Each regional human service center must be headed by a regional director appointed by the commissioner of the department. The regional director must be accountable to the commissioner of the department or the commissioner’s designee. Each regional director may employ the staff necessary to discharge the center’s responsibilities. A regional director, subject to the approval of the commissioner of the department or the commissioner’s designee, and within the limit of legislative appropriations, may make contractual arrangements with public or private agencies or with individuals and organizations to discharge the regional human service center’s service delivery responsibilities. Each regional director shall hire a qualified medical professional who must be designated as the medical director of the center. The medical director is responsible for coordinating mental health and medically related services. The medical director’s position may be part time or full time as determined appropriate by the regional director, with the concurrence of the commissioner of the department or the commissioner’s designee. As used in this section, “qualified medical professional” means a board-eligible or board-certified psychiatrist, when such an individual can be employed, and when this is not possible, an individual possessing at least a medical degree.