The Food and Drug Administration (FDA) is classifying the phase-changing fiducial marker for radiation therapy into class II (special controls). Interference with image-guided radiation therapy or radiotherapy response assessment Clinical performance testing; Non-clinical performance testing; and Labeling. Treatment delays due to device malfunction, marker migration, or inability to locate marker on imaging Clinical performance testing; Non-clinical performance testing; and Labeling. Inaccurate radiation dose delivery due to incorrect marker positioning, marker migration, or implantation Clinical performance testing; Non-clinical performance testing; Usability testing; and Labeling. Complications due to implantation of marker or marker migration Clinical performance testing; Animal performance testing; and Labeling.