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

Abstract

ObjectivesStereotactic body radiotherapy (SBRT) is being increasingly used for the treatment of patients with lung cancer or lung metastasis who are medically unfit to undergo resection. In order to improve accuracy and confidence in targeting tumors, 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).MethodsWe retrospectively quantified the individual and group migrations of SuperLock nitinol coil fiducials for 15 patients receiving lung stereotactic body radiotherapy (SBRT), in order to evaluate the reliability of using these fiducials as a target surrogate for cases where tumors 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.ResultsA total of 16 lung targets were included in our study for these 15 patients (one patient 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.ConclusionsWe found that the SuperLock nitinol 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.

Fiducial marker placement with electromagnetic navigation bronchoscopy: a subgroup analysis of the prospective, multicenter NAVIGATE study

“…The authors also observed minimal interfractional fiducial migration during the course of radiation treatment. 27 In another study, the VortX coil FM had a retention rate of 96.7% (from pretreatment radiation planning CT scan to the first day of therapy) compared to two-band (72%) and the gold-seed (69%) markers. 19 The VortX FM was the second most common marker utilized in the NAVIGATE study.…”

Prospective evaluation of fiducial marker placement quality and toxicity in liver CyberKnife stereotactic body radiotherapy

“…Oldrini et al [ 21 ] evaluated the imaging technique for fiducial placement and concluded that ultrasound-guided placement is equivalent to CT guided placement. Rong et al [ 24 ] evaluated the migration parameters after placement. Choi et al [ 25 ] evaluated the safety and technical feasibility of endoscopic ultrasonography (EUS)-guided fiducial placement.…”

Endobronchial treatment of peripheral tumors: ongoing development and perspectives

“…The place to insert (within or around the tumor), and the number of fiducial markers (1 to 3 or more) to insert is not well established. The migration rate of some markers is very low (21).…”