Abstract: A method of fabrication of a collimator structure on a detector that includes applying a first layer of resist to a semiconductor sensor, applying a second layer of resist over the first layer of resist and the semiconductor sensor to cover both the first layer of resist and the semiconductor sensor, exposing the second layer of resist to ultraviolet (UV) light with a photomask to transfer a pattern from the photomask to the second layer of resist, removing portions of the second layer of resist corresponding to the pattern from the photomask to produce openings in the second layer of resist, which expose upper portions of the semiconductor sensor, and depositing a layer of metal in the openings and on the second layer of resist to cover the openings, the first layer of resist, the second layer of resist, and the semiconductor sensor.

Abstract: An apparatus is provided that includes a digital processing circuit to obtain a digital signal corresponding to an output signal of a photon-counting detector; determine, from the obtained digital signal, a plurality of X-ray photons received by the photon-counting detector during a measurement period; determine a corresponding energy level of each of the plurality of X-ray photons; determine, based on the corresponding energy level, a corresponding weight for each of the plurality of X-ray photons; and calculate a sum of the corresponding weights of the plurality of X-ray photons.

Abstract: A method and apparatus for determining a parameter vector that includes a plurality of parameters of a detector pileup model of a photon-counting detector, the detector pileup model being used for pileup correction for a spectral computed-tomography scanner. The method includes setting values of the parameters, the parameters including a dead time parameter and individual probabilities of different pileup events, the probabilities including a probability of single photon events, a probability of double quasi-coincident photon events, and a probability of at least three quasi-coincident photon events. The method include determining, using (1) a detector response model, (2) an incident spectrum, and (3) the set values of the parameter vector, a plurality of component spectra, each component spectrum corresponding to one of the individual probabilities of the different pileup events, and summing the plurality of component spectra to generate an output spectrum.

Abstract: A Computed Tomography (CT) method, apparatus, and detector, which includes a plurality of energy-discriminating detector elements configured to capture incident X-ray photons emitted from an X-ray source. Each of the plurality of energy-discriminating detector elements of the detector is configured to have a respective bias voltage individually switched ON or OFF, based on a signal received from a controller.

Abstract: A method for performing reconstruction for a region of interest (ROI) of an object is provided. The method includes designating the ROI within the object, the ROI being located within a scan field of view (FOV) of a combined third- and fourth-generation CT scanner, the CT scanner including fixed photon-counting detectors (PCDs), and an X-ray source that rotates about the object in synchronization with a rotating detector. Further, the method includes determining, for each PCD, as a function of view angle, an on/off timing schedule, based on a size and location of the designated ROI, and performing a scan to obtain a first data set from the rotating detector and a second data set from the plurality of PCDs, while turning each PCD on and off according to the determined schedule. Finally, the method includes performing reconstruction using the first and second data sets to obtain ROI spectral images.

Abstract: A positron emission tomography (PET) detector module includes an array of scintillation crystal elements and a plurality of photosensors arranged to at least partially cover the array of scintillation crystal elements. The photosensors are configured to receive light emitted from the array of scintillation crystal elements. The module includes a transparent adhesive arranged between the array of scintillation crystal elements and the plurality of photosensors. The transparent adhesive extends directly from a surface of at least one of the scintillation crystal elements to a surface of at least one of the photosensors and is configured to distribute the light emitted from one of the scintillation crystal elements to more than one of the photosensors. A method of manufacturing the module includes various steps utilizing a fixture. A PET scanner uses multiple modules arranged circumferentially around an area to be scanned.

Abstract: A method and apparatus for determining a parameter vector that includes a plurality of parameters of a detector pileup model of a photon-counting detector, the detector pileup model being used for pileup correction for a spectral computed-tomography scanner. The method includes setting values of the parameters, the parameters including a dead time parameter and individual probabilities of different pileup events, the probabilities including a probability of single photon events, a probability of double quasi-coincident photon events, and a probability of at least three quasi-coincident photon events. The method include determining, using (1) a detector response model, (2) an incident spectrum, and (3) the set values of the parameter vector, a plurality of component spectra, each component spectrum corresponding to one of the individual probabilities of the different pileup events, and summing the plurality of component spectra to generate an output spectrum.

