# ERROR to find events

**URL:** <https://castor-project.discourse.group/t/error-to-find-events/167>\
**Category:** General Discussions\
**Created:** [August 20, 2020, 2:52pm UTC](https://castor-project.discourse.group/t/error-to-find-events/167 "2020-08-20T14:52:50Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![Pedro\_Henrique\_Durao](https://avatars.discourse-cdn.com/v4/letter/p/50afbb/32.png) [@Pedro\_Henrique\_Durao](https://castor-project.discourse.group/u/Pedro_Henrique_Durao)\
**Post date:** [August 20, 2020, 2:52pm UTC](https://castor-project.discourse.group/t/error-to-find-events/167/1 "2020-08-20T14:52:50Z")

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Dear CASToR users,

I’m trying to reconstruct a monolithic PET with 10 detectors off 50x50x10 mm3 and a point source of 148kBq. The following error occurred:

\*\*\*\*\* iScannerPET::GetPositionsAndOrientations() → Crystal index 1 (56221040) out of range [0:9] !  
\*\*\*\*\* The following error message was issued by MPI instance 0  
\*\*\*\*\* vProjector::Project() → A problem occurred while getting positions and orientations from scanner !  
\*\*\*\*\* The following error message was issued by MPI instance 0  
\*\*\*\*\* oProjectorManager::ComputeProjectionLine() → A problem occurred while forward projecting an event !  
\*\*\*\*\* The following error message was issued by MPI instance 0  
\*\*\*\*\* iIterativeAlgorithm::StepInnerLoopInsideSubsetLoop() → A problem occurred while computing the projection line !  
\*\*\*\*\* The following error message was issued by MPI instance 0

Someone can help me with this?  
Regards,  
Pedro

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**Author:** ![FILIPOVIC\_PIERUCCI\_M](https://avatars.discourse-cdn.com/v4/letter/f/8491ac/32.png) [@FILIPOVIC\_PIERUCCI\_M](https://castor-project.discourse.group/u/FILIPOVIC_PIERUCCI_M)\
**Post date:** [August 20, 2020, 3:05pm UTC](https://castor-project.discourse.group/t/error-to-find-events/167/2 "2020-08-20T15:05:07Z")

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Hi,

The error says that the index of one of the detectors related to a data element (list-mode event or histogram bin) while reading your datafile is 56221040, whereas you have only 10 detectors, so the indices go from 0 to 9. For all the histogram bins or list-mode events, the indices of the related detectors should be comprised between 0 and 9, if I understand your scanner correctly.

Hope this helps

Marina