[Rtk-users] Lateral blur in a FDK reconstructed volume

[Jasper Albertus Nijkamp]

Hi Vincent,

From just these two images, it is a bit hard to help. However, I have seen similar challenges when the detector vertical offset is not properly set. If you could share a bit more data (fx projection data and the geometry), more people might be able to help.

Jasper

-----Original Message-----
From: Rtk-users <rtk-users-bounces at public.kitware.com> On Behalf Of Vincent Libertiaux
Sent: Friday, 15 April 2022 17:15
To: rtk-users <rtk-users at public.kitware.com>
Cc: Damien Koch <dk at xris.eu>
Subject: [Rtk-users] Lateral blur in a FDK reconstructed volume

Hello rtk users !

I am facing a problem for which I have exhausted all the possibilities except asking you.
I have performed a standard FDK reconstruction of a lego bricks assembly.  I used a custom-made code to compute the detector horizontal offset and tilt angle, found to be 1.15 mm and 0.02° respectively.  The result of the reconstruction is shown in the picture
https://ibb.co/LdMzJF2 .  The volume looks mostly sharp, except on the lateral edges, let's say on the last half brick.

We had the opportunity to have the same volume reconstructed with two commercial solutions.  The first one, "A", produced the same results than rtk.  The second, "B", produced the result shown in the picture https://ibb.co/VwXMmRH

In this case, the edges are sharp too.  The offset values found with this software were very close (1.13mm and 0.025° respectively) and feeding them to rtksimulatedgeometry didn't change my result.  No other correction was allegedly applied.

I thought that the edge blurring was due to a wobbling artefact but it can't be the case according to the result with the "B" software.

Do you have any idea on what could cause this blurring on the edges ?

I thank you very much for any clue.

Best regards,

Vincent

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