Abstract: A spectral computed tomography scanner apparatus, including a rotating X-ray source, a plurality of fixed energy-discriminating detectors, a processor that generates a shadow map that indicates, for each detector/view angle, a shadow state of the detector, the shadow state indicating that one of X-rays are completely blocked by a second detector and do not reach the detector, the X-rays are partially blocked by the second detector and partially reach the detector, the X-rays are not blocked by any of the detectors and reach the detector, and the detector is not with the scan field of view at the view angle, and a controller configured to cause the scanner apparatus to perform a scan of an object over a first range of view angles to collect view data, wherein the processor is configured to perform scatter correction using the collected view data and the generated shadow map.

Abstract: A method and apparatus for determining a coincidence window for imaging a region of interest of an object using a Positron Emission Tomography (PET) scanner. The method includes determining a diameter of a transverse field of view (FOV) for imaging the region of interest of the object; and calculating the coincidence window based on the determined diameter, a ring diameter of the PET scanner, an axial length of the PET scanner, and a time-of-flight resolution of the PET scanner.

Abstract: A method and system for calibrating an imaging system in which a positron-emitting radioisotope source is arranged in or adjacent to an imaging region of the imaging system, an annihilation target is arranged at a position separated from the positron-emitting radioisotope source by a predetermined distance, coincident event pairs resulting from annihilation of positrons at the annihilation target are detected, a calibration time offset for a detector element in the imaging system is calculated based on the detected coincident event pairs, and the detector element is calibrated with the completed calibration time offset.

Abstract: A method and system for use in positron emission tomography, wherein a list-based reconstructor means (129) is configured to generate first portion volumetric data responsive to a first portion of a plurality of positron annihilation events detected during a positron emission tomography scan; generate a human-readable image indicative of the first portion volumetric data; use a list-based reconstruction technique to generate composite volumetric data responsive to the first portion volumetric data and a second portion of the plurality of positron annihilation events; and generate a composite human-readable image indicative of the composite volumetric data. In another aspect the reconstructor (129) is configured to selecting first or second portion event quantities responsive to one or more parameters including image definition requirements and processing time requirements.

Abstract: A computed-tomography apparatus that includes a CT scanner including an X-ray source and a detector covering respective angle ranges in the axial and transaxial planes of the CT scanner. The CT detector includes first detector elements disposed on a first surface to capture incident X-ray photons emitted from the X-ray source, and second detector elements sparsely disposed on a second surface different from the first surface, the second surface being farther away from the scanner than the first surface, the second detector elements being smaller in number than the first detector elements. Each of the second detector elements is reachable only by X-ray photons originating in a small angle range around a line connecting the X-ray source and a center of the surface of the detector element, the small angle range being determined by the predetermined distance separating the first and second surfaces and a size of the detector element.

Abstract: A positron emission tomography (PET) detector module includes an array of scintillation crystal elements and a plurality of photosensors arranged to at least partially cover the array of scintillation crystal elements. The photosensors are configured to receive light emitted from the array of scintillation crystal elements. The module includes a transparent adhesive arranged between the array of scintillation crystal elements and the plurality of photosensors. The transparent adhesive extends directly from a surface of at least one of the scintillation crystal elements to a surface of at least one of the photosensors and is configured to distribute the light emitted from one of the scintillation crystal elements to more than one of the photosensors. A method of manufacturing the module includes various steps utilizing a fixture. A PET scanner uses multiple modules arranged circumferentially around an area to be scanned.

Abstract: A method and apparatus for determining a coincidence window for imaging a region of interest of an object using a Positron Emission Tomography (PET) scanner. The method includes determining a diameter of a transverse field of view (FOV) for imaging the region of interest of the object; and calculating the coincidence window based on the determined diameter, a ring diameter of the PET scanner, an axial length of the PET scanner, and a time-of-flight resolution of the PET scanner.

