Spatially variant PMT cluster constitution and spatially variant PMT weights

A gamma camera system comprising:

• a scintillation detector for receiving gamma radiation, said scintillation detector having an array of photomultipliers wherein individual photomultipliers generate channel signals;
• and
• an apparatus for processing said channel signals, said apparatus comprising:
• integration circuitry integrating said channel signals responsive to a gamma event and generating integration results therefrom;
• peak circuitry for determining a peak photomultiplier based on said integration results;
• cluster circuitry addressed by said peak circuitry and responsive to a signal indicative of said peak photomultiplier for generating addresses of photomultipliers of a photomultiplier cluster associated with said peak photomultiplier, said cluster circuitry containing a listing of photomultiplier clusters associated with photomultipliers of said array;
• said cluster circuitry also for generating a type value signal indicative of a type of said photomultiplier cluster;
• and
• weight circuitry responsive to (1) said addresses of photomultipliers within said photomultiplier cluster and (2) said type value signal, said weight circuitry for generating individual coordinate weight value signals associated with individual photomultipliers of said photomultiplier cluster.

A gamma camera system comprising:

• a scintillation detector for receiving gamma radiation, said scintillation detector having a crystal and an array of photomultipliers optically coupled to said crystal wherein individual photomultipliers generate channel signals in response to a gamma event;
• and
• process circuitry for processing said channel signals for generating a spatial coordinate associated with said gamma event, said process circuitry comprising:
• (a) integration circuitry integrating said channel signals from said scintillation detector responsive to said gamma event and generating integration results therefrom;
• (b) peak circuitry for determining a peak photomultiplier based on said integration results and generating a signal indicative of said peak photomultiplier;
• and
• (c) 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 an individual photomultiplier cluster for individual photomultipliers of said array, 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 including a normal cluster type, an edge cluster type and a corner cluster type.

In a gamma camera system having a scintillation detector for receiving gamma radiation, said scintillation detector having an array of photomultipliers, a method of determining a spatial coordinate of a gamma event, said method comprising the steps of:

• generating channel signals originating from individual photomultipliers of said array in response to said gamma event;
• integrating said channel signals from said scintillation detector to generate integration results therefrom;
• determining a peak photomultiplier based on said integration results and generating a signal indicative of said peak photomultiplier;
• referencing a memory circuit to generate a cluster type signal responsive to said signal indicative of said peak photomultiplier, said cluster type signal indicating a geometric type of said photomultiplier cluster including a normal cluster type, an edge cluster type and a corner cluster type;
• responsive to said signal indicative of said peak photomultiplier, referencing said memory circuit to generate a photomultiplier cluster associated with said peak photomultiplier, said memory circuit containing an individual photomultiplier cluster for individual photomultipliers of said array;
• and
• responsive to integration results of photomultipliers within said photomultiplier cluster and responsive to said cluster type signal, performing a centroid computation to determine said spatial coordinate of said gamma event.

In a gamma camera system having a scintillation detector for receiving gamma radiation, said scintillation detector having an array of photomultipliers wherein individual photomultipliers generate channel signals, an apparatus for generating spatially dependent weight factors, said apparatus comprising:

• integration circuitry integrating said channel signals from said scintillation detector responsive to a gamma event and generating integration results therefrom;
• cluster circuitry responsive to said integration results for generating signals indicative of photomultipliers within a photomultiplier cluster defined by said gamma event;
• circuitry for generating a type value signal indicative of a type of said photomultiplier cluster;
• and
• weight circuitry responsive to (1) said signals indicative of photomultipliers within said photomultiplier cluster and (2) said type value signal, for generating individual coordinate weight value signals associated with individual photomultipliers of said photomultiplier cluster.

In a gamma camera system having a scintillation detector for receiving gamma radiation, said scintillation detector having an array of photomultipliers wherein individual photomultipliers generate channel signals, an apparatus for generating a photomultiplier cluster, said apparatus comprising:

• integration circuitry integrating said channel signals from said 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;
• a resolution mode signal indicative of a high or low resolution mode of said gamma camera system;
• and
• cluster circuitry addressed by said peak circuitry and by said resolution mode signal and responsive to said signal indicative of said peak photomultiplier and said resolution mode signal for generating (1) a photomultiplier cluster and (2) a cluster type signal, both associated with said peak photomultiplier, said cluster circuitry containing an individual photomultiplier cluster and an individual cluster type for individual photomultipliers of said photomultiplier array.

In a gamma camera system having a scintillation detector for receiving gamma radiation, said scintillation detector having an array of photomultipliers wherein individual photomultipliers generate channel signals, a method for generating spatially dependent weight factors, said method comprising the steps of:

• integrating said channel signals from said scintillation detector responsive to a gamma event and generating integration results therefrom;
• generating addresses indicative of photomultipliers within a photomultiplier cluster defined by said gamma event;
• generating a type value signal indicative of a type of said photomultiplier cluster;
• and
• accessing a memory circuit responsive to (1) said addresses indicative of photomultipliers within said photomultiplier cluster and (2) said type value signal and generating in response thereto individual coordinate weight value signals associated with individual photomultipliers of said photomultiplier cluster.