The purpose of the CT-Adapter is to position and secure the patient in the correct position in the CT scanner, and to ensure that the position is accurately reproducible in subsequent scans. CT Table Fixation needs to be ordered separately. The adapter is fitted to the CT Table Fixation, which is fitted to the table of the scanner in place of the headrest. When the coordinate frame is fitted into the adapter, it is held in an exactly perpendicular position to the gantry of the scanner, so that captured CT images are parallel to the plane of the coordinate frame. This optimizes the precision of the fiducial markers which are imposed on the CT images. It also ensures repeatability, so that scans can be superimposed on each other and images can be compared in the scan study. The adapter is specifically designed to hold the frame, and thus the skull of the patient, firmly in place. However, it does allow the frame to be detached in the event of emergency. If for this or any other reason the scan is interrupted, the adapter permits the frame to be relocated in the same position.

The CT Adapter attaches to the bed of the CT scanner by means of an appropriate CT table fixation. A range of table fixations is available from Elekta to fit most CT scanners.