1. Potential Advantages of Digitally Sampling Scintillation Pulses in Timing Determination in PET
Qingguo Xie1,2, Chien-Min Kao1, Xi Wang2, Ning Guo2,
Caigang Zhu2, Henry Frisch3, William W. Moses4, and
C.-T. Chen1
1Department of Radiology, The University of Chicago, Chicago, IL, USA
2Department of Biomedical Engineering, Huazhong University of Science and Technology, Wuhan, Hubei, China
3Enrico Fermi Institute, The University of Chicago, Chicago, IL, USA
4Lawrence Berkeley National Laboratory, Berkeley, California, USA

2. Pulse Library LSO/PMT (Bill’s Module)

3. Pulse Library LSO/PMT (Bill’s Module)

4. Pulse Library LSO/PMT (Bill’s Module)

5. Pulse Library LSO/PMT Sample Pulse @ 511keV

6. Pulse Library HRRT Module
The HRRT detector head contains an array of 9 by 13 crystal blocks that are coupled to an array of 10 by 14 photomultiplier tubes (PMTs) by using the PMT-quadrant-sharing configuration (PQS). Each crystal block of the HRRT is made of 8x8 double-layered LSO/LYSO phoswich scintillators.

7. Pulse Library HRRT Module
HRRT Detector Heads
The prototype consists of two HRRT (High Resolution Research Tomograph) detector heads. The spacing between detectors shown is ~6 cm, which is adequate for imaging rodents.
A single double-layered, 8 x 8 LSO crystal block affixes onto 4 photomultiplier tubes in the quadrant-sharing configuration.

8. Pulse Library HRRT Module Sample Pulse @ 511keV

9. Pulse Library HRRT Module Sample Pulse @ 511keV

10. Pulse Library LYSO/MPPC

11. An MPPC having 100 microcells Hamamatsu S10362-11-100C Sample 171
MPPC Principle
Equivalent circuit
An MPPC having 100 microcells Hamamatsu S C Sample 171

12. Pulse Library LYSO/MPPC Sample Pulse @ 511keV
50-mm

13. Datasets Dataset 1 Dataset 2 Bill’s Module 1500 pulses LLD:~370keV

14. Energy Histogram Dataset 2

15. Energy Histogram Dataset 2

16. Average Pulses Ch1 (1621 pulse pairs)

17. Average Pulses Ch1 Averaged Pulse

18. Average Pulses Ch1 Noise Variance

19. Average Pulses Ch1 Noise Standard Deviation

20. Average Pulses Ch1 Noise sum{|Nx|}

21. Average Pulses Ch2 Averaged Pulse (1731 pulse pairs)

22. Average Pulses Dataset 1

23. Average Pulses Dataset 1

24. Multi-threshold Time Picking-up

25. Coincidence Timing Resolution 350 keV, 4 Thresholds, 312 ps FWHM
4Thresholds, FWHM=312ps
Threshold_Ch2=40mv, 90mv, 140mv, 190mv
Threshold_Ch1= 216/267*Threshold_Ch2

26. Coincidence Timing Resolution 350 keV, 6 Thresholds, 296 ps FWHM
6 Thresholds, FWHM=296ps
Threshold_Ch2=40mv, 70mv, 100mv, 130mv, 160mv, 190mv
Threshold_Ch1= 216/267*Threshold_Ch2

27. Coincidence Timing Resolution 350 keV, 8 Thresholds, 291 ps FWHM
8 Thresholds, FWHM=291ps
Threshold_Ch2=40mv, 60mv, 80mv, 100mv, 120mv, 140mv, 160mv, 180mv
Threshold_Ch1= 216/267*Threshold_Ch2

28. Coincidence Timing Resolution 350keV and 400keV
# Thresholds 350keV 400keV
ps 304ps
ps 288ps
ps 283ps
Dataset 2:
350keV, 3579 pulse pairs
400keV, 3140 pulse pairs

29. Coincidence Timing Resolution 4 Thresholds

30. Coincidence Timing Resolution 6 Thresholds

31. Coincidence Timing Resolution 8 Thresholds

32. Coincidence Timing Resolution Energy Groups
Ch2 En1 En2 En3
Ch1
En ps 305ps 303ps
En ps 293ps 283ps
En ps 295ps 250ps
En1:
En2: (+-5%)
En3: >536

33. Coincidence Timing Resolution Fixed Time Digitized Pulse Fitting

34. Coincidence Timing Resolution Fixed Time Digitized Pulse Fitting

35. Coincidence Timing Resolution CFD
TH FWHM
085keV 341ps
175keV 313ps
350keV 297ps

36. Coincidence Timing Resolution Software CFD
~ , 1.6ns for 370keV using dataset 1

37. System Block Digitized pulse

38. System Block Digitized pulse

39. Discussion
Timing resolution obtained from digitized pulses is comparable to analog CFD.
Efficient calibration, especially system level for TOF PET
Benefits for PET: Position, Energy, Time, and Count-rate
Advanced algorithms
Dependence between shapes and scintillators, energy (Average Pulse Fitting, slightly better timing resolution, pulse simulation, Monte Carlo, pattern reconzation)
Noise pattern

40. Acknowledgement Collaborators: Bo Zhang Robert Wagner Gary Drake
John Anderson
Camden D. Ertley
Jean Francois
Patrick LeDu
Christophe Royon
Joy Lin
Octavia
Fukun Tang
Seungryong Cho
Jeffrey S. Souris
Qian Zhang
Shuijin Su
Zheng Tian