# Cherenkov Photons vs cylindricalPET vs CASToR with TOF vs CASTor without TOF....

**URL:** <https://castor-project.discourse.group/t/cherenkov-photons-vs-cylindricalpet-vs-castor-with-tof-vs-castor-without-tof/69>\
**Category:** General Discussions\
**Created:** [July 24, 2018, 3:46pm UTC](https://castor-project.discourse.group/t/cherenkov-photons-vs-cylindricalpet-vs-castor-with-tof-vs-castor-without-tof/69 "2018-07-24T15:46:28Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![Dania\_Consuegra](https://avatars.discourse-cdn.com/v4/letter/d/cc9497/32.png) [@Dania\_Consuegra](https://castor-project.discourse.group/u/Dania_Consuegra)\
**Post date:** [July 24, 2018, 3:46pm UTC](https://castor-project.discourse.group/t/cherenkov-photons-vs-cylindricalpet-vs-castor-with-tof-vs-castor-without-tof/69/1 "2018-07-24T15:46:28Z")

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_Dear_ _CASToR_ _users,_

_I’m_ _getting nice_ _CASToR_ _reconstructions_ _for Cherenkov Photon PET_ _using as starting point my Gate simulation_ _output t\*\*hat use a_ _CylindricalPET_ _system…\*\*._

_I’m_ _interested in evaluate the influence of TOF in the reconstructed images._ _So, f\*\*or a same inicial Gate simulation output,_ _I would like to be able to compare between reconstructed images using_ _CASToR_ _with and without TOF…._

_How can I do that_ _?_

_So far what I could do for a same_ _Gate output_ _is compare the reconstruction using_ _CASToR_ _(without TOF) and the reconstruction using MLP (with TOF)…._

Any help I would really appreciate it….

Kind regards,

Dania Consuegra Rodríguez

_Phd student_ _ **Jožef Stefan Institute** _

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**Author:** ![STUTE\_Simon](https://avatars.discourse-cdn.com/v4/letter/s/b3f665/32.png) [@STUTE\_Simon](https://castor-project.discourse.group/u/STUTE_Simon)\
**Post date:** [July 25, 2018, 4:12pm UTC](https://castor-project.discourse.group/t/cherenkov-photons-vs-cylindricalpet-vs-castor-with-tof-vs-castor-without-tof/69/2 "2018-07-25T16:12:48Z")

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Hi,

You will have to modify the tool for GATE conversion to CASToR, in order to write the TOF information for each event.  
Page 33, you will find the specifications of a CASToR list-mode event, you will have to write the TOF information at the right position.

If you added a time blurring module in GATE, then you can directly write the difference in time arrival of the two singles.  
If you did not, you will have to add that stochastic time blurring for each of the two singles of each coincidence in the conversion tool.

Also as you simulate the cherenkov photons to make GATE singles, beware of what is the time actually written in the ROOT file (I do not know what GATE does); is it the first photon, the integration time of all photons, etc.

Best  
Simon