Pet scanner with digital trigger

1 . A PET scanner comprising:

a plurality of detector modules, each detector module including

a detector for detecting a candidate signal;

a module processor; and

a digital trigger in communication with the detector module and the module processor, the digital trigger being configured to selectively trigger processing of the candidate signal by the module processor.

2 . The PET scanner of claim 1 , further comprising a memory in communication with the digital trigger, the memory being configured to store samples of the candidate signal.

3 . The PET scanner of claim 2 , wherein the memory comprises a FIFO memory.

4 . The PET scanner of claim 2 , wherein the memory comprises a first FIFO memory for storing consecutive samples of the candidate signal separated by a first sampling interval, and a second FIFO memory for storing consecutive samples of the candidate signal separated by a second sampling interval.

5 . The PET scanner of claim 1 , wherein the digital trigger is configured:

to execute, in parallel, a first qualifier for providing a first qualifier output representative of a classification of a candidate signal and a second qualifier for providing a second qualifier output representative of a classification of a candidate signal; and

to cause the module processor to further process the candidate signal at least in part on the basis of the first and second qualifier outputs.

6 . The PET scanner of claim 1 , wherein the digital trigger comprises a single-stage digital trigger.

7 . The PET scanner of claim 1 , wherein the digital trigger comprises a multi-stage digital trigger.

8 . The PET scanner of claim 1 , wherein the digital trigger is configured

to execute cascaded first and second qualifiers,

the first qualifier having a first qualifier output, and

the second qualifier having a second qualifier input and a second qualifier output,

the second qualifier input including information provided by the first qualifier output; and

to cause the module processor to further process the candidate signal on the basis of the second qualifier output.

9 . The PET scanner of claim 8 , wherein the first qualifier is configured to generate

first data indicative of the candidate signal, and

second data indicative of an outcome of processing by the first qualifier; and

wherein the second qualifier is configured to generate an output that depends in part on the second data.

10 . The PET scanner of claim 1 , wherein the digital trigger is configured to execute a first qualifier that recursively executes a second qualifier.

11 . The PET scanner of claim 1 , wherein the digital trigger is configured to execute

an energy qualifier for classifying a candidate signal at least in part on the basis of a first sample set of samples from the candidate signal, and

a timing qualifier for classifying a candidate signal at least in part on the basis of a second sample set of samples from the candidate signal.

12 . The PET scanner of claim 11 , wherein the first sample set includes samples of the candidate signal obtained at a first sampling frequency and the second sample set includes samples of the candidate signal at a second sampling frequency that is greater than the first sampling frequency.

13 . The PET scanner of claim 1 , wherein the digital trigger is configured to be re-programmable.

14 . In a PET scanner, a method for causing a module processor to process a candidate signal, the method comprising:

storing samples of a candidate signal in a memory;

selectively retrieving samples from the memory;

on the basis of the selectively retrieved samples, determining that the candidate signal is indicative of an event; and

sending the module processor information identifying the candidate signal for processing.

15 . The method of claim 14 , further comprising modifying at least one rule used to determine that the candidate signal is indicative of an event.

16 . The method of claim 14 , wherein determining that the candidate signal is indicative of an event comprises:

executing a first process for classifying a candidate signal as being indicative of an event;

executing a second process for classifying a candidate signal as being indicative of an event; and

on the basis of an outcome of the first and second processed, classifying the candidate signal as an event.

17 . The method of claim 14 , wherein determining that a candidate signal is indicative of an event comprises:

retrieving, from the memory, a first set of samples of the candidate signal, the first set including consecutive samples separated by a first sampling interval, and

retrieving, from the memory, a second set of samples of the candidate signal, the second set including consecutive samples separated by a second sampling interval;

on the basis of the first set, generating a first output classifying the candidate signal as being indicative of an event; and

on the basis of the second set, generating a second output classifying the candidate signal as being indicative of an event.

18 . The method of claim 14 , wherein determining that a candidate signal is indicative of an event comprises:

retrieving, from memory, a set of samples of the candidate signal;

executing a first process for classifying the candidate signal on the basis of the set of samples; and

executing a second process for classifying the candidate signal at least in part on the basis of an output of the first process.

19 . A computer-readable medium having encoded thereon software for causing a module processor to process a candidate signal, the software comprising instructions

storing samples of a candidate signal in a memory;

selectively retrieving samples from the memory;

on the basis of the selectively retrieved samples, determining that the candidate signal is indicative of an event; and

sending the module processor information identifying the candidate signal for processing.

20 . A computer-readable medium having encoded thereon software for execution by a digital trigger in a PET scanner having a module processor, the software including instructions that, when executed by the digital trigger, cause the digital trigger to cause processing of a candidate signal by the module processor.