The difference in dose in the presence and absence of a magnetic field

hello guys;
I’m trying to calculate the dose difference in presence and absence of magnetic field but I don’t know how can I implement it in my class (D (3Tesla) -D (0Tesla)). Can anybody help me ?

Hi, I would run two different simulations and calculate the difference in post-processing.

Thank you @guatelli for your reply. Yes I have already calculate it using two field values after I processed the data with root.