Detector in an imaging system

1. A method for evaluating a working condition of a photodetector of a detector in an imaging device comprising:

receiving radiation by the detector in response to which a plurality of single events occur, wherein the detector includes a scintillator and the radiation is generated by a background radiation of the scintillator;

generating, by the photodetector, an electronic signal relating to the plurality of single events;

determining a parameter of the electronic signal relating to a photon energy spectrum of the plurality of single events; and

evaluating the working condition of the photodetector based on the parameter.

2. The method of claim 1 , wherein the electronic signal comprises a pulse signal.

3. The method of claim 1 , wherein the electronic signal comprises time related information processed by a time-to-digital convertor (TDC) having multiple TDC channels.

4. The method of claim 1 , the determining a parameter of the electronic signal relating to the plurality of single events comprising:

obtaining a counting distribution of the plurality of single events.

5. The method of claim 4 , wherein the counting distribution of the plurality of single events relates to multiple TDC channels of a time-to-digital convertor (TDC).

6. The method of claim 5 , the evaluating the working condition of the photodetector based on the parameter comprising:

selecting a reference channel from the multiple TDC channels;

dividing the multiple TDC channels into a first set of TDC channels and a second set of TDC channels based on the reference channel, wherein a number of single events corresponding to the first set of TDC channels is equal to a number of single events corresponding to the second set of TDC channels;

setting a reference time to the reference channel; and

calculating a time value relating to one of the multiple TDC channels according to the reference time.

7. The method of claim 6 , wherein the time value relating to one of the multiple TDC channels is calculated based on the reference time, a serial number of one of the multiple TDC channels, the single event count of one of the multiple TDC channels, and a clock period of the TDC.

8. The method of claim 6 , wherein the reference time is set as half of a clock period of the TDC.

9. The method of claim 1 , the determining a parameter of the electric signal relating to the plurality of single events comprising:

determining a first peak of the photon energy spectrum of the plurality of single events.

10. The method of claim 9 , the evaluating the working condition of the photodetector comprising:

determining a characteristic radiation peak relating to the plurality of single events;

determining a deviation between the first peak and the characteristic radiation peak; and

evaluating the working condition of the photodetector based on the deviation.

11. The method of claim 10 , the evaluating the working condition of the photodetector further comprising:

determining whether the deviation between the first peak and the characteristic radiation peak is below a threshold; and

in response to the determination that the deviation between the first peak and the characteristic radiation peak is below the threshold, assigning the photodetector into a first set.

12. A system, comprising:

a detector configured to receive radiation in response to which a plurality of single events occur;

a photodetector of the detector configured to generate an electronic signal relating to the plurality of single events; and

a processing module configured to:

determine a first peak of a photon energy spectrum of the plurality of single events based on the electronic signal;

determine a characteristic radiation peak of the plurality of single events;

determine a deviation between the first peak and the characteristic radiation peak; and

evaluate a working condition of the photodetector based on the deviation.

13. The system of claim 12 , wherein the radiation received by the detector is generated by a radiation source placed in a field of view of the detector.

14. The system of claim 12 , wherein the photodetector comprises at least one device selected from a group consisting of a photomultiplier, a silicon photomultiplier, and an avalanche diode.

15. The system of claim 12 , wherein the photodetector is connected with a voltage divider.

16. The system of claim 12 , wherein the radiation received by the detector is from a background radiation of a scintillator.

17. The system of claim 16 , wherein the scintillator exhibits at least one characteristic radiation.

18. The system of claim 16 , wherein the scintillator comprises a lutetium compound.

19. The system of claim 12 , wherein the processing module is further configured to:

determine whether the deviation between the first peak and the characteristic radiation peak is below a threshold; and

in response to the determination that the deviation between the first peak and the characteristic radiation peak is below the threshold, assign the photodetector into a first set.

20. The system of claim 12 , wherein the electronic signal comprises time related information processed by a time-to-digital convertor (TDC).