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Scintillator having integrated collimator and method of manufacturing sameRelated Patent Categories: X-ray Or Gamma Ray Systems Or Devices, Specific Application, Computerized Tomography, Beam Detection SystemScintillator having integrated collimator and method of manufacturing same description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20070211848, Scintillator having integrated collimator and method of manufacturing same. Brief Patent Description - Full Patent Description - Patent Application Claims
CROSS REFERENCE TO RELATED APPLICATIONS [0001] The present application is a continuation of and claims priority of U.S. Ser. No. 11/275,684 filed on Jan. 24, 2006, which is a continuation of U.S. Ser. No. 10/249,699 filed Apr. 30, 2003, now U.S. Pat. No. 7,112,797, the disclosures of which are incorporated herein by reference. BACKGROUND OF THE INVENTION [0002] The present invention relates generally to diagnostic imaging and, more particularly, to an integrated scintillator and collimator and method of manufacturing same. [0003] Typically, in computed tomography (CT) imaging systems, an x-ray source emits a fan-shaped beam toward a subject or object, such as a patient or a piece of luggage. Hereinafter, the terms "subject" and "object" shall include anything capable of being imaged. The beam, after being attenuated by the subject, impinges upon an array of radiation detectors. The intensity of the attenuated beam radiation received at the detector array is typically dependent upon the attenuation of the x-ray beam by the subject. Each detector element of the detector array produces a separate electrical signal indicative of the attenuated beam received by each detector element. The electrical signals are transmitted to a data processing system for analysis which ultimately produces an image. [0004] Generally, the x-ray source and the detector array are rotated about the gantry within an imaging plane and around the subject. X-ray sources typically include x-ray tubes, which emit the x-ray beam at a focal point. X-ray detectors typically include a collimator for collimating x-ray beams received at the detector, a scintillator for converting x-rays to light energy adjacent the collimator, and photodiodes for receiving the light energy from the adjacent scintillator and producing electrical signals therefrom. [0005] As stated above, typical x-ray detectors include a collimator for collimating x-ray beams such that collection of scattered x-rays is minimized. As such, the collimators operate to attenuate off-angle scattered x-rays from being detected by a scintillator cell. Reducing this scattering reduces noise in the signal and improves the final reconstructed image. Therefore, it is necessary that the scintillator array and the collimator, typically plates extending along one dimension above the scintillator array, are uniformly aligned. That is, exact mechanical alignment is required between the collimator plates and the cast reflector lines in the array of scintillators. [0006] Known manufacturing processes attempt this exact alignment by constructing a continuous collimator that is sized to dimensionally match the width and length of the entire detector array. That is, the collimator plates are arranged or arrayed in a continuous consistent pattern or pitch that spans the entire detector length and is placed and attached to the detector rail structure. As such, individual scintillator arrays or packs are must then be exactly aligned to the continuous collimator to ensure that all scintillator cells and collimator cells are aligned exactly; otherwise the collimator must be discarded or repaired, or the scintillator packs must be discarded. This process requires excessively tight tolerancing and requires great operator skill and patience to assemble. Accordingly, these known processes are susceptible to waste of parts, material, and labor. [0007] Additionally, as CT detectors grow in the z-direction, alignment requirements will tighten and the number of cells requiring alignment will increase. Therefore, the low process yields and high-end process scrap and re-work associated with these known manufacturing processes will increase the cost and time associated with CT detector assembly. [0008] Notwithstanding the advances made in CT detector manufacturing, these known detector assemblies and assembly processes result in a detector with less than optimal collimation. Referring to FIG. 10, a known CT detector 1 fabricated according to known manufacturing processes is shown. The CT detector 1 includes a series of tungsten collimator plates 2 that collimate x-rays projected toward scintillator cells 3 of a scintillator array 4. As shown, each of the collimator plates 2 is generally aligned with a reflector line 5 disposed between adjacent scintillators 3. The reflector lines 5 prevent light from being emitted between adjacent scintillators. The scintillator array is coupled to a photodiode array 6 that detects light emissions from the scintillator array and transmits corresponding electrical signals to a data acquisition system for signal processing. As readily shown, the collimator plates are not integrated with the individual scintillator elements 3. That is, an air gap 7 exists between the collimator plates and