beam location during the date acquisition.

Abstract: A spectral correction algorithm for correcting dense object-induced spectral artifacts is described. In one embodiment, a calibration object, representative of typical head scanning conditions is scanned and the data reconstructed to provide an image. A water or water-equivalent cylinder of about the same diameter also is scanned and reconstructed, on the same display field of view (DFOV). These two images are designated respectively by BWEQ and WEQ. The ratio of images BWEQ and WEQ is then evaluated, and a region of interest extracted by multiplying the ratio by a function II(r), to obtain a calibration pattern CP. The calibration pattern is then averaged in azimuth to obtain a calibration vector. This calibration vector is fitted with low--order polynomial, and then divided by the fitting polynomial, to take out from the vector the low frequency components that, for instance, would be introduced on an "ideal" scanner. By subtracting 1.

Abstract: A CT Fluoro System display which includes apparatus and methods for facilitating effective performance of an interventional procedure. The apparatus and methods are generally referred to herein as partial image display, dynamic image reformation, in-room control, flat panel display, in-room display, and magnification. More particularly, an important performance parameter for a CT Fluoro System is the time to first image. Accordingly, and to reduce the time to first image, a partially reconstructed image can be displayed. In addition to fast image reconstruction, it sometimes is necessary to examine a needle position from different orientations, i.e., views. Accordingly, the present display provides dynamic image reformation wherein axial images are displayed at a very high rate and the operator may reformat the axial images and display the reformatted images in real time.

Abstract: Methods and apparatus for performing channel dependent and gain dependent smoothing filter (across channels) to compensate for noise in a multislice imaging system are described. The smoothing mainly affects the radial resolution. The filter can be combined with the matrix deconvolution filter typically used in multi-slice scanners. The filter is channel and DAS gain dependent and provides that an image generated from data collected in a multi-slice scan has about the same image quality, e.g., noise reduction, as images generated by other types of scanners.

Abstract: A fluoroscopy imaging system which, in one embodiment, includes a modified halfscan image reconstruction algorithm which provides acceptable image quality along with the benefits of an enhanced temporal response as compared to the OS algorithm, is described. In an exemplary embodiment, the algorithm includes the steps of dividing the projection data into a preselected number of subsets, and for each subset, two partial images are generated: one with a first set of weights (denoted by T.sub.i) and the other with a second, i.e., unity, set of weights (denoted by U.sub.i). The final image, P.sub.i, is generated from the two partial images.

Abstract: The present invention, in one form, is a system for performing image reconstruction from projection data acquired in a helical scan. More specifically, the system implements an incremental reconstruction algorithm for helical scan projection data which does not require filtering, weighting and backprojecting such projection data for generating each image. Particularly, a segmentation algorithm divides the projection into a plurality of segments so that subsequent images are generated by generating image data only for those segments that have changed from the base image.