Measurement of repositioning accuracy during fractionated stereotactic radiotherapy for intracranial tumors using noninvasive fixation of BrainLAB radiotherapy equipment

Purpose: A noninvasive fixation mask device is used for stereotactic radiotherapy (SRT) in our hospital. Fractionated SRT is useful because it results in less damage to normal tissues, for which the positioning accuracy of the removable noninvasive fixation device is important. We examined the repositioning accuracy of a BrainLAB removable noninvasive fixation device on the coordinates of computed tomography (CT) for treatment planning. Methods and Materials: The subjects were 13 patients who had undergone head SRT. The removable noninvasive fixation mask device used was a noninvasive fixation device for the BrainLAB system. The accuracy of the irradiation apparatus was evaluated using Winston-Lutz test film, and the repositioning accuracy of the fixation device was examined using differences in the distance on the X, Y, and Z coordinates between the treatment planning and repositioning times determined by comparing the relative coordinates. The evaluation was performed using the relative coordinates of the standard and test points. Results: The accuracy of the irradiation center with the apparatus was within 0.5 mm. In the 13 patients, the difference in the distance between the treatment planning and repositioning procedures ranged from 0.1 to 2.080 mm, and an accuracy of within 2 mm was obtained in 84.6% of the patients using the fixation device. Conclusion: The BrainLAB noninvasive SRT fixation device was considered useful for routine treatment with high accuracy.