the scintillator cells 3. The air gap 7 typically results in a separation between the collimator plates and the scintillator array of approximately two to four thousands of an inch. This air gap occurs as a result of the manufacturing process whereupon the collimator plates are formed as a single collimator assembly that accepts and aligns an array of scintillators. The air gap, however, makes the CT detector susceptible to x-rays received between two collimator plates impinging upon an adjacent scintillator thereby resulting in undesirable anomalies in the final reconstructed CT image. [0009] Therefore, it would be desirable to design an integrated scintillator and collimator absent the aforementioned air gap as well as a method of manufacturing such an integrated scintillator and collimator. BRIEF DESCRIPTION OF THE INVENTION [0010] The present invention is directed to an integrated scintillator and collimator and method of manufacturing same that overcome the aforementioned drawbacks. The integrated scintillator and collimator reduces x-ray cross-talk between adjacent detector cells and improves dimensional alignment between collimator septum and scintillator reflector walls by integrating collimator plates with a top reflector surface of a scintillator. A pixilated array of scintillators is placed on a tooling base whereupon a mold having a series of parallel aligned air cavities is positioned atop the array of scintillators. The air cavities within the mold are positioned such that each aligns with a reflector line in the scintillator array. Using high precision tooling, the mold and the scintillator array are precisely aligned relative to one another. Upon proper alignment, a vacuum pump is used to remove the air cavities from within the mold. Thereafter, an injector is used to dispose collimator mixture within the mold and which is allowed to cure. Once the collimator mixture has cured, the integrated scintillator/collimator is formed. [0011] Therefore, in accordance with one aspect of the present invention, a method of manufacturing a detector having an integrated scintillator and collimator is provided. The method includes the steps of positioning an array of scintillator elements or pack on a tooling base and positioning a collimator mold housing having a collimator mold cavity therein on the block. As a result, the mold cavity will be very accurately aligned to the scintillator array pattern. A collimator mixture is then disposed into the mold cavity and allowed to cure to form an integrated scintillator and collimator. [0012] In accordance with another aspect of the present invention, a detector for a CT system includes an array of scintillation elements arranged to convert received x-rays to light. A plurality of collimator elements is integrally formed in a top surface of the array of scintillation elements and operates to attenuate off-angle scattered x-rays from being detected by scintillator elements. The detector further includes an array of photodiode elements arranged to receive light emissions from the array of scintillation elements. [0013] According to another aspect of the present invention, an integrated scintillator and collimator array is formed by the steps of placing an array of pixilated scintillators on a tooling base and positioning a collimator mold defining a plurality of cavities that extend to a top surface of the array adjacent the array. A collimator material is then disposed within the plurality of cavities and cured so as to form the integrated scintillator and collimator array. [0014] In accordance with yet another aspect of the present invention, an apparatus for manufacturing an integrated scintillator and collimator includes a tooling base designed to support a block of scintillating material and a mold to be positioned on the block of scintillating material. An alignment mechanism is provided to align the block in the mold in an aligned arrangement as well as a mold evacuator designed to remove air cavities within the mold. A collimator mixture supply is also provided to supply collimator material to the mold. [0015] According to yet another aspect of the present invention, a system to manufacture an integrated scintillator/collimator includes means for positioning a block of scintillator pack on a tooling base as well as means for positioning a collimator mold over the block. Means for aligning the block and the collimator mold is provided as well as means for removing air cavities from the mold. The system also includes means for disposing collimator material into a volume previously occupied by the removed air cavities and means for curing the collimator material to form an integrated scintillator and collimator. [0016] Various other features, objects and advantages of the present invention will be made apparent from the following detailed description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS [0017] The drawings illustrate one preferred embodiment presently contemplated for carrying out the invention. [0018] In the drawings: [0019] FIG. 1 is a pictorial view of a CT imaging system. [0020] FIG. 2 is a block schematic diagram of the system illustrated in FIG. 1. Continue reading about Scintillator having integrated collimator and method of manufacturing same... 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