A pivot table consists of COLUMN, ROW, DATA and PAGE. I have dropped a
field called Department in the PAGE section. Can I give userlevel
access to only that dropdown box?

For example I have around 15 departments in the pivot table. If windows
user maxim logs in, he should be allowed to select all departments from
that dropdown box but if somebody else logs in (any other windows user
besides maxim), that person can access only two departments.