Room: Exhibit Hall | Forum 3
Purpose: To present our initial experience with the recently released Calypso lung beacons to track lung tumor location during SBRT treatments.
Methods: Three recent lung SBRT patients had Calypso lung beacons implanted for tumor tracking during treatment. Beacons were placed by a pulmonologist using the Medtronics superDimension Fluroscopic Navigation system within a week of planning 4DCT acquisition. Patients were immobilized in a full-body double-vacuum bag. On the first day of treatment, a verification 4DCT was obtained with the patient in the treatment position to assess both the motion of the tumor and beacons relative to planning day, and any beacon migration or possible variation in individual beacon motion. For each treatment fraction, Calypso tracking data was used to position the patient. A verification CBCT confirmed the Calypso-defined target position was appropriate. Tracking information was compared to an action level of the tumor motion encompassed by the planning ITV plus the ITV-to-PTV margin.
Results: For two patients, the implant procedure was well-tolerated, while the third patient did develop a pneumothorax immediately post implant. This resolved by the time the planning CT was acquired but one beacon had migrated to be adjacent to another. This required one beacon to be deactivated in the Calypso software but tracking was still possible for all three patients. Cone-beam CT confirmed the appropriateness of Calypso-based positioning, and tracking showed that the tumor position never exceeded the action level.
Conclusion: All patients were successfully treated for SBRT using the newly released Calypso lung beacons. Initial positioning was confirmed by our current clinical standard of conebeam CT. The system also allowed us to validate, with real time confirmation, that the planned ITVâ€™s were appropriate to each dayâ€™s extent of actual tumor motion. An efficient and effective workflow for utilizing the new lung beacons for SBRT treatments was developed.