TOMOTHERAPY RADIOSURGERY FOR TRIGEMINAL NEURALGIA: A TECHNICAL PERSPECTIVE

摘要

We present the technical parameters used in this first application of TomoTherapy for the treatment of Trigeminal Neuralgia. A total of seven patients were treated between November 2007 and October 2011. Treatments were delivered to the trigeminal nerve root, and a 2 mm margin, in a single fraction of 30 or 35 Gy. TomoTherapy megavolt-age GT imaging prior to treatment was carried out with a new 1 mm imaging collimator configuration, effectively doubling the best resolution previously available. Treatments were carried out using the 1 cm collimator yielding pencil beams of 0.64x1.0 cm. The pitch used varied from 0.05-0.10. The total beam-on time for the treatments varied from a high of 63.7 minutes for the earlier software versions to a low of 26.5 minutes for version 4. The minimum dose to 95% of the target ranged from 28.3-36.1 Gy while the mean target dose ranged 31.2-42.0 Gy. The mean dose to the brainstem was 1.01-1.55 Gy and the maximum dose to a volume of 0.02 cc ranged from 7.3-12.3 Gy. The results indicate that TomoTherapy can be configured for use in the treatment of TGN with acceptable dose to the target and to sensitive organs.