Abstract:
An improved method for computed tomographic scanning is disclosed. A beam of electromagnetic radiation subtending an angle .phi. is alternately translated and rotated past a patient. The intensity of the beam is detected by an array after the radiation passes the patient and a reconstructed image created from the detected intensities. Each rotation of the array is through an angle less than the angle .phi. subtended by the array producing redundant intensity readings for similarly oriented beam paths through the patient. This redundant intensity data is modified according to a scheme which tends to reduce motion and misalignment artifacts within the patient.
Abstract:
A one-dimensional multi-element photo detector (120) includes a photodiode array (122) with a first upper row of photodiode pixels and a second lower row of photodiode pixels. The photodiode array (122) is part of the photo detector (120). A scintillator array (126) includes a first upper row and a second lower row of scintillator pixels. The first upper and second lower rows of scintillator pixels are respectively optically coupled to the first upper and second lower rows of photodiode pixels. The photo detector (120) also includes readout electronics (124), which are also part of the photo detector (120). Electrical traces (512) interconnect the photodiode pixels and the readout electronics (124).
Abstract:
A radiation sensitive detector array includes a plurality of detector modules (118) extending along a z-axis direction and aligned along an x-axis direction with respect to the imaging system (100). At least one of the detector modules (118) includes a module backbone (124) and at least one detector tile (122). The at least one detector tile (122) is coupled to the module backbone (124) through a non-threaded fastener (142). The at least one detector tile (122) includes a two-dimensional detector (126) and a two-dimensional anti-scatter grid (128) that is focused at a focal spot (112) of an imaging system (100).
Abstract:
An ionizing radiation detector module (22) includes a detector array (200), a memory (202), signal processing electronics (208), a communications interface (210), and a connector (212). The memory contains detector performance parameters (204) and detector correction algorithms (206). The signal processing electronics (208) uses the detector performance parameters (204) to correct signals from the detector array (200) in accordance with the detector correction algorithms (206).
Abstract:
X-rays from an x-ray tube (16) pass through an examination region (14) and are detected by a single or two-dimensional x-ray detector (20). The x-ray detector (20) includes an array (22) of photodiodes, CCD devices, or other opto-electrical transducer elements. A matching array (24) of transparent scintillator crystals, e.g., CdWO4, is supported on and optically coupled to the photoelectric transducer array. A layer (26) of a high efficiency scintillator with a good spectral match with the opto-electrical transducer array but with limited light transmissiveness is optically coupled to the transparent scintillator array. The layer (26) is preferably zinc selenide ZnSe (Te). Electrical signals from the transducer array are reconstructed (32) into an image representation and converted into a human-readable display (38). To reduce cross-talk, the zinc selenide layer is etched with pits (40), sliced into strips (26′), cut into rectangles (26″), or has channels (44) cut into it. Scatter grids (46) are advantageously received in the channels. Alternately, the zinc selenide can be powdered, encased in a transparent binder, and applied as a coating layer (26″′) to the individual transparent scintillator elements.
Abstract:
A CT scanner (10) includes a reconstruction processor (32) and a mosaic X-Radiation detector (20). The mosaic detector includes plural detector elements (22, 22, 23, 24, 25, 26) arranged in abutting relationship and configured for the desired imaging application. The detector elements include scintillating crystals (50) in optical communication with a back-illuminated photodiode array (52) or modified top-surface photodiode array (152, 252) for converting emitted light into electrical charge. The photodiode array is mounted on a carrier substrate (58) via bump (56) bonding. The carrier substrate provides a conductive path routing the photodiode array output through to contacts on the back side for connection to readout electronics (60). The carrier substrate and readout electronics are contained within the footprint defined by the photodiode array, allowing the detector elements to be abutted on any and all sides, thus permitting the mosaic detector to be tailored to any desired size and shape.
Abstract:
In a fourth generation CT scanner, source views or data sets are generated for reconstruction processing. A fan beam (16) of radiation rays is rotated around an image region (12) to irradiate subsets of detectors of a detector ring (10). A data sampler (B) samples the detectors of each irradiated subset a plurality of times, each time with the radiation fan beam displaced incremently from the preceding time to generate a plurality of the source views or data sheets from the same detectors. A plurality of consecutive source views or data sets are interleaved to produce a signal interleaved view or data fan. More specifically, the data sets are stored in data set memories (20-26) and interleaved serially into a data fan memory (30). Each time the fan beam rotates sufficiently to irradiate a different detector subset, an additional plurality of data sets are generated and interleaved into another data fan. The data fans are reconstructed (E) into a representation of an image of radiation absorptive properties of an object disposed in the image region. This reconstruction method is especially applicable to cardiac synchronization or gated patient scanning. This method improves the dynamic scan capacity of fourth generation scanners, improves tolerance to detector drifts, and improves tolerance to temporal x-ray fluctuations.
Abstract:
A dual axial scanner in a transverse tomography system collects nonredundant data throughout one or more substantially 360.degree. orbital scan paths with uniform motion about a patient. A set of N X-ray beams scans the patient in a manner to allow collection of two sets of non-redundant data corresponding to a pair of 180.degree. scans in each 360.degree. scan. Overall time to conduct the study is decreased, and the number of required accelerations and decelerations of the assemblies is minimized.Adjacent beams of radiation are separated by an angle .alpha., which is one degree in the preferred embodiment to provide a radiation field of ##EQU1## degrees on either side of a center of the radiation field. The source and detector assemblies are positioned prior to the first orbit such that the field center is offset a distance D from a center of orbit lying in the orbital plane. The source and detector assemblies are mounted for rotation through a rotation angle .phi..sub.j about an orbital source axis which passes through the source assembly at a distance d from the center of orbit. While maintaining the offset distance D, the assemblies orbit the patient, and radiation intensity data is collected at predetermined angles .gamma..sub.j of orbit.In one embodiment for doubling the effective field size of the patient scanned, the source and detector assemblies are rotated about the source axis to provide the distance D. From an initial position on the center of orbit, the assemblies are rotated by an offset angle ##EQU2## degrees where R is the number of total orbits selected to constitute a complete study. In another embodiment for single field exposure the source and detector assemblies are rotated by the offset angle .phi. defined substantially by the equation ##EQU3## degrees, where "b" is zero for an odd number N of detectors and is one for an even number N of detectors. For multiorbit studies, the assemblies are rotated between orbits by an amount ##EQU4## degrees depending on the study.
Abstract:
A detector tile (116) of an imaging system (100) includes a photosensor array (204) and electronics (208) electrically coupled to the photosensor array (204), wherein the electronics includes a dose determiner (402) that determines a deposited dose for the detector tile (116) and generates a signal indicative thereof. In one non-limiting instance, this signal is utilized to correct parameters such as gain and thermal coefficients, which may vary with radiation dose.
Abstract:
An imaging system (100) includes a radiation source (108) that emits radiation that traverses an examination region (106) and a detection system (114) that detects radiation that traverses the examination region (106) and generates a signal indicative thereof. The detection system (114) includes a first detector array (1141-114N) and a second detector array (1141-114N). The first and second detector arrays (1141-114N) are separately distinct detector arrays and at least one of the detector arrays (1141-114N) is moveable with respect to the radiation beam. A reconstructor (116) reconstructs the signal and generates volumetric image data indicative thereof.