[Castor-users] Problem on Reconstruction from GATE root output

tmerlin Thibaut.Merlin at univ-brest.fr
Fri Sep 8 20:53:53 CEST 2017


Hello Ying-yu,

For your questions:

Q1: Yes, the -t option only converts true unscattered events and there 
is no current option to keep only trues and scatters. However you could 
make some small changes in the file 
/toolkits/castor-GATERootToCastor.cc/ in order to recover both trues and 
scatters:

Around line 1492, replace:

/if (true_only_flag==true && kind != KIND_TRUE)/

by

/if (true_only_flag==true && kind != KIND_TRUE && ///kind != KIND_SCAT 
/////&& ///kind != KIND_MSCAT/// ) /

and around line 1646, replace:

/      Out_data_file->SetNbEvents( (true_only_flag) ?//nLORs_trues ://  
nLORs_tot ) ;/

by

/      Out_data_file->SetNbEvents( (true_only_flag) ?////nLORs_trues 
/+/nLORs_scatters ://nLORs_tot ) ;/

/
/then recompile. Then the datafile should include scatters as well./
/

/
/

Q2://Maximum ring difference set to -1 just mean there is no restriction 
regarding the ring difference. So it will be equal to 51 in your case./
/

/
/

Q3://I am not sure what is wrong in the reconstructed images. The 
positions of the sphere sources in the image are not correct ?/
/

/
/

Best regards,

Thibaut/
/

/
/

/
/


On 07/09/2017 10:00, Ying-yu Chen wrote:
> Dear CASToR users,
>
> I'm trying to build an PET simulation using the GATE ecat system. The 
> Geometry macro "Geometry.mac" is attached for reference.
>
> I first simulated two 2.5mm-radius sphere sources in a phantom.From 
> raw sinogram, I think I can see the two sphere sources.  Root datafile 
> and raw sinogram could be downloaded through the following link.
> https://drive.google.com/open?id=0B0vKwnYlHgr1LWpiclpnTUFZbUE
>
> I converted the GATE geometry to the .geom file ("GATE_PET.geom" as 
> attached) and then converted root datafile to CASToR datafile with -t 
> option. ("aq4.log", "aq4_CstrProj.Cdh" and "aq4_CstrProj.Cdf" as attached)
>
> Q1: It seems that the -t option only converts true unscattered events. 
> Is it able to convert true unscattered and scattered events (no random)?
>
> Q2: In aq4_CstrProj.Cdh, the maximum ring difference is -1. Since the 
> simulated PET has 52 detector rings, I think the maximum ring 
> difference should be 51. I would like to know why is it -1?
>
> Then I use the following command to perform the reconstruction.
>
> castor-recon -df aq4_CstrProj.Cdh -dout recon_aq4 -it 3:8 -dim 
> 400,400,109 -fov 780,780,218
>
>
> Q3: The reconstructed images are not right. Is there any idea how I 
> can solve it?
> https://drive.google.com/open?id=0B0vKwnYlHgr1V3F2Q2JTLTlyc00
>
> Thank you very much and I'm looking forward to hearing from you.
>
> Your sincerely,
> Ying-Yu Chen
>
>
>
>
> _______________________________________________
> Castor-users mailing list
> Castor-users at lists.castor-project.org
> http://lists.castor-project.org/listinfo/castor-users

-- 
Thibaut MERLIN -- PhD

Docteur en Imagerie Médicale au Laboratoire de Traitement de l'Information Medicale (LaTIM - INSERM UMR 1101)
Bâtiment 1
CHRU Morvan - 2, Av. Foch
29609 Brest CEDEX - FRANCE
Tel: 06.75.12.24.90

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