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SU‐E‐T‐580: Study of the Positioning Accuracy of the BrainLab Mask for Frameless Stereotactic Head Radiotherapy Using the ExacTrac IGRT System
Author(s) -
Granero D,
Rosello J,
Vicedo A,
Brualla L,
GarciaHernandez T
Publication year - 2011
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.3612542
Subject(s) - image guided radiation therapy , radiosurgery , nuclear medicine , computer science , standard deviation , stereotactic radiotherapy , medical imaging , medicine , medical physics , mathematics , artificial intelligence , radiation therapy , radiology , statistics
Purpose: In our institution we perform frameless fractionated stereotactic. The accuracy of this treatment is highly dependent on patient positioning and immobilization. For the patient position we use the target positioner overlays and for the setup verification, the BrainLab ExacTrac X‐Ray image guided system. The aim of this study is to analyse, in a set of patients, the corrections given by the image guided system in order to obtain an estimation of the positioning accuracy achievable with our system. Methods: We use the BrainLab frameless mask system for stereotactic procedures. The patient is treated using a Siemens Mevatron Primus accelerator with the micro multileaf m3 of BrainLab. The setup of the patient is done using target positioner overlays obtained from the treatment planning system Bscan 5.31. The whole system setup is verified using the ExacTrac X‐Ray image guided system (IGRT).The displacements and angles given by the ExacTrac are analysed. Results: The mean shifts, rotations, and standard deviations were determined, as a measure of the systemˈs accuracy. Average translations measured were 0.4 ± 0.7 mm, −0.9 ±1.1 mm and 0.6 ± 0.6 mm, respectively, for vertical, longitudinal and lateral directions. The mean deviations take place in the longitudinal direction and usually in the same sense of direction. Conclusions: The system specifications (2 mm in all directions) are fulfilled in most of the analysed cases, however some special patients (those with orientation problems which no cooperate) present important deviations in the longitudinal direction up to 8 mm. Professionals must be aware in these cases, and should use an IGRT verification system.