Abstract: A method for reconstructing list mode data comprises: reconstructing all list mode data of a list mode data set (30, 160) to generate a first reconstructed image (32, 62); selecting a sub-set of the list mode data set; and reconstructing the sub-set of the list mode data set to generate an enhanced reconstructed image (84, 86). An image generation system comprises: a reconstruction module (24) configured to perform a standard reconstruction of a list mode data set to generate a standard reconstructed image (32, 62); and a re-reconstruction module (24, 70, 80, 82, 150, 152, 154) configured to perform a reconstruction other than the standard reconstruction of at least a portion of the list mode data set to generate an enhanced reconstructed image (84, 86).

Abstract: An apparatus and method for channel count reduction in solid-state-based positron emission tomography that multiplexes read-outs from photo-detectors using a sum delay circuit, including a sum channel and a delay-sum channel. The sum channel sums signals from sensors in an array and is digitized to extract the timing and energy information. A delay-sum channel includes a discrete delay line that introduces a known delay after each sensor, creating a time signature for the sensor, followed by a summing circuit that adds the delayed signals. The delay-sum channel is digitized using a high speed counters to extract location information. Start and Stop signals for the counter are derived when the sum channel output and the delay-sum channel output cross a pulse ID threshold, respectively. The pulse ID threshold is chosen to minimize the Compton scatter and not clip the photo-peak events.

Abstract: A positron emission tomography (PET) detector module includes an array of scintillation crystal elements and a plurality of photosensors arranged to at least partially cover the array of scintillation crystal elements. The photosensors are configured to receive light emitted from the array of scintillation crystal elements. The module includes a transparent adhesive arranged between the array of scintillation crystal elements and the plurality of photosensors. The transparent adhesive extends directly from a surface of at least one of the scintillation crystal elements to a surface of at least one of the photosensors and is configured to distribute the light emitted from one of the scintillation crystal elements to more than one of the photosensors. A method of manufacturing the module includes various steps utilizing a fixture. A PET scanner uses multiple modules arranged circumferentially around an area to be scanned.

Abstract: A Computed Tomography (CT) method, apparatus, and detector, which includes a plurality of energy-discriminating detector elements configured to capture incident X-ray photons emitted from an X-ray source. Each of the plurality of energy-discriminating detector elements of the detector is configured to have a respective bias voltage individually switched ON or OFF, based on a signal received from a controller.

Abstract: A computed-tomography apparatus that includes a CT scanner including an X-ray source and a detector covering respective angle ranges in the axial and transaxial planes of the CT scanner. The CT detector includes first detector elements disposed on a first surface to capture incident X-ray photons emitted from the X-ray source, and second detector elements sparsely disposed on a second surface different from the first surface, the second surface being farther away from the scanner than the first surface, the second detector elements being smaller in number than the first detector elements. Each of the second detector elements is reachable only by X-ray photons originating in a small angle range around a line connecting the X-ray source and a center of the surface of the detector element, the small angle range being determined by the predetermined distance separating the first and second surfaces and a size of the detector element.

Abstract: When compensating for truncated patient scan data acquired by a multi-modal PET/CT or PET/MR imaging system (14, 16), such as occurs when a patient is larger than a field of view for an anatomical imaging device, a segmented contour of a non-attenuation-corrected (NAC) PET image is used to identify a contour of the truncated region. An appropriate tissue type is used to fill in truncated regions of a truncated CT or MR image for the attenuation map. The corrected attenuation map is then used to generate an attenuation-corrected PET image of the patient or a region of interest. Alternatively, the system can be employed in PET/CT or PET/MR imaging scenarios where two modalities are performed sequentially (e.g., not simultaneously), and thus the contour derived from the PET scan can be compared to the CT or MR image to infer potential subject motion between the PET and CT or MR scans.