[Gate-users] Potential bug in ring repeaters in GATE

[Zhengzhi Liu]

After looking into the singles file, it looks alright. There are many
qualified coincidence events in the singles file, but they were not
captured by coincidence sorter. This consistently happens when the times of
ring repeater is set to 2, but it works fine when the times of ring
repeater is set to other values (>2). Thus I believe it might be a bug that
set the times of ring repeater to 2 would cause the failure of coincidence
sorter in PET.

Has anyone experienced this issue before? Any thoughts?

Sincerely appreciate any help you can provide.

Zhengzhi

On Sat, Jan 25, 2020 at 4:12 PM Zhengzhi Liu <zliu36 at stanford.edu> wrote:

> It looks like ring repeaters does not like twice, other times of
> repartition seem to work fine.
>
> On Sat, Jan 25, 2020 at 3:53 PM Zhengzhi Liu <zliu36 at stanford.edu> wrote:
>
>> Dear GATE developers and users,
>>
>> I recently came across a weird situation in GATE and have spent a few
>> days on it, but still could not figure it out why. Here is the problem:
>>
>> In benchPET
>> <https://github.com/OpenGATE/Gate/blob/develop/benchmarks/benchPET/camera.mac> and
>> GateContrib
>> <https://github.com/OpenGATE/GateContrib/blob/master/imaging/PET/PET_CylindricalPET_System.mac>,
>> the original code works fine, but soon as I change the times in the ring
>> repeater to 2 in the following code, there will be no coincidence event
>> recorded:
>>
>> /gate/head/repeaters/insert                          ring
>> /gate/head/ring/setRepeatNumber               4
>>
>> I did check all the details and nothing seems to have been changed
>> fundamentally, except that there are fewer detectors in the transaxial
>> plane. Even so, there are still two detector panels facing each other as
>> shown in the attached figure (benchPET_ring_repeaters_2.png). Each detector
>> panel has registered many singles as shown in the root plot
>> (hits_on_detectors.png). However, there was no coincidence event
>> registered, not event a single coincidence event. Originally I thought it
>> might be due to low geometrical sensitivity but after moving these detector
>> panels closer to each other and increasing simulation time, there was still
>> no coincidence event registered.
>>
>> This phenomenon happens in both PET simulation cases mentioned above and
>> other PET simulations. Has anyone come across this problem before? Is this
>> a bug or simply my mistake?  Please give me any thoughts or help.
>>
>> Thank you very much,
>> Sincere regards.
>>
>> Zhengzhi
>>
>>
>>
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