title: Estimation of patient setup uncertainty using BrainLAB Exatrac X-Ray 6D system in image-guided radiotherapy.
abstract: The purpose of this study was to evaluate setup uncertainties for brain sites with ExacTrac X-Ray 6D system and to provide optimal margin guidelines. Fifteen patients with brain tumor were included in this study. Two X-ray images with ExacTrac X-Ray 6D system were used to verify patient position and tumor target localization before each treatment. The 6D fusion software first generates various sets of DRRs with position variations in both three translational and three rotational directions (six degrees of freedom) for the CT images. Setup variations (translation and rotation) after correction were recorded and corrected before treatment. The 3D deviations are expressed as mean ± standard deviation. The random error (Σ(σi)), systematic error (μi), and group systematic error (M(μi)) for the different X-ray were calculated using the definitions of van Herk.(1) Mean setup errors were calculated from X-ray images acquired after all fractions. There is moderate patient-to-patient variation in the vertical direction and small variations in systematic errors and magnitudes of random errors are smaller. The global systematic errors were measured to be less than 2.0 mm in each direction. Random component of all patients are smaller ranging from 0.1-0.3 mm small. The safety margin (SM) to the lateral, is 0.5 mm and 2.6 mm for van Herk(1) and Stroom et al.,(2) respectively, craniocaudal axis is 1.5 mm and 3.4 mm, respectively, and with respect to the antero-posterior axis, 2.3 mm and 3.9 mm. Daily X-ray imaging is essential to compare and assess the accuracy of treatment delivery to different anatomical locations.
authors.affiliation: Campus Bio-Medico University of Rome. e.infusino@unicampus.it.
authors.forename: Erminia
authors.initials: E
authors.lastname: Infusino
authors.forename: Lucio
authors.initials: L
authors.lastname: Trodella
authors.forename: Sara
authors.initials: S
authors.lastname: Ramella
authors.forename: Rolando M
authors.initials: RM
authors.lastname: D'Angelillo
authors.forename: Carlo
authors.initials: C
authors.lastname: Greco
authors.forename: Aurelia
authors.initials: A
authors.lastname: Iurato
authors.forename: Luca E
authors.initials: LE
authors.lastname: Trodella
authors.forename: Alessandro
authors.initials: A
authors.lastname: Nacca
authors.forename: Patrizia
authors.initials: P
authors.lastname: Cornacchione
authors.forename: Alessandra
authors.initials: A
authors.lastname: Mameli
mesh_terms: D001932:Brain Neoplasms / Q000601:surgery*; D003287:Contrast Media; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D056888:Patient Positioning; D016634:Radiosurgery; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D061106:Radiotherapy Setup Errors; D061089:Radiotherapy, Image-Guided; D014965:X-Rays
chemical_list: D003287:Contrast Media