Multi-head nuclear medicine camera for dual SPECT and PET imaging
First Claim
1. A nuclear camera system comprising:
- a first detector and a second detector for detecting scintillation events, said first detector and said second detector coupled to an acquisition computer system;
a input mechanism for selecting between a PET imaging mode and a SPECT imaging mode;
a switchable trigger detection unit that is automatically switchable between coincidence detection when said PET imaging mode is selected and non-coincidence detection when said SPECT imaging mode is selected;
said switchable trigger detection unit coupled to supply a first valid event trigger signal to said first detector causing said first detector to record a scintillation event and coupled to supply a second valid event trigger signal to said second detector causing said second detector to record a scintillation event.
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Abstract
A multi-detector head nuclear camera system automatically switchable (and optimized) to perform either SPECT imaging or PET imaging. The camera system employs, in one embodiment, multi-detector configuration having dual head scintillation detectors but can be implemented with more than two detector heads. The detectors contain switchable triggering circuitry so that coincidence detection for PET imaging and non-coincidence detection for SPECT imaging is available. Using a variable integration technique with programmable integration interval, the event detection and acquisition circuitry of the camera system is switchable to detect events of different energy distribution and count rate which are optimized for PET and SPECT imaging. The system also includes dual integrators on each scintillation detector channel for collecting more than one event per detector at a time for PET or SPECT mode. In PET or SPECT mode, the system also employs variable PMT cluster sizing having smaller cluster sizes for PET imaging and relatively larger cluster sizes for SPECT. In PET or SPECT mode, the system also employs variable centroid shape and zonal triggering. Utilizing the above programmable settings, the camera system can be automatically configured to operate in either SPECT or PET imaging modes.
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Citations
49 Claims
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1. A nuclear camera system comprising:
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a first detector and a second detector for detecting scintillation events, said first detector and said second detector coupled to an acquisition computer system; a input mechanism for selecting between a PET imaging mode and a SPECT imaging mode; a switchable trigger detection unit that is automatically switchable between coincidence detection when said PET imaging mode is selected and non-coincidence detection when said SPECT imaging mode is selected; said switchable trigger detection unit coupled to supply a first valid event trigger signal to said first detector causing said first detector to record a scintillation event and coupled to supply a second valid event trigger signal to said second detector causing said second detector to record a scintillation event. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A trigger signal generator switchable between PET and SPECT operational modes, said trigger signal generator comprising:
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first SPECT event detection circuitry for generating a first trigger signal upon detection of a scintillation event within a first detector; second SPECT event detection circuitry for generating a second trigger signal upon detection of a scintillation event within a second detector; first PET event detection circuitry for generating a third trigger signal upon detection of a scintillation event within said first detector; second PET event detection circuitry for generating a fourth trigger signal upon detection of a scintillation event within said second detector; a coincidence detector coupled to said third and fourth trigger signals for generating a coincidence signal upon coincidence of said third and fourth trigger signals; and a switchable unit receiving said coincidence signal and said first and second trigger signals, said switchable unit for providing said first and second detector with said coincidence signal when in said PET operational mode and for providing said first and second detector with said first and second trigger signals, respectively, when in said SPECT operational mode. - View Dependent Claims (12, 13, 14, 15)
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16. For a channel circuit associated with a photomultiplier of a scintillation detector, an accumulator circuit comprising:
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a programmable register for containing a programmable integration period; an analog to digital converter for receiving a first signal representative of energy detected by said photomultiplier as a result of a scintillation event and for digitizing said first signal to generate a digital signal therefrom; a first integrator for integrating said digital signal over said programmable integration period to arrive at a result; a memory circuit for containing said result of said first integrator. - View Dependent Claims (17, 18, 19, 20)
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21. An event detection apparatus comprising:
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(a) at least a pair of scintillation detectors for reporting a pair of events occurring in coincidence for PET imaging and for reporting events individually for SPECT imaging, each of said pair of scintillation detectors comprising; (i) an analog to digital converter for receiving a channel signal representative of energy detected by a photomultiplier as a result of a scintillation event and for digitizing said channel signal to generate a digital signal therefrom; (ii) a first integrator circuit coupled to receive said digital signal and for integrating said digital signal over a first time period of a programmable integration interval; (iii) a second integrator circuit coupled to said digital signal and for integrating said digital signal over a second time period of said programmable integration duration; and (iv) a programmable register for containing a value representative of said programmable integration duration; and (b) a mechanism for recording said events. - View Dependent Claims (22, 23, 24, 25, 26, 27, 28)
