Minimal Inter-Fractional Fiducial Migration during Image-Guided Lung Stereotactic Body Radiotherapy Using SuperLock XXXX Coil Fiducial Markers.

@entity1 @entity5 @entity2 @entity3 @entity5648
OBJECTIVES: Stereotactic body radiotherapy (SBRT) is being increasingly used for the treatment of @entity1 with @entity2 or lung @entity3 who are medically unfit to undergo resection. In order to improve accuracy and confidence in targeting @entity5 , many centers rely on fiducial implantation. We evaluated the migration of a novel fiducial marker specifically designed for lung tissue implanted via electromagnetic navigation bronchoscopy (ENB). METHODS: We retrospectively quantified the individual and group migrations of SuperLock @entity5648 coil fiducials for 15 @entity1 receiving lung stereotactic body radiotherapy (SBRT), in order to evaluate the reliability of using these fiducials as a target surrogate for cases where @entity5 cannot be clearly delineated on cone beam CTs (CBCTs). For each fraction, we compared the individual and group migrations of the fiducials between the planning CT and the acquired CBCT. The group migration was defined as the distance between the centroids of the fiducial group and GTV. RESULTS: A total of 16 lung targets were included in our study for these 15 @entity1 (one @entity1 with two targets). Of 55 fiducials placed, we observed a 100% retention rate. The mean individual migration was 1.87 mm (range, 0.63-5.25 mm) with a standard deviation of 1.26 mm. The mean group migration was 1.94 mm (range, 0.03-6.19 mm) with a standard deviation of 1.45 mm. Overall, there was minimal change in the relative locations of the markers with respect to each other, as well as to the target. CONCLUSIONS: We found that the SuperLock @entity5648 coil fiducial marker positions are stable throughout the radiation treatment, and can be used as a reliable surrogate to target, and to avoid geometric misses during gated treatments.
