Multisession Cyberknife Surgery for Parasellar Tumors Adjacent to Optic Apparatus; Safety for Optic Apparatus: Preliminary Study

초록

INTRODUCTION: Multisession Cyberknife surgery has been known as a good alternative in the parasellar tumors adjacent to optic apparatus. In order to use it more broadly and safely, exact optic apparatus tolerance dose should be obtained. We performed this study to get safe multisession schedule for these lesions. METHODS: Nine patients with pituitary adenoma (n=2), metastatic brain tumor (n=2), meningioma (n=2), craniopharyngioma (n=1) and nasal cavity cancer (n=1), which had been situated within 3 mm of optic apparatus, underwent multisession Cyberknife surgery. Cyberknife radiosurgery was delivered in four to six sessions and cumulative average marginal dose was 2400cGy to 3500cGy. Contouring and measuring volume of optic apparatus had been based on the MRI. We measured cumulative dose on the optic apparatus. Formal visual testing or clinical examinations were performed before treatment and about 6 months later after treatment. RESULTS: Cumulative maximal dose on the optic apparatus were under about 2500cGy in all patients. Single maximal dose had been kept below about 500cGy. There were no acute complications. Six months after treatment, visual functions had not been changed in five cases and improved in four cases. CONCLUSION: : If cumulative maximal dose was kept below about 2500cGy and single session dose below about 500cGy on the optic apparatus, we can do safely multisession Cyberknife surgery for parasellar tumors adjacent to optic apparatus. KEYWORDS: Cyberknife, Optic nerve, Optic chiasm, Radiosurgery