Hospitals may render bills for board and room accommodations, medical and surgical supplies and nursing facilities. Voluntary hospitals may bill for X-ray services when rendered by an X-ray laboratory or bureau of such hospital duly licensed by the chair. Hospitals may bill for physiotherapeutic, anesthesia and pathologic services when rendered by or under the supervision of salaried physicians on the staff. The names and qualifications of all physicians and persons rendering services for which charges are made by hospitals must be included in all bills, and all medical and X-ray reports shall be promptly filed with the board and with the employer or its insurance carrier.