Nuclear medicine diagnosis apparatus

1. A nuclear medicine diagnosis apparatus comprising:

a light signal generating unit configured to repeatedly generate light signals;

a photodetection unit configured to repeatedly detect the generated light signals, repeatedly generate first output signals corresponding to intensities of the detected light signals, repeatedly detect gamma rays emitted from a subject, and repeatedly generate second output signals corresponding to intensities of the detected gamma rays;

a measurement unit configured to repeatedly measure light signal detection times of the light signals in the photodetection units and repeatedly measure gamma ray detection times of the gamma rays in the photodetection unit;

a calculation unit configured to calculate a difference between a target gamma ray detection time and a target light signal detection time of the light signal detection times for each of the gamma ray detection times, the target light signal detection time being measured before the target gamma ray detection time; and

a storage unit configured to store the calculated difference in association with a target second output signal of the second output signals.

2. The apparatus according to claim 1 , wherein the photodetection unit includes a plurality of photodetectors provided around a long axis of a top on which the subject is placed,

the light signal generating unit is joined to the plurality of photodetectors via a plurality of photoconductive paths, and

the plurality of photoconductive paths have substantially the same length.

3. The apparatus according to claim 2 , wherein each of the plurality of photodetectors comprises a scintillator configured to generate fluorescence upon receiving light, an electrical signal generating unit configured to generate an electrical signal upon receiving fluorescence generated by the scintillator, and a light guide placed between the scintillator and the electrical signal generating unit, and

the light signal generating unit simultaneously applies the light signals to the respective light guides.

4. The apparatus according to claim 2 , wherein each of the plurality of photodetectors comprises a scintillator configured to generate fluorescence upon receiving light and an electrical signal generating unit configured to generate an electrical signal upon receiving fluorescence generated by the scintillator, and

the light signal generating unit simultaneously applies the light signals to the respective scintillators.

5. The apparatus according to claim 2 , wherein the light signal generating unit simultaneously applies a plurality of light signals to the plurality of photodetectors via the plurality of photoconductive paths.

6. The apparatus according to claim 2 , wherein each of the plurality of photoconductive paths comprises an optical fiber.

7. The apparatus according to claim 2 , wherein a target gamma ray and a target light signal measured by a same photodetector of the plurality of photodetectors, the target gamma ray being each of the gamma rays, the target light signal being each of the light signals.

8. The apparatus according to claim 7 , wherein the target light signal comprises a light signal measured immediately before the target gamma ray detection time.

9. The apparatus according to claim 1 , further comprising an identifying unit configured to identify a pair of second output signals, of the second output signals, which originate from a pair of annihilation gamma rays by using the difference as a time stamp.

10. The apparatus according to claim 1 , further comprising an identifying unit configured to identify a pair of second output signals among the second output signals based on the difference and a predetermined time frame, the pair of second output signals originating from a pair of annihilation gamma rays.

11. The apparatus according to claim 10 , further comprising a reconstruction unit configured to reconstruct image data concerning the subject based on the identified second output signals.