Cal. Penal Code § 11171.5

(a) If a peace officer, in the course of an investigation of child abuse or neglect, has reasonable cause to believe that the child has been the victim of physical abuse, the officer may apply to a magistrate for an order directing that the victim be X-rayed without parental consent.
Any X-ray taken pursuant to this subdivision shall be administered by a physician and surgeon or dentist or their agents.
(b) With respect to the cost of an X-ray taken by the county coroner or at the request of the county coroner in suspected child abuse or neglect cases, the county may charge the parent or legal guardian of the child-victim the costs incurred by the county for the X-ray.
(c) No person who administers an X-ray pursuant to this section shall be entitled to reimbursement from the county for any administrative cost that exceeds 5 percent of the cost of the X-ray.