[Castor-users] How to handle GATE noise events?

[tmerlin]

Dear Timothee,

Thank you for noticing this issue, it was definitely an overlook. The 
problem will arise from coincidence generated from two "noisy" singles. 
I believe these events should be considered as random events and treated 
accordingly in the /ComputeKindGATEEvent()/ function. This will be 
addressed in a future patch.

Thanks again and best regards,
Thibaut


On 25/05/2021 18:15, Timothee Zaragori wrote:
> Dear CASToR users and developers,
>
> I recently faced a problem while trying to convert the results of a 
> GATE 9.0 simulation that used noise in the digitizer to CASToR LM format.
> (link to the GATE documentation about noise : 
> https://opengate.readthedocs.io/en/latest/digitizer_and_detector_modeling.html#noise) 
>
> Noise events will have special values assigned to some root keys such 
> as event_ID that will be set to -2 or values related to 
> Compton/Rayleigh interactions that will be set to -1. Here is an 
> example of such a noise coincidence event :
>
>       -1      -2    -1 0.000e+00 0.000e+00 0.000e+00 
> 1.96002948492605288954849e+00 4.799e-01 -3.543e+02 -1.694e+02 
> 5.570e+01     0     1    17     0     2     0 -1     0    -1     0 
> 0.000e+00 0.000e+00       0   16611 0 1.453e+00 -4.481e+01 2.934e+02 
> 1.96002948537939247763973e+00 5.699e-01 3.744e+02 -8.549e+01 
> 7.148e+01     0     8    17     9     3    0      0 0     0     0 
> 0.000e+00 0.000e+00
>
> During the conversion, this event will be classified as an unknown 
> event by the function ComputeKindGATEEvent. With the block checking 
> the restrictions of castor v3.1 (l.2186 of 
> castor-GATERootToCastor.cc), the unknown events will be written to the 
> CASToR LM no matter the restrictions. However, the number of events 
> written in the CASToR LM header will not take into account the unknown 
> events added (l. 2558 of castor-GATERootToCastor.cc) except when no 
> restrictions are applied. When a restriction is applied, this will 
> create a difference between the number of events considered as written 
> in the CASToR LM header versus the number of events actually written 
> in the CASToR LM file resulting in an error when using castor-recon 
> that checks the consistency between the number of events in the header 
> and the length of the LM file.
>
> For my personal use, since I only use true coincidences, I simply 
> added an if block to the block checking the restrictions in order to 
> not write the event in the CASToR LM file if true_only_flag is true. 
> However, I wanted to share with you this case and discuss how these 
> events should be taken into account because I don't think my solution 
> is the right one.
>
>
> Thanking you in advance for your responses,
> Sincerely,
>
> Timothée Zaragori, PhD Student
> Nancyclotep Imaging Platform & IADI (INSERM U1254)
> CHRU de Nancy Brabois, Rue du Morvan
> 54511 Vandoeuvre-Les-Nancy, France
>
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-- 
Thibaut MERLIN -- PhD

Docteur en Imagerie Médicale au Laboratoire de Traitement de l'Information Medicale (LaTIM - INSERM UMR 1101)
Institut Brestois de recherche en Bio-Santé (IBRBS)
12 Avenue Foch, 29200 Brest, FRANCE
Tel: 06.75.12.24.90

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