[Rtk-users] Isocenter question

[Solomon Tang]

Hi Simon,

Thanks for the quick reply. This solved the issue I was having. I simply
changed the offset value in the mhd file, created the projection and moved
the offset value of the final reconstruction back to its original value so
the world coordinates would be the same.

Just as a side question, do you know what the center of rotation values are
used for in mhd files? They're all 0 0 0 and I am not noticing any
differences when I change the values.

On Wed, Feb 3, 2016 at 10:14 PM, Simon Rit <simon.rit at creatis.insa-lyon.fr>
wrote:

> Hi,
> If you want to move a volume around space and keep the same geometry for
> the source and detector positions, the best is to modify the origin of your
> itk image. I don't know what is the original file format but with mhd
> files, you simply have to change the Offset value in the mhd file.
> Good luck,
> Simon
>
>
> On 04/02/2016 00:25, Solomon Tang wrote:
>
> Dear rtk-users,
>
> I am having success with forward projection and reconstruction of complete
> cases much like in the example from the wiki. However, I am interested in
> creating projections of cropped images. I took the 00.mha from the example
> and cropped it. When I create the projection, using rtkforwardprojections,
> the cropped projection rotates around the isocenter of the original
> uncropped file around the AP axis as expected.
>
> Is there a way to create a projection of a cropped image such that the
> cropped projection rotates around a newly centered AP axis?
>
> I am certain that the origin and spacing values of the geometry are
> correct. I have tried messing with the sid and the sdd values but they do
> not influence the distance between the isocenter and the cropped object.
>
> Thanks
>
>
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