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29. In a nuclear medicine camera, an apparatus for generating a photomultiplier cluster, said apparatus comprising:
at least a pair of scintillation detectors for reporting a pair of events occurring in coincidence for PET imaging and for reporting events individually for SPECT imaging, each of said pair of scintillation detectors comprising; an array of photomultipliers wherein individual photomultipliers generate channel signals, integration circuitry integrating said channel signals from each scintillation detector responsive to a gamma event and generating integration results therefrom; peak circuitry for determining a peak photomultiplier based on said integration results and for generating a signal indicative of said peak photomultiplier; and cluster circuitry addressed by said peak circuitry and responsive to said signal indicative of said peak photomultiplier for generating a photomultiplier cluster associated with said peak photomultiplier, said cluster circuitry containing separate photomultiplier clusters for individual photomultipliers of said array of photomultipliers and wherein said cluster circuitry also generates a cluster type signal responsive to said signal indicative of said peak photomultiplier wherein said cluster type signal indicates a geometric type of said photomultiplier cluster. - View Dependent Claims (30, 31, 32, 33, 34, 35, 36)
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37. In a nuclear medicine camera, an apparatus for generating a photomultiplier cluster, said apparatus comprising:
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(a) a user selectable operational mode between PET imaging and SPECT imaging; (b) at least a pair of scintillation detectors for reporting a pair of events occurring in coincidence for said PET imaging and for reporting events individually for said SPECT imaging, each of said pair of scintillation detectors comprising; an array of photomultipliers, individual photomultipliers for generating output channel signals indicative of energy detected by said individual photomultipliers; peak circuitry coupled to receive said output channel signals and for determining a peak photomultiplier of said array of photomultipliers; and cluster circuitry addressed by said peak circuitry and responsive to said signal indicative of said peak photomultiplier for generating a photomultiplier cluster associated with said peak photomultiplier, said cluster circuitry containing separate photomultiplier clusters for each peak photomultiplier, said cluster circuitry for providing photomultiplier clusters of a first size provided said operational mode is said PET imaging and for providing photomultiplier clusters of a second size provided said operational mode is said SPECT imaging; and (c) a mechanism for recording said events detected by said pair of scintillation detectors. - View Dependent Claims (38, 39)
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40. In a nuclear medicine camera, an apparatus for generating a trigger signal indicative of an event, said apparatus comprising:
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(a) a user selectable operational mode between PET imaging and SPECT imaging; (b) at least a pair of scintillation detectors for reporting a pair of events occurring in coincidence for said PET imaging and for reporting events individually for said SPECT imaging, each of said pair of scintillation detectors comprising; an array of photomultipliers, individual photomultipliers for generating output channel signals indicative of energy detected by said individual photomultipliers, wherein said array of photomultipliers is divided into zones; a first plurality of event detection circuits wherein each of said event detection circuits receive channel signals from a particular zone of said zones of said array of photomultipliers; and a first trigger circuit coupled to said first plurality of event detection circuits for generating a trigger signal upon receiving an event indication from any event detection circuit of said first plurality of event detection circuits. - View Dependent Claims (41, 42, 43, 44, 45)
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46. In a nuclear medicine camera, an apparatus for optimizing said camera for either PET or SPECT imaging modes, said apparatus comprising:
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a switchable operational mode between said PET imaging and said SPECT imaging modes; at least a pair of scintillation detectors for reporting a pair of events occurring in coincidence for said PET imaging mode and for reporting events individually for said SPECT imaging mode, said pair of scintillation detectors for rotating about a patient and for collecting projection image data under said PET or SPECT imaging modes; programmable integration circuitry coupled to channel signals output from photomultiplier tubes of said pair of scintillation detectors, said programmable circuitry for integrating said channel signals over a first integration period or over a second integration period in response to said operational mode; a programmable trigger circuit coupled to event detection logic within said pair of scintillation detectors, said programmable trigger circuit for generating valid event trigger signals based on coincidence between said pair of scintillation detectors or not based on coincidence between said pair of scintillation detectors in response to said operational mode; and a programmable photomultiplier cluster circuit responsive to values over said channel signals, said programmable photomultiplier cluster for utilizing a cluster of a first size for localizing detected events and for utilizing a cluster of a second size for localizing detected events in response to said operational mode. - View Dependent Claims (47, 48, 49)
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Specification