Sec. 1. (a) As used in this chapter, "administrator" means a person who is the administrative head of a hospital, a sanitarium, an institution, an agency, or an instrumentality:
(1) maintained or provided by the United States or an agency or instrumentality of the United States; and
(2) where mental illnesses or developmental disabilities are treated.
(b) The term, for purposes of this chapter and a court order, includes successors in office.