Abstract: A multiplexing circuit for a positron emission tomography (PET) detector includes a delay circuit and a multiplexer communicating with the delay circuit. The delay circuit configured to receive a plurality of timing pickoff (TPO) signals from a plurality of positron emission tomography (PET) detector units, add a delay time to at least one of the plurality of TPO signals, and transmit the TPO signals based on the delay time to the multiplexer, the multiplexer configured to a multiplex the TPO signals and output a single TPO signal from the plurality of TPO signals to a Time-to-Digital Convertor (TDC). A method of operating a multiplexer and a imaging system including a multiplexer are also provided.

Abstract: Methods and systems for signal communication in gamma ray detectors are provided. One gamma ray detector includes a scintillator block having a plurality of scintillator crystals and a plurality of light sensors coupled to the scintillator crystals and having a plurality of microcells. Each of the plurality of light sensors have a local summing point in each of a plurality of signal summing regions, wherein the local summing points are connected to the plurality of microcells. The plurality of light sensors also each include a main summing point connected to the plurality of local summing points, wherein the main summing point is located a same distance from each of the local summing points.

Abstract: A method for gain calibration of a gamma ray detector includes measuring signals generated by one or more light sensors of a gamma ray detector, generating one or more derived curves using the measured signals as a function of bias voltage and identifying a transition point in the one or more derived curves. The method also includes determining a breakdown voltage of the one or more light sensors using the identified transition point and setting a bias of the one or more light sensors based on the determined breakdown voltage.

Abstract: A multichannel application specific integrated circuit (ASIC) for interfacing with an array of photodetectors in a positron emission tomography (PET) imaging system includes a front end circuit configured to be coupled to the photodetectors and to receive discrete analog signals therefrom. The ASIC further includes a time discriminating circuit operably coupled to the front end circuit and configured to generate a hit signal based on a combination of the discrete analog signals, and an energy discriminating circuit operably coupled to the front end circuit and configured to generate a summed energy output signal based on each of the discrete analog signals and summed row and column output signals based on each of the discrete analog signals. The summed energy output signal represents an energy level of the detected radiation in the array of photodetectors, and the summed row and column output signals represent a location of the detected radiation.

Abstract: Methods and systems for signal communication in gamma ray detectors are provided. One gamma ray detector includes a scintillator block having a plurality of scintillator crystals and a plurality of light sensors coupled to the scintillator crystals and having a plurality of microcells. Each of the plurality of light sensors has a first set of signal traces connected to the microcells and a second set of signal traces connected along the first set of signal traces and together forming a signal path to a summing signal trace. Each of the plurality of light sensors also has a pin-out connected to the summing signal trace.

Abstract: Methods and systems for gain calibration of a gamma ray detector are provided. One method includes measuring signals generated by one or more light sensors of a gamma ray detector, generating one or more derived curves using the measured signals as a function of bias voltage and identifying a transition point in the one or more derived curves. The method also includes determining a breakdown voltage of the one or more light sensors using the identified transition point and setting a bias of the one or more light sensors based on the determined breakdown voltage.

Abstract: A Positron Emission Tomography (PET) detector assembly includes a cold plate having a first side and an opposite second side, the cold plate being fabricated from a thermally conductive and electrically non-conductive material, a plurality of PET detector units coupled to the first side of the cold plate, and a readout electronics section coupled to the second side of the cold plate. A radio frequency (RF) body coil assembly and a dual-modality imaging system are also described herein.

Abstract: Apparatus and methods for detector scatter recovery for positron emission tomography systems are provided. One method includes identifying detected gamma events in different detector units of a nuclear medicine (NM) imaging detector and determining whether the detected gamma events occurred within a predetermined time period and have a summed energy of at least a predetermined level to define gamma events for reconstitution. The method further includes reconstituting the defined gamma events into single valid gamma events.

Abstract: A method and apparatus are provided for correcting primary and secondary emission data. The method includes obtaining an emission data set having primary and secondary emission data representative of primary and secondary emission particles emitting from a region of interest and applying a scatter correction model to the emission data set to derive an estimated scatter vector. The method also includes comparing the emission data set to the estimated scatter vector to identify an amount of secondary emission data in the emission data set and correcting the emission data set based on the amount of secondary emission data identified in the comparing operation.

Abstract: Apparatus and methods for detector scatter recovery for positron emission tomography systems are provided. One method includes identifying detected gamma events in different detector units of a nuclear medicine (NM) imaging detector and determining whether the detected gamma events occurred within a predetermined time period and have a summed energy of at least a predetermined level to define gamma events for reconstitution. The method further includes reconstituting the defined gamma events into single valid gamma events.

Abstract: A method and apparatus are provided for correcting primary and secondary emission data. The method includes obtaining an emission data set having primary and secondary emission data representative of primary and secondary emission particles emitting from a region of interest and applying a scatter correction model to the emission data set to derive an estimated scatter vector. The method also includes comparing the emission data set to the estimated scatter vector to identify an amount of secondary emission data in the emission data set and correcting the emission data set based on the amount of secondary emission data identified in the comparing operation.

Abstract: Methods and systems for controlling a positron emission tomography (PET) system are provided. The method includes receiving timing information from a PET system during an imaging scan using the PET system. The method further includes processing the received timing information and timing bias information relating to the PET system to control the PET system.

Abstract: Methods and apparatus for correcting for at least one of deadtime losses and random coincidences in a positron emission tomography (PET) medical imaging device having a plurality of detectors at successive locations circumferentially spaced about a viewing area, the method comprising, receiving signals indicative of positron-electron annihilation events occurring along a line of response between pairs of detectors for a plurality of predetermined time segments of data acquisition of the events, calculating a correction sinogram for each predetermined time segment from data acquired during each respective single time segment, calculating corrected counts in the correction sinogram for each time segment, calculating a time-weighted correction sinogram for each time segment, combining the time-weighted correction sinogram to generate an acquisition sinogram, and generating an image from the acquisition sinogram.

Abstract: The invention is directed to a method and apparatus for timing calibration in a PET scanner. According to one embodiment, the invention relates to a method for timing calibration in a PET scanner having a plurality of scintillator blocks. The method comprises: detecting, in a first scintillator block, a first radiation event, wherein the first scintillator block time-stamps the first radiation event; detecting, in a second scintillator block that is adjacent to the first scintillator block, a second radiation event that corresponds to the first radiation event, wherein the second scintillator block time-stamps the second radiation event; and determining a timing characteristic of the first scintillator block with respect to the second scintillator block based on a comparison between the time-stamps of the first radiation event and the second radiation event.

Abstract: A method and system for normalization of a positron emission tomography system are provided. The method includes determining a plurality of block busy fractions for a positron emission tomography system and using the determined block busy fractions to provide correction during normalization of the positron emission tomography system.

Abstract: A method and apparatus for eliminating the picket fence effect in PET scanners where the scanner includes a master clock and an event processing circuit that generates time stamps during each clock cycle, the scanner also including a coincidence detector that compares the time stamps during each clock cycle to identify coincidence events, the method including the steps of, for consecutive master clock cycles, identifying an overlap period that includes a portion of a first of the master cycles adjacent a second of the master cycles, adding an overlap period that occurs during the overlap period to the second of the master cycles to generate an extended cycle, identifying overlap events that occur during the overlap period in the first of the master cycles, copying the overlap events to the overlap period in the extended second cycle and performing a comparison of the events in the extended cycle to identify coincidence event pairs

Abstract: A combined emission-transmission imaging apparatus, the apparatus comprising oppositely facing first and second photon detector segments disposed on opposite sides of an imaging area and defining the imaging area there between and a radiation source disposed adjacent and outside the imaging area and adjacent at least one of the detector segments, the source generating a fan beam of radiation that emanates from a focal point and juxtaposed such that the fan beam is directed along a trajectory through the imaging area and toward the other of the detector segments, wherein the segments collect both emission and transmission radiation.

Abstract: A method and apparatus for eliminating the picket fence effect in PET scanners where the scanner includes a master clock and an event processing circuit that generates time stamps during each clock cycle, the scanner also including a coincidence detector that compares the time stamps during each clock cycle to identify coincidence events, the method including the steps of, for consecutive master clock cycles, identifying an overlap period that includes a portion of a first of the master cycles adjacent a second of the master cycles, adding an overlap period that occurs during the overlap period to the second of the master cycles to generate an extended cycle, identifying overlap events that occur during the overlap period in the first of the master cycles, copying the overlap events to the overlap period in the extended second cycle and performing a comparison of the events in the extended cycle to identify coincidence event pairs

Abstract: A cascaded delay asynchronous clock (CDAC) for operating control logic (16) to process an event signal. The clock includes a flip-flop (15) for receiving the event signal and generating a clock enable signal and a logic gate (14) connected to the flip-flop (15) for receiving the clock enable signal and generating a clock signal. The clock signal is then communicated to the control logic (16) for use in the control process. The CDAC further includes a plurality of cascaded delays (10) connected in series, such that the first cascaded delay (10) is connected to receive as an input the clock signal, and the last delay (10) is further connected to the logic gate (14). The output of each of the plurality of cascaded delays (10) is fed back to the control logic (16) to generate timing signals. In another aspect of the invention, a variable duty cycle asynchronous clock (VDAC) for operating control logic (40) to process an event signal is disclosed.