Abstract: Timing is determined in positron emission tomography (PET). Two or more different types of timing detection are used for each event. The difference in time from the different types of timing detection may indicate whether or not an error has occurred. An average difference or other typical offset difference may be used to correct the error. During pile up, the difference information may be used to create a missing time, such as using an average difference between second derivative and constant fraction discrimination as an offset to determine constant fraction timing from second derivative timing.

Abstract: A printed circuit board (PCB) assembly of a data processing unit for an integrated magnetic resonance (MR) and positron emission tomography (PET) system, the PCB assembly includes a plurality of PCB layers disposed in a stacked arrangement, first and second PET signal processing circuits carried by a first layer of the plurality of PCB layers, first and second ground plane structures carried by a second layer of the plurality of PCB layers and configured relative to the first and second PET signal processing circuits, respectively, and a ground partition that separates the first PET signal processing circuit from the second PET signal processing circuit on the first layer. The ground partition extends through the first layer to provide electromagnetic interference (EMI) shielding between the first and second PET signal processing circuits.

Abstract: A positron emission tomography (PET) system includes a PET detector configured to generate energy signals indicative of a set of events at the PET detector, a first discriminator coupled to the PET detector and configured to generate a primary timing signal in response to a primary event of the set of events, a second, derivative-based discriminator coupled to the PET detector and configured to generate a pileup timing signal in response to a piled-up event of the set of events, and a logic circuit to gate the primary and pileup timing signals of the first and second discriminators.

Abstract: Timing is determined in positron emission tomography (PET). Two or more different types of timing detection are used for each event. The difference in time from the different types of timing detection may indicate whether or not an error has occurred. An average difference or other typical offset difference may be used to correct the error. During pile up, the difference information may be used to create a missing time, such as using an average difference between second derivative and constant fraction discrimination as an offset to determine constant fraction timing from second derivative timing.

Abstract: A representative method for determining a zero baseline value of a channel from a detector device of a nuclear medicine imagining system to allow for correction caused by noise or interference on the detector device includes calculating a first value of a baseline based on a first sample of analog electrical signals from analog-to-digital converters (ADCs) coupled to the detector device; comparing a predetermined value with the first value of the baseline; determining whether there is a small change between the predetermined value and the first value of the baseline; and responsive to determining that the small change exists, adjusting the baseline of the ADCs by a fraction of the small change based on the comparison between the predetermined value and the first value of the baseline.

Abstract: Methods, computer-readable mediums, and a circuit are provided. In one embodiment, a method is provided which obtains a digital sample. The method calculates a second derivative of the digital sample and thereafter determines when the second derivative passed through a zero crossing point. A master clock value and the second derivative value before and after the second derivate passes through zero are used to calculate a clock fraction and add the clock fraction to the master clock value. Thereafter, an event start signal is triggered to initiates signal processing.

Abstract: PET signals are amplified in a hybrid PET/MR system. An amplifier structure is provided for operation in the magnetic field of the MR magnets. By filtering to remove signals at the MR frequency (e.g., about 123 MHz) as part of the amplification circuit, the amplification circuit may be positioned within the RF cabin, within the magnetic field, and even within a same housing as the MR magnets. MR interference may be reduced by staged amplification. The filtering may be bi-directional, such as using parallel and series traps. Digitization of the PET signals may be provided within the magnetic field with no or little interference with MR operation.

Abstract: A data processing process and embodiment for optimizing the signal path for multi-modality imaging is described. The embodiment and process optimizes the signal to noise ratio in a positron emission tomography (PET) signal path utilizing scintillation crystals, avalanche photo diodes, and charge sensitive preamplifiers in a dual modality MRI/PET scanner. The dual use of both and analog pole zero circuit and a digital filter enables higher signal levels or a fixed ADC input range and thus a higher possible signal to noise ratio in the presence of significant pileup caused by high positron activity. The higher signal to noise ratio is needed in the PET signal architecture, because of the presence of non-modal time varying electromagnetic fields from the MR, which are a significant source of noise for the wideband PET signal modality.

Abstract: A representative method for determining a zero baseline value of a channel from a detector device of a nuclear medicine imagining system to allow for correction caused by noise or interference on the detector device includes calculating a first value of a baseline based on a first sample of analog electrical signals from analog-to-digital converters (ADCs) coupled to the detector device; comparing a predetermined value with the first value of the baseline; determining whether there is a small change between the predetermined value and the first value of the baseline; and responsive to determining that the small change exists, adjusting the baseline of the ADCs by a fraction of the small change based on the comparison between the predetermined value and the first value of the baseline.

Abstract: Methods, computer-readable mediums, and a circuit are provided. In one embodiment, a method is provided which obtains a digital sample. The method calculates a second derivative of the digital sample and thereafter determines when the second derivative passed through a zero crossing point. A master clock value and the second derivative value before and after the second derivate passes through zero are used to calculate a clock fraction and add the clock fraction to the master clock value. Thereafter, an event start signal is triggered to initiates signal processing.

