Abstract: A CT system includes a rotatable gantry having an opening to receive an object to be scanned, a high-voltage generator, an x-ray tube positioned on the gantry to generate x-rays through the opening, and a pixelated detector positioned on the gantry to receive the x-rays. The system includes a computer programmed to cause the x-ray tube to generate x-rays, at a given high-voltage generator voltage (kV), toward a sub-set of detector pixels when no object is present within the opening, measure an output of the sub-set of detector pixels for a given number of views during the x-ray generation and for a total integration time, and determine a calibration factor based on the measured output and based on a generator feedback current measured during the total integration time.

Abstract: A computed tomography (CT) system includes a rotatable gantry having an opening to receive an object to be scanned, an x-ray tube having an anode, the x-ray tube positioned on the rotatable gantry to generate x-rays from a first focal spot at a first z-location, and from a second focal spot at a second z-location, a pixelated detector positioned on the rotatable gantry to receive the x-rays from the first z-location and from the second z-location, and a computer. The computer is programmed to acquire a first dataset in a fan geometry at a first z-location, acquire a second dataset in the fan geometry at a second z-location, and reconstruct an image based on the first dataset and the second dataset, wherein the reconstruction is performed without combining the first dataset and the second dataset into one dataset with a single geometry from which the image reconstruction is performed.

Abstract: A detector assembly for a CT system includes a plurality of detector modules, each detector module including a grid of pixelated scintillators, a photodiode having pixelations that correspond with the pixelated scintillators, and an electronics package for processing acquired X-ray data, a support structure extending along a Z-direction of the CT system and having the plurality of detector modules positioned thereon, and a heat sink extending along the Z-direction and having the support structure mounted thereon, the heat sink including a passageway passing therethrough and along the Z-direction, such that cooling air may pass into the passageway at a first end of the heat sink and exit the passageway at a second end of the heat sink opposite the first end.

Abstract: A computed tomography (CT) system includes a rotatable gantry having an opening to receive an object to be scanned, a high-voltage generator, an x-ray tube positioned on the gantry to generate x-rays through the opening, a pixelated detector positioned on the gantry to receive the x-rays, and a computer. The computer is programmed to obtain a scout image of the object, calculate an equivalent diameter of a water cylinder based on the scout image over a length of the scout image, calculate a major axis and a minor axis for an equivalent ellipse over the length, calculate, based on a noise index and based on the equivalent diameter as the function of the length, an mA modulation as a function of the length, and obtain image data of the object by modulating an mA applied to the x-ray tube based on the calculated mA modulation.

Abstract: A CT system includes a rotatable gantry having, an x-ray tube having a focal spot, and a detector assembly positioned to receive the x-rays that pass through the object. The detector assembly includes an array of module support structures positioned along a channel direction, each module support structure having module support surfaces extending along the Z-axis, the array including a first module support structure and a second module support structure that are side-by-side, and a plurality of detector modules positioned on each module support structure and having collimating elements that are generally aligned toward the focal spot. Each of the first and second module support structures includes two steps symmetrically disposed along the Z-axis, such that a first gap between the detector modules of the first and second module support structures at a center of each is less than a second gap formed at each step.

Abstract: A CT system includes a rotatable gantry having an opening to receive an object to be scanned, an x-ray tube having an anode, the x-ray tube positioned on the gantry to generate x-rays from a focal spot of the anode and through the opening, and a pixelated detector positioned on the gantry to receive the x-rays. The system includes a computer programmed to acquire CT data based on x-rays passing through the opening and to the pixelated detector, generate projection data from the acquired CT data, the projection data is corrected to account for heel effect by a correction factor that is determined based in part on an interaction depth of the x-rays within the anode, and based on an angular direction from the interaction depth to particular pixels within the pixelated detector, and reconstruct an image based on the generated projection data.

Abstract: A scintillator module for a CT detector includes an array of pixelated scintillators extending in a first direction at a first spacing, and extending in a second direction at a second spacing, a reflector on the array and between the pixelated scintillators, the reflector having a first thickness and forming notches having a second thickness that is greater than the first thickness. The module includes an anti-scatter grid having plates, each plate extending along a length such that, when the CT detector is positioned in a CT system, the length of the plates extend approximately toward a focal spot. The plates are separated from one another at one of the first spacing and the second spacing, and two of the notches have a gap therebetween that engages one of the plates. An adhesive positioned in the gap to adhere the one plate to the reflector.

