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Deflection-equipped ct system with non-rectangular detector cellsDeflection-equipped ct system with non-rectangular detector cells description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20070248208, Deflection-equipped ct system with non-rectangular detector cells. Brief Patent Description - Full Patent Description - Patent Application Claims
CROSS-REFERENCE TO RELATED APPLICATION [0001]The present application is a continuation-in-part of U.S. Ser. No. 11/379,407, filed on Apr. 20, 2006, the disclosure of which is incorporated herein by reference. BACKGROUND OF THE INVENTION [0002]The present invention relates generally to CT imaging systems and, more particularly, to a CT detector with non-rectangular detector cells and to imaging systems and methodologies employing such detectors. [0003]In conventional multi-row CT detectors, a two dimensional array of detector cells extend in both the x and z directions. Moreover, in conventional detectors, each cell of the array is constructed to have a rectangular-shaped active area. This active area is generally perpendicular to a plane of x-ray source rotation and, in the context of energy integrating scintillators, converts x-rays to light. The light emitted by each scintillator is sensed by a respective photodiode and converted to an electrical signal. The amplitude of the electrical signal is generally representative of the energy (number of x-rays x energy level of x-rays) detected by the photodiode. The outputs of the photodiodes are then processed by a data acquisition system for image processing. [0004]As described above, each of the detector cells of the 2D array has a generally rectangular or square face, and is contiguous in both the x and z directions. As such, there is no overlapping in either of the x or z directions. This lack of overlapping places an upper limit on the spatial frequency of the region-of-interest, i.e., anatomy of interest, which can be resolved artifact free. A number of approaches have been developed to overcome the upper sampling limitations of conventional 2D detector arrays. [0005]In one proposed solution, miniaturization efforts have led to a reduction in the size of the individual detector cells or pixels. Because the output of each detector cell corresponds to a pixel in a reconstructed image; conventionally, detector cells are also referred to as pixels. Segmenting the detector active area into smaller cells increases the Nyquist frequency but with the added expense of data channels and system bandwidth. Moreover, system DQE is degraded due to reduced quantum efficiency and increased electronic noise which results in a degradation in image quality. [0006]In another proposed technique, focal spot deflection by deflecting the x-ray focal spot in the x and/or z direction at 2.times. or 4.times. the normal sampling rate has been found to provide additional sets of views. The different sets of views are acquired from slightly different perspectives which results in unique samples that provide overlapping views of the region-of-interest without subpixellation. This approach typically utilizes a data acquisition system channel capable of very high sampling rates and x-ray source hardware dedicated to rapid beam deflection. However, while the use of x-ray focal spot deflection provides additional unique views, such deflection essentially results in increased reconstruction data in only an x or z direction (depending upon the direction of deflection). Moreover, present detectors are not particularly optimized for receiving deflected x-ray beams. [0007]Another proposed approach to increasing sampling density of a CT detector involves the staggering of pixels. Specifically, it is has been proposed that sampling density may be improved by offsetting, in the z direction, every other channel or column of detector cells in the x direction. In one proposed approached, the offset is equal to one-half of a detector width. This proposed CT detector design, as well as a more conventional CT detector design, are illustrated in FIGS. 1-2. [0008]As shown in FIG. 1, a conventional CT detector 2 is defined by a 2D array of detector cells 3 that are rectangular in their active area shape. As shown and described above, the array extends in both the x and z directions. In the CT detector design illustrated in FIG. 2, every other channel 4 (column) of detector cells 3 is offset. This provides an intermediate sample location between rows 5 increasing the number cells, decreasing cell size, or increasing the data acquisition system sampling rate. However, such a staggered design is difficult to fabricate since all the rows are not aligned. [0009]Therefore, it would be desirable to design a CT detector that provides increased sampling density that is practical to fabricate yet does not over-burden the data acquisition system or necessitate an impractical number of data acquisition channels. It would also be desirable for such a detector to function effectively with deflected focal spot x-ray sources. BRIEF DESCRIPTION OF THE INVENTION [0010]The present invention is directed to a CT detector constructed to overcome the aforementioned drawbacks. The CT detector is comprised of detector cells having diagonally oriented perimeter walls. With such a construction, the CT detector has improved spatial coverage (sampling density), and detects deflected focal spot x-rays more effectively. The number of detector channels is also not increased despite the increase in spatial coverage. Moreover, the detector cells can be constructed with a conventional cutting technique. [0011]Therefore, in accordance with one aspect, the invention includes a CT scanner having a rotatable gantry, an x-ray source arranged to project x-rays from the gantry, an x-ray detector disposed in the gantry opposite the x-ray source, and a data processing unit connected to acquire data from the x-ray detector. The x-ray detector has an array of detector cells that each have one perimeter side not parallel to two other perimeter sides. A program on the data processing unit causes one or both of an interpolation of x-ray detector data or an x-ray oversampling to occur. [0012]According to another aspect of the invention, an x-ray detector is disclosed. The detector includes an array of x-ray detector cells configured to convert radiation projected from an x-ray source into data signals. Each detector cell has a number of perimeter sides wherein an angle of intersection formed between a pair of the perimeter sides is acute. The sampling rate of the array is set so that multiple data acquisitions are output during a projection period of the x-ray source. [0013]In accordance with another aspect, the invention is embodied in a method for implementing an x-ray detection system. The method includes the steps of providing a scintillator array having a number of divisions at a first angle and a number of divisions at a second angle more than 90 degrees from the first angle, connecting outputs of the scintillator array to a data acquisition system, and programming the data acquisition system. When executing the program, the data acquisition system should acquire a matrix of data samples from the scintillator array having a number of values in a column direction and a number of values in a row direction and then augment the matrix of data samples with additional values in the row direction. [0014]In accordance with yet another aspect of the present invention, a method is disclosed for acquiring x-ray incidence data. The method includes projecting deflecting radiation from a x-ray source towards a detector during a projection period and sampling a set of acquisition data from the detector. The set of acquisition data is indicative of the incidence of radiation on portions of the detector having an edge that is not parallel to either the slice direction or the subject direction. The method also includes integrating other data values with set of acquisition data to increase the apparent sampling resolution in the slice direction or the subject direction. [0015]Various other features and advantages of the present invention will be made apparent from the following detailed description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS [0016]The drawings illustrate one preferred embodiment presently contemplated for carrying out the invention. [0017]In the drawings: [0018]FIG. 1 is a plan view of a conventional rectangular CT detector matrix comprised of square-shaped detector cells. [0019]FIG. 2 is a plan view of a CT detector matrix with staggered detector channels. [0020]FIG. 3 is a pictorial view of a CT imaging system. Continue reading about Deflection-equipped ct system with non-rectangular detector cells... Full patent description for Deflection-equipped ct system with non-rectangular detector cells Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Deflection-equipped ct system with non-rectangular detector cells patent application. Patent Applications in related categories: 20090285354 - Optical coherence tomographic imaging device and imaging method of optical coherence tomographic image - An optical tomographic imaging device and the like which suppress influence in the case of a measuring beam being truncated by an iris, and can ensure reliability of a tomographic image which is acquired, when imaging the tomographic image of a retina in an eyeground of an examined eye. An ... ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. 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