Significance of positional correction of planned couch angles with the ExacTrac system

This study evaluated the benefits of the ExacTrac system for non-coplanar beams in brain stereotactic radiotherapy (SRT) by comparing pre- and post-X-ray verification (XV) positioning data. Data from 62 patients undergoing brain SRT were analyzed, focusing on 151 non-coplanar beams. Patient positioning involved initial infrared marker alignment, followed by ExacTrac kV x-ray acquisition and 6D robotic couch adjustments. Patient positioning was corrected within a tolerance of 0.5 mm and 0.5° for translation and rotation, respectively. Pre and post-XV positioning data were compared at each planned couch angle. Results showed that 54% of non-coplanar beams had positioning errors exceeding the specified tolerances on the pre-XV. Significant differences were observed in translational and rotational corrections between pre- and post-XV positioning at each planned couch angle. These results demonstrate that XV at any each planned couch angle using the ExacTrac system significantly improves patient positioning accuracy in brain SRT.