Brenda,
Hi

It might help him relax if he works out a sign system with the radiation technicians to stop the treatment and take him out of his mask if that's what he needs.

When I bad mucous towards the end of treatment, the technicians said that all i had to do was raise my right arm off the table and they would interrupt the treatment, come into the room and get me upright. They also rushed in once the treatment was over to get me out of a horizontal position as quickly as possible.
Hang in there. - Sheldon