[Gate-users] Help, problems with PET system consists of different detectors (multiple system simulation)

[Li, Ke]

Dear GATE users,


I'm trying to run some simulation of a PET scanner that has two different kinds of crystal and corresponding electronics. Using the multi-system feature in GATE v6.2 I could define two-system PET scanner. Following is my setup:


# First Scanner (cylindricalPET)
/gate/world/daughters/name Scanner_1
/gate/world/daughters/systemType cylindricalPET
........................
# Second Scanner (cylindricalPET)
/gate/world/daughters/name Scanner_2
/gate/world/daughters/systemType cylindricalPET

.........................



The system, and its modules are successfully attached.

Then for the Digitizer part, I have 2 digitizer:


# For Scanner_1, using default singles chain "Singles"
/gate/digitizer/Singles/insert systemFilter
/gate/digitizer/Singles/systemFilter/selectSystem Scanner_1
....................
# For Scanner_2, adding another singles chain "Singles_2"
/gate/digitizer/name Singles_2
/gate/digitizer/insert singleChain
/gate/digitizer/Singles_2/insert systemFilter
/gate/digitizer/Singles_2/systemFilter/selectSystem Scanner_2
..................



Then these two singles chain go to 2 coincidence sorter:



# Using default "Coincidences" for default single chain "Singles"
/gate/digitizer/Coincidences/setInputName Singles

..................

# Adding another coincidence sorter "Coincidences_2" using singles input "Singles_2"
/gate/digitizer/name Coincidences_2
/gate/digitizer/insert coincidenceSorter
/gate/digitizer/Coincidences_2/setInputName Singles_2


?After simulation(ASCII output), I got 2 singles file and 2 coincidence file. Here comes my problems:


Question 1.

According to the user guide, Data output part, http://wiki.opengatecollaboration.org/index.php/Users_Guide_V6.2:Data_output?

In the singles.dat file, column 7-12 should be the ID of the volumes of detection, in which column 7 is "ID of volume attached to the "base" level of the system". In this multi-system PET, I expect to see this value be different(say 0 and 1) in the two singles.dat file (corresponding to Scanner_1 and Scanner_2). But actually in both files, this value is 0, which means I could not tell from an entry that which system this single comes from. Is this normal? If so, what does "the "base" level of the system" mean?


Question 2.

In GATE 6.2, is there any ways to find the coincidence across different systems? For example, I would like to have coincidence between Scanner_1 and Sanner_2, or let the coincidence processor not only find coincidence within single chain "Singles" and "Singles_2" but also coincidences that has one event in "Singles" and the other event in "Singles_2"

I noticed there is a chapter on using the TriCoincidence processor to find coincidence between a coincidence pulse and a singles list. But this is not what I want. This is finding coincidence between a coincidence pulse and a singles list. I need to find coincidence between two singles list.


Thanks.



Ke Li
PhD student
Department of Electrical and System Engineering
Washington University in St. Louis
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