The procedures involve placement of a stereotactic frame on the patient's skull, localization of the target coordinates with an imaging modality, treatment planning, and finally the treatment delivery. There are two advantages of the stereotactic radiosurgery technique: its submillimeter geometrical accuracy of the treatment delivery system and high conformity with steep dose gradients. Various stereotactic radiosurgery techniques have been developed and clinically used. These include gamma knife surgery, LINAC-based stereotactic radiosurgery, frameless stereotactic radiosurgery (Cyberknife), and charged-particle accelerators such as proton beam stereotactic radiosurgery.4
To deliver a precise target dose by means of stereotactic radiosurgery, comprehensive quality assurance is essential. The total spatial error is accumulated through the processes of target localization using medical imaging, image fusion, dose planning, mechanical errors, patient positioning, intraoperative movements, target positioning overlays, and radiation dose delivery system. There are numerous publications in which the spatial accuracy and quality assurance of the gamma knife unit7 and LINAC stereotactic radiosurgery systems have been assessed.3,9,10,12
The purpose of this study was to assess the geometrical accuracy of BrainLAB's Novalis system (BrainLAB, Heimstetten, Germany) in the treatment of trigeminal neuralgia. To measure the geometrical accuracy and the Novalis system in treating trigeminal neuralgia, we performed a simulation of the whole procedure. Novalis is a dedicated LINAC radiosurgery system with stringent isocentricity standards. The system has a maximum field size of 10 × 10 cm2 and is equipped with a micromultileaf collimator. The leaf width of the micromultileaf collimator is 3, 4.5, and 5.5 mm, respectively. In addition, cones of various sizes ranging from 4 to 20 mm can be attached to the gantry. The planned radiation dose is delivered using multiple arcs converged at the isocenter by means of either cones or a micromultileaf collimator. In addition, conformal static beams, intensity-modulated radiosurgery planning, and dose delivery are available.