# How to use rtkCudaIterativeFDKConeBeamReconstructionFilter and rtkParkerShortScanImageFilter together

**URL:** <https://discourse.itk.org/t/how-to-use-rtkcudaiterativefdkconebeamreconstructionfilter-and-rtkparkershortscanimagefilter-together/6367>\
**Category:** Engineering\
**Created:** [December 19, 2023, 6:56am UTC](https://discourse.itk.org/t/how-to-use-rtkcudaiterativefdkconebeamreconstructionfilter-and-rtkparkershortscanimagefilter-together/6367 "2023-12-19T06:56:26Z")\
**Posts on this page:** 7\
**Page:** 1

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**Author:** ![ma1282029525](https://discourse.itk.org/user_avatar/discourse.itk.org/ma1282029525/32/3084_2.png) [@ma1282029525](https://discourse.itk.org/u/ma1282029525)\
**Post date:** [December 19, 2023, 6:56am UTC](https://discourse.itk.org/t/how-to-use-rtkcudaiterativefdkconebeamreconstructionfilter-and-rtkparkershortscanimagefilter-together/6367/1 "2023-12-19T06:56:26Z")

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How to use rtkCudaIterativeFDKConeBeamReconstructionFilter and rtkParkerShortScanImageFilter together

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**Author:** ![ma1282029525](https://discourse.itk.org/user_avatar/discourse.itk.org/ma1282029525/32/3084_2.png) [@ma1282029525](https://discourse.itk.org/u/ma1282029525)\
**Post date:** [December 19, 2023, 7:40am UTC](https://discourse.itk.org/t/how-to-use-rtkcudaiterativefdkconebeamreconstructionfilter-and-rtkparkershortscanimagefilter-together/6367/2 "2023-12-19T07:40:01Z")

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I don not find the SetAngularGapThreshold interface。

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**Author:** ![ma1282029525](https://discourse.itk.org/user_avatar/discourse.itk.org/ma1282029525/32/3084_2.png) [@ma1282029525](https://discourse.itk.org/u/ma1282029525)\
**Post date:** [December 19, 2023, 8:37am UTC](https://discourse.itk.org/t/how-to-use-rtkcudaiterativefdkconebeamreconstructionfilter-and-rtkparkershortscanimagefilter-together/6367/3 "2023-12-19T08:37:41Z")

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When I modified the source code and added SetAngularGapThreshold, it didn’t work。

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**Author:** ![dzenanz](https://discourse.itk.org/user_avatar/discourse.itk.org/dzenanz/32/1093_2.png) [@dzenanz](https://discourse.itk.org/u/dzenanz)\
**Post date:** [December 19, 2023, 2:55pm UTC](https://discourse.itk.org/t/how-to-use-rtkcudaiterativefdkconebeamreconstructionfilter-and-rtkparkershortscanimagefilter-together/6367/4 "2023-12-19T14:55:19Z")

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@simon.rit and @LucasGandel might answer this.

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**Author:** ![simon.rit](https://discourse.itk.org/letter_avatar_proxy/v4/letter/s/f08c70/32.png) [@simon.rit](https://discourse.itk.org/u/simon.rit)\
**Post date:** [December 19, 2023, 8:43pm UTC](https://discourse.itk.org/t/how-to-use-rtkcudaiterativefdkconebeamreconstructionfilter-and-rtkparkershortscanimagefilter-together/6367/5 "2023-12-19T20:43:10Z")

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rtkCudaIterativeFDKConeBeamReconstructionFilter is rtkIterativeFDKConeBeamReconstructionFilter with the Cuda implementation of FDK. If you look at the [documentation of rtkIterativeFDKConeBeamReconstructionFilter](http://www.openrtk.org/Doxygen/classrtk_1_1IterativeFDKConeBeamReconstructionFilter.html), it’s already implemented. So there is nothing to do, it’s already there, i.e., it will detect a short scan and implement it. However, there is no SetAngularGapThreshold so you will need to add it to rtkIterativeFDKConeBeamReconstructionFilter if you want to pass it to Parker.

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**Author:** ![ma1282029525](https://discourse.itk.org/user_avatar/discourse.itk.org/ma1282029525/32/3084_2.png) [@ma1282029525](https://discourse.itk.org/u/ma1282029525)\
**Post date:** [December 27, 2023, 1:10am UTC](https://discourse.itk.org/t/how-to-use-rtkcudaiterativefdkconebeamreconstructionfilter-and-rtkparkershortscanimagefilter-together/6367/6 "2023-12-27T01:10:05Z")

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But my data can be reconstructed correctly using FDKConeBeamReconstructionFilter with SetAngularGapThreshold, but it cannot be reconstructed using only rtkCudaIterativeFDKConeBeamReconstructionFilter

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**Author:** ![simon.rit](https://discourse.itk.org/letter_avatar_proxy/v4/letter/s/f08c70/32.png) [@simon.rit](https://discourse.itk.org/u/simon.rit)\
**Post date:** [December 29, 2023, 11:15am UTC](https://discourse.itk.org/t/how-to-use-rtkcudaiterativefdkconebeamreconstructionfilter-and-rtkparkershortscanimagefilter-together/6367/7 "2023-12-29T11:15:58Z")

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If you need to change the default value of AngularGapThreshold of m\_ParkerFilter, you need to add a setter for m\_ to rtkIterativeFDKConeBeamReconstructionFilter. A similar thing is done for [HannCutFrequency](http://www.openrtk.org/Doxygen/classrtk_1_1IterativeFDKConeBeamReconstructionFilter.html#a19bc4660369a644918d0157a13fe2732) of m\_FDKFilter.