Her2 and whole brain radiation

My wife has multi brain mast. We are getting two conflicting stories on whether Her2 tumors respond to this treatment. Two radioligists say that Her2 tumors are resistant to whole brain because they cannot hit the tumors with enough energy to kill Her2 cells. The other says there are no studies that breakdown effectiveness with Her2 vs other tumors. Also, what side effects can we expect to see? My wife is a teacher and wants to conyinue to work.