Résumé
Objective To study the setup accuracy and other factors during frameless stereotactic radiosurgery (SRS) of intracraial tumor using ExacTrac X-ray image guide system.Methods Totally 119 intracranial tumor patients from August 2014 to February 2016 underwent auto setup with infrared marker.Bilateral oblique cross field images were obtained with ExacTrac X-ray system,and went through comparison,registration and correction with the digitally reconstructed ones of the planning system.Then the translation accuracy errors at LAT,LNG and VRT directions and corresponding rotational accuracy errors were acquired,and the errors experienced extended analysis.Results The translation errors at LAT,LNG and VRT directions acquired with ExacTrac X-ray image guidance system and 6DOF couch were (0.16±0.13) mm,(0.17±0.14) mm and (0.15±0.11) mm respectively,the corresponding rotational errors were (0.21±0.15),(0.18±0.15),(0.18±0.14)° respectively,and the vector error was (0.32±0.16) mm.All of 3 translation and 3 rotational errors were in the SRS error range.Conclusion ExacTrac X-ray image guidance system combined with 6 degrees-of-freedom couch increases the treatment accuracy during frameless SRS,and thus is worthy promoting practically.