Spatial accuracy of the stereotactic Leksell^® Vantage™ head frame in comparison with the standard stereotactic Leksell^® G Frame for Gamma-Knife

Abstract

Purpose: Since January 2021, the Leksell® Vantage head frame (V-frame) is used for Gamma Knife® treatments in addition to the historical Leksell® G-Frame known as the reference. The aim of this study was to compare the spatial accuracy of treatments with these two frames. Methods: Firstly, the constancy of the geometric accuracy of the system according to the Elekta quality assurance process was carried out during sixteen months with V and G–frames’ adaptors. Then, End-to-end test was carried out with both V and G-frame using an anthropomorphic phantom and Gafchromic® films. The overall precision of the radiation center was calculated as the displacement vector for a 4mm collimator shot. Additionally, the Cone Beam Computed Tomography (CBCT) positioning system was used to assess the precision of the Leksell coordinates system defined by V-frames on 64 patients in comparison with G-frames for 46 patients. To ensure that patient’s head movement was not possible during treatment with the V-frame, a final CBCT was performed at the end of the irradiation. Results: The QA constructor’s tests done with the G-frame and V-frame adaptor gave similar results over sixteen months. End-to-end tests demonstrated that the mean positioning accuracy were 0.54mm (SD of 0.14mm) and 0.70mm (SD of 0.14mm) with V-frame and G-frame respectively. The displacement vector given by CBCT ranged from 0.02 to 1.05mm with a mean value of 0.38mm (SD of 0.18mm) for the 64 V-framed patients and from 0 to 0.92mm with a mean value of 0.31 mm (SD of 0.18mm) for the 46 G-framed patients. The mean translation movement between the beginning and the end of the 64 treatments with V-frame was 0.08mm (SD of 0.04mm, maximum value of 0.19mm). Conclusion: We estimated that V-frames are as precise as G-frames with a targeting accuracy of less than 1mm.