Integrate field along particle trajectory

Hi all,
I have a file with 3D field map from OPERA-3D and I use them as a local field in my model in some volume. Class for this field is the same as field class in example purging_magnet. I need to get integrals of this field along particles trajectory.
I generate one particle in each event and about 1000 in each run. After a run, I want to have 1000 values of field integrals along particle trajectory.
Could anyone help me with that?
Thank you!