Initial clinical experience with frameless stereotactic radiosurgery: Analysis of accuracy and feasibility

Purpose: To report on preliminary clinical experience with a novel image-gu ided frameless stereotactic radiosurgery system. Methods and Materials: Fifteen patients ranging in age from 14 to 81 receiv ed radiosurgery using a commercially available frameless stereotactic radio surgery system. Pathologic diagnoses included metastases (12), recurrent pr imary intracranial sarcoma (1), recurrent central nervous system (CNS) lymp homa (1), and medulloblastoma with supratentorial seeding (1). Treatment ac curacy was assessed from image localization of the stereotactic reference a rray and reproducibility of biteplate reseating. We chose 0.3 min vector tr anslation error and 0.3 degree rotation about each axis as the maximum tole rated misalignment before treating each are. Results: The biteplates were found on average to reseat with a reproducibil ity of 0.24 mm. The mean registration error From CT localization was found to be 0.5 mm, which predicts that the average error at isocenter was 0.82 m m. No patient treatment was delivered beyond the maximum tolerated misalign ment. The radiosurgery treatment was delivered in approximately 25 min per patient. Conclusion: Our initial clinical experience with stereotactic radiotherapy using the infrared camera guidance system was promising, demonstrating clin ical feasibility and accuracy comparable to many frame-based systems. (C) 2 001 Elsevier Science Inc.