[Castor-users] Problems with –im (involuntary patient motion correction)

[Chalampalakis, Zacharias]

Good afternoon Igne

Thank you for your email.
We actually just released a new version of CASToR ( V3.1 ) which fixed some bugs related to the handling of motion timestamps.

Maybe you could try with this version , if it is not too difficult , to check if the behaviour you experience is related to these bugs ?

In the latest version , the oDynamidDataManager will remove all timestamps that occur after the end of the last frame.
Normally the duration of the frame ( even when not specifying framing ) is set by the Start time (s) and Duration (s) entries in the datafile header.
Do you have these entries in your datafile header?

Kind Regards,
Zacharias Chalampalakis


From: Castor-users <castor-users-bounces at lists.castor-project.org> On Behalf Of Schagt, I.H. van der
Sent: Monday, September 21, 2020 4:33 PM
To: castor-users at lists.castor-project.org
Subject: [Castor-users] Problems with –im (involuntary patient motion correction)


Dear all,



I am having trouble with motion correction reconstruction when using the –im option. When I try to apply motion correction reconstruction I get the error:

Error, the 2th motion trigger timestamp: xxx occurs after the end of the last frame (frame 1, timestop: 0!
This error occurs in the code in the file oDynamicDataManager line 413 and arises incorrectly. When I do –im reconstruction in combination with 1 frame (so no framing), the time stop value of the frame remains 0s, it is not read from the data file. As a result, the time steps of the motion triggers are greater than the time stop value of the frame (line 407) and you will eventually get an error. When I manually adjust this time stop value to the correct value myself, this error message goes away, but I get incorrect reconstructed images. I only get black images after reconstruction where each voxel has NaN as its value. When I apply the same motion correction where I also divide the data into, for example, 2 frames (-frm…), I get correctly reconstructed images.


Does anyone of you know why the option –im gives these weird results, or what I maybe do wrong?
I use list-mode PET data with a total duration of 900 seconds. For the motion correction, I used three motion triggers (and deformations).



Thanks in advance!

Inge

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