Modular signal processing backbone for PET

An imaging system having a scalable event processing architecture, comprising:

• a plurality of detector modules arranged around an associated imaging region to detect radiation events emitted from a subject disposed within the imaging region;
• a plurality of sets of processing elements, each set including processing elements of at least one of the plurality of radiation detector modules, each processing element:
• digitizing detected radiation events;
• time-stamping the detected radiation events;
• and
• inserting event packets, each event package including one of the time-stamped events, into a chronological position within a data stream of the time-stamped events;
• and
• a dummy packet inserting component that inserts time stamped dummy packets which contain non-event information chronologically into the data stream such that a continuous flow of packets through each of the processing elements is ensured and such that locating chronological positions within the stream of events for event packet insertions is facilitated;
• and
• coincident detecting circuitry that receives the chronologically ordered stream of packets and detectors coincident pairs of events in the event packets for use in reconstructing one or more associated images of the object.

A method for sorting radiation events prior to coincident detectors, the method comprising:

• detecting radiation events at each of a plurality of radiation detection modules;
• generating a time-stamped packet representing each event;
• inserting each packet into a stream of packets in a corresponding chronological order, the stream serially traversing the detector modules;
• passing the stream through each module a plurality of times;
• and
• examining the stream of packets for coincident pairs.

A processor for sorting coincident events in medical imaging devices, comprising:

• one or more different sets of processing elements that are coupled to form a data path for carrying a stream of sorted packets;
• at least one inserter associated with each of the one or more different set of processing elements, each inserter:
• determines a chronological position in the stream for a packet being inserted,
• inserts the packet into the chronological position in the stream,
• computes a time difference between a time stamp of a packet currently traversing the inserter and a time stamp of the packet being inserted, and
• periodically monitors packets in the stream to locate the chronological position of the packet being inserted based on the time difference.

An imaging system comprising:

• a plurality of radiation detector modules disposed in one or more rings around an examination region, each module including an array of radiation detectors which produce signals indicative of radiation events and a plurality of processing elements, each processing element digitizes the radiation event signals, time stamps the digitized radiation event signals, forms time-stamped packets each including one of the digitized radiation event signals and an event location, and inserts the time-stamped radiation event packets chronologically in order in a packet stream;
• a packet stream path which connects the plurality of processing elements, the packet stream path running from a first of the processing elements on a given detector module and through a signal processing element on each of a plurality of others of the detector modules before running through a second of the processing elements on said given detector module;
• a plurality of intramodule packet paths, each of the intramodule packet paths connecting a pair of processing elements in the given detector module, such that the time-stamped radiation event events packets of the given detector module can be inserted into the packet stream in any of a plurality of passes of the packet stream through the given detector module;
• a dummy packet inserting component connected to the packet stream, the dummy packet inserting component inserting time-stamped dummy packets into the data stream, the dummy packets carrying other than radiation event information;
• and
• a coincidence detector connected with the packet stream path to receive the packet stream, the coincidence detector detecting coincident pairs of radiation events from the time stamps of the time-stamped radiation event packets, the coincident pairs of radiation events defining lines of response to be used to reconstruct an image of a subject in the examination region.