Notwithstanding any other provision of this chapter, residential treatment centers shall be open to inspections by the Department to investigate and resolve any complaint concerning: Resident care; Safety; Medical and nursing supervision; Physical environment; Sanitation; or Dietary matters. Complaints. To expeditiously resolve a complaint that alleges the existence of any non-life-threatening deficiency, the Department may refer the complaint directly to the residential treatment center. If appropriate, issues relating to the practice of medicine or the licensure or conduct of a health professional may be referred to the residential treatment center and to the appropriate health occupation licensing board for resolution. If the Department determines that the center has not satisfactorily addressed the referred complaint or if the complaint alleges the existence of a potentially serious or life-threatening deficiency, the Department shall conduct an independent investigation. When conducting its independent investigation of an accredited residential treatment center, the Department shall use the standards of the accreditation organization that accredits the residential treatment center and this chapter.