“Real-time tumor-tracking radiotherapy with SyncTraX for primary liver tumors requiring isocenter shift”
Abstract (extract): The SyncTraX series enables real-time tumor-tracking radiotherapy through the real-time recognition of a fiducial marker using fluoroscopic images. In this system, the isocenter should be located within approximately 5–7.5 cm from the marker, depending on the version, owing to the limited field of view. If the marker is placed away from the tumor, the isocenter should be shifted toward the marker. This study aimed to investigate stereotactic body radiotherapy (SBRT) outcomes of primary liver tumors treated with SyncTraX in cases where the isocenter was shifted marginally or outside the planning target volume (PTV). Twelve patients with 13 liver tumors were included in the analysis. Their isocenter was shifted toward the marker and was placed marginally or outside the PTV.
Materials and Methods (extract): A 2-mm-diameter, spherical, pure gold marker (Medikit, Tokyo, Japan) or 0.4×20mm Gold Anchor (Naslund Medical AB, Huddinge, Sweden) was used as the fiducial marker.
Conclusion (extract): An isocenter shift enabled all patients to complete their scheduled SBRT using the SyncTraX series, even in patients where the fiducial marker was distant from the tumor. Furthermore, the treatment outcomes in these patients are comparable to those reported in previous studies. These results suggest that SBRT using the SyncTraX series is feasible when the isocenter is marginal to or outside the PTV.