Castor-users Digest, Vol 36, Issue 13

Hello Thibaut,

You are totally right, I enabled CASToR_BUILD_SAMPLE_UTILITIES in Cmake and that worked. I can now build the projects and do reconstructions.

Lastly, I noticed one more thing. When I reconstruct images with the -im option and I use attenuation correction, the attenuation map doesn’t move along with the deformations, while this was the case for the -rm option (respiratory motion).

Is this the intention and/or is it possible to let the attenuation map move along with the deformations?

Above all, many thanks for your help!


Hi Inge,

I am not sure about what you mean by moving along the deformations.

  • With involuntary patient motion (-im), a sensitivity image is computed for each subset of data between motion triggers. If an attenuation image is provided, it is transformed using the “forward” deformation parameters. They are then transformed back to the reference position, and receive the proper weighing before being merged together (finally you get one sensitivity image by frame, or just one image if you don’t have any frame).

  • The process is similar with motion correction for gating. One sensitivity image is computed for each set of transformation parameters (i.e, each gate), then they are deformed back into the reference position and merged together.

During reconstruction, these sensitivity images are always used on images transformed back in the reference position.

I hope this helps to clarify the process.