Fiducial Marker

**Semantic type:** Medical Device

**Definition:** A medical device placed on or inserted in an anatomic site for accurate visualization of a particular area, prior to radiation treatment or surgery. Examples include markers inserted in the prostate gland for visualization of the site affected by cancer, prior to radiation therapy; markers taped to the scalp prior to imaging in frameless stereotactic brain surgery; and femoral and tibial pins used for spatial orientation in total knee replacement.

**Synonyms:** - FID - Fiduciary Marker - Spatial Fiducials