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Cranial fiducial markers are tiny objects placed under the skin on the head to mark an area for proton therapy. Markers are about the size of a grain of rice.
Children 12 and younger need markers because the bones of the head are not developed enough to give doctors a way to line up the radiation beams correctly for each treatment.
Proton therapy is a specific and targeted kind of radiation therapy. Fiducials mark the position of the beam. They help the radiation therapy staff place your child in exactly the right position on the treatment table each day. It may also mean less time on the table.
A surgeon places the markers. Your child will have 3–4 fiducials.
Your child will get sedation medicine. This will help them be comfortable during the procedure. Your child should not have anything to eat or drink beforehand. The nurse or surgery staff will give you instructions to prepare your child.
After making a small cut in the skin, the surgeon places the marker into the skull. Then, the cut is closed with adhesive or a stitch that will dissolve over time. The markers do not move after the surgery. You cannot see them from outside the skin.
If your child is having neurosurgery, the surgeon may place the markers at the same time.
The markers usually stay in place after your child finishes proton therapy. They do not cause problems with magnetic resonance imaging (MRI) or set off metal detectors. If they cause your child any discomfort, a doctor can remove them.
Reviewed: September 2022