[Rtk-users] rotating the detector around itself

[Simon Rit]

Hi,
With 9 degrees of freedom, you can define any position and orientation of
the source / detector with the current parametrization. What you are
showing is a different GantryAngle with a SourceOffset. It's not always
obvious how these should be set but there is a simpler solution: provide
the source position, detector position and coordinates of the two axes of
the detector:
http://www.openrtk.org/Doxygen/classrtk_1_1ThreeDCircularProjectionGeometry.html#a0fb1475ed76a28cde24fac85eae18e1e
I hope it helps,
Simon


On Wed, Jul 10, 2024 at 8:13 AM Nikolay Filatov <filatovna83 at gmail.com>
wrote:

> Hello RTK users. I've got a question about geometry. I want to rotate the
> detector for all orientations around itself and InPlaneAngle,
> OutOfPlaneAngle perform two rotations, but GantryAngle is not exactly what
> I need (https://imgur.com/a/kDpfk5G)
> Thanks to geometry invariant I can specify this angle through source_x,
> detector_x offset, but source_x affects InPlaneAngle and OutOfPlaneAngle.
> IMHO one of the possible solutions is to change RTK geometry final matrix -
> swap Mrotation and Mtranslation, so source_x shouldn't affect InPlaneAngle
> and OutOfPlaneAngle.
>
> Here
> rtkThreeDCircularProjectionGeometry.cxx
> void rtk::ThreeDCircularProjectionGeometry::AddProjectionInRadians(...)
> {
> ...
>   matrix = this->GetProjectionTranslationMatrices().back().GetVnlMatrix() *
>            this->GetMagnificationMatrices().back().GetVnlMatrix() *
>            this->GetSourceTranslationMatrices().back().GetVnlMatrix();
>            this->GetRotationMatrices().back().GetVnlMatrix();
> --->
>   matrix = this->GetProjectionTranslationMatrices().back().GetVnlMatrix() *
>            this->GetMagnificationMatrices().back().GetVnlMatrix() *
>            this->GetRotationMatrices().back().GetVnlMatrix();
>            this->GetSourceTranslationMatrices().back().GetVnlMatrix();
> ...
> }
> didn't give desired result.
>
> So, is it somehow possible to specify this angle along with InPlaneAngle,
> OutOfPlaneAngle ?
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