# partial pet image reconstruction

**URL:** <https://castor-project.discourse.group/t/partial-pet-image-reconstruction/225>\
**Category:** General Discussions\
**Created:** [July 10, 2021, 6:00pm UTC](https://castor-project.discourse.group/t/partial-pet-image-reconstruction/225 "2021-07-10T18:00:05Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![Jform\_M](https://avatars.discourse-cdn.com/v4/letter/j/eb8c5e/32.png) [@Jform\_M](https://castor-project.discourse.group/u/Jform_M)\
**Post date:** [July 10, 2021, 6:00pm UTC](https://castor-project.discourse.group/t/partial-pet-image-reconstruction/225/1 "2021-07-10T18:00:05Z")

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Dear CASToR users and developers,  
I simulated a partial cylindrical pet scanner in Gate (suitable for bladder cancer therapy) and the root file is made and I want to define the .geom file to reconstruct but I don’t have any idea to do this well.  
I wrote some .geom files but they didn’t work properly.  
is it possible to reconstruct a partial pet root file in castor?

can anyone help me to reconstruct the root file?

Thanking you in advance for your responses,

Sincerely,

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**Author:** ![tmerlin](https://yyz2.discourse-cdn.com/free1/user_avatar/castor-project.discourse.group/tmerlin/32/216_2.png) [@tmerlin](https://castor-project.discourse.group/u/tmerlin)\
**Post date:** [July 15, 2021, 8:13am UTC](https://castor-project.discourse.group/t/partial-pet-image-reconstruction/225/2 "2021-07-15T08:13:05Z")

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Hi,

The Gate converter tools will work properly only if the geometry could be derived by castor from the macro files. It is possible that the custom geom file you wrote corresponds to the actual geometry, but the conversion of root system IDs (rsectorID, crystalID, etc…) to castorIDs is erroneous as the geometry cannot be read properly by castor-GATERootToCastor.

If the geometry cannot be read (for example if the blocks are placed by hands), then both the geometry and the datafile must be manually converted. You could have a look to _ConvertIDcylindrical()_ and _CreateGeomWithCylindrical()_ functions in _src/gDataConversionUtilities.cc_ to get some hints regarding how the IDs are converted.

Hope this helps,  
Thibaut