Abstract: A scintillator module for a CT detector includes an array of pixelated scintillators extending in a first direction at a first spacing, and extending in a second direction at a second spacing, a reflector on the array and between the pixelated scintillators, the reflector having a first thickness and forming notches having a second thickness that is greater than the first thickness. The module includes an anti-scatter grid having plates, each plate extending along a length such that, when the CT detector is positioned in a CT system, the length of the plates extend approximately toward a focal spot. The plates are separated from one another at one of the first spacing and the second spacing, and two of the notches have a gap therebetween that engages one of the plates. An adhesive positioned in the gap to adhere the one plate to the reflector.

Abstract: A CT scanning system includes a rotatable gantry having an opening for receiving an object to be scanned, an x-ray tube, and a detector comprising an imaging area of pixels and a calibration area of pixels. The system further includes a pre-patient collimator positioned between the x-ray tube and the detector having first and second apertures that pass x-rays respectively to at least a portion of the imaging area of pixels, and to the calibration area of pixels, a motor configured to move the pre-patient collimator, and a computer programmed to determine a focal spot location using energy derived from x-rays that fall upon the calibration area of pixels, and issue commands to a motor to adjust a position of the pre-patient collimator based on the determination.

Abstract: A CT detector includes a base substrate, a photodiode array having a plurality of pixels, and the photodiode array is attached to the base substrate. A scintillator array is coupled to the photodiode array and includes a plurality of pixels that correspond with those of the photodiode. An anti-scatter grid (ASG) includes a base sheet, a top sheet, and a plurality of anti-scatter plates attached to the base sheet and the top sheet. The plurality of anti-scatter plates includes a first set of plates having a first thickness and a first length, and a second set of two plates each having a second thickness that is less than the first thickness and a second length that is greater than the first length, the two plates positioned respectively at bookend positions of the base sheet and top sheet.

Abstract: A photodetector array readout and dynamic multiplexing method for reducing the overall channel count in a PET scanner system is disclosed. A PET system includes detector modules mounted on a ring-shaped gantry, each module including an array of M×N pixelated scintillators with photosensors attached to each pixelated scintillator on at least one of the top and the bottom surfaces. The multiplexer includes row and column summing, pulse shaping, and dynamic switching circuits multiplexing M×N inputs to a single output representing the energy and timing of the detected radiation. A position encoder is configured to receive outputs from the N+M summing circuits, and determine which pixelated scintillator had a gamma ray interaction. When photosensors are attached on both surfaces, the depth of interaction is determined as well based on the relative strength of the top and bottom surface readouts.

Abstract: A CT scanning system includes a rotatable gantry having an opening for receiving an object to be scanned, an x-ray tube, and a detector comprising an imaging area of pixels and a calibration area of pixels. The system further includes a pre-patient collimator positioned between the x-ray tube and the detector having first and second apertures that pass x-rays respectively to at least a portion of the imaging area of pixels, and to the calibration area of pixels, a motor configured to move the pre-patient collimator, and a computer programmed to determine a focal spot location using energy derived from x-rays that fall upon the calibration area of pixels, and issue commands to a motor to adjust a position of the pre-patient collimator based on the determination.

Abstract: A CT detector includes a base substrate, a photodiode array having a plurality of pixels, and the photodiode array is attached to the base substrate. A scintillator array is coupled to the photodiode array and includes a plurality of pixels that correspond with those of the photodiode. An anti-scatter grid (ASG) includes a base sheet, a top sheet, and a plurality of anti-scatter plates attached to the base sheet and the top sheet. The plurality of anti-scatter plates includes a first set of plates having a first thickness and a first length, and a second set of two plates each having a second thickness that is less than the first thickness and a second length that is greater than the first length, the two plates positioned respectively at bookend positions of the base sheet and top sheet.

Abstract: A PET scanning system includes a plurality of detector modules, each having an array of pixelated scintillators, the array having N rows of pixelated scintillators, and M columns of pixelated scintillators. Each detector module includes a first set of N light guides optically coupled to the top surface that accumulate optical signals, and a second set of M light guides optically coupled to the bottom surface that accumulate optical signals. Each light guide is coupled to a light sensor which converts optical signals into analog electrical outputs. A processor is coupled to outputs from the first set and the second set, the processor configured to determine which pixelated scintillator within the array had a gamma ray interact therewith, and its depth of interaction, based on the outputs. Thus, gamma ray detection in an array of M×N scintillator pixels is accomplished using only M+N channels.