Feasibility of insertion/implantation of 2.0-mm-diameter gold internal fiducial markers for precise setup and real-time XXXX tracking in radiotherapy.

@entity1 @entity263 @entity66 @entity96 @entity5
PURPOSE: To examine the feasibility and reliability of insertion of internal fiducial markers into various organs for precise setup and real-time @entity5 tracking in radiotherapy (RT). MATERIALS AND METHODS: Equipment and techniques for the insertion of 2.0-mm-diameter gold markers into or near the @entity5 were developed for @entity66 , @entity263 , and @entity96 . Three markers were used to adjust the center of the mass of the target volume to the planned position in @entity263 (the three-marker method). The feasibility of the marker insertion and the stability of the position of markers were tested using stopping rules in the clinical protocol (i.e., the procedure was abandoned if 2 of 3 or 3 of 6 @entity1 experienced marker dropping or migration). After the evaluation of the feasibility, the stability of the marker positions was monitored in those @entity1 who entered the dose-escalation study. RESULTS: Each of the following was shown to be feasible: bronchoscopic insertion for the peripheral lung; image-guided transcutaneous insertion for the liver; cystoscopic and image-guided percutaneous insertion for the prostate; and surgical implantation for @entity66 . Transcutaneous insertion of markers for @entity66 and bronchoscopic insertion for central lung lesions were abandoned. Overall, marker implantation was successful and was used for real-time @entity5 tracking in RT in 90 (90%) of 100 lesions. No serious complications related to the marker insertion were noted for any of the 100 lesions. Using three markers surgically implanted into the vertebral bone, the mean +/- standard deviation in distance among the three markers was within 0.2 +/- 0.6 mm (range -1.4 to 0.8) through the treatment period of 30 days. The distance between the three markers gradually decreased during RT in five of six @entity263 , consistent with a mean rate of volume regression of 9.3% (range 0.015-13%) in 10 days. CONCLUSIONS: Internal 2.0-mm-diameter gold markers can be safely inserted into various organs for real-time @entity5 tracking in RT using the prescribed equipment and techniques. The three-marker method has been shown to be a useful technique for precise setup for @entity263 .
