Investigating the Visibility of Three Types of Surgical Clips as Fiducial Markers in a Breast Phantom

To facilitate online setup correction in breast radiotherapy, we studied the visibility of three types of surgical clips of differing materials using three different image verification methods. Titanium, tantalum and stainless steel clips of identical size were embedded in various orientations in the breast attachments of a tissue-equivalent phantom. Clip visibility was assessed for isocentric megavoltage, isocentric kilovoltage, and floor-mounted kilovoltage imaging. Based upon this phantom study, titanium clips are recommended for isocentric kilovoltage verification imaging, and tantalum clips are recommended for isocentric megavoltage and floor-mounted kilovoltage verification imaging.