How is initial alignment offset stored with respect to the images and the structures

[Silvia]

Dear Deshan, dear readers,

We have been doing some registration error analysis on DIR results from the command line and realized that we are not sure which frame of reference is used for the images and structures in the data sets.

We load two CT images (cropped with CERR) that each have a structure set, align the images, and perform DIR. The images together with the structures and the registration results are stored in a project. The images seem to be stored in their original frame of reference, with the offset stored in a separate field. However, the structure sets seem to have been stored with the offset included. We would like to perform calculations, via the Matlab command line or m-files, on the images and on the structures using the DVF and IDVF, in the correct frame of reference.

These are our questions:

-       Does the DVF include the initial image offset, or does this need to be applied separately?

-       How can we apply the offset to the images via the Matlab command line?

-       How do we correctly apply the DVF or IDVF to the images and structures?

It would be very helpful if someone can help us, or can refer us to the specific DIRART mfiles that may provide us with the answers.

Kind regards,

Silvia