Abstract: A method is provided for determining, for a fourth-generation computed tomography (CT) scanner that includes a third-generation X-ray source and detector system and a plurality fixed, sparse photon-counting detectors (PCDs), a position of each PCD of the plurality of PCDs. The method includes determining, for a given PCD, a set of view angles at which the PCD will cast a shadow on the third-generation detector; determining, for each view, by analyzing projection data obtained from a reference scan, a corresponding shadow location on the third-generation detector caused by the given PCD; generating, for each view, a line connecting a position of the X-ray source at the view angle, and a corresponding shadow location of the set of shadow locations; determining locations of all intersection points of the set of lines; and determining a PCD centerline of the given PCD based on the locations of the intersection points.

Abstract: A method is provided for determining, in a fourth-generation computed tomography (CT) scanner, a positional offset of a center of a ring of fixed energy-discriminating detectors with respect to an iso-center of a third-generation X-ray source/detector system. The method includes obtaining a plurality of offset images, each offset image being obtained from a scan executed with the ring of fixed energy-discriminating detectors positioned in a known offset location with respect to the iso-center; performing a current scan executed with the ring positioned in an unknown offset location with respect to the iso-center, to obtain a current image; calculating, for each offset image, a corresponding error value between the offset image and the current image; and determining the positional offset of the center of the ring to be an offset location corresponding to an offset image having the smallest error value.

Abstract: A method is provided for determining, for a fourth-generation computed tomography (CT) scanner that includes a third-generation X-ray source and detector system and a plurality fixed, sparse photon-counting detectors (PCDs), a position of each PCD of the plurality of PCI)s. The method includes determining, for a given PCD, a set of view angles at which the PCI) will cast a shadow on the third-generation detector; determining, for each view, by analyzing projection data obtained from a reference scan, a corresponding shadow location on the third-generation detector caused by the given PCD; generating, for each view, a line connecting a position of the X-ray source at the view angle, and a corresponding shadow location of the set of shadow locations; determining locations of all intersection points of the set of lines; and determining a PCD centerline of the given PCD based on the locations of the intersection points.

Abstract: A method and an apparatus for determining primary and secondary escape probabilities for a large photon-counting detector without pile-up. A model for the detector with no pile-up is formulated and used for spectrum correction in a computed tomography scanner. The method includes computing primary K-escape and secondary K-escape probabilities occurring at a certain depth within the photon-counting detector. Further, a no pile-up model for the photon-counting detector is formulated by determining a response function, based on the computed primary and secondary K-escape probabilities and geometry of the photon-counting detector. The method includes obtaining a measured CT scan of an object and further performs spectrum correction by determining the incident input spectrum based on the response function and the measured spectrum of the large photon-counting detector.

Abstract: Calibrating a photon-counting detector can include receiving a reference signal, by circuitry, where the reference signal is measured by a reference detector that measures an output from an X-ray tube. Determining circuitry can then determine, for a detector channel of the photon-counting detector, a mapping between a first true count rate on the detector channel without an object and the reference signal in accordance with a linear relationship between the reference signal and the first true count rate, based on a measured count rate on the detector channel and a predefined relationship between the first true count rate and the measured count rate.

Abstract: A hybrid CT dataset is obtained from a combination of an integrating detector and a photon-counting detector. The hybrid CT dataset contains sparse spectral energy data and dense energy integration data. The dense panchromatic data sets inherit the resolution properties of the integrating detector while the sparse spectral data sets inherit the spectral information of the photon-counting detector. Subsequently, the sparse spectral energy data sets are pansharpened based upon at least one dense panchromatic data set that lacks spectral information according to a pansharpening algorithm.

Abstract: A hybrid CT dataset is obtained from a combination of a integrating detector and a photon-counting detector. The hybrid CT dataset contains low-resolution photon-counting data and high-resolution integrating data. High-resolution panchromatic images are generated from the high-resolution integrating data, and low-resolution spectral images are generated from the low-resolution photon-counting data. The high-resolution panchromatic images inherit the resolution properties of the integrating detector while the low-resolution spectral images inherit the spectral information of the photon-counting detector. Subsequently, the low resolution spectral images are pansharpened based upon at least one high resolution panchromatic image that lacks spectral information according to a pansharpening algorithm.