Abstract: A printed circuit board (PCB) assembly of a data processing unit for an integrated magnetic resonance (MR) and positron emission tomography (PET) system, the PCB assembly includes a plurality of PCB layers disposed in a stacked arrangement, first and second PET signal processing circuits carried by a first layer of the plurality of PCB layers, first and second ground plane structures carried by a second layer of the plurality of PCB layers and configured relative to the first and second PET signal processing circuits, respectively, and a ground partition that separates the first PET signal processing circuit from the second PET signal processing circuit on the first layer. The ground partition extends through the first layer to provide electromagnetic interference (EMI) shielding between the first and second PET signal processing circuits.

Abstract: PET signals are amplified in a hybrid PET/MR system. An amplifier structure is provided for operation in the magnetic field of the MR magnets. By filtering to remove signals at the MR frequency (e.g., about 123 MHz) as part of the amplification circuit, the amplification circuit may be positioned within the RF cabin, within the magnetic field, and even within a same housing as the MR magnets. MR interference may be reduced by staged amplification. The filtering may be bi-directional, such as using parallel and series traps. Digitization of the PET signals may be provided within the magnetic field with no or little interference with MR operation.

Abstract: A data processing process and embodiment for optimizing the signal path for multi-modality imaging is described. The embodiment and process optimizes the signal to noise ratio in a positron emission tomography (PET) signal path utilizing scintillation crystals, avalanche photo diodes, and charge sensitive preamplifiers in a dual modality MRI/PET scanner. The dual use of both and analog pole zero circuit and a digital filter enables higher signal levels or a fixed ADC input range and thus a higher possible signal to noise ratio in the presence of significant pileup caused by high positron activity. The higher signal to noise ratio is needed in the PET signal architecture, because of the presence of non-modal time varying electromagnetic fields from the MR, which are a significant source of noise for the wideband PET signal modality.

Abstract: Method and system are provided for calibrating a nuclear medical imaging apparatus for DC shift caused by gamma event afterglow pulses. Detector responses to weak and to high count rate radiation sources are compared with each other, and a zero correction value is incremented until the detector response is the same for the weak source and the high count rate source. The zero correction value is then stored as a static zero correction value, which multiplies a dynamic zero correction value obtained just prior to the occurrence of a gamma event, in order to remove the effects of DC shifts from the output energy signal Esum.

Abstract: Method and system are provided for calibrating a nuclear medical imaging apparatus for DC shift caused by gamma event afterglow pulses. Detector responses to weak and to high count rate radiation sources are compared with each other, and a zero correction value is incremented until the detector response is the same for the weak source and the high count rate source. The zero correction value is then stored as a static zero correction value, which multiplies a dynamic zero correction value obtained just prior to the occurrence of a gamma event, in order to remove the effects of DC shifts from the output energy signal Esum.

Abstract: Method and system are provided for calibrating a nuclear medical imaging apparatus for DC shift caused by gamma event afterglow pulses. Detector responses to weak and to high count rate radiation sources are compared with each other, and a zero correction value is incremented until the detector response is the same for the weak source and the high count rate source. The zero correction value is then stored as a static zero correction value, which multiplies a dynamic zero correction value obtained just prior to the occurrence of a gamma event, in order to remove the effects of DC shifts from the output energy signal Esum.

Abstract: Methods and apparatus provide for determining whether X-rays produced by a computer tomography (CT) scanner have infiltrated a single photon emission computed tomography (SPECT) scanner and shutting down at least one of a power source to one or more photo-multiplier tubes (PMTs) of the SPECT scanner, and an X-ray source of the CT scanner, when the determination is affirmative.

Abstract: The afterglow and count rate/dead time of a nuclear imaging detector are calculated for use in correcting event detection and energy integration circuits. Energy value signals and event triggering signals are respectively integrated as a function of the decay setting of the detector, until they reach stable values, which are respectively used as afterglow and count rate/dead time signals used by a data processor of the detector.

Abstract: Method and system are provided for calibrating a nuclear medical imaging apparatus for DC shift caused by gamma event afterglow pulses. Detector responses to weak and to high count rate radiation sources are compared with each other, and a zero correction value is incremented until the detector response is the same for the weak source and the high count rate source. The zero correction value is then stored as a static zero correction value, which multiplies a dynamic zero correction value obtained just prior to the occurrence of a gamma event, in order to remove the effects of DC shifts from the output energy signal Esum.

Abstract: Digital detection of the occurrence of nuclear medicine radiation interaction events in a detector utilizes a digital energy signal sample to trigger signal processing of event signals from the detector by performing mathematical operations on the energy signal sample to determine the existence of a set of predetermined conditions that indicate the beginning of an interaction